United States

Department of

Agriculture

Animal and

Plant Health

Inspection Service

Veterinary

Services

National

Animal Health

Monitoring

System

May 2010

Dairy 2007

Biosecurity Practices on U.S. Dairy Operations,

1991-2007
USDA APHIS VS / i

Items of Note Items of Note

Dairy 2007 marks the fourth time that the National Animal Health Monitoring System has conducted

a national study of the U.S. dairy industry. This report contains the latest information on the

biosecurity practices used on U.S. dairies and, when possible, provides comparisons of these

practices over time.

Preventing and reducing the presence of disease on dairy operations is important and often difficult.

Biosecurity and biocontainment practices can significantly reduce the risk of introducing or

spreading diseases. Biosecurity is a system of management practices used to prevent the entry of

disease-causing agents. Biocontainment is a system of management practices used to prevent the

spread of disease between groups of animals on an operation. Sources of potential disease include

the introduction of cattle from outside sources and contact with other animals, employees, visitors,

vehicles, or equipment.

Disease familiarity The implementation of biosecurity and biocontainment practices aimed at a specific disease requires

that producers have a basic knowledge of the disease or consult with a veterinarian to design an

appropriate disease-prevention system. In 2002 and 2007, most producers were fairly

knowledgeable or knew some basics about foot-and-mouth disease, BSE, Johne’s disease, and

Mycoplasma mastitis; however, the majority of producers were unfamiliar with heartwater,

screwworm, bluetongue, vesicular stomatitis, and hemorrhagic bowel syndrome.

Information

sources

In 2002 and 2007, most producers indicated that they would use their private veterinarian for

disease information if a foreign animal disease occurred in the United States. Similarly, most

producers would contact their veterinarian if they suspected that a foreign animal disease was on

their operation. The fact that producers would first turn to their veterinarian in the case of a foreign

animal disease occurrence highlights the continuing need to educate veterinary practitioners on

foreign animal diseases and provide training on how to handle animals suspected of having a foreign

animal disease.
ii / Dairy 2007

New additions From 1996 to 2007, approximately one of four operations brought any cattle onto the operation

from outside sources. Biosecurity practices that can reduce the risk of new cattle introducing disease

to an operation include having knowledge of the disease status of the source operation, testing new

cattle for specific diseases before or immediately after arrival, implementing a quarantine period,

and vaccinating for specific diseases. Of operations that introduced new cattle to their operation in

2007, 47.2 percent required vaccination for new additions, 23.3 percent required testing, and

20.3 percent quarantined newly introduced cattle.

Contact with

wildlife

Cattle on many dairy operations frequently have contact with cats, dogs, and deer, all of which are

capable of spreading disease to cattle. Deer can transmit tuberculosis to cattle and vice versa and are

difficult to exclude from cattle pastures. Wildlife access to hay stacks and other stored feed can be

limited through the use of buildings and fences. Almost one-half of dairy operations in 2007 limited

cattle contact with wildlife or other livestock (48.5 percent) or controlled access to cattle feed

(49.9 percent).

Employees and

visitors

Employees or visitors—especially those who have contact with animals from other operations—can

introduce disease agents via their boots, clothing, vehicles, or other equipment. As people travel

more frequently throughout the world, the risk of inadvertent or intentional introduction of disease

agents foreign to the United States increases. Establishing written policies or guidelines pertaining

to travel and animal contact by visitors and employees will help reduce the risk of disease

introduction. The percentage of operations that had employees increased from 47.2 percent in 2002

to 75.7 percent in 2007. As expected, the number of full-time employees increased as herd size

increased. More than one-half of all operations in 2007 had visitors 1 to 14 times per week. In 2007,

30.4 percent of operations had guidelines for determining which visitors were allowed in animal

areas, and 51.3 percent had restrictions on vehicles entering animal areas.
USDA APHIS VS / iii

Vaccination Vaccination can reduce the prevalence and/or severity of specific diseases. The percentage of

operations that vaccinated heifers against any disease decreased from 91.3 percent in 1991 to

83.0 percent in 2007. The percentage of operations that vaccinated heifers against brucellosis

decreased from 1991 to 2007 (66.8 and 41.6 percent, respectively). This decrease may be due to the

fact that from 1991 to 2007 many States switched from a mandatory to a voluntary brucellosis

vaccination program. In addition, the number of States certified brucellosis-free increased from 34

in 1996 to 49 in 2007, which may have impacted the number of operations that vaccinated against

brucellosis. Overall, vaccine use in cows remained at approximately 80 percent from 1996 to 2007.

The highest percentage of vaccines administered to heifers and cows were primarily for viral

respiratory diseases.

Disease conditions The three most common diseases/conditions in dairy cattle identified by producers in 2007 were

clinical mastitis, lameness, and infertility problems (16.5, 14.0, and 12.9 percent of cows,

respectively). In addition, these diseases/conditions accounted for the majority of cows permanently

removed from the herd and for about one-third of cow deaths.

Mortality Animal deaths represent the least desirable health outcome. Once a death has occurred, determining

cause is important in preventing future deaths and improving the health of the herd. The percentage

of preweaned heifer deaths decreased from 10.8 percent in 1996 to 7.8 percent in 2007. Weaned

heifer-calf deaths increased from 2.2 percent in 1991 to 2.8 percent in 2002 then decreased to 1.8

percent in 2007. In contrast to heifer deaths, cow deaths increased from 3.8 percent in 1996 to 5.7

percent in 2007. A relatively low percentage of operations performed necropsies on dead

preweaned heifers, weaned heifers, or cows (8.0, 7.1, and 13.0 percent, respectively).
iv / Dairy 2007

Selected Highlights of Biosecurity Selected Highlights of Biosecurity

Practices on U.S. Dairy Opera ractices on U.S. Dairy Operations,

1991–2007 1991–2007

Most producers were fairly knowledgeable or knew some basics about foot-and-mouth disease,

BSE, Johne’s disease, and Mycoplasma mastitis; however, the majority of producers were

unfamiliar with heartwater, screwworm, bluetongue, vesicular stomatitis, and hemorrhagic bowel

syndrome in 2002 and 2007.

Most producers in 2002 and 2007 indicated that they would use their private veterinarian for disease

information if a foreign animal disease occurred in the United States or contact their veterinarian if

they suspected that a foreign animal disease was on their operation.

In Dairy 2007, the most common classes of cattle brought on the operation from outside sources

were: lactating dairy cows, added by 13.8 percent of operations; weaned dairy bulls, added by

12.5 percent of operations; and bred dairy heifers, added by 12.2 percent of operations.

Almost one-half of cow replacements for large operations (47.8 percent) were born on the operation

but raised off-site. In 2007, nearly two-thirds of operations that sent heifers off-site to be raised

(63.8 percent) used a rearing facility in which the heifers had contact with cattle from other

operations.

Of operations bringing dairy cattle from outside sources onto the operation, less than one-half

(47.2 percent) required vaccination of new additions prior to arrival; approximately one of five

operations (20.3 percent) quarantined new additions, and nearly one of four operations

(23.3 percent) required testing for new additions.

The percentage of operations that had employees increased from 47.2 percent in 2002 to

75.7 percent in 2007. In addition to employees, dairy operations had regular and frequent visits from

a variety of people doing business with the operation, including delivery people, milk haulers, cattle

haulers, artificial insemination technicians, nutritionists, and veterinarians. These people, who may

or may not have had contact with cattle on the operation and multiple other operations, can carry

diseases from one operation to another. In an average week, over one-half of all operations (51.6

percent) had between 1 and 14 visits by people coming onto the operation.

In 2007, 3 of 10 operations (30.4 percent) had guidelines for determining which visitors were

allowed in animal areas. Of operations that had visitors in the 12 months prior to the 2007 interview,

6.9 percent had footbaths for visitors entering animal areas. A higher percentage of operations in

2007 than in 2002 required disposable or clean boots for visitors entering animal areas and had
USDA APHIS VS / v

restrictions on vehicles entering animal areas. The percentage of operations that had guidelines

about which visitors were allowed in animal areas or that had footbaths for visitors entering animal

areas remained unchanged from 2002 to 2007.

Dogs, cats, and members of the deer family were the three animal types most often reported as

having contacts with dairy cattle. On operations in which deer or other members of the deer family

had contact with cattle and/or their feed or water in 2007, 90.8 percent of operations reported that

cattle could possibly or sometimes have face-to-face contact with deer. There were no differences by

region in the percentages of operations that reported face-to-face contact between cattle and deer.

The percentage of operations that separated newborn calves from their dams immediately after they

were born doubled from 1991 to 2007 (28.0 to 55.9 percent of operations, respectively).

Overall, only 2.1 percent of operations routinely measured passive transfer status via serum total

proteins.

In 2007, about one-third of operations (32.2 percent) routinely used the same equipment to handle

manure and to feed cattle; another one-third (35.6 percent) rarely used the same equipment; and

another one-third (32.2 percent) never used the same equipment to handle both manure and feed. In

2002 and 2007, about one of three operations shared equipment with other livestock operations.

The percentage of operations that administered any vaccine to heifers decreased from 91.3 percent

in 1991 to 83.0 percent in 2007. The percentage of operations that vaccinated heifers against

brucellosis decreased from 66.8 percent in 1991 to 41.6 percent in 2007. In cows, the use of the

most common vaccines (BVD, IBR, PI3, BRSV, and leptospirosis) has remained steady since 1996.

The three most common disease conditions in cows identified by producers in 2007 were clinical

mastitis, lameness, and infertility problems (16.5, 14.0, and 12.9 percent of cows, respectively).

The percentages of preweaned and weaned heifer calves that died decreased from 1996 to 2007,

while the percentage of cows that died increased. The percentage of cow deaths due to lameness or

injury increased from 12.7 percent in 1996 to 20.0 percent in 2007.

In 2007, a relatively low percentage of operations performed necropsies on dead preweaned heifers,

weaned heifers, or cows (8.0, 7.1, and 13.0 percent, respectively) to determine cause of death.

Although rendering remained the primary method of dead-cow disposal, the percentage of

operations that used this method decreased from 62.4 percent in 2002 to 56.9 percent in 2007.
vi / Dairy 2007

Acknowledgements Acknowledgements

This report has been prepared from material received and analyzed by the U.S. Department of

Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS), Veterinary Services

(VS) via four national studies of health management and animal health on U.S. dairy operations

conducted in 1991, 1996, 2002, and 2007.

The NAHMS dairy studies were cooperative efforts between State and Federal agricultural

statisticians, animal health officials, university researchers, and extension personnel. We want to

thank the National Agricultural Statistics Service (NASS) enumerators, State and Federal veterinary

medical officers (VMOs), and animal health technicians (AHTs) who visited the farms and collected

the data. Their hard work and dedication to the National Animal Health Monitoring System

(NAHMS) are invaluable. The roles of the producer, Area Veterinarian in Charge (AVIC), NAHMS

Coordinator, VMO, AHT, and NASS enumerator were critical in providing quality data for all the

dairy reports. Thanks also to the personnel at the Centers for Epidemiology and Animal Health

(CEAH) for their efforts in generating and distributing valuable reports from the data. Additional

support was afforded by the generous contributions of collaborators for the Dairy studies, including

• USDA–APHIS, National Veterinary Services Laboratories;

• USDA–APHIS, National Animal Disease Center;

• USDA–ARS, Beltsville Agricultural Research Center;

• USDA–ARS, Russell Research Center;

• Antel BioSystems, Inc.;

• BIOCOR Animal Health;

• Colorado State University, College of Veterinary Medicine and Biomedical Sciences;

• Cornell University Animal Health Diagnostic Laboratory;

• IDEXX Laboratories;

• Quality Milk Production Services;

• Tetracore, Inc.;

• TREK Diagnostic Systems;

• University of British Columbia, Canada, Animal Welfare Program;

• University of California, Davis;

• University of Pennsylvania, New Bolton Center;

• University of Wisconsin, Madison; and

• Wisconsin Veterinary Diagnostic Laboratory.

All participants are to be commended, particularly the producers whose voluntary efforts made the

Dairy studies possible.

Larry M. Granger

Director

Centers for Epidemiology and Animal Health
USDA APHIS VS / vii

Suggested bibliographic citation for this report:

USDA. 2010. Biosecurity Practices on U.S. Dairy Operations, 1991–2007

USDA–APHIS–VS, CEAH. Fort Collins, CO

#544.0510

Contacts for further information:

Questions or comments on data analysis: Dr. Jason Lombard (970) 494–7000

Information on reprints or other reports: Ms. Abby Fienhold (970) 494–7000

Email: NAHMS@aphis.usda.gov

Feedback:

Feedback, comments, and suggestions regarding the Dairy 2007

study reports are welcomed. Please forward correspondence via email

at: NAHMS@aphis.usda.gov, or you may submit feedback via online survey at:

http://nahms.aphis.usda.gov

(Click on “FEEDBACK on NAHMS reports.”)
viii / Dairy 2007

Introduction 1

Biosecurity and Biocontainment 1

Importance of Biosecurity 1

Biosecurity Development 2

Terms Used in This Report 5

Section I: Population Estimates 7

A. Producer Familiarity with Disease 7

1. Knowledge of specific diseases 7

2. Information sources in case of a foreign animal disease outbreak 9

3. Resource contacts 10

B. Herd Addition Risks 11

1. Classes of cattle brought onto dairy operations from outside sources 11

2. Source of replacements 15

3. Number of cow-replacement shipments 21

4. Replacement heifer calves 23

5. Vaccination requirements 26

6. Quarantine 29

7. Testing requirements 32

8. Herd-of-origin disease status 36

C. On-farm Biosecurity and Biocontainment Practices 39

1. Employees and visitors 39

2. Specific biosecurity practices 46

3. Calving/maternity areas 50

4. Newborn calf risks and contact with other cattle 60

5. Colostrum feeding 62

6. Measuring passive transfer of immunity 66

7. Colostrum pooling and storage 68

8. Pasteurization of colostrum 69

9. Calf-feeding equipment 71

10. Physical contact with other animals 72

11. Equipment handling for manure and feed 74

12. Equipment sharing with other livestock operations 76

13. Water sources for cows 78

14. Milking personnel and training 80

15. Milking biosecurity practices 83

Table of Contents able of Contents
USDA APHIS VS / ix

D. Vaccination and Prevention Practices 85

1. Heifer vaccination 85

2. Cow vaccination 87

3. BVD vaccinations 89

4. BVD testing 91

5. Mastitis vaccinations 93

6. Preventive practices 95

E. Incidence of Disease or Illness 98

1. Cow morbidity 98

2. Disease confirmation 100

3. Milk cultures 106

4. Abortions 115

F. Mortality, Necropsy, and Carcass Disposal 119

1. Mortality 119

2. Necropsy 126

3. Carcass disposal 128

Section II: Methodology Dairy 2007 130

A. Needs Assessment 130

B. Sampling and Estimation 131

1. State selection 131

2. Operation selection 132

3. Population inferences 132

C. Data Collection 133

D. Data Analysis 133

Validation 133

E. Sample Evaluation 134

1. Phase I: Validation—General Dairy Management Report 134

2. Phase II: VS Initial Visit 136

3. Phase II: VS Second Visit 137
x / Dairy 2007

Appendix I: Sample Profile Dairy 2007 138

A. Responding Operations 138

Appendix II: U.S. Milk Cow Population and Operations 139

Appendix III: Methodology Overview, Phase I (1991–2007) 140

Appendix IV: Methodology Overview, Phase II VS Initial Visit (1996–2007) 141

Appendix V: Study Objectives and Related Outputs 142

Appendix VI: References 144
USDA APHIS VS / 1

Introduction

Introduction oduction

Biosecurity and Biocontainment

Biosecurity and biocontainment methods can

significantly reduce the risk of introducing new

diseases to an operation or of spreading disease

among animals on the operation. Biosecurity is a

system of management practices used to prevent

the entry of disease-causing agents.

Biocontainment is a system of management

practices used to prevent the spread of disease

between groups of animals on an operation

(Villarroel et al., 2007). A good biocontainment

plan can limit the spread of disease already

present on the operation and also serve to back

up the biosecurity plan in the event that a new

disease is introduced to an operation.

Biosecurity and biocontainment measures are

both necessary to reduce the potential impacts of

a disease outbreak.

Recognizing and understanding all aspects of

potential biosecurity breaches are essential to

managing a successful biosecurity program.

Generally, the biosecurity issues that receive the

most attention are: the process of introducing

new animals to the operation, which includes

Importance of Biosecurity

Infectious diseases can have a devastating

impact on the productivity of any dairy

operation. Virtually every disease results in

productivity losses, and in some cases these

losses can be substantial, particularly on larger

operations in which more animals are at risk.

Milk production and quality can decrease,

resulting in immediate financial consequences.

knowing the source and health history of new

animals; isolating new animals from the main

herd and testing them for appropriate diseases;

designing strategic vaccination programs; and

sanitation practices, including milking

procedures, disinfection of equipment, and

manure management. Many other key

components of disease control are often

overlooked. For example, minimizing stress

helps animals resist and overcome disease

challenges. Animal stress can be reduced by

providing a comfortable and clean environment,

sufficient housing space, adequate bunk space,

and by segregating cattle into appropriate age

and/or size groups. Providing quality feed and

water, maintaining a balanced ration with proper

nutrient levels, and providing transition diets to

cows around the time of calving also help

decrease nutritional stress and ensure optimal

immune function for disease resistance.

Managing and regulating visitors, service

personnel, employees, and animal traffic are

also essential aspects of biosecurity. Finally,

controlling animals’ exposure to wildlife,

insects, and wind-borne pathogens are other

areas for consideration.

Reproductive efficiency can decline,

compounding the financial strain by increasing

days open and culling rates. As a result, calf

numbers are negatively affected and

replacement costs rise. Furthermore, treatment

expenses, debilitated animals, and increased

death losses certainly have financial

implications, but also may limit animal
2 / Dairy 2007

Introduction

marketing options. Finally, depending on the

nature of the pathogen, public health issues may

arise, such as the spread of zoonoses,

antimicrobial resistance, drug residues, and

impaired or reduced food safety.

On a national level, biosecurity programs are

crucial in keeping the country free from

numerous animal diseases exotic to the United

States. Due to the threat of bioterrorism and the

recent international outbreaks of infectious

diseases such as foot-and-mouth and bovine

spongiform encephalopathy, strict import and

trade restrictions have been implemented as

Biosecurity Development

components of a national biosecurity plan. In

addition, there are current and past eradication

programs for many diseases familiar to most

livestock producers, such as tuberculosis,

brucellosis, classical swine fever (hog cholera),

and pseudorabies. These programs include

national-level biosecurity protections.

Whether motivation stems from risk of

decreased productivity on individual operations

or producer responsibility to exclude or

eradicate disease on a national level, the net

benefit of biosecurity is improved animal and

public health.

Developing a formal biosecurity plan is an

exercise in risk assessment. As such, there are

four steps to include in the assessment process:

1. Hazard identification,

2. Exposure assessment,

3. Risk characterization, and

4. Mitigation plan.

1. Hazard identification—The preliminary step

in designing a biosecurity plan is to assess the

specific risks for the operation. Wells (2000)

suggests that the operation first identify its chief

source of income. For example, on most dairies

milk is the primary product. Diseases that cause

decreased milk production and quality and result

in early culling should have the highest priority.

In contrast, dairies that market primarily animal

semen or embryos should concentrate

biosecurity efforts against reproductive diseases,

as well as diseases with international trade

implications such as bovine leukosis virus and

bluetongue virus (Dargatz et al., 2002;

McCluskey, 2002).

2. Exposure assessment—Operations must

identify which specific diseases are most likely

to be hazards for their particular farms and

identify the most probable means by which

cattle would be exposed. Many factors should

be considered, including: the addition of new

animals; disease history; proximity to other

livestock operations; potential contact with

wildlife; prospective visitors; off-farm animal

travel; geographic location; rodent, insect, and

bird populations; and wind and weather patterns

(Wells, 2000; BAMN, 2001a; Kirk, 2009).

3. Risk characterization—Once potential

hazards have been assessed, the degree of risk

must be characterized for the operation. This

qualitative assessment can be done

simultaneously with the exposure assessment.
USDA APHIS VS / 3

Introduction

Operations that purchase replacement heifers

have a higher risk of introducing infectious

diseases to the premises than those that do not

make off-site animal purchases. In addition,

dairies that allow the same employees to work

with calves, sick cows, and milk cows have a

higher potential risk of transferring disease

agents between groups of animals than dairies

that assign employees to one specific group of

animals. The risk of transmitting

Mycobacterium avium, subspecies

paratuberculosis (the causative agent of

Johne’s disease) is increased on operations that

feed pooled colostrum and/or unpasteurized

pooled milk to calves (Nielsen et al., 2008).

This risk is compounded if the colostrum comes

from cows with unknown Johne’s disease status.

Another component of characterizing an

operation’s greatest risks is evaluating the

potential means of disease control and how the

mitigation plan will be implemented on the

operation. Vaccine availability and efficacy for

certain diseases also must be considered.

Vaccination is relatively efficacious for diseases

such as infectious bovine rhinotracheitis, but

vaccines are not generally available for other

diseases, such as anaplasmosis and Johne’s

disease.

4. Mitigation plan—All information obtained

from steps 1 through 3 should be assimilated

into a final plan for mitigation. The mitigation

plan should include: the diseases of utmost

importance; where control efforts are to be

directed; a detailed plan to assess the current

levels of disease on the operation (serologic or

fecal testing, for example); and written strategies

detailing what will be done to prevent the

introduction or spread of these diseases

(McCluskey, 2002).

Numerous checklists and scorecards have been

developed to aid in the analysis process. These

assessments can serve as guidelines to help

identify potential hazards and the degree of risk

for disease acquisition or transmission on an

operation. Risk assessments are available for

specific diseases or situations. For example, The

Center for Food Security and Public Health at

Iowa State University has a series of risk

assessment tools available for veterinarians and

dairy producers: http://www.cfsph.iastate.edu/

Infection_Control/index.php (Center for Food

Safety and Public Health). The New York State

Cattle Health Assurance Program provides a risk

assessment tailored to herd expansion

biosecurity concerns (New York State Cattle

Health Assurance Program), and a Johne’s

disease risk assessment is available at: http://

johnesdisease.orgHandbook%20for%20Vets

%20&%20Beef%20Producers.pdf.

This report, “Biosecurity Practices on U.S.

Dairy Operations, 1991–2007”, provides

national estimates of dairy cattle health and

management practices for comparable

populations from the National Dairy Heifer

Evaluation Project (NDHEP) 1991, NAHMS

Dairy 1996, Dairy 2002, and Dairy 2007 studies

(see map, next page). The latest study, Dairy

2007, was conducted in 17 of the Nation’s major

dairy States and provides participants,

stakeholders, and the industry as a whole with
4 / Dairy 2007

Introduction

valuable information representing 79.5 percent

of U.S. dairy operations and 82.5 percent of

U.S. dairy cows. State and Federal veterinary

medical officers (VMOs) and animal health

technicians (AHTs) conducted the questionnaire

interviews. Due to educational efforts, producer

awareness and recognition of some diseases

have increased and may be partially responsible

for changes observed in disease prevalence.
USDA APHIS VS / 5

Introduction

Terms Used in This Report

Biocontainment: Management practices used to

prevent the spread of disease between groups of

animals on an operation.

Biosecurity: Management practices used to

prevent the entry of disease-causing agents onto

an operation.

Bovine viral diarrhea (BVD): An infectious

disease of cattle caused by a pestivirus.

Infection can result in early embryonic death,

abortion, stillbirths, and congenital defects such

as cerebellar agenesis, which results in ataxia or

lack of coordination. Cattle infected with BVD

virus in utero are referred to as persistently

infected. Persistently infected animals

continuously shed large quantities of the virus

via nasal discharge, saliva, semen, urine, feces,

tears, and milk, thereby serving as a source of

persistently infected cattle.

Cow: Female dairy bovine that has calved at

least once.

Heifer: Female dairy bovine that has not yet

calved.

Herd size: Herd size is based on the respective

January 1 cow inventory. Small herds are those

with fewer than 100 cows; medium herds are

those with 100 to 499 cows; and large herds are

those with 500 or more cows.

Operation average: The average value for all

operations. A single value for each operation is

summed over all operations reporting divided by

the number of operations reporting. For

example, operation average number of

shipments (see table a., p 21) is calculated by

summing reported average number of shipments

over all operations divided by the number of

operations.

Population estimates: The estimates in this

report make inference to all of the operations

with dairy cows in the target population (see

Section II: Methodology, p 130). Data from the

operations responding to the survey are

weighted to reflect their probability of selection

during sampling and to account for any survey

nonresponse.
6 / Dairy 2007

Introduction

Standard Errors

(1.0)

10

9

8

7

6

5

4

3

2

1

0

(0.3)

Examples of a 95% Confidence Interval

95% Confidence 

Intervals

Precision of population estimates: Estimates

in this report are provided with a measure of

precision called the standard error. A 95-percent

confidence interval can be created with bounds

equal to the estimate plus or minus two standard

errors. If the only error is sampling error, the

confidence intervals created in this manner will

contain the true population mean 95 out of 100

times. In the example to the right, an estimate of

7.5 with a standard error of 1.0 results in limits

of 5.5 to 9.5 (two times the standard error above

and below the estimate). The second estimate of

3.4 shows a standard error of 0.3 and results in

limits of 2.8 and 4.0. Alternatively, the

90-percent confidence interval would be created

by multiplying the standard error by 1.65 instead

of 2. Most estimates in this report are rounded

to the nearest tenth. If rounded to 0, the standard

error was reported (0.0). If there were no reports

of the event, no standard error was reported

(--). References to estimates being higher or

lower than other estimates are based on the

95-percent confidence intervals not

overlapping.

Regions (2007):

• West: California, Idaho, New Mexico, Texas,

Washington

• East: Indiana, Iowa, Kentucky, Michigan,

Minnesota, Missouri, New York, Ohio,

Pennsylvania, Vermont, Virginia, Wisconsin

Sample profile: Information that describes

characteristics of the operations from which data

were collected.
USDA APHIS VS / 7

Section I: Population Estimates—A. Producer Familiarity with Disease

Section I: P Section I: Population Es opulation Estimates

NOTE: Unless otherwise specified, estimates in the following tables represent only operations with 30 or more dairy

cows.

A. Producer Familiarity with Disease

1. Knowledge of

specific diseases

Familiarity with the signs of various diseases is

an important part in developing an effective

biosecurity plan. Familiarity with diseases may

also help limit the spread of a disease, should it

be introduced into the herd.

Producer familiarity with diseases varied greatly.

In 2002 and 2007, most producers were fairly

knowledgeable or knew some basics about footand-mouth disease, bovine spongiform

encephalopathy, Johne’s disease, and

Mycoplasma mastitis; however, the majority of

producers were unfamiliar with heartwater,

screwworm, bluetongue, vesicular stomatitis,

and hemorrhagic bowel syndrome. In 2002, the

percentage of producers that were fairly

knowledgeable about foot-and-mouth disease

was about twice that of producers in 2007 (16.5

and 8.9 of operations, respectively). The

percentage of operations that were fairly

knowledgeable about Johne’s disease,

Mycoplasma mastitis, and hemorrhagic bowel

syndrome increased from 2002 to 2007.
8 / Dairy 2007

Section I: Population Estimates—A. Producer Familiarity with Disease

Percentage of operations by level of familiarity with specific cattle diseases in 

2007 

Percent Operations 

Level of Familiarity 

Fairly 

Knowledgeable Know Some 

Basics 

Recognized the 

Name, Not 

Much Else 

Had Not Heard 

of it Before 

Dairy 

2002 

Dairy 

2007 

Dairy 

2002 

Dairy 

2007 

Dairy 

2002 

Dairy 

2007 

Dairy 

2002 

Dairy 

2007 

Disease 

Pct. 

(SE) 

Pct. 

(SE) 

Pct. 

(SE) 

Pct. 

(SE) 

Pct. 

(SE) 

Pct. 

(SE) 

Pct. 

(SE) 

Pct. 

(SE) 

Foot-and-mouth 

disease 

16.5 

(1.5) 

8.9 

(1.2) 

54.6 

(2.1) 

49.3 

(2.9) 

28.1 

(1.9) 

40.7 

(2.9) 

0.8 

(0.3) 

1.1 

(0.7) 

Heartwater 0.3 

(0.2) 

0.6 

(0.3) 

0.9 

(0.3) 

1.0 

(0.4) 

3.7 

(0.7) 

4.5 

(1.0) 

95.1 

(0.8) 

93.9 

(1.1) 

Bovine spongiform 

encephalopathy 

(BSE) 

13.9 

(1.5) 

19.6 

(2.0) 

46.5 

(2.2) 

60.8 

(2.7) 

38.0 

(2.1) 

18.8 

(2.2) 

1.6 

(0.5) 

0.8 

(0.6) 

Screwworm 5.9 

(1.0) 

4.0 

(0.8) 

11.5 

(1.2) 

15.1 

(1.9) 

45.1 

(2.2) 

37.4 

(2.6) 

37.5 

(2.2) 

43.5 

(2.7) 

Johne’s disease 

(Mycobacterium 

paratuberculosis) 

45.3 

(2.1) 

57.9 

(2.9) 

42.3 

(2.1) 

36.2 

(2.8) 

11.4 

(1.4) 

4.4 

(1.2) 

1.0 

(0.3) 

1.5 

(0.6) 

Bluetongue 2.6 

(0.6) 

2.2 

(0.9) 

5.2 

(0.8) 

8.5 

(1.2) 

40.7 

(2.0) 

41.0 

(2.8) 

51.5 

(2.1) 

48.3 

(2.8) 

Vesicular 

stomatitis 

1.1 

(0.3) 

0.7 

(0.3) 

2.8 

(0.5) 

3.4 

(0.8) 

12.9 

(1.3) 

14.1 

(1.7) 

83.2 

(1.4) 

81.8 

(1.9) 

Anthrax 9.6 

(1.2) 

5.1 

(1.2) 

32.6 

(2.0) 

28.4 

(2.6) 

54.0 

(2.2) 

56.3 

(2.8) 

3.8 

(0.8) 

10.2 

(1.8) 

Mycoplasma

mastitis 

8.7 

(1.0) 

20.3 

(1.8) 

21.8 

(1.7) 

39.9 

(2.8) 

46.6 

(2.2) 

30.4 

(2.8) 

22.9 

(2.0) 

9.4 

(1.8) 

Hemorrhagic 

bowel syndrome 

(HBS) 

1.0 

(0.2) 

8.2 

(1.1) 

2.5 

(0.4) 

17.6 

(1.9) 

8.7 

(1.3) 

22.6 

(2.3) 

87.8 

(1.3) 

51.6 

(2.7) 

() = standard error.
USDA APHIS VS / 9

Section I: Population Estimates—A. Producer Familiarity with Disease

2. Information

sources in case of a

foreign animal

disease outbreak

The introduction of a foreign animal disease into

the United States could be catastrophic.

Knowing where producers would turn for

information in the event of a foreign animal

disease outbreak is critical to planning for the

control of an outbreak.

Most producers in 2002 and 2007 indicated they

would use their private veterinarian as an

information source if a foreign animal disease

outbreak occurred in the United States (92.8 and

93.6 percent, respectively). Other resources

would be used, but not to the extent of the

private veterinarian.

Percentage of operations by likelihood of using the following information sources 

if an outbreak of foreign animal disease occurred in the United States 

Percent Operations 

Likelihood 

Very Likely Somewhat Likely Not Likely 

Dairy 2002 Dairy 2007 Dairy 2002 Dairy 2007 Dairy 2002 Dairy 2007 

Information 

Source Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Other dairy 

producers 40.5 (2.1) 41.4 (2.8) 34.5 (2.0) 37.8 (2.7) 25.0 (1.9) 20.8 (2.3) 

Private 

veterinarian 92.8 (1.1) 93.6 (1.3) 6.6 (1.1) 5.4 (1.3) 0.6 (0.3) 1.0 (0.5) 

Extension 

agent 34.2 (2.0) 32.5 (2.7) 36.9 (2.1) 38.9 (2.9) 28.9 (2.0) 28.6 (2.5) 

Dairy 

organization 

or cooperative 

30.3 (1.9) 30.7 (2.6) 41.8 (2.1) 42.3 (2.8) 27.9 (1.9) 27.0 (2.6) 

Magazines 41.8 (2.1) 39.0 (2.8) 44.7 (2.1) 49.4 (2.8) 13.5 (1.5) 11.6 (1.5) 

Internet 19.0 (1.6) 23.1 (2.2) 27.4 (1.9) 28.8 (2.6) 53.6 (2.1) 48.1 (2.8) 

State 

Veterinarian’s 

office 

34.7 (2.1) 26.7 (2.4) 31.3 (2.0) 37.4 (2.8) 34.0 (2.1) 35.9 (2.9) 

U.S. 

Department of 

Agriculture 

25.1 (1.8) 22.6 (2.4) 38.1 (2.2) 42.5 (2.8) 36.8 (2.1) 34.9 (2.7) 

Television/ 

newspapers 30.7 (2.1) 25.8 (2.5) 35.2 (2.0) 38.8 (2.8) 34.1 (2.0) 35.4 (2.6) 

Other 3.7 (0.9) 4.7 (1.2) 0.8 (0.3) 2.4 (1.0) 95.5 (1.0) 92.9 (1.6) 
10 / Dairy 2007

Section I: Population Estimates—A. Producer Familiarity with Disease

3. Resource

contacts

Most producers indicated they would contact

their private veterinarian if they suspected a

foreign animal disease on their operation. About

4 of 10 operations would contact the State

Veterinarian’s office. These responses highlight

the continuing need to educate veterinary

practitioners on the identification and handling

of suspected foreign animal diseases on

livestock operations.

Percentage of operations that would contact the following resources if an animal 

on the operation was suspected of having foot-and-mouth disease or another 

foreign animal disease 

Percent Operations 

Dairy 2002 Dairy 2007 

Resource Percent Std. Error Percent Std. Error 

Extension agent/university 25.4 (1.8) 20.8 (2.3) 

State Veterinarian’s office 43.9 (2.2) 35.7 (2.6) 

U.S. Department of Agriculture 25.5 (1.8) 21.8 (2.3) 

Private veterinarian 97.9 (0.7) 98.6 (0.5) 

Feed company or milk 

cooperative representative 28.0 (1.9) 25.7 (2.3) 

Other 3.3 (0.7) 4.1 (1.3) 
USDA APHIS VS / 11

Section I: Population Estimates—B. Herd Addition Risks

B. Herd Addition Risks

1. Classes of cattle

brought onto dairy

operations from

outside sources

For most dairies, the introduction of new

animals poses one of the greatest threats to

biosecurity. All other factors being equal, the

number of new animals introduced onto the

operation and the number of times new animals

are introduced (number of shipments) can help

quantify the level of risk. Each age group or

class of animals brought onto an operation poses

its own biosecurity risks. Lactating cows can

harbor contagious mastitis pathogens, which can

easily be spread to other cows in the string. Bred

cattle can harbor reproductive pathogens, and

calves can introduce new strains of respiratory

and enteric pathogens to other calves (Villarroel

et al., 2007). A comprehensive biosecurity

program examines the risks particular to each

operation through the introduction of each group

of cattle and institutes a series of controls to

help reduce the risks.

In Dairy 2007, the most common classes of

cattle brought onto the operation from outside

sources were lactating dairy cows (13.8 percent

of operations), weaned dairy bulls (12.5 percent

of operations), and bred dairy heifers

(12.2 percent of operations). The percentages of

operations that introduced bred heifers or

lactating cows decreased from 1996 to 2007.

From 1996 to 2007, about 4 of 10 operations

brought any cattle from outside sources onto the

operation. A lower percentage of operations in

2007 brought on any cattle compared with 2002.
12 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks

*Operations with any dairy cows.

a. Percentage of operations* that brought the following classes of cattle onto the 

operation 

Percent 

Operations 

Percent 

Operations 

Cattle Class

Dairy 

1996 

Std. 

Error Cattle Class 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Preweaned 

calves (dairy or 

beef) 

5.0 (0.7) 

Preweaned 

calves (dairy or 

beef) 

5.1 (0.7) 3.4 (0.6) 

Dairy heifers 

weaned, but 

not bred 

7.3 (0.7) 

Dairy heifers 

weaned, but 

not bred 

6.7 (0.7) 6.4 (0.7) 

Bred dairy 

heifers 18.5 (0.9) Bred dairy heifers 15.8 (0.9) 12.2 (0.9) 

Lactating dairy 

cows 

19.9 (1.0) Lactating dairy 

cows 

16.4 (1.0) 13.8 (1.0) 

Dry dairy cows 7.1 (0.8) Dry dairy cows 5.9 (0.6) 4.3 (0.6) 

Bulls (weaned) 8.7 (0.7) 

Dairy bulls 

(weaned) 13.7 (0.9) 12.5 (0.9) 

Beef bulls 

(weaned) 2.3 (0.4) 1.7 (0.3) 

Other heifers 

and cows 

(including beef) 

1.9 (0.4) Beef heifers 

and cows` 1.5 (0.3) 1.3 (0.3) 

Steers 

(weaned) 2.0 (0.3) Steers (weaned) 1.1 (0.3) 1.8 (0.4) 

Any 43.9 (1.3) Any 45.7 (1.4) 38.9 (1.4) 
USDA APHIS VS / 13

Section I: Population Estimates—B. Herd Addition Risks

Only 1.0 percent of large operations and

3.8 percent of small operations added

preweaned calves from outside sources in 2007.

A higher percentage of large operations brought

on dairy heifers, bred dairy heifers, dairy bulls,

and any beef or dairy cattle compared with

medium or small operations.

b. Percentage of operations* that brought the following classes of cattle onto the 

operation, by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Cattle Class Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Preweaned calves 

(dairy or beef) 3.8 (0.8) 2.5 (0.6) 1.0 (0.3) 3.4 (0.6) 

Dairy heifers 

weaned, but not 

bred 

5.3 (0.8) 7.6 (1.2) 16.3 (2.6) 6.4 (0.7) 

Bred dairy heifers 8.9 (1.0) 18.1 (1.8) 34.7 (2.6) 12.2 (0.9) 

Lactating dairy 

cows 

13.2 (1.3) 16.0 (1.7) 13.0 (1.9) 13.8 (1.0) 

Dry dairy cows 4.1 (0.8) 4.3 (0.9) 5.5 (1.5) 4.3 (0.6) 

Beef heifers and 

cows 

0.9 (0.3) 2.5 (0.7) 1.1 (0.6) 1.3 (0.3) 

Dairy bulls 

(weaned) 11.4 (1.1) 14.1 (1.6) 22.5 (2.4) 12.5 (0.9) 

Beef bulls 

(weaned) 1.5 (0.4) 2.2 (0.6) 1.5 (0.5) 1.7 (0.3) 

Steers (weaned) 2.0 (0.5) 1.3 (0.5) 0.7 (0.6) 1.8 (0.4) 

Any 35.6 (1.7) 44.3 (2.3) 61.6 (2.8) 38.9 (1.4) 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007.
14 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks

A higher percentage of operations in the West

region added any cattle from outside sources

compared with operations in the East region

(49.3 and 38.0 percent of operations,

respectively).

c. Percentage of operations* that brought the following classes of cattle onto the 

operation, by region 

Percent Operations 

Region 

West East 

Cattle Class Percent Std. Error Percent Std. Error 

Preweaned calves (dairy or beef) 0.6 (0.3) 3.6 (0.6) 

Dairy heifers weaned, but not bred 12.6 (2.2) 5.9 (0.7) 

Bred dairy heifers 21.1 (2.3) 11.5 (0.9) 

Lactating dairy cows 8.5 (1.5) 14.3 (1.1) 

Dry dairy cows 2.3 (0.7) 4.4 (0.7) 

Beef heifers and cows 1.5 (0.7) 1.3 (0.3) 

Dairy bulls (weaned) 21.8 (2.6) 11.8 (0.9) 

Beef bulls (weaned) 2.8 (0.9) 1.6 (0.3) 

Steers (weaned) 0.3 (0.3) 1.9 (0.4) 

Any 49.3 (3.0) 38.0 (1.5) 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007.
USDA APHIS VS / 15

Section I: Population Estimates—B. Herd Addition Risks

2. Source of

replacements

Many diseases are initially introduced into a

herd by the purchase of an infected animal.

Knowing the source of purchased cattle may

provide the buyer the opportunity to directly

inquire about diseases on the source operation.

Almost two-thirds of operations (64.2 percent)

did not introduce cattle into their herds during

the previous 12 months, which is slightly higher

than the 61.1 percent reported in table b., p 13.

The difference between the two estimates is

likely the result of the different populations used

to make the estimates: the 64.2 percent

represents operations with 30 or more cows,

while 61.1 percent represents operations with

any dairy cows.

Only 2.6 percent of operations did not know the

source of any cattle introduced in 2007, while

24.2 percent knew the source of all cattle

introduced. A higher percentage of small

operations than large operations had no

incoming cattle. Of small operations,

67.4 percent had no incoming cattle, and

22.0 percent knew the source of all incoming

cattle. About one-third of large operations

(32.0 percent) knew the source of all incoming

cattle, while 43.5 percent had no incoming

cattle.

a. Percentage of operations in which the producer was aware of the source and 

geographic origin of all, some, or none of the incoming cattle during the 

previous 12 months, by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Knew the Source 

and Geographic 

Origin of ... Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

All incoming cattle 22.0 (3.3) 28.0 (3.8) 32.0 (5.2) 24.2 (2.4) 

Some incoming 

cattle 8.6 (2.3) 7.8 (2.3) 19.1 (3.7) 9.0 (1.7) 

None of the 

incoming cattle 2.0 (1.2) 3.6 (1.6) 5.4 (2.9) 2.6 (0.9) 

No incoming 

cattle* 67.4 (3.7) 60.6 (4.2) 43.5 (5.7) 64.2 (2.8) 

Total 100.0 100.0 100.0 100.0 

*If the operation sent heifers off-site but cattle were not commingled with cattle from other operations, these 

operations were considered to have no incoming cattle. 

Source: NAHMS Dairy 2007.
16 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks

Almost all operations (97.0 percent) had some

replacement cows enter the milking herd.

Replacement cows entering the milking herd

accounted for over one-third (38.4 percent) of

the January 1, 2007, cow inventory. Calves born

and raised on the operation entered the milking

herd as replacements on the majority of

operations (89.8 percent). Cow replacements

were born off the operation on 14.1 percent of

operations, while 6.8 percent of operations had

replacements born on the operation but raised

elsewhere. Estimates for the percentage of cows

entering the milking herd in table b. below and

in table c. on the next page differ slightly

because table b. represents operations with any

dairy cows and table c. represents operations

with 30 or more dairy cows; however, when

considering the standard errors, the difference in

the estimates are not statistically significant.

b. Percentage of operations1 (and percentage of cow inventory), by source of cow 

replacements that entered the milking herd 

Replacement Source

Percent 

Operations 

Standard 

Error 

Percent 

Cows2

Standard 

Error 

Born and raised 

on operation 89.8 (0.8) 27.8 (0.8) 

Born on operation, 

raised off operation 6.8 (0.6) 8.0 (0.7) 

Born off operation 14.1 (1.0) 2.6 (0.2) 

Any replacements 97.0 (0.5) 38.4 (0.8) 

1

Operations with any dairy cows. 

2

Number of replacements that entered the milking herd during 2006, as a percentage of the January 1, 2007, 

cow inventory. 

Source: NAHMS Dairy 2007.
USDA APHIS VS / 17

Section I: Population Estimates—B. Herd Addition Risks

On operations with 30 or more dairy cows, over

one-third of the milking herd inventory

(36.2 percent) consisted of cow replacements

that had entered the milking herd during the

previous 12 months. There were no substantial

differences by herd size.

c. Cow replacements that entered the milking herd during the previous 

12 months, as a percentage of cow inventory on the day of interview, by herd 

size 

Percent Cow Inventory 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

33.0 (1.1) 34.5 (1.1) 39.0 (2.6) 36.2 (1.2) 

Source: NAHMS Dairy 2007. 

Heifers born and raised on the operation

constituted the highest percentage of cow

replacements (58.8 percent) on all operations,

over four-fifths of replacements on small

operations (81.5 percent), three-fourths of

replacements on medium operations

(73.8 percent), and two-fifths of replacements

on large operations (40.5 percent).

Some operations sent their heifer calves to

off-site raising facilities—operations dedicated

to raising dairy replacement calves. There are

several advantages to off-site calf raising. The

potential for contact between calves and older

cattle is greatly reduced, decreasing the risk that

young calves will contract diseases from older

animals. The work force is dedicated solely to

raising calves and, as a result, closer attention

may be paid to the calves’ care and feeding. In

addition, off-site calf raising frees up space on

the milking operation, creating more space for

lactating cows. One disadvantage of off-site calf

raising is the risk that calves will be exposed to

infectious agents while off-site and return to

their home operations carrying diseases which

are new to the home herd. This is especially true

if calves from more than one operation are

commingled at a calf raising site (Villarroel et

al., 2007).
18 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks

Heifers born on the operation and raised off-site

accounted for the second highest percentage of

cow replacements for all operations. Almost

one-half of cow replacements for large

operations (47.8 percent) were born on the

operation but raised off-site. Heifers born

on-site and raised off-site constituted much

lower percentages of cow replacements for

medium and small operations (17.2 and

9.2 percent, respectively).

d. Percentage of cow replacements that entered the milking herd during the 

previous 12 months, by source and by herd size 

Percent Cow Replacements 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Source of Cow 

Replacements Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Born and raised 

on the operation 81.5 (3.3) 73.8 (3.5) 40.5 (6.3) 58.8 (3.5) 

Born on operation, 

raised off-site 9.2 (2.2) 17.2 (3.4) 47.8 (6.0) 30.8 (3.3) 

Purchased directly 

from other dairies 4.6 (1.6) 5.4 (1.1) 4.2 (1.2) 4.6 (0.8) 

Purchased from 

a dealer 0.7 (0.4) 2.2 (0.6) 3.9 (1.0) 2.7 (0.5) 

Purchased from 

auction markets 3.7 (1.4) 0.7 (0.3) 3.4 (1.9) 2.7 (1.0) 

Purchased from 

other source 0.3 (0.2) 0.7 (0.5) 0.2 (0.1) 0.4 (0.1) 

Total 100.0 100.0 100.0 100.0 

Source: NAHMS Dairy 2007.
USDA APHIS VS / 19

Section I: Population Estimates—B. Herd Addition Risks
20 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks

There were no substantial regional differences in

the source of dairy cow replacements.

e. Percentage of cow replacements that entered the milking herd during the 

previous 12 months, by source and by region 

Percent Cow Replacements 

Region 

West East 

Source of Cow Replacements Percent Std. Error Percent Std. Error 

Born and raised 

on the operation 50.6 (7.4) 64.3 (3.1) 

Born on operation, 

raised off-site 40.4 (7.1) 24.3 (2.8) 

Purchased directly 

from other dairies 2.3 (1.2) 6.2 (1.0) 

Purchased from a dealer 2.2 (0.7) 3.1 (0.7) 

Purchased from 

auction markets 4.2 (2.4) 1.7 (0.6) 

Purchased from other source 0.3 (0.2) 0.4 (0.2) 

Total 100.0 100.0 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 21

Section I: Population Estimates—B. Herd Addition Risks

3. Number of

cow-replacement

shipments

Each shipment of cattle arriving at an operation

presents the risk of introducing new pathogens

to the operation, and more shipments mean more

opportunities for disease introduction. Large

operations received an average of 48.1 cowreplacement shipments during the previous 12

months compared with medium and small

operations (6.0 and 2.6 shipments, respectively).

Heifers born on-site and raised off-site

constituted the most shipments of incoming

cattle to operations of any size. Animals

purchased from auction markets comprised the

second largest average number of shipments

received by large operations, which had an

average of 28.3 shipments from auction markets

during the previous 12 months. The operation

average number of shipments for all cowreplacement sources was 9.7.

a. Operation average number of shipments by source of cow replacements during 

the previous 12 months, and by herd size 

Operation Average Number of Shipments 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Source of Cow 

Replacements Avg. 

Std. 

Error Avg. 

Std. 

Error Avg. 

Std. 

Error Avg. 

Std. 

Error 

Born on 

operation, 

raised off-site 

5.5 (1.6) 11.1 (1.3) 55.9 (16.2) 20.9 (5.1) 

Purchased 

directly from 

other dairies 

1.5 (0.2) 2.3 (0.3) 5.3 (1.0) 2.1 (0.2) 

Purchased 

from a dealer 1.4 (0.3) 2.9 (0.5) 6.0 (1.0) 3.3 (0.5) 

Purchased from 

auction markets 3.0 (1.0) 2.0 (0.7) 28.3 (17.1) 7.8 (3.9) 

Purchased from 

other source 4.0 (0.0) 3.0 (1.1) 2.8 (0.8) 3.3 (0.5) 

All 2.6 (0.6) 6.0 (0.8) 48.1 (12.3) 9.7 (1.9) 

Source: NAHMS Dairy 2007. 
22 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks

Operations in the West region had more

shipments of heifers born on the operation but

raised off-site (65.8 per year) than operations in

the East region (10.9 per year). The number of

shipments received from other sources was

similar for the West and East regions. Although

the average number of shipments from auction

markets for operations in the West region was

higher than the East region, the standard error is

large and suggests a large variability in

shipments among operations in the West region.

b. Operation average number of shipments by source of cow replacements during 

the previous 12 months, and by region 

Operation Average Number of Shipments 

Region 

West East 

Source of Cow Replacements Average Std. Error Average Std. Error 

Born on operation, 

raised off-site 65.8 (24.0) 10.9 (1.3) 

Purchased directly from 

other dairies 5.9 (1.8) 1.9 (0.2) 

Purchased from a dealer 5.5 (1.1) 2.7 (0.4) 

Purchased from 

auction markets 28.3 (17.3) 2.9 (0.9) 

Purchased from other source 3.7 (1.3) 3.2 (0.6) 

All 45.5 (14.4) 5.0 (0.5) 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 23

Section I: Population Estimates—B. Herd Addition Risks

4. Replacement

heifer calves

The percentage of operations in which heifers

were born and raised on the operation decreased

from 2002 to 2007. Accordingly, the percentage

of heifers that were born on the operation and

raised off the operation increased from 2002 to

2007, while the percentage of heifers born off

the operation decreased. In 2002 and 2007, the

majority of heifers were born and raised on the

same operation, and the majority of operations

had heifers that were born and raised on the

operation. In 2007, more than 9 of 10 operations

(96.5 percent) had some heifers that were born

and raised on the operation; these operations

accounted for 87.4 percent of heifers. On

4.7 percent of operations, heifers were born on

the operation and raised off-site; these

operations accounted for 11.5 percent of heifers.

Of the January 1, 2007, heifer inventory,

12.6 percent of heifers spent part of their lives at

another facility; they were either born on the

operation and raised elsewhere (11.5 percent) or

born off the operation (1.1 percent).

a. Percentage of operations1 and percentage of heifers2, by source of heifer 

replacements 

Dairy 2002 Dairy 2007 

Operations Heifers Operations Heifers 

Source of 

Replacement Heifers Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Born and raised 

on operation 98.1 (0.3) 89.5 (1.0) 96.5 (0.4) 87.4 (1.2) 

Born on operation, 

raised off operation 3.6 (0.4) 7.2 (0.8) 4.7 (0.5) 11.5 (1.2) 

Born off operation 6.7 (0.7) 3.3 (0.8) 6.6 (0.8) 1.1 (0.2) 

Total 100.0 100.0 

1

Operations with any dairy cows.

2

As a percentage of January 1 heifer inventory.
24 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks

Less than 1 of 10 operations (9.3 percent) raised

heifers off-site in 2007. The percentage of

operations using off-site heifer raisers increased

as herd size increased, which was true for all

heifer classes. Nearly one-half of large

operations (46.0 percent) raised heifers off-site,

compared with a noticeably smaller percentage

of medium (15.5 percent) and small

(4.7 percent) operations. Preweaned heifers

were raised off-site by over one-third of large

operations (35.3 percent), compared with

7.1 percent of medium and 1.7 percent of small

operations. Similar herd-size differences were

also seen in the percentages of operations that

raised weaned and bred heifers off-site.

b. Percentage of operations* that raised any heifers off-site, by heifer class and by 

herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Heifer Class Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Preweaned 1.7 (0.5) 7.1 (1.2) 35.3 (2.9) 4.6 (0.5) 

Weaned 4.3 (0.7) 14.6 (1.6) 44.2 (2.9) 8.6 (0.7) 

Bred 4.1 (0.7) 11.5 (1.5) 22.5 (2.3) 6.7 (0.6) 

Any 4.7 (0.7) 15.5 (1.7) 46.0 (2.9) 9.3 (0.7) 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 25

Section I: Population Estimates—B. Herd Addition Risks

A major biosecurity concern related to off-site

rearing facilities is the potential for heifers from

one operation to have contact with animals from

another operation. These contacts increase the

likelihood that heifers will be exposed to new

pathogens that can be carried back to their

operations of origin. Ideally, only calves from a

single operation would be housed at an off-site

rearing facility. In 2007, about one-third of

operations (36.2 percent) sent heifers to rearing

facilities where they had no contact with cattle

from other operations. Nearly two-thirds of

operations that sent heifers off-site to be raised

(63.8 percent) sent heifers to rearing facilities

where they had contact with cattle from other

operations.

c. Percentage of operations* that sent heifers off-site to be raised, by primary offsite rearing facility 

Off-site Rearing Facility 

Percent 

Operations 

Standard 

Error 

Heifers sent to a single rearing facility and 

did not have contact with cattle from 

other operations 

27.7 (3.3) 

Heifers sent to multiple rearing facilities 

and did not have contact with cattle from 

other operations 

8.5 (2.1) 

Heifers sent to a single rearing facility 

and had contact (commingled) with cattle 

from other operations 

51.3 (4.0) 

Heifers sent to multiple rearing facilities and 

had contact (commingled) with cattle from 

other operations 

12.5 (3.0) 

Total 100.0 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007. 
26 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks

5. Vaccination

requirements

There are several ways to decrease the risk

associated with introducing new animals.

Vaccination, quarantine, pre-introduction

screening tests, testing of the source herd, and

preventive treatments are all management

practices that can reduce the disease risks

associated with introducing new animals.

Knowing the vaccination history and status of

new cattle entering the operation and requiring

vaccination of new cattle against specific

diseases prior to entry can protect the herd from

the risk of diseases introduced by the new cattle.

In addition, the new cattle can be protected from

diseases endemic to the operation through

vaccination.

Of operations bringing dairy cattle from outside

sources onto the operation, less than one-half

(47.2 percent) required vaccination of new

additions prior to arrival. The vaccinations most

commonly required were: bovine viral diarrhea

(BVD) [42.9 percent of operations]; infectious

bovine rhinotracheitis (IBR) [41.9 percent of

operations]; leptospirosis (38.8 percent of

operations); and brucellosis (35.6 percent of

operations). For the diseases listed in the

following table, a lower percentage of small

operations required vaccination of new

additions prior to arrival than medium or large

operations.

No change occurred from 1996 to 2007 in the

percentages of operations that vaccinated new

additions for BVD, IBR, and leptospirosis

before the cattle were brought onto the

operation. With the exception of Neospora,

about one-third to one-half of operations

vaccinated for the diseases mentioned in the

following table. The percentage of operations

that vaccinated for brucellosis decreased for

each herd size from 1996 to 2007. Since many

different ages of cattle were brought onto

operations, the lower brucellosis vaccination

percentages may partially be due to cattle too

old for vaccination or to cattle that were already

vaccinated for brucellosis at the time of

purchase. Neospora vaccination remained

unchanged in purchased cattle since 2002 for

small, large, and all operations. The percentages

of operations that vaccinated for any disease

decreased for small, large, and all operations.
USDA APHIS VS / 27

Section I: Population Estimates—B. Herd Addition Risks

Percentage of operations* that normally required vaccination against the following 

diseases before bringing animals onto the operation, by herd size 

Percent Operations 

Herd Size (Number of Cows) 

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Disease 1996 2002 2007 1996 2002 2007 1996 2002 2007 1996 2002 2007 

Brucellosis 48.9 

(2.5) 

33.4 

(2.5) 

28.0 

(2.6) 

63.6 

(2.9) 

51.3 

(2.7) 

50.2 

(3.5) 

85.2 

(3.0) 

60.0 

(3.1) 

52.2 

(3.9) 

52.9 

(2.0) 

39.9 

(1.9) 

35.6 

(2.0) 

Bovine viral 

diarrhea (BVD) 

43.1 

(2.4) 

36.2 

(2.5) 

34.8 

(2.8) 

59.4 

(2.9) 

51.2 

(2.7) 

59.9 

(3.4) 

58.8 

(4.8) 

53.9 

(3.2) 

56.7 

(3.7) 

46.8 

(2.0) 

41.3 

(1.9) 

42.9 

(2.1) 

Infectious 

bovine 

rhinotracheitis 

(IBR) 

39.2 

(2.3) 

35.8 

(2.6) 

34.2 

(2.8) 

57.9 

(2.9) 

50.5 

(2.7) 

57.3 

(3.4) 

57.4 

(4.8) 

51.2 

(3.2) 

57.1 

(3.7) 

43.4 

(1.9) 

40.8 

(1.9) 

41.9 

(2.1) 

Leptospirosis 41.9 

(2.4) 

32.5 

(2.5) 

32.0 

(2.7) 

57.7 

(2.9) 

48.5 

(2.7) 

53.6 

(3.4) 

54.3 

(4.8) 

47.5 

(3.2) 

48.4 

(3.8) 

45.4 

(2.0) 

37.8 

(1.8) 

38.8 

(2.1) 

Neospora NA 11.1 

(1.6) 

10.8 

(1.7) NA 15.5 

(1.8) 

26.6 

(3.1) NA 16.1 

(2.3) 

22.4 

(3.3) NA 12.6 

(1.2) 

15.7 

(1.5) 

Other 8.2 

(1.1) 

4.3 

(0.8) 

4.2 

(1.1) 

12.8 

(2.2) 

8.4 

(1.4) 

8.7 

(1.8) 

16.5 

(3.6) 

7.7 

(1.5) 

6.5 

(1.6) 

9.4 

(1.0) 

5.6 

(0.7) 

5.5 

(0.9) 

Any 58.0 

(2.5) 

44.6 

(2.7) 

37.7 

(2.9) 

74.8 

(2.6) 

64.0 

(2.7) 

65.2 

(3.3) 

88.8 

(2.9) 

71.9 

(3.0) 

68.5 

(3.2) 

62.3 

(2.0) 

51.6 

(2.0) 

47.2 

(2.2) 

*Operations with any dairy cows. 

()=standard error. 
28 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks
USDA APHIS VS / 29

Section I: Population Estimates—B. Herd Addition Risks

6. Quarantine For the purpose of this report, quarantine is

defined as the physical separation of an animal

or group of animals from other cattle on the

operation. Purchased cattle should be

quarantined for a minimum of 10 days and,

ideally, up to 3 weeks (Villarroel et al., 2007).

Quarantining can reduce the likelihood that new

diseases will be introduced to the operation and

usually provides sufficient time for the

incubation and detection of some infectious

diseases, namely: salmonellosis, vesicular

stomatitis, foot-and-mouth disease, clinical

BVD virus infections, and infections due to IBR

virus. Quarantining is not effective in detecting

infectious diseases with long incubation periods,

such as Johne’s disease and Neospora

(Villarroel et al., 2007).

The objective of implementing a quarantine

period is to prevent the transmission of

respiratory, gastrointestinal, reproductive, and

mastitis pathogens between animals.

Quarantined animals should have no physical

contact with other animals. Physical contact

includes sniffing, touching, licking, nose-to-nose

contact, shared fence lines, and shared waterers

or feeders. Additionally, resident cattle should

not have contact with the secretions, fluids, or

manure of quarantined cattle, or the pen runoff

from quarantined cattle. Moreover, the

quarantine area should be far enough away from

resident cattle to prevent airborne disease

transmission.

In addition to the prevention of physical contact

between new additions and resident cattle,

attention must be paid to the people and

equipment entering and leaving the quarantine

area. Dedicating equipment and personnel

exclusively to the quarantine area is the best

way to prevent the spread of agents from

quarantined animals. However, dedicating

equipment and personnel exclusively to the

quarantine area is not always feasible. In this

case, equipment should be cleaned and

disinfected before it is used outside the

quarantine area. Personnel that care for both

resident animals and quarantined new additions

should work with the quarantined animals last

and should wash their hands, change clothes,

and clean and disinfect their boots before

entering and leaving the quarantine area. Finally,

personnel should be trained to recognize signs

of illness in animals and frequently monitor the

quarantined animals for signs of illness or

disease.
30 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks

Of operations that brought on new cattle in 2002

and 2007, approximately one of five (20.6 and

20.3 percent, respectively) quarantined new

cattle. On operations that quarantined new cattle

in 2007, the most common age groups

quarantined were preweaned dairy or beef

calves (44.2 percent of operations), beef heifers

and cows (30.1 percent of operations), weaned

steers (30.0 percent of operations), and dairy

heifers, weaned but not bred (23.0 percent of

operations). The most common additions to

herds—bred dairy heifers, lactating cows, and

dairy bulls—were quarantined on less than 20

percent of operations (14.5, 12.1, and

17.1 percent, respectively). There were no

differences in the percentages of operations that

quarantined new cattle of any class from 1996 to

2007.

a. Percentage of operations* that quarantined the following classes of cattle on 

arrival 

Percent 

Operations 

Percent 

Operations 

Cattle Class

Dairy 

1996 

Std. 

Error Cattle Class 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Preweaned 

calves 

(dairy or beef) 

26.9 (5.2) 

Preweaned 

calves (dairy 

or beef) 

37.0 (7.3) 44.2 (8.3) 

Dairy heifers 

weaned, but 

not bred 

24.9 (4.7) 

Dairy heifers 

weaned, but 

not bred 

23.9 (3.9) 23.0 (4.7) 

Bred dairy 

heifers 16.0 (2.0) Bred dairy heifers 19.6 (2.3) 14.5 (2.3) 

Lactating 

dairy cows 6.2 (1.7) Lactating dairy cows 

9.5 (1.6) 12.1 (2.4) 

Dry dairy cows 17.9 (4.8) Dry dairy cows 7.1 (2.2) 15.9 (4.8) 

Dairy bulls 

(weaned) 15.9 (2.4) 17.1 (2.9) 

Bulls (weaned) 11.2 (2.4) Beef bulls 

(weaned) 23.6 (6.5) 20.3 (6.5) 

Other heifers 

and cows 

(including beef) 

15.7 (6.0) Beef heifers 

and cows` 24.0 (8.5) 30.1 (9.8) 

Steers 

(weaned) 21.0 (6.6) Steers (weaned) 40.0 (11.4) 30.0 (9.6) 

Any 16.2 (1.5) Any 20.6 (1.6) 20.3 (1.7) 

*Operations with any dairy cows. 
USDA APHIS VS / 31

Section I: Population Estimates—B. Herd Addition Risks

The operation average number of days in

quarantine for preweaned calves and weaned but

not bred heifers were similar from 1996 to 2007.

Preweaned calves spent about 40 days in

quarantine and weaned but not bred heifers were

quarantined for about 20 days. The length of

quarantine for dry cows increased from an

average of 8.9 days in 1996 to an average of

16.5 days in 2007.

b. Operation* average number of days new arrivals were quarantined, by cattle 

class 

Average Number 

of Days 

Average Number 

of Days 

Cattle Class

Dairy 

1996 

Std. 

Error Cattle Class 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Preweaned 

calves 

(dairy or beef) 

40.8 (5.7) 

Preweaned 

calves (dairy 

or beef) 

49.2 (9.3) 42.4 (4.8) 

Dairy heifers 

weaned, but 

not bred 

21.5 (4.2) 

Dairy heifers 

weaned, but 

not bred 

28.2 (6.0) 20.0 (3.6) 

Bred dairy 

heifers 16.8 (2.3) Bred dairy heifers 23.7 (4.0) 22.0 (3.1) 

Lactating 

dairy cows 11.7 (2.3) Lactating dairy cows 

20.1 (4.1) 15.6 (2.5) 

Dry dairy 

cows 8.9 (2.1) Dry dairy cows 21.4 (4.3) 16.5 (4.3) 

Dairy bulls 

(weaned) 19.0 (2.5) 25.3 (3.5) Bulls 

(weaned) 21.0 (3.1) Beef bulls 

(weaned) 32.0 (12.9) 31.9 (12.6) 

Other heifers 

and cows 

(including 

beef) 

24.3 (9.1) Beef heifers 

and cows` 31.1 (6.6) 33.3 (12.1) 

Steers 

(weaned) 41.5 (22.0) Steers (weaned) 41.3 (14.0) 40.7 (18.7) 

*Operations with any dairy cows.
32 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks

7. Testing

requirements

Testing individual animals for specific diseases

before introducing them to the operation reduces

the risk of introducing new diseases to the

operation.

Nearly one-fourth of operations (23.3 percent)

required testing for new additions in 2007. Of

operations that brought beef or dairy cattle onto

the operation, a higher percentage of large and

medium operations (34.7 and 28.2 percent,

respectively) than small operations

(20.2 percent) required pre-introduction testing.

The diseases most frequently tested for by all

operations included: brucellosis, bovine

tuberculosis (TB), and BVD (14.3, 13.8, and

13.3 percent of operations, respectively). There

was no substantial change from 2002 to 2007 in

the percentages of operations that tested new

additions for brucellosis, Johne’s disease, BVD,

or TB.

Brucellosis testing for new additions decreased

across herd sizes from 1996 to 2007. TB testing

also decreased for small, large, and all

operations from 1996 to 2007. Testing for

Mycobacterium avium subspecies

paratuberculosis and BVD remained unchanged

for all operations from 1996 to 2007. The

percentage of operations that performed any

testing decreased for small, large, and all

operations from 1996 to 2007. Less than one of

four operations that added new additions

(23.3 percent) performed any testing during

2007.
USDA APHIS VS / 33

Section I: Population Estimates—B. Herd Addition Risks

a. Percentage of operations* that required testing of individual animals before introduction to 

the herd, by disease and by herd size 

Percent Operations 

Herd Size (Number of Cows) 

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Disease 1996 2002 2007 1996 2002 2007 1996 2002 2007 1996 2002 2007 

Brucellosis 28.5 

(2.1) 

13.1 

(1.8) 

11.6 

(1.9) 

38.3 

(2.9) 

19.5 

(2.1) 

19.8 

(2.8) 

50.6 

(4.4) 

29.9 

(2.7) 

19.0 

(3.0) 

31.0 

(1.7) 

15.9 

(1.3) 

14.3 

(1.5) 

Mycobacterium 

avium 

subspecies 

paratuberculosis

(Johne’s 

disease) 

8.5 

(1.3) 

8.3 

(1.4) 

9.9 

(1.8) 

11.0 

(2.3) 

12.7 

(1.9) 

16.6 

(2.7) 

9.6 

(2.9) 

12.2 

(1.9) 

7.2 

(1.8) 

9.1 

(1.1) 

9.8 

(1.1) 

11.4 

(1.4) 

Bovine viral 

diarrhea (BVD) 

15.1 

(1.6) 

8.6 

(1.4) 

10.7 

(1.8) 

18.4 

(2.5) 

15.6 

(2.1) 

19.4 

(2.8) 

19.4 

(3.9) 

15.0 

(2.1) 

15.8 

(2.7) 

15.9 

(1.3) 

10.9 

(1.1) 

13.3 

(1.4) 

Bovine 

tuberculosis (TB) 

22.3 

(1.9) 

10.8 

(1.5) 

12.0 

(1.8) 

26.8 

(2.7) 

14.3 

(1.7) 

17.8 

(2.7) 

31.4 

(4.2) 

20.7 

(2.3) 

15.8 

(2.3) 

23.4 

(1.6) 

12.4 

(1.1) 

13.8 

(1.4) 

Contagious 

mastitis 

pathogens 

NA NA 10.5 

(1.8) NA NA 13.1 (2.3) NA NA 16.3 (3.3) NA NA 11.7 (1.4) 

Other 2.3 

(0.5) 

2.8 

(0.8) 

1.6 

(0.6) 

3.6 

(1.4) 

4.3 

(1.3) 

2.2 

(1.0) 

3.9 

(2.1) 

3.5 

(1.1) 

0.4 

(0.2) 

2.6 

(0.5) 

3.2 

(0.6) 

1.7 

(0.5) 

Any 31.3 

(2.1) 

21.2 

(2.2) 

20.2 

(2.4) 

40.0 

(2.9) 

29.4 

(2.5) 

28.2 

(3.2) 

54.3 

(4.5) 

38.8 

(2.9) 

34.7 

(3.8) 

33.7 

(1.8) 

24.5 

(1.6) 

23.3 

(1.8) 

*Operations with any dairy cows. 

()=standard error.
34 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks
USDA APHIS VS / 35

Section I: Population Estimates—B. Herd Addition Risks

Of operations that in 2007 did not require that

new cattle be tested before introduction into the

herd regardless of disease, about one-fourth

reported that testing had been performed at the

herd of origin or that the disease was not a

concern to their operation. “Other” reasons for

not requiring testing included: animals were not

eligible for testing; animals were not at risk for

disease transmission (such as testing weaned

heifers or bulls for contagious mastitis

pathogens); owners trusted the herd of origin;

owners vaccinated and tested after the animals

arrived; owners did not know how to vaccinate

and/or test; and owners were bringing back their

own cattle.

b. For operations that brought beef or dairy cattle onto the operation and did not 

require individual animal testing, percentage of operations* by reason for not 

testing and by disease 

Percent Operations 

Disease 

Brucellosis 

Johne’s 

Disease BVD TB 

Contagious 

Mastitis 

Pathogens 

Reason Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Tests already 

performed by 

herd of origin 

25.6 (2.0) 22.3 (1.9) 25.9 (2.1) 25.1 (2.0) 23.8 (1.9) 

Too expensive 

to test 4.3 (1.1) 5.9 (1.3) 4.1 (1.0) 4.2 (1.1) 4.3 (1.0) 

Not enough 

time to test 9.5 (1.7) 8.9 (1.5) 9.9 (1.6) 9.4 (1.6) 10.7 (1.7) 

Not 

recommended by 

veterinarian 

7.7 (1.3) 6.8 (1.2) 6.1 (1.2) 7.4 (1.3) 5.7 (1.1) 

Too many 

sources to test 2.5 (0.9) 1.8 (0.6) 2.7 (0.9) 2.3 (0.9) 2.8 (0.9) 

Tests not reliable 0.2 (0.2) 4.4 (1.0) 1.0 (0.4) 0.7 (0.3) 0.7 (0.3) 

Disease is 

not a concern to 

my operation 

28.0 (2.3) 28.6 (2.2) 27.5 (2.2) 29.1 (2.3) 27.9 (2.2) 

Other 22.2 (1.9) 21.3 (1.9) 22.8 (2.0) 21.8 (1.9) 24.1 (2.0) 

Total 100.0 100.0 100.0 100.0 100.0 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007.
36 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks

8. Herd-of-origin

disease status

Test results from the herd of origin can provide

an indication of whether cattle from a particular

herd may be infected with certain disease

organisms. For many diseases, such as Johne’s

disease and contagious mastitis, knowing the

disease status of the herd of origin can be more

reliable than testing individual animals (Wells,

2000). In 2007 almost 3 of 10 operations

(28.7 percent) required some information on the

disease status of the herd of origin. The most

commonly requested information was bulk-tank

somatic cell count. The second and third most

often requested test results were BVD status and

Johne’s disease status (18.9 and 17.2 percent of

operations, respectively). The percentage of

operations that required bulk-tank cultures for

mastitis-causing organisms varied between small

and large operations, with a lower percentage of

small operations than large operations requiring

cultures (10.1 and 20.9 percent, respectively).

a. Percentage of operations* by herd-of-origin information normally required by 

operation, and by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Herd-of-origin 

Information Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

BVD status 16.7 (2.3) 24.5 (3.0) 19.8 (3.0) 18.9 (1.7) 

Johne’s disease 

(Mycobacterium 

paratuberculosis) 

status 

16.0 (2.2) 21.9 (2.9) 12.7 (2.3) 17.2 (1.7) 

Bulk-tank milk 

somatic cell count 18.8 (2.4) 24.4 (3.1) 19.8 (2.9) 20.3 (1.8) 

Bulk-tank 

milk culture 10.1 (1.7) 17.8 (2.8) 20.9 (2.9) 13.0 (1.4) 

Other 2.8 (1.0) 2.3 (1.2) 1.3 (0.8) 2.6 (0.7) 

Any information 25.4 (2.7) 36.0 (3.4) 32.9 (3.3) 28.7 (2.0) 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007.
USDA APHIS VS / 37

Section I: Population Estimates—B. Herd Addition Risks

For operations that did not require herd-oforigin information on the disease status for new

arrivals in 2007, the most common reasons

given for not requiring information

(approximately 30 percent of operations across

categories) were that the disease and/or bulktank milk somatic cell counts were not a concern

to the operation. Additionally, 30.0 percent of

these operations indicated that bulk-tank milk

cultures from the herd of origin were not a

concern to their operation, despite the fact that

bulk-tank milk cultures are used to identify

mastitis pathogens. Mastitis was the most

prevalent disease-causing illness in cows, the

second highest reported reason for removing

cows from the herd, and the second highest

reported cause of death. Similarly, 30.5 percent

of operations that did not require herd-of-origin

information indicated that BVD was not a

concern to their operation, even though

infertility—which can be associated with

BVD—was the third most prevalent disease on

operations. Moreover, reproductive problems,

which include infertility, were the most common

reason for permanently removing cows from the

operation.

Other reasons for not evaluating herd-of-origin

information were similar to reasons for not

testing incoming cattle: trusted the herd of

origin, owned the herd of origin, would address

disease issues after cattle arrived, and did not

know to test or inquire about these diseases.
38 / Dairy 2007

Section I: Population Estimates—B. Herd Addition Risks

b. For operations that brought beef or dairy cattle onto the operation and did not 

require the following herd-of-origin information, percentage of operations* by 

reason for not requiring information 

Percent Operations 

Herd-of-origin Information 

BVD Status

Johne’s 

Disease Status

Bulk-tank Milk 

Somatic Cell 

Count 

Bulk-Tank 

Milk Culture 

Reason 

Not Required Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Tests already 

performed by 

herd of origin 

18.6 (1.8) 15.2 (1.6) 15.2 (1.6) 15.7 (1.6) 

Too expensive 

to test 3.9 (1.1) 4.4 (1.2) 3.2 (1.0) 3.8 (1.1) 

Not enough 

time to test 9.3 (1.6) 9.3 (1.5) 9.2 (1.6) 10.6 (1.6) 

Not 

recommended 

by veterinarian 

8.1 (1.4) 8.9 (1.4) 8.6 (1.4) 8.4 (1.4) 

Too many 

sources to test 3.0 (1.0) 3.0 (1.0) 3.5 (1.1) 3.1 (1.0) 

Tests not 

reliable 1.1 (0.4) 3.3 (0.9) 1.5 (0.5) 1.4 (0.5) 

Not a concern to 

the operation 30.5 (2.4) 31.6 (2.3) 30.2 (2.3) 30.0 (2.3) 

Other 25.5 (2.2) 24.3 (2.1) 28.6 (2.2) 27.0 (2.1) 

Total 100.0 100.0 100.0 100.0 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007.
USDA APHIS VS / 39

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

C. On-farm Biosecurity and Biocontainment Practices

1. Employees and

visitors

Employees or visitors—especially those who

have contact with animals off the operation—

can introduce disease agents via their boots,

clothing, vehicles, or other equipment. As

people travel more frequently throughout the

world, the risk increases for inadvertent or

intentional introduction of disease agents

foreign to the United States. Establishing written

policies or guidelines pertaining to visitor and

employee animal contacts and travel is an

important step in reducing the risk of disease

introduction.

The percentage of operations that had

employees increased from 47.2 percent in 2002

to 75.7 percent in 2007. The percentage of small

operations with employees doubled from

32.2 percent in 2002 to 65.6 percent in 2007.

a. Percentage of operations that had employees during the previous 12 months, 

by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Study Year Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

2002 32.2 (2.5) 84.2 (2.4) 99.0 (0.6) 47.2 (2.0) 

2007* 65.6 (4.1) 95.0 (2.0) 98.0 (1.9) 75.7 (2.8) 

*Question variation: 2007 estimates specifically exclude owners and family members. 

Source: NAHMS Dairy 2007. 
40 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

Not surprisingly, the number of full-time

employees increased as herd size increased.

Small operations averaged 2.0 full-time

employees compared with 3.8 and 12.9 full-time

employees on medium and large operations,

respectively. Medium operations employed

more part-time people on average than large

operations (2.4 and 1.2 employees,

respectively).

b. Operation average number of employees, by employee type and by herd size 

Operation Average Number Employees* 

Herd Size (Number of Cows) 

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Employee Type Avg. 

Std. 

Error Avg. 

Std. 

Error Avg. 

Std. 

Error Avg. 

Std. 

Error 

Full-time 2.0 (0.1) 3.8 (0.1) 12.9 (0.8) 3.1 (0.1) 

Part-time 1.8 (0.1) 2.4 (0.2) 1.2 (0.2) 1.9 (0.1) 

*Paid and unpaid, including owners and family members assigned work duties directly related to the dairy’s 

operation. 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 41

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices
42 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

Operations in the West region averaged more

full-time employees (7.8) than operations in the

East region (2.7). Operations in the East region

averaged more part-time employees than

operations in the West region. These differences

were likely related to the larger herd sizes in the

West region.

c. Operation average number of employees, by employee type and by region 

Operation Average Number Employees* 

Region 

West East 

Employee Type Average Std. Error Average Std. Error 

Full-time 7.8 (0.7) 2.7 (0.1) 

Part-time 1.0 (0.1) 2.0 (0.1) 

*Paid and unpaid, including owners and family members assigned work duties directly related to the dairy’s 

operation. 

Source: NAHMS Dairy 2007. 

Photo courtesy of Dr. Jason Lombard.
USDA APHIS VS / 43

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

In addition to employees, dairy operations have

regular and frequent visits from a variety of

people doing business with the operation,

including delivery people, milk haulers, cattle

haulers, artificial insemination technicians,

nutritionists, and veterinarians. These people,

who may or may not have contact with cattle on

the operation and multiple other operations,

have the potential to carry diseases from one

operation to another.

d. Percentage of operations by number of visits* per week and by herd size 

Percent Operations 

Herd Size (Number of Cows) 

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Number of 

Visits 

(per Week) Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

1 to 7 35.6 (3.7) 13.7 (3.0) 1.2 (0.7) 28.0 (2.7) 

8 to 14 28.4 (3.6) 16.5 (3.3) 0.8 (0.5) 23.6 (2.6) 

15 to 21 9.0 (2.0) 12.5 (2.8) 13.7 (4.8) 10.2 (1.6) 

22 to 28 7.0 (1.7) 9.7 (2.6) 12.1 (4.0) 8.0 (1.4) 

29 or more 20.0 (3.1) 47.6 (4.1) 72.2 (5.3) 30.2 (2.4) 

Total 100.0 100.0 100.0 100.0 

*Includes employees, veterinarians, neighbors, nutritionists, milk haulers, etc. 

Source: NAHMS Dairy 2007. 

In an average week, over one-half of all

operations (51.6 percent) had between 1 and

14 visits by people coming onto the operation.

Nearly two-thirds of small operations reported

between 1 and 14 visits, and one-fifth of small

operations reported 29 or more visits per week.

As expected, the number of visits per week

increased as herd size increased. Nearly threefourths of large operations (72.2 percent)

reported 29 or more visits per week compared

with about one-half of medium operations

(47.6 percent) and one-fifth of small operations

(20.0 percent).
44 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

For operations in which any visits to the

operation involved contact with animals on the

operation, about one-half of operations

(50.7 percent) had one to seven visits per week

that involved contact with animals on the

operation. About 1 of 6 operations

(16.0 percent) had 29 or more visits that resulted

in contact with animals. The number of visits

that involved animal contact increased as herd

size increased.

e. Percentage of operations by number of visits per week that involved animal 

contact, and by herd size 

Percent Operations 

Herd Size (Number of Cows) 

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Number of 

Visits 

(Per Week) Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

0 or None 8.7 (1.9) 1.5 (0.7) 0.0 (0.0) 6.4 (1.3) 

1 to 7 61.3 (3.7) 31.0 (3.8) 10.3 (3.7) 50.7 (2.8) 

8 to 14 7.2 (1.9) 13.1 (2.8) 10.9 (3.8) 8.9 (1.5) 

15 to 21 10.5 (2.4) 13.5 (3.1) 7.9 (3.4) 11.1 (1.8) 

22 to 28 5.9 (1.8) 9.7 (2.2) 6.2 (3.1) 6.9 (1.4) 

29 or more 6.4 (1.8) 31.2 (3.6) 64.7 (5.4) 16.0 (1.6) 

Total 100.0 100.0 100.0 100.0 
USDA APHIS VS / 45

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices
46 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

2. Specific

biosecurity

practices

Implementing biosecurity practices reduces the

introduction of disease. Since employees and

visitors are potential sources of disease,

operations should have restrictions and

guidelines for employees and visitors designed

to limit disease introduction.

Specific biosecurity practices that help keep

human and vehicle traffic in animal areas to a

minimum include: controlling the number of

visitors and their contact with animals,

establishing a designated farm entrance and

visitor parking, and requiring that visitors check

in at the office. In addition, locating feed storage

areas and areas for carcass pickup at the

perimeter of the operation restricts vehicle

contact with animal areas on the operation.

Requiring visitors who enter animal areas to

have clean boots and clothing, or providing

them with boots and coveralls, also helps reduce

the risk of disease introduction.

Approximately one of five operations with

employees (18.1 percent) had restrictions on

employee ownership of livestock outside the

operation in 2007. Overall, about 1 of 10

operations had guidelines regarding foreign

travel by employees: 14.7 percent of large,

16.0 percent of medium, and 9.7 percent of

small operations had such guidelines.

Biosecurity plans are easiest to implement if

they are in writing and reviewed and adjusted

periodically to meet the changing needs of the

operation (Center for Food Security and Public

Health-b). Written plans can be referred to at

any time for review and to address questions

about the plan’s requirements. In 2007, only

1 of 10 operations (12.2 percent) had written

standard operating procedures (SOPs) for

procedures other than milking. A higher

percentage of large operations (23.0 percent)

had written SOPs than medium and small

operations (13.2 and 10.9 percent, respectively).

Training employees in proper practices is also

critical to the success of any biosecurity

program. For a plan to be successful, all team

members must understand and support the plan.

A higher percentage of large operations

(47.3 percent) trained employees in performing

biosecurity practices in 2007 compared with

medium and small operations (23.7 and

17.8 percent, respectively).
USDA APHIS VS / 47

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

The percentage of operations that placed

restrictions on employee ownership of livestock

outside the operation, had guidelines regarding

foreign travel by employees, and trained

employees in performing biosecurity practices

declined from 2002 to 2007. Alternatively, the

percentage of operations that had written SOPs

(other than milking procedures) increased from

5.1 percent in 2002 to 12.2 percent in 2007.

a. Percentage of operations by employee biosecurity practices used and by herd size 

Percent Operations 

Herd Size (Number of Cows) 

Small 

(Fewer than 100)

Medium 

(100-499)

Large 

(500 or More)

All 

Operations 

2002 2007 2002 2007 2002 2007 2002 2007 

Employee 

Biosecurity 

Practice Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Restrictions 

on employee 

livestock 

ownership 

outside this 

operation 

19.7 (3.5) 17.4 (3.7) 34.6 (3.1) 18.6 (3.5) 38.6 (4.1) 20.1 (4.7) 27.7 (2.2) 18.1 (2.5) 

Guidelines 

regarding 

foreign travel 

by employees 

19.9 (4.1) 9.7 (2.7) 22.6 (2.6) 16.0 (3.6) 28.8 (3.9) 14.7 (3.7) 21.8 (2.3) 12.0 (2.0) 

Written SOP 

(other than 

milking 

procedures) 

7.4 (2.4) 10.9 (2.7) 6.7 (1.4) 13.2 (2.9) 18.9 (13.1) 23.0 (4.8) 5.1 (0.8) 12.2 (2.0) 

Training for 

employees in 

performing 

biosecurity 

practices 

35.0 (4.5) 17.8 (3.4) 48.5 (3.3) 23.7 (3.6) 50.9 (4.2) 47.3 (6.2) 42.1 (2.7) 21.9 (2.5) 
48 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

In 2007, 3 of 10 operations (30.4 percent) had

guidelines for determining which visitors were

allowed in animal areas, and 6.9 percent had

footbaths for visitors entering animal areas.

About twice the percentage of large operations

(12.1 percent) had footbaths compared with

medium and small operations (7.2 and

6.3 percent, respectively). Over one-fourth of

operations that had visitors (28.3 percent)

provided disposable or clean boots to visitors

entering animal areas. A higher percentage of

medium and large operations (42.1 and

36.3 percent, respectively) provided footwear

A higher percentage of operations in 2007 than

in 2002 required disposable or clean boots for

visitors entering animal areas and had

restrictions on vehicles entering animal areas.

The percentage of operations that had guidelines

regarding which visitors were allowed in animal

areas or that had footbaths for visitors entering

animal areas remained unchanged from 2002 to

2007.

compared with small operations (22.7 percent).

Over one-half of operations (51.3 percent) had

restrictions on vehicles entering animal areas.

b. Percentage of operations by visitor biosecurity practices used and by herd size 

Percent Operations 

Herd Size (Number of Cows) 

Small 

(Fewer than 100)

Medium 

(100-499)

Large 

(500 or More)

All 

Operations 

2002 2007 2002 2007 2002 2007 2002 2007 

Visitor 

Biosecurity 

Practice Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Guidelines 

regarding 

which visitors 

are allowed in 

animal areas 

33.3 (2.9) 28.0 (3.4) 49.9 (3.3) 35.2 (4.3) 55.2 (4.4) 39.9 (5.9) 38.6 (2.0) 30.4 (2.6) 

Footbaths for 

visitors 

entering 

animal areas 

4.6 (1.2) 6.3 (1.7) 10.1 (1.8) 7.2 (1.9) 12.7 (2.1) 12.1 (3.5) 6.3 (1.0) 6.9 (1.3) 

Disposable or 

clean boots 

for visitors 

entering 

animal areas 

13.2 (2.0) 22.7 (3.3) 31.5 (3.0) 42.1 (4.2) 39.0 (4.2) 36.3 (5.5) 18.9 (1.6) 28.3 (2.6) 

Restrictions 

on vehicles 

entering 

animal areas 

40.4 (3.0) 51.0 (3.8) 46.3 (3.2) 54.5 (4.1) 39.0 (4.3) 41.9 (6.1) 41.8 (2.3) 51.3 (2.9) 
USDA APHIS VS / 49

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

The majority of operations used insect and

rodent control practices during 2002 and 2007.

Nearly one-half of operations limited cattle

contact with other livestock, elk, and deer and

controlled access to feed by other livestock and

wildlife. There were no differences in the

percentages of all operations that implemented a

specific biosecurity practice from 2002 to 2007.

In 2007, over one-half of operations

(56.2 percent) had closed herds, defined as all

replacements come from the operation and the

herd has no contact with cattle from other

operations. A higher percentage of small

operations than large operations (60.1 and

40.6 percent, respectively) were closed herds.

c. Percentage of operations that used the following biosecurity practices during the previous 

12 months to prevent disease, by herd size 

Percent Operations 

Herd Size (Number of Cows) 

Small 

(Fewer than 100)

Medium 

(100-499)

Large 

(500 or More)

All 

Operations 

2002 2007 2002 2007 2002 2007 2002 2007 

Biosecurity 

Practice Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Insect control 93.8 (1.3) 86.5 (2.7) 88.7 (2.1) 88.3 (2.7) 92.8 (2.0) 93.6 (3.0) 92.5 (1.1) 87.4 (2.0) 

Rodent 

control 96.0 (1.1) 95.7 (1.4) 91.7 (1.9) 91.8 (2.0) 88.6 (2.7) 90.3 (3.4) 94.7 (0.9) 94.4 (1.1) 

Bird control 25.2 (2.4) 29.4 (3.6) 38.8 (3.0) 44.3 (4.2) 42.1 (4.0) 41.4 (5.6) 29.1 (1.9) 33.8 (2.7) 

Limit cattle 

contact with 

other 

livestock, elk, 

and deer 

36.4 (2.7) 44.8 (3.8) 53.7 (3.0) 55.7 (4.2) 58.9 (4.1) 59.6 (5.6) 41.4 (2.1) 48.5 (2.8) 

Control 

access to 

cattle feed by 

other 

livestock and 

wildlife 

52.1 (2.7) 52.0 (3.9) 58.7 (2.9) 46.8 (4.2) 52.0 (4.2) 40.1 (5.4) 53.7 (2.1) 49.9 (2.9) 

Closed herd* 64.5 (2.7) 60.1 (3.9) 47.6 (3.1) 49.5 (4.2) 38.4 (4.2) 40.6 (5.6) 59.5 (2.1) 56.2 (2.9) 

*All replacements are from the operation; no contact with cattle from other operations. 
50 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

3. Calving/

maternity areas

Parturition presents disease risks to cows and

newborn calves. Periparturient cows may be

immunosuppressed, and newborn calves have

immature immune systems, placing both groups

at high risk for contracting disease (McGuirk

and Collins, 2004). Newborn calves are

susceptible to respiratory and enteric pathogens,

including Mycobacterium avium subspecies

paratuberculosis, which causes Johne’s disease.

Having a dedicated maternity area separate from

lactating cows reduces the risk of disease

transmission to both newborn calves and their

dams.

Nearly two-thirds of operations (60.0 percent)

had a separate maternity area from lactating

cows in 2007. About 9 of 10 large operations

and 8 of 10 medium operations (90.4 and

80.8 percent, respectively) had separate

maternity areas compared with 5 of 10 small

operations (51.5 percent). A higher percentage

of small and medium operations in 2007 than in

1996 housed maternity cows separately from

lactating cows. The use of separate maternity

housing increased from 45.4 percent of

operations in 1996 to 60.0 percent in 2007.

a. Percentage of operations* in which maternity housing was separate from 

housing used for lactating cows, by herd size 

Percent Operations 

Herd Size 

(Number of Cows) 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Small (fewer than 100) 39.1 (1.3) 43.5 (1.6) 51.5 (1.7) 

Medium (100 to 499) 72.6 (2.1) 81.6 (1.7) 80.8 (1.8) 

Large (500 or more) 94.5 (1.8) 91.9 (1.5) 90.4 (2.0) 

All operations 45.4 (1.2) 53.1 (1.3) 60.0 (1.3) 

*Operations with any dairy cows.
USDA APHIS VS / 51

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

The usual calving area was defined as an area

designated specifically for calving and separate

from housing for lactating cows. Tie stalls or

stanchions were not considered usual calving

areas for the purpose of this report. The

percentage of operations with a usual calving

area ranged from 62.5 percent of small

operations to 98.2 percent of large operations.

b. Percentage of operations that had a usual calving area, by herd size

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100)

Medium 

(100-499)

Large 

(500 or More)

All 

Operations 

Percent 

Std. 

Error Percent 

Std. 

Error Percent 

Std. 

Error Percent 

Std. 

Error 

62.5 (3.8) 83.7 (3.3) 98.2 (1.2) 70.1 (2.7) 

Source: NAHMS Dairy 2007. 

In 2007 nearly 90 percent of calves on

operations with a usual calving area were born

in the calving area. Large operations had a

higher percentage of calves born in a usual

calving area (93.6 percent) than small

operations (79.9 percent).

c. For the 70.1 percent of operations with a usual calving area, percentage of 

calves born in a usual calving area, by herd size 

Percent Calves 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

79.9 (2.0) 89.0 (1.3) 93.6 (1.3) 89.8 (0.9) 

Source: NAHMS Dairy 2007. 
52 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

A higher percentage of small operations

(37.6 percent) had between 0.0 and 75.9 percent

of calves born in a usual calving area compared

with medium and large operations (14.9 and

7.3 percent, respectively). In addition,

91.0 percent or more of calves were born in a

usual calving area on 33.8, 56.1, and

68.7 percent of small, medium, and large

operations, respectively.

d. Percentage of operations by percentage of calves born in a usual calving area, 

and by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Percent 

Calves Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

0.0 to 50.9 19.3 (3.8) 8.4 (2.5) 3.7 (2.0) 14.7 (2.5) 

51.0 to 75.9 18.3 (3.9) 6.5 (2.3) 3.6 (2.0) 13.5 (2.5) 

76.0 to 90.9 28.6 (4.3) 29.0 (4.2) 24.0 (4.5) 28.3 (3.0) 

91.0 to 99.9 16.6 (3.2) 38.4 (4.5) 45.8 (5.7) 25.6 (2.5) 

100 17.2 (3.3) 17.7 (3.3) 22.9 (5.5) 17.9 (2.3) 

Total 100.0 100.0 100.0 100.0 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 53

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

In 2007, 70.0 percent of operations used

multiple-animal areas or pens for calving. A

higher percentage of medium operations

(79.8 percent) used a multiple-animal area/pen

for calving compared with small operations

(65.6 percent).

Slightly more than one-fourth of operations

(25.5 percent) used an individual calving area/

pen that was cleaned between calvings, and onefourth of operations (26.2 percent) used an

individual calving area/pen that was cleaned

after two or more calvings.

e. Percentage of operations by area usually used for calving and by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Calving Area Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Multiple animal 

area/pen 65.6 (3.5) 79.8 (3.5) 78.5 (4.3) 70.0 (2.6) 

Individual animal 

area/pen cleaned 

between each 

calving 

30.6 (3.4) 14.6 (3.3) 13.5 (3.9) 25.5 (2.5) 

Individual animal 

area/pen cleaned 

after two or more 

calvings 

25.4 (3.3) 27.4 (3.7) 30.3 (5.6) 26.2 (2.5) 

Other 5.1 (1.7) 3.6 (1.4) 3.1 (1.7) 4.6 (1.2) 

Source: NAHMS Dairy 2007. 
54 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

Of operations with a usual calving area in 2007,

39.9 percent moved cows into the calving area

within a day prior to calving. Over 40 percent of

operations in the East region (41.4 percent)

placed cows in calving pens/areas within 1 day

of calving compared with less than 3 of

10 operations in the West region (28.6 percent).

Operations in the West region moved cows into

calving pens earlier than operations in the East

region.

f. For the 70.1 percent of operations with a usual calving area, percentage of 

operations by number of days cows remained in a usual calving area/pen prior

to calving, and by region 

Percent Operations 

Region 

West East All Operations 

Number of Days Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

1 or less 28.6 (4.9) 41.4 (3.6) 39.9 (3.2) 

1.1 to 3.0 8.3 (2.9) 15.4 (2.6) 14.6 (2.3) 

3.1 to 14.0 36.4 (5.6) 25.3 (3.1) 26.6 (2.8) 

14.1 or more 26.7 (4.9) 17.9 (2.5) 18.9 (2.3) 

Total 100.0 100.0 100.0 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 55

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

In 2007, few operations (12.9 percent) removed

cows from the calving area in the first hour after

calving. A higher percentage of small operations

(25.0 percent) left cows in the calving area for

more than 14 hours compared with large

operations (6.2 percent). On 41.4 percent of

operations, cows spent 3.1 to 14.0 hours in a

calving area/pen after calving.

g. For the 70.1 percent of operations with a usual calving area, percentage of 

operations by number of hours cows remained in the usual calving area/pen 

after calving, and by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Number of 

Hours Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Removed 

immediately 4.4 (1.8) 2.7 (1.3) 7.2 (3.0) 4.2 (1.2) 

0.25 to 1.0 8.0 (2.3) 7.8 (2.1) 16.5 (3.8) 8.7 (1.6) 

1.1 to 3.0 22.5 (4.0) 26.1 (4.0) 28.0 (5.4) 24.1 (2.8) 

3.1 to 14.0 40.1 (4.6) 44.0 (4.4) 42.1 (5.5) 41.4 (3.2) 

14.1 or more 25.0 (4.2) 19.4 (3.9) 6.2 (3.2) 21.6 (2.8) 

Total 100.0 100.0 100.0 100.0 

Source: NAHMS Dairy 2007. 
56 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

No regional differences were observed in the

length of time cows spent in the calving area

after calving in 2007.

h. For the 70.1 percent of operations with a usual calving area, percentage of 

operations by number of hours cows remained in the usual calving area/pen 

after calving, and by region 

Percent Operations 

Region 

West East 

Number of Hours Percent Std. Error Percent Std. Error 

Removed immediately 6.7 (2.7) 3.9 (1.3) 

0.25 to 1.0 7.3 (2.7) 8.9 (1.7) 

1.1 to 3.0 22.6 (4.9) 24.3 (3.1) 

3.1 to 14.0 44.6 (5.8) 41.0 (3.5) 

14.1 or more 18.8 (4.9) 21.9 (3.2) 

Total 100.0 100.0 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 57

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

Keeping sick cows in the calving area is a

potential source of disease for dams and

newborn calves. Over one-third of operations

(34.2 percent) allowed sick cows in the calving

area in 2007. A higher percentage of small

operations (37.3 percent) allowed sick cows in

the calving area compared with large operations

(16.5 percent). Almost one-half of operations

(51.6 percent) allowed lame cows into the

calving area.

i. For the 70.1 percent of operations with a usual calving area, percentage of 

operations that allowed sick and/or lame cows in the calving area, by cattle 

class and by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Cattle Class Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Sick cows 37.3 (4.6) 33.0 (4.5) 16.5 (4.4) 34.2 (3.2) 

Lame cows 51.8 (4.6) 57.9 (4.4) 28.6 (4.5) 51.6 (3.1) 

Other 5.4 (2.0) 5.8 (2.3) 4.1 (2.2) 5.4 (1.4) 

Any of the 

above 56.4 (4.6) 62.3 (4.2) 30.7 (4.6) 55.8 (3.1) 

Source: NAHMS Dairy 2007. 
58 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

The percentage of operations participating in a

Johne’s disease control or certification program

has increased for each herd size category and for

all operations since 1996. Less than 1 percent of

operations participated in a Johne’s disease

control or certification program in 1996

compared with 11.2 percent in 2002 and

31.7 percent in 2007.

j. Percentage of operations that participated in any Johne’s disease control or 

certification program, by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Study Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Dairy 1996* 1.0 (0.4) 0.5 (0.4) 0.4 (0.4) 0.9 (0.3) 

Dairy 2002* 9.5 (1.7) 16.5 (2.3) 11.3 (2.3) 11.2 (1.4) 

Dairy 2007 27.7 (3.3) 42.1 (4.1) 33.3 (4.5) 31.7 (2.5) 

*Question variation: In 1996: “Is this operation currently on a Johne’s certification program.” In 2002: “Does 

operation participate in a Johne’s disease herd status, control, or certification program.” 

A Johne’s disease control program may include

testing individual animals in order to identify

those shedding Mycobacterium avium

subspecies paratuberculosis, which present a

risk to uninfected animals on the operation. The

percentage of operations that tested for Johne’s

disease increased across herd sizes from 1996 to

2002 and for all operations from 1996 to 2007:

13.1 percent of operations tested for Johne’s in

1996, 25.7 percent tested in 2002, and

35.3 percent tested in 2007. A higher percentage

of medium operations (47.6 percent) tested for

Johne’s disease in 2007 compared with small

operations (30.7 percent). Based on the

percentage of operations that participated in a

control program (see previous table), a

substantial percentage of operations performed

testing without being formally enrolled in a

Johne’s disease control or certification program.
USDA APHIS VS / 59

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

k. Percentage of operations that performed any testing for Johne’s disease, by 

herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Study Year Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

1996* 10.5 (1.3) 22.0 (2.4) 19.9 (4.3) 13.1 (1.1) 

2002 20.4 (2.5) 39.5 (3.3) 38.3 (4.0) 25.7 (1.9) 

2007 30.7 (3.4) 47.6 (4.1) 37.5 (5.7) 35.3 (2.6) 

*Question variation: 1996 estimate was operations that tested in the last 24 months, while the 2002 and 2007 

estimates are for testing performed in the previous 12 months.

Cows test-positive for Johne’s disease can

contaminate the calving area and transmit the

disease to newborn calves. Test-positive animals

should not be allowed in the calving area or

other calf areas. There was no herd-size

difference in the percentage of operations that

allowed Johne’s disease test-positive animals

into the calving area; 15.5 percent of operations

that tested for Johne’s disease allowed testpositive cows in the calving area in 2007.

l. For operations with a usual calving area and that tested for Johne’s disease, 

percentage of operations that allowed Johne’s test-positive cows in the usual 

calving area, by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

12.0 (4.5) 18.0 (5.0) 30.2 (8.3) 15.5 (3.2) 

Source: NAHMS Dairy 2007. 
60 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

4. Newborn calf

risks and contact

with other cattle

Separating newborn calves from their dams soon

after they are born helps prevent disease

transmission that can occur through nursing or

contact with adult cow feces in maternity areas.

Milk from dams infected with Mycoplasma,

Salmonella, E. coli, Mycobacterium avium

subspecies paratuberculosis, or BVD can

transmit these diseases to calves (Wells, 2000;

Nielsen et al., 2008). Feeding preweaned calves

pasteurized milk, milk replacer, or milk from

known disease-free cows is recommended.

The percentage of operations that separated

newborn calves from their dams immediately

after they were born doubled from 1991 to 2007

(28.0 to 55.9 percent of operations,

respectively). In 2007, 22.2 percent of

operations allowed calves to nurse from their

dams but removed them from their dams less

than 12 hours following birth. In 2007, about

two-thirds of calves (65.6 percent) were on

operations that removed calves from their dams

immediately following birth. Less than 1 of

10 operations (7.3 percent)—representing

2.6 percent of calves—allowed calves to stay

with their dams for more than 24 hours.

a. Percentage of operations* by number of hours following birth that calves were 

separated from their dams 

Percent 

Operations 

Percent 

Operations 

Number 

of Hours

NDHEP 

1991 

Std. 

Error 

Number 

of Hours 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Removed 

immediately 28.0 (1.7) Removed 

immediately 47.9 (1.3) 52.9 (1.3) 55.9 (1.4) 

Less 

than 12 39.6 (1.7) 

After nursing, 

but less than 

12 hours 

20.8 (1.0) 22.5 (1.1) 22.2 (1.2) 

12 to 24 22.0 (1.4) 12 to 24 17.4 (1.1) 15.9 (1.0) 14.6 (1.0) 

More than 24 10.4 (1.0) More than 24 13.9 (1.0) 8.7 (0.8) 7.3 (0.8) 

Total 100.0 Total 100.0 100.0 100.0 

*Operations with any dairy cows.
USDA APHIS VS / 61

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

Keeping preweaned calves separate from older

animals is an effective way to reduce their

exposure to disease. Preweaned calves are more

susceptible to disease than older, healthy

animals because their immune system is not yet

fully developed (BAMN, 2001b). Physical

contact between preweaned calves and cattle

from older age groups (including nose-to-nose,

sniffing, touching, licking, or contact across

b. Percentage of operations1 in which after separation from the dam preweaned 

heifers did not have physical contact2 with the following cattle classes 

Percent Operations 

Cattle Class

NDHEP 

1991 

Std. 

Error 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Weaned 

calves less 

than 

approximately 

4 months of 

age 

68.5 (2.0) 

Calves from 

approximately 

4 months of 

age to 

breeding 

89.6 (1.3) 

67.0 (1.3) 77.2 (1.2) 76.0 (1.2) 

Bred heifers 

not yet calved 95.4 (0.9) 81.2 (1.1) 86.7 (0.9) 86.8 (1.0) 

Adult cattle 89.8 (1.3) 79.8 (1.1) 84.6 (1.0) 84.3 (1.1) 

1

 Operations with any dairy cows 

2 Physical contact = possible nose-to-nose contact or sniffing/touching/licking each other, including through a 

fence.

fence lines) increases the risk of exposing the

calves to diseases such as salmonellosis, Johne’s

disease, and upper respiratory diseases.

The percentage of operations in which

preweaned heifers were not exposed to weaned

calves, bred heifers, or adult cattle increased

from 1996 to 2007.
62 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

5. Colostrum

feeding

Feeding calves high quality colostrum

immediately following birth helps provide

calves with the antibodies needed to withstand

disease challenges and is recommended to

maximize calf health (BAMN, 2001b). The

effectiveness of colostral transfer of immunity to

calves depends on the antibody mass delivered

to calves, the timing of feeding, and the health

status of the calves. Antibody mass is a function

of antibody concentration and the volume of

colostrum delivered to the calves. Administering

colostrum to calves rather than allowing calves

to obtain colostrum by nursing their dams

enables producers to evaluate colostrum quality,

determine the timing of the first feeding, and the

total amount of colostrum calves receive. Calves

that receive colostrum solely through nursing

might not receive the proper quantity or quality

of colostrum in a timely manner (BAMN,

2001b). Additionally, if the calving area is not

properly maintained, calves might ingest manure

and pathogens from the environment while

searching for teats and suckling colostrum.

“A Guide to Colostrum and Colostrum

Management for Dairy Calves”, published by

The Bovine Alliance on Management and

Nutrition, recommends that calves get 3 quarts

of high quality colostrum by nipple bottle within

1 hour of birth and an additional 3 quarts in

12 hours, or 4 quarts of high quality colostrum

by esophageal feeder within 1 hour of birth

(BAMN, 2001b).

On average, calves received hand-fed colostrum

3.3 hours following birth.

a. For operations that immediately removed calves from their dams and hand-fed 

colostrum, operation* average number of hours following birth that heifer 

calves received their first colostrum feeding, by herd size 

Operation Average Hours 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Hours 

Std. 

Error Hours 

Std. 

Error Hours 

Std. 

Error Hours 

Std. 

Error 

3.4 (0.1) 3.3 (0.1) 2.8 (0.2) 3.3 (0.1) 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007.
USDA APHIS VS / 63

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

During all study years, about one-third of

operations allowed heifers to get colostrum

during their first nursing.

b. Percentage of operations* by method normally used for heifers’ first feeding of 

colostrum 

Percent Operations 

Method 

NDHEP 

1991 

Std. 

Error 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

First nursing 33.7 (1.7) 33.5 (1.2) 30.5 (1.2) 36.3 (1.4) 

Hand-fed from 

bucket or bottle 64.0 (1.7) 62.5 (1.2) 64.8 (1.3) 59.2 (1.4) 

Hand-fed using 

esophageal 

feeder 

2.3 (0.6) 3.6 (0.4) 4.4 (0.5) 4.3 (0.5) 

No colostrum 0.0 (0.0) 0.4 (0.2) 0.3 (0.1) 0.2 (0.1) 

Total 100.0 100.0 100.0 100.0 

*Operations with any dairy cows.

Photo courtesy of Dr. Jason Lombard.
64 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

From 1991 to 2007, operations provided calves

about the same amount of colostrum during their

first 24 hours of life: about one-fourth of

operations fed calves 2 quarts or less and about

one-third fed calves 4 quarts or more. Nearly

one-half of operations (45.8 percent) fed

newborn dairy heifers more than 2 quarts but

less than 4 quarts of colostrum. An additional

30.9 percent of operations fed 4 or more quarts

of colostrum to newborn dairy heifers during

their first 24 hours.

c. For operations that normally hand-fed colostrum to heifers, percentage of 

operations* by amount of colostrum fed during the first 24 hours 

Percent Operations 

Amount 

(Quarts) 

NDHEP 

1991 

Std. 

Error 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

2 or less 25.6 (1.8) 21.4 (1.3) 21.4 (1.4) 23.3 (1.6) 

More than 

2, but less 

than 4 

48.2 (2.1) 46.6 (1.6) 47.2 (1.7) 45.8 (1.9) 

4 or more 26.2 (1.9) 32.0 (1.5) 31.4 (1.5) 30.9 (1.7) 

Total 100.0 100.0 100.0 100.0 

*Operations with any dairy cows.
USDA APHIS VS / 65

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices
66 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

6. Measuring

passive transfer of

immunity

Measuring immunoglobulin G (IgG) or serum

total protein levels in calves within the first

3 days of life is a relatively simple way to

measure passive transfer of immunity and the

effectiveness of the colostrum management

program. Overall, in 2007 only 2.1 percent of

operations routinely measured passive transfer

via serum total proteins. Of large operations,

14.5 percent measured serum proteins, while

only 2.4 percent of medium operations and 1.1

percent of small operations measured total

serum proteins.

Measuring immunoglobulin levels in colostrum

is one way to evaluate its quality. Of operations

that hand-fed colostrum in 2007, 13.0 percent

either estimated immunoglobulin levels or

evaluated colostrum quality before feeding it to

newborn calves, compared with 5.2 percent of

operations in 2002. The percentage of

operations that estimated immunoglobulin levels

in colostrum or evaluated its quality increased

across herd sizes from 2002 to 2007. A higher

percentage of large operations (45.2 percent)

evaluated colostrum than medium or small

operations (19.8 and 7.6 percent, respectively)

in 2007.

a. Percentage of operations* that routinely monitored serum proteins (as a 

measure of passive transfer) in heifers within the first 3 days of life, by herd 

size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

1.1 (0.4) 2.4 (0.6) 14.5 (1.7) 2.1 (0.3) 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 67

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

b. For operations that hand-fed colostrum, percentage of operations* that 

estimated immunoglobulin levels of colostrum or evaluated its quality, by herd 

size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Study Year Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

2002 2.1 (1.6) 10.6 (1.5) 32.2 (2.8) 5.2 (0.5) 

2007 7.6 (1.3) 19.8 (2.3) 45.2 (3.2) 13.0 (1.1) 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007.

The most commonly used methods of evaluating

colostrum were a colostrometer and visual

appearance (43.7 and 41.6 percent of

operations, respectively).

c. For the 13.0 percent of operations that estimated immunoglobulin levels in 

colostrum or evaluated its quality, percentage of operations* by primary 

method used for measuring immunoglobulin 

Primary Method Percent Std. Error 

Colostrometer 43.7 (4.2) 

Visual appearance 41.6 (4.3) 

Volume of first milking colostrum (pounds) 9.7 (2.8) 

Other 5.0 (2.7) 

Total 100.0 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007.
68 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

7. Colostrum

pooling and

storage

Pooling colostrum from several cows to feed

calves increases the risk of spreading diseasecausing agents (including the agent causing

Johne’s disease) to more than one calf (BAMN,

2001b). The percentage of large and medium

operations that pooled colostrum decreased

from 2002 to 2007. Of operations that normally

fed colostrum to newborn calves in 2007,

21.0 percent pooled colostrum; 56.9 percent of

large operations, and 26.0 and 16.0 percent of

medium and small operations, respectively,

pooled colostrum in 2007.

a. For operations that normally hand-fed colostrum to newborn calves, 

percentage of operations* that pooled colostrum from more than one cow, by 

herd size 

Percent Operations 

Herd Size 

(Number of Cows) 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Small (fewer than 100) 22.1 (1.4) 16.0 (1.7) 

Medium (100 to 499) 37.4 (2.0) 26.0 (2.4) 

Large (500 or more) 70.6 (2.4) 56.9 (3.1) 

All operations 27.0 (1.1) 21.0 (1.3) 

*Operations with any dairy cows.
USDA APHIS VS / 69

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

The proper handling and storage of excess

colostrum is important in protecting its quality.

Storing colostrum at warm, ambient

temperatures rapidly increases bacterial growth

(McGuirk and Collins, 2004). Refrigerating

colostrum results in intermediate rates of

bacterial proliferation. The use of a preservative

and refrigeration to store colostrum results in

b. For operations that hand-fed colostrum to newborn calves, percentage of 

operations* by primary method used for storing colostrum 

Percent Operations 

Method 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Stored without refrigeration 4.4 (0.6) 3.9 (0.7) 

Stored in refrigerator 7.8 (0.6) 11.1 (0.9) 

Stored in freezer 27.7 (1.1) 28.2 (1.6) 

Other 0.5 (0.2) 0.0 (--) 

Not stored 59.6 (1.3) 56.8 (1.8) 

Total 100.0 100.0 

*Operations with any dairy cows.

8. Pasteurization of

colostrum

Pasteurization is a proven method for reducing

pathogens in colostrum (Godden et al., 2006). A

high-temperature, short-time (HTST) system is

one method of pasteurizing colostrum. HTST

pasteurizers, however, cause colostrum to gel

and reduce the amount of antibodies present,

particularly IgG. A batch pasteurizer uses a

lower temperature and longer heating time

compared with HTST. Batch pasteurizers do not

cause colostrum to gel and do not significantly

lower rates of bacterial growth than refrigeration

alone. For long-term storage, colostrum should

be frozen (McGuirk and Collins, 2004).

The percentages of operations by methods used

for storing colostrum remained essentially

unchanged from 2002 to 2007, with the highest

percentage of operations not storing colostrum.

Approximately 6 of 10 operations did not store

colostrum in 2002 or 2007.

reduce IgG concentrations (Godden et al.,

2006). Although pasteurization decreases the

pathogens in colostrum, it does not improve the

quality of the colostrum in terms of increasing

maternal antibodies. Although pasteurization is

commonly used for milk and can be used for

colostrum, the technical issues inherent in

pasteurization may be one reason that dairies

have been slow to adopt this management

practice.
70 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

The percentage of operations that pasteurized

colostrum did not change from 2002 to 2007. In

2007, less than 1 percent of operations that

hand-fed colostrum (0.8 percent) pasteurized the

colostrum before feeding it to newborn calves.

Large operations were more likely to pasteurize

colostrum (6.4 percent) than medium and small

operations (0.9 and 0.2 percent, respectively).

a. For operations that hand-fed colostrum to newborn calves, percentage of 

operations* that pasteurized colostrum, by herd size 

Percent Operations 

Herd Size 

(Number of Cows) 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Small (fewer than 100) 0.4 (0.2) 0.2 (0.2) 

Medium (100 to 499) 0.8 (0.3) 0.9 (0.4) 

Large (500 or more) 3.6 (0.9) 6.4 (1.6) 

All operations 0.6 (0.2) 0.8 (0.2) 

*Operations with any dairy cows.

Colostrum from Johne’s test-positive cows can

transmit the disease to calves. Therefore,

producers should feed colostrum from testnegative cows or pasteurize it prior to feeding.

In 2007, only 4.9 percent of operations fed

newborn calves colostrum from Johne’s testpositive cows.

b. For operations that tested for Johne’s disease, percentage of operations in 

which newborn calves were fed colostrum from cows that tested positive for 

Johne’s disease, by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

6.0 (2.9) 3.8 (2.8) 0.6 (0.4) 4.9 (2.0) 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 71

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

9. Calf-feeding

equipment

To prevent the spread of disease from one calf

to another, calf-feeding equipment (bottles,

buckets, and nipples) should be cleaned and

disinfected between calves. In 2007, about onefourth of operations (24.4 percent) cleaned calffeeding equipment between calves. A higher

percentage of large and medium operations

(39.1 and 30.9 percent, respectively) cleaned

calf-feeding equipment between calves

compared with small operations (21.4 percent).

Over one-half of operations across herd sizes

cleaned calf-feeding equipment daily. A higher

percentage of medium and small operations

(5.2 and 7.0 percent, respectively) cleaned calffeeding equipment weekly compared with large

operations (1.3 percent). A high percentage of

operations that listed “other” for cleaning

frequency indicated that they cleaned calffeeding equipment twice a day, but not between

calves.

Percentage of operations1 by frequency calf-feeding equipment2 was cleaned and 

disinfected, and by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Frequency Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Between calves 21.4 (1.5) 30.9 (2.2) 39.1 (2.7) 24.4 (1.2) 

Daily 59.8 (1.8) 55.9 (2.3) 51.8 (2.8) 58.5 (1.4) 

Weekly 7.0 (1.0) 5.2 (0.9) 1.3 (0.9) 6.4 (0.8) 

Monthly 3.8 (0.7) 1.4 (0.6) 2.2 (1.0) 3.2 (0.5) 

Other 8.0 (1.0) 6.6 (1.1) 5.6 (1.3) 7.5 (0.8) 

Total 100.0 100.0 100.0 100.0 

1

Operations with any dairy cows. 

2 Bottles, buckets, nipples. 

Source: NAHMS Dairy 2007. 
72 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

10. Physical

contact with other

animals

Other animals can be the source of many

different diseases. These diseases can be spread

by direct contact or through ingestion of

contaminated feed or water. For example,

Neospora is a parasitic disease that is shed via

the feces of dogs and other canids and can cause

abortions in cattle, if ingested. Malignant

catarrhal fever is spread to cattle by sheep. In

some parts of the country, populations of deer

are infected with TB, which can be spread to

cattle.

Dogs, cats, and members of the deer family

were the three animal types most often

reported as having contacts with dairy cattle.

The percentage of operations in which pigs,

sheep, or beef cattle had physical contact with

dairy cattle and/or their feed, minerals, or

water was lower in 2007 than in 1991. Dairy

cattle contact with the other listed animals

remained unchanged from 1991 to 2007.

a. Percentage of operations1 in which the following animals had physical contact 

with dairy cattle and/or their feed, minerals, or water 

Percent Operations 

Animal Type

NDHEP 

1991 

Std. 

Error 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Chickens/other 

poultry 10.6 (1.4) 7.5 (0.8) 6.8 (0.7) 8.3 (0.8) 

Horses or 

other equids2 15.0 (1.6) 11.6 (0.9) 12.8 (0.9) 13.3 (1.0) 

Pigs 5.5 (1.0) 3.9 (0.6) 2.3 (0.4) 2.0 (0.4) 

Sheep 3.0 (0.6) 2.3 (0.5) 1.3 (0.3) 0.9 (0.3) 

Goats 3.1 (0.7) 3.0 (0.5) 2.8 (0.5) 2.5 (0.4) 

Beef cattle 17.3 (1.7) 18.5 (1.1) 10.5 (0.8) 11.3 (1.0) 

Exotic species NA 0.8 (0.2) 0.6 (0.2) 0.7 (0.2) 

Deer or other 

cervidae3 56.1 (2.2) 49.3 (1.1) 53.1 (1.3) 49.3 (1.4) 

Dogs NA 77.8 (1.1) 70.6 (1.2) 68.9 (1.3) 

Cats NA 90.2 (0.8) 87.8 (0.8) 85.2 (0.9) 

1

 Operations with any dairy cows 

2 In 1991, “horses” was the animal type; “other equids” was not listed. 

3 In 1991, “deer” was the animal type; “other cervidae” was not listed.
USDA APHIS VS / 73

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

TB is transmitted most commonly by the

respiratory route, whereby invisible droplets

(aerosols) containing TB bacteria are exhaled or

coughed by infected animals and then inhaled by

susceptible animals or humans. The risk of

exposure is greatest in enclosed areas; however,

livestock can become infected if they share a

common eating or watering place contaminated

with the saliva and other discharges from

infected deer or other animals. Direct contact

between cattle and deer infected with TB

increases the risk cattle contracting TB.

On operations in which deer or other members

of the deer family had contact with cattle and/or

their feed or water in 2007, 90.8 percent of

operations reported that cattle could possibly or

sometimes have face-to-face contact with deer.

There were no differences by region in the

percentages of operations that reported face-toface contact between cattle and deer.

b. For operations in which deer had physical contact with cattle and/or their feed, 

minerals, or water, percentage of operations* by frequency that members of 

the deer family had face-to-face contact with cattle, and by region 

Percent Operations 

Region 

West East All Operations 

Frequency Percent 

Std. 

Error Percent 

Std. 

Error Percent 

Std. 

Error 

Never 4.8 (2.1) 9.4 (1.2) 9.2 (1.2) 

Possibly 56.3 (8.0) 64.3 (2.1) 64.1 (2.0) 

Sometimes 38.9 (7.9) 26.3 (1.9) 26.7 (1.9) 

Total 100.0 100.0 100.0 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007.
74 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

11. Equipment

handling for

manure and feed

Using the same equipment for both manure

removal and feed handling increases the risk of

contaminating feed with disease-causing

organisms, especially Salmonella and

Mycobacterium avium subspecies

paratuberculosis. On some operations it may

not be feasible to have equipment dedicated

solely to feed handling or manure removal. In

those cases, implementing procedures for

cleaning and disinfecting equipment between

uses and training employees to use those

procedures will reduce the likelihood of feed

contamination with feces and pathogens.

About one-third of operations (32.2 percent)

routinely used the same equipment to handle

manure and to feed cattle in 2007; another onethird (35.6 percent) rarely used the same

equipment, and another one-third (32.2 percent)

never used the same equipment to handle both

manure and feed. No differences were observed

across herd sizes.

a. Percentage of operations by frequency that the same equipment was used to 

handle manure and feed cattle during the previous 12 months, and by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Frequency Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Routinely 34.1 (3.6) 29.8 (3.9) 20.3 (4.7) 32.2 (2.7) 

Rarely 34.4 (3.6) 36.4 (4.0) 46.0 (5.6) 35.6 (2.7) 

Never 31.5 (3.6) 33.8 (3.9) 33.7 (5.5) 32.2 (2.7) 

Total 100.0 100.0 100.0 100.0 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 75

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

For operations that used the same equipment to

handle manure and feed cattle, about 5 percent

washed and chemically disinfected the

equipment between uses in 2002 and 2007. The

majority of operations washed equipment with

water or steam, and less than 1 percent of

operations used chemical disinfectants only. The

majority of the 23.2 percent of operations that

used “other” procedures in 2007 used separate

loader buckets. More than 1 of 10 operations

that used the same equipment to handle manure

and feed cattle performed no procedures on the

equipment between uses in 2002 or 2007.

b. For operations that used the same equipment to handle manure and feed 

cattle, percentage of operations by procedure that best describes what was 

usually done with equipment after handling manure 

Percent Operations 

Procedure 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Wash equipment with 

water or steam only 54.2 (2.9) 61.0 (3.4) 

Chemically disinfect only 0.0 (--) 0.1 (0.1) 

Wash equipment and 

chemically disinfect 5.7 (1.5) 4.6 (1.5) 

Other 24.9 (2.5) 23.2 (3.1) 

No procedures done 15.2 (2.2) 11.1 (2.3) 

Total 100.0 100.0 
76 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

12. Equipment

sharing with other

livestock

operations

Sharing equipment between operations can

spread disease from one operation to another.

Sanitation and disinfection procedures should be

used to ensure that all shared equipment is

cleaned prior to use. In 2002 and 2007, about

one of three operations shared equipment with

other livestock operations.

a. Percentage of operations that shared any heavy equipment (tractors, feeding 

equipment, manure spreaders, trailers, etc.) with other livestock operations, by 

herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Study Year Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

2002 40.0 (2.7) 33.4 (2.8) 28.0 (3.7) 38.0 (2.1) 

2007 35.9 (3.7) 41.0 (4.1) 21.3 (4.3) 36.2 (2.8) 

Photo courtesy of Dr. Jason Lombard.
USDA APHIS VS / 77

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

The majority of all operations (63.8 percent)

had not shared any heavy equipment with other

livestock operations during the previous

b. Percentage of operations by number of times heavy equipment was shared 

during the previous 12 months, and by herd size

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Number 

of Times Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

0 64.1 (3.7) 59.0 (4.1) 78.7 (4.3) 63.8 (2.8) 

1 to 2 11.1 (2.6) 15.5 (3.1) 5.3 (2.3) 11.8 (2.0) 

3 to 5 12.6 (2.5) 7.0 (2.4) 3.1 (1.1) 10.6 (1.8) 

6 or more 12.2 (2.3) 18.5 (3.4) 12.9 (3.8) 13.8 (1.8) 

Total 100.0 100.0 100.0 100.0 

Source: NAHMS Dairy 2007. 

For the 36.2 percent of operations that shared

equipment with other operations in 2007, the

majority of operations performed no cleaning

c. For operations that shared equipment with other livestock operations, 

percentage of operations by cleaning procedure usually performed on 

equipment shared with other operations prior to use on the operation 

Procedure Percent Operations Standard Error 

Wash equipment with 

water or steam only 26.6 (3.9) 

Chemically disinfect only 0.0 (--) 

Wash equipment and 

chemically disinfect 0.5 (0.3) 

Other 9.9 (3.2) 

No procedures done 63.0 (4.6) 

Total 100.0 

Source: NAHMS Dairy 2007. 

12 months. More than 12 percent of operations

across all herd sizes shared equipment at least

six times during the previous 12 months.

procedures prior to using the equipment on their

own operations (63.0 percent), while

26.6 percent washed equipment with water or

steam.
78 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

13. Water sources

for cows

Water sources for cows have changed since

1996. For example, the use of a single cup/bowl

by only one cow decreased from 52.5 percent of

operations in 1996 to 11.4 percent in 2007. The

percentage of operations that used a single cup/

bowl for multiple cows increased from 50.0

percent of operations in 1996 to 64.1 percent in

2007. The percentage of operations that used a

water tank or trough increased from 77.9

percent in 1996 to 93.2 percent in 2007. The

changes in water sources mirror the changes in

housing, in which cows are in loose housing

rather than restricted to a single stall and water

source.

a. Percentage of operations by source of drinking water for cows 

Percent Operations 

Water Source

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Single cup/bowl waterer 

used by one cow only 52.5 (1.6) 10.7 (1.4) 11.4 (2.0) 

Single cup/bowl waterer 

used by multiple cows 50.0 (1.8) 61.7 (1.8) 64.1 (2.4) 

Water tank or trough 

(covered or uncovered) 77.9 (1.5) 89.1 (1.4) 93.2 (1.5) 

Lake, pond, stream, 

river, etc. 37.1 (1.7) 35.1 (2.0) 33.4 (2.7) 

Other source 1.1 (0.4) 2.1 (0.7) 3.9 (1.3) 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 79

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

For operations that used a water tank or trough,

the percentage of operations that cleaned water

tanks/troughs 13 or more times a year increased

from 13.6 percent of operations in 1996 to

34.2 percent of operations in 2007.

b. For operations that used a water tank or trough, percentage of operations by 

average number of times per year water tank or trough was drained and

cleaned 

Percent Operations 

Number of Times 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

0 8.4 (1.2) 6.2 (1.1) 4.6 (1.4) 

1 to 4 51.8 (2.1) 46.5 (2.3) 37.1 (3.2) 

5 to 12 26.2 (1.9) 22.3 (1.9) 24.1 (2.8) 

13 or more 13.6 (1.4) 25.0 (1.9) 34.2 (2.8) 

Total 100.0 100.0 100.0 

From 1996 to 2007, about 9 percent of

operations chlorinated drinking water for cows.

c. Percentage of operations that 

usually chlorinated drinking water 

for cows 

Percent Operations 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

 Dairy 

2007 

Std. 

Error 

10.7 (1.0) 9.8 (1.0) 8.7 (1.2) 
80 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

14. Milking

personnel and

training

Owners of large operations were usually more

involved in overall management of the operation

rather than in specific labor-intensive

procedures such as milking cows. In 2007, the

percentage of operations in which owners/

operators milked the majority of cows decreased

from 74.8 percent of small operations to 0.0

percent of large operations. Family members

milked the majority of cows on 17.4 percent of

small operations and 14.3 percent of medium

operations. No large operations reported family

members performing the majority of milking.

The number of employees increased as herd size

increased. Large operations averaged almost 13

full-time employees (including owners and

family members), while small operations

averaged 2 (see table b. p 40). The percentage

of operations in which hired workers milked the

majority of cows increased as herd size

increased. Hired workers milked the majority of

cows on 100.0 percent of large operations.

a. Percentage of operations by personnel who milked the majority of cows, and 

by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Personnel Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Owner/operator 74.8 (3.3) 33.7 (3.9) 0.0 (--) 59.8 (2.5) 

Family member(s) 

of operator 17.4 (3.0) 14.3 (3.1) 0.0 (--) 15.6 (2.2) 

Hired worker(s) 7.8 (1.8) 52.0 (3.9) 100.0 (0.0) 24.6 (1.7) 

Total 100.0 100.0 100.0 100.0 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 81

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

Good milking practices include training milkers

in proper procedures such as hygiene, the

correct attachment of milking units, and how to

recognize the signs of mastitis. Training is

usually an ongoing processes, as milking

protocols are often modified or updated.

In 2007, milker training increased as herd size

increased, with 50.3 percent of small operations

training milking personnel compared with

79.0 percent of medium operations and

97.8 percent of large operations. About one of

four operations (42.5 percent) trained new

employees only, while about one-third

(37.3 percent) provided no milker training. A

lower percentage of small operations

(3.2 percent) performed training one to two

times per year for all milkers compared with

medium and large operations (14.9 and

25.5 percent, respectively).

b. For the 75.7 percent of operations with employees, percentage of operations by 

how frequently milking personnel were trained, and by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Frequency Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

As new 

employees only 39.6 (4.4) 48.4 (4.2) 42.3 (5.7) 42.5 (3.1) 

1 to 2 times/year 

for all milkers 3.2 (1.2) 14.9 (3.0) 25.5 (5.4) 8.5 (1.3) 

3 to 4 times/year 

for all milkers 2.8 (1.7) 4.3 (1.4) 14.0 (3.8) 4.2 (1.2) 

5 times/year or 

more for all 

milkers 

1.4 (1.2) 7.0 (2.5) 10.8 (3.5) 3.8 (1.1) 

Other 3.3 (1.6) 4.4 (1.9) 5.2 (2.6) 3.7 (1.2) 

No milker training 49.7 (4.5) 21.0 (3.7) 2.2 (2.2) 37.3 (3.1) 

Total 100.0 100.0 100.0 100.0 

Source: NAHMS Dairy 2007. 
82 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

A higher percentage of operations in the West

region than in the East region provided milker

training (89.0 and 59.6 percent, respectively). A

higher percentage of operations in the West

region than in the East region provided milker

training one or two times per year for all milkers

(20.8 and 7.1 percent, respectively).

c. For the 75.7 percent of operations with employees, percentage of operations by 

how frequently milking personnel were trained, and by region 

Percent Operations 

Region 

West East 

Frequency Percent Std. Error Percent Std. Error 

As new employees only 57.1 (5.6) 40.7 (3.4) 

1 to 2 times/year for all milkers 20.8 (4.2) 7.1 (1.3) 

3 to 4 times/year for all milkers 7.2 (3.1) 3.8 (1.3) 

5 times/year or more 

for all milkers 1.7 (1.0) 4.1 (1.2) 

Other 2.2 (1.5) 3.9 (1.3) 

No milker training 11.0 (3.4) 40.4 (3.4) 

Total 100.0 100.0 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 83

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

Almost all operations that trained milkers

(97.1 percent) used on-the-job training. Almost

one-third of operations (31.9 percent) used

discussion/lecture to train milkers, while less

than 1 of 10 (6.9 percent) used video training.

15. Milking

biosecurity

practices

The percentage of operations in which milkers

wore gloves to milk all cows increased from

32.9 percent in 2002 to 55.2 percent in 2007.

The percentage of cows on operations in which

milkers wore gloves increased from 48.7 in

2002 to 76.8 percent in 2007.

a. Percentage of operations (and percentage of cows on these operations) in 

which milkers wore gloves to milk all cows 

Percent Operations Percent Cows 

Dairy 2002 Dairy 2007 Dairy 2002 Dairy 2007 

Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

32.9 (1.9) 55.2 (2.8) 48.7 (1.9) 76.8 (2.5) 

d. For the 62.7 percent of operations that trained milking personnel, percentage of 

operations by training method used 

Method Percent Operations Standard Error 

Video training 6.9 (1.1) 

Discussion/lecture 31.9 (3.2) 

On-the-job training 97.1 (0.9) 

Other 3.9 (1.0) 

Source: NAHMS Dairy 2007. 
84 / Dairy 2007

Section I: Population Estimates—C. On-farm Biosecurity and Biocontainment Practices

To reduce the exposure of noninfected cows to

mastitis organisms, cows with clinical mastitis

should be milked at the end of milking, with a

separate milking unit, or in a separate string.

Across herd sizes, about one of three operations

used a separate milking unit to milk cows with

mastitis. A higher percentage of large operations

(83.4 percent) milked cows with mastitis in a

separate string from healthy cows compared

with medium and small operations (33.4 and

29.8 percent, respectively).

b. Percentage of operations by method used for milking cows with clinical 

mastitis, and by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Method Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Separate milking 

unit from healthy 

cows 

38.5 (3.7) 25.7 (3.6) 31.5 (5.3) 34.9 (2.7) 

Separate string 

from healthy cows 29.8 (3.5) 33.4 (3.8) 83.4 (4.7) 34.1 (2.6) 

Source: NAHMS Dairy 2007. 

About 6 of 10 operations in the West region

(59.9 percent) milked cows with clinical mastitis

in a separate string from healthy cows compared

c. Percentage of operations by method used to milk cows with clinical mastitis, 

and by region 

Percent Operations 

Region 

West East 

Method Percent Std. Error Percent Std. Error 

Separate milking 

unit from healthy cows 27.5 (4.9) 35.6 (2.9) 

Separate string from 

healthy cows 59.9 (5.0) 31.6 (2.8) 

Source: NAHMS Dairy 2007. 

with approximately 3 of 10 operations in the

East region (31.6 percent) in 2007.
USDA APHIS VS / 85

Section I: Population Estimates—D. Vaccination and Prevention Practices

D. Vaccination and Prevention Practices

1. Heifer

vaccination

The percentage of operations that administered

any vaccine to heifers decreased from

91.3 percent in 1991 to 83.0 percent in 2007.

With the exceptions of parainfluenza (PI3),

brucellosis, and Johne’s disease vaccines, use of

vaccines for other diseases increased or

remained the same. Interestingly, only the use of

brucellosis vaccine has decreased since 1991.

The percentage of operations that vaccinated

heifers against brucellosis decreased from

66.8 percent in 1991 to 41.6 percent in 2007.

This decrease may be due to the fact that many

States switched from a mandatory to a voluntary

brucellosis program from 1991 to 2007. In

addition, the number of States that were certified

brucellosis-free increased from 34 in 1996 to 49

in 2007, which may have impacted how many

operations vaccinated against brucellosis.

Percentage of operations* that normally vaccinated heifers against the following 

diseases 

Percent Operations 

Disease

NDHEP 

1991 

Std. 

Error 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Bovine viral 

diarrhea (BVD) 58.4 (2.1) 69.7 (1.3) 71.5 (1.2) 73.7 (1.3) 

Infectious bovine 

rhinotracheitis 

(IBR) 

60.6 (2.1) 66.1 (1.3) 67.0 (1.3) 70.4 (1.3) 

Parainfluenza Type 

3 (PI3) 57.6 (2.1) 60.1 (1.3) 60.0 (1.3) 61.0 (1.4) 

Bovine respiratory 

syncytial virus 

(BRSV) 

44.0 (2.1) 58.7 (1.3) 58.2 (1.3) 64.9 (1.4) 

Haemophilus 

somnus 14.7 (1.4) 37.3 (1.3) 31.4 (1.2) 34.2 (1.3) 

Leptospirosis 56.1 (2.2) 67.0 (1.3) 65.1 (1.3) 67.7 (1.3) 

Salmonella NA 18.9 (1.0) 16.8 (1.0) 21.5 (1.1) 

E. coli mastitis NA 18.1 (0.9) 21.3 (1.0) 24.1 (1.1) 

Clostridia 

(blackleg/ 

malignant edema) 

20.7 (1.4) 32.3 (1.1) 32.8 (1.1) 34.6 (1.3) 

Brucellosis 66.8 (1.9) 63.8 (1.3) 51.0 (1.3) 41.6 (1.3) 

Mycobacterium 

avium subspecies 

paratuberculosis 

(Johne’s disease) 

NA 5.4 (0.6) 4.6 (0.5) 5.0 (0.6) 

Neospora NA NA 3.6 (0.4) 6.3 (0.6) 

Other NA 7.3 (0.6) 6.9 (0.6) 6.8 (0.7) 

Any 91.3 (1.3) 86.4 (1.0) 84.4 (1.1) 83.0 (1.1) 

*Operations with any dairy cows.
86 / Dairy 2007

Section I: Population Estimates—D. Vaccination and Prevention Practices
USDA APHIS VS / 87

Section I: Population Estimates—D. Vaccination and Prevention Practices

2. Cow vaccination About four of five operations (82.2 percent)

vaccinated cows in 2007. The use of

Salmonella, E. coli, and clostridia vaccines has

increased since 1996. The use of the most

common vaccines (BVD, IBR, PI3, BRSV, and

leptospirosis) has remained steady since 1996.

Percentage of operations* that normally vaccinated cows against the following 

diseases 

Percent Operations 

Disease

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Bovine viral 

diarrhea (BVD) 71.4 (1.3) 74.2 (1.2) 75.0 (1.3) 

Infectious bovine 

rhinotracheitis (IBR) 69.0 (1.3) 69.3 (1.3) 71.3 (1.3) 

Parainfluenza 

Type 3 (PI3) 62.5 (1.3) 62.2 (1.3) 61.9 (1.4) 

Bovine respiratory 

syncytial virus (BRSV) 60.8 (1.3) 61.1 (1.3) 65.0 (1.4) 

Haemophilus somnus 38.4 (1.3) 32.4 (1.2) 33.6 (1.3) 

Leptospirosis 70.7 (1.3) 70.1 (1.3) 70.0 (1.3) 

Salmonella 18.8 (1.0) 17.1 (1.0) 23.0 (1.1) 

E. coli mastitis 26.6 (1.1) 31.7 (1.2) 33.5 (1.2) 

Clostridia 21.8 (1.0) 25.0 (1.1) 27.7 (1.2) 

Neospora NA 3.3 (0.4) 5.9 (0.6) 

Other 6.5 (0.6) 7.2 (0.6) 7.4 (0.7) 

Any 81.1 (1.1) 82.8 (1.1) 82.2 (1.1) 

*Operations with any dairy cows.
88 / Dairy 2007

Section I: Population Estimates—D. Vaccination and Prevention Practices
USDA APHIS VS / 89

Section I: Population Estimates—D. Vaccination and Prevention Practices

3. BVD

vaccinations

In 1996, the majority of operations that

administered BVD vaccines to heifers gave

killed vaccines (58.4 percent of operations). In

2007, the majority gave modified live vaccines

(62.2 percent of operations).

a. For operations that gave BVD vaccinations to heifers, percentage of 

operations* by type of BVD vaccine given 

Percent Operations 

Type of BVD 

Vaccine 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Killed 58.4 (1.5) 50.6 (1.6) 43.1 (1.6) 

Modified live 40.7 (1.5) 49.2 (1.6) 62.2 (1.5) 

*Operations with any dairy cows.

Although the majority of operations

administered killed BVD vaccines to cows in

1996, 2002, and 2007, the percentage of

operations that used modified live vaccines

increased from 29.3 percent in 1996 to

48.9 percent in 2007. The use of killed BVD

vaccines decreased slightly during the same

period.

b. For operations that gave BVD vaccinations to cows, percentage of operations* 

by type of BVD vaccine given 

Percent Operations 

Type of BVD 

Vaccine 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Killed 65.4 (1.4) 61.9 (1.5) 56.3 (1.6) 

Modified live 29.3 (1.3) 36.7 (1.5) 48.9 (1.6) 

*Operations with any dairy cows.
90 / Dairy 2007

Section I: Population Estimates—D. Vaccination and Prevention Practices

A higher percentage of operations used a

combination of Type I and Type II BVD

vaccines in 2007 compared with 2002 (60.8 and

39.4 percent, respectively). Producers are

becoming more aware of the type of BVD

vaccine they use, as the percentage of operations

that did not know which vaccine was used

decreased from 47.6 percent in 2002 to

27.2 percent in 2007. Interestingly, a Type II

only vaccine is not currently available,

suggesting that these producers did not know

which strain they were administering, or gave a

combination and were primarily concerned with

the Type II strain.

c. For operations that gave any BVD vaccinations, percentage of operations* by 

strain of BVD contained in vaccine administered 

Percent Operations 

BVD Strain Dairy 2002 Std. Error Dairy 2007 Std. Error 

Type I only 5.4 (0.6) 4.3 (0.6) 

Type II only 7.6 (0.9) 7.7 (0.8) 

Combination 

(Type I and Type II) 39.4 (1.4) 60.8 (1.5) 

Did not know 47.6 (1.5) 27.2 (1.4) 

Total 100.0 100.0 

*Operations with any dairy cows.

The percentage of operations that gave annual

BVD booster injections was similar in 1996,

2002, and 2007, with about 80 percent of

operations giving booster injections.

d. For operations that gave BVD vaccinations to cows, percentage of operations* 

that gave annual BVD booster injections 

Percent Operations 

Dairy 1996 Std. Error Dairy 2002 Std. Error Dairy 2007 Std. Error 

77.4 (1.3) 82.9 (1.2) 80.2 (1.3) 

*Operations with any dairy cows.
USDA APHIS VS / 91

Section I: Population Estimates—D. Vaccination and Prevention Practices

4. BVD testing Animals persistently infected with BVD virus

(BVDV) become infected while in utero and

shed large quantities of BVDV following birth.

This shedding can infect susceptible animals and

create the next generation of persistently

infected animals. The most efficient method of

determining if the dam and her calf are

persistently infected with BVDV is to test the

calf. Since a persistently infected cow will

always produce a persistently infected calf, the

dam is negative if the calf tests negative. In

2007, few operations (4.0 percent) routinely

tested dairy heifer replacements for persistent

infection with BVDV. The percentage of

operations that did test increased as herd size

increased.

a. Percentage of operations* that routinely tested heifer replacements to 

determine if animals were persistently infected with BVDV, by herd size 

Percent Operations

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

1.9 (0.5) 6.7 (1.1) 21.2 (2.4) 4.0 (0.4) 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007.
92 / Dairy 2007

Section I: Population Estimates—D. Vaccination and Prevention Practices

Of operations that tested dairy heifer

replacements for persistent infection with

BVDV, the majority (66.8 percent) used

individual ear-notch tests, while 21.1 percent

tested individual serum samples.

b. For operations that routinely tested 

heifer replacements to determine if 

animals were persistently infected 

with BVDV, percentage of 

operations* by testing method used 

Testing 

Method 

Percent 

Operations 

Standard 

Error 

Individual 

ear notch 66.8 (5.7) 

Pooled ear 

notch 11.4 (4.0) 

Individual 

serum 

sample 

21.1 (5.4) 

Pooled 

serum 

sample 

6.0 (3.0) 

Other 6.5 (2.4) 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007.

Photo courtesy of Dr. Jason Lombard
USDA APHIS VS / 93

Section I: Population Estimates—D. Vaccination and Prevention Practices

5. Mastitis

vaccinations

Although the efficacy of certain mastitis

vaccines has been questioned, coliform vaccines

have generally provided good protection.

Coliform vaccines were used on at least some

cows on 37.6 percent of operations in 2007,

compared with vaccines for Salmonella

(13.4 percent), siderophore receptors and porins

(4.1 percent), Mycoplasma (1.8 percent), and

Staphylococcus aureus (7.3 percent).

Salmonella vaccine might also help prevent

coliform mastitis.

a. Percentage of operations by type of vaccine used and by proportion of cows 

vaccinated 

Percent Operations 

Proportion of Cows 

All Some None 

Vaccine Type Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Total 

Coliform mastitis 32.6 (2.4) 5.0 (1.1) 62.4 (2.6) 100.0 

Salmonella 11.1 (1.5) 2.3 (0.7) 86.6 (1.6) 100.0 

Siderophore receptors 

and porins (SRPs) 

vaccine 

3.3 (0.7) 0.8 (0.4) 95.9 (0.8) 100.0 

Mycoplasma 1.4 (0.5) 0.4 (0.2) 98.2 (0.6) 100.0 

Staphylococcus aureus 5.7 (1.1) 1.6 (0.6) 92.7 (1.2) 100.0 

Source: NAHMS Dairy 2007. 
94 / Dairy 2007

Section I: Population Estimates—D. Vaccination and Prevention Practices

Regional differences in vaccine use were

observed for coliform mastitis and Salmonella

vaccines. More operations in the West region

vaccinated their cows against coliforms and

Salmonella in 2007 than operations in the East

region.

b. Percentage of operations that vaccinated at least some cows, by vaccine type 

and by region 

Percent Operations 

Region 

West East 

Vaccine Type Percent Std. Error Percent Std. Error 

Coliform mastitis 65.1 (4.7) 35.0 (2.8) 

Salmonella 36.4 (4.8) 11.1 (1.7) 

Siderophore receptors and 

porins (SRPs) vaccine 9.2 (2.9) 3.6 (0.8) 

Mycoplasma 4.1 (2.5) 1.6 (0.6) 

Staphylococcus aureus 13.2 (3.5) 6.7 (1.3) 

Source: NAHMS Dairy 2007. 

There were no changes from 2002 to 2007 in the

percentages of operations that administered

coliform mastitis and Salmonella vaccines. As

reported in 2002 and 2007, about 4 of

10 operations vaccinated for coliform mastitis

and about 1 of 10 vaccinated for Salmonella.

c. Percentage of operations by type of vaccination used 

Percent Operations 

Vaccine Type Dairy 2002* Std. Error Dairy 2007 Std. Error 

Coliform mastitis 35.8 (2.0) 37.6 (2.6) 

Salmonella 10.4 (1.3) 13.4 (1.6) 

*Question variation: majority of cows. 
USDA APHIS VS / 95

Section I: Population Estimates—D. Vaccination and Prevention Practices

6. Preventive

practices

Preventive practices such as deworming and the

use of coccidiostats, vitamin and mineral

supplements, and ionophores can help ensure

that cattle are not parasitized and can more

efficiently utilize nutrients. In addition, these

practices can help cattle withstand the stresses

associated with transport and arrival at a new

facility.

The use of specific preventive practices for

heifers has remained stable or increased since

1991; over 90 percent of all operations used at

least one preventive practice on heifers in all

four studies. In 2007, the most commonly used

preventive practices were the use of

vitamin A-D-E supplements in feed

(74.4 percent of operations), selenium

supplementation in feed (69.3 percent of

operations), and dewormers (69.4 percent of

operations). The largest increases in the use of

preventive practices since 1991 were observed

for coccidiostats in feed, vitamins A-D-E in

feed, and selenium in feed.

a. Percentage of operations* by preventive practices normally used for heifers 

Percent Operations 

Preventive 

Practice

NDHEP 

1991 

Std. 

Error 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Dewormers 62.2 (2.2) 67.3 (1.3) 69.0 (1.2) 69.4 (1.3) 

Coccidiostats 

in feed 37.8 (2.0) 46.5 (1.2) 44.4 (1.3) 46.5 (1.4) 

Vitamins A-D-E 

injection 11.8 (1.3) 16.3 (1.0) 15.3 (1.0) 10.4 (0.7) 

Vitamins A-D-E 

in feed 57.4 (2.2) 76.9 (1.1) 72.7 (1.2) 74.4 (1.2) 

Selenium injection 16.2 (1.8) 12.7 (0.8) 13.3 (0.9) 13.2 (0.9) 

Selenium in feed 50.3 (2.2) 70.8 (1.2) 67.6 (1.3) 69.3 (1.3) 

Ionophores in feed 

(e.g., Rumensin®, 

Bovatec®) 

40.0 (2.2) 42.2 (1.2) 44.2 (1.3) 45.2 (1.4) 

Probiotics NA 13.1 (0.9) 14.2 (0.9) 20.0 (1.1) 

Anionic salts 

in feed NA NA 20.6 (1.1) 20.9 (1.1) 

Other NA 4.8 (0.6) 3.8 (0.5) 4.6 (0.7) 

Any 91.7 (1.1) 93.6 (0.7) 94.9 (0.6) 94.6 (0.7) 

*Operations with any dairy cows.
96 / Dairy 2007

Section I: Population Estimates—D. Vaccination and Prevention Practices

Nearly all operations (95.3 percent) used some

preventive practice on their cows in 2007. The

most frequent practices used included

supplementing feed with vitamins A-D-E or

selenium and dewormers. Since 1996, the use of

dewormers, selenium injections, and probiotics

has increased.

b. Percentage of operations1 by preventive practices normally used for cows 

Percent Operations 

Preventive Practice

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Dewormers 53.4 (1.3) 60.3 (1.3) 63.3 (1.4) 

Vitamins 

A-D-E injection 15.5 (0.9) 17.1 (1.0) 12.9 (0.8) 

Vitamins 

A-D-E in feed 81.4 (1.1) 80.2 (1.1) 80.2 (1.2) 

Selenium injection 8.42 (0.6) 18.0 (1.0) 14.9 (0.9) 

Selenium in feed 72.52 (1.2) 75.7 (1.1) 76.1 (1.2) 

Probiotics 16.7 (0.9) 20.4 (1.0) 26.1 (1.2) 

Anionic salts in feed NA 27.0 (1.2) 26.7 (1.2) 

Limited potassium in 

dry cow ration NA 45.0 (1.3) 46.9 (1.4) 

Ionophores in feed NA NA 26.8 (1.1) 

Other 4.4 (0.5) 5.4 (0.6) 3.6 (0.6) 

Any 91.5 (0.8) 96.3 (0.6) 95.3 (0.7) 

1

 Operations with any dairy cows. 

2 Lactating cows only.
USDA APHIS VS / 97

Section I: Population Estimates—D. Vaccination and Prevention Practices
98 / Dairy 2007

Section I: Population Estimates—E. Incidence of Disease or Illness

E. Incidence of Disease or Illness

1. Cow morbidity The percentage of cows with clinical mastitis,

lameness, respiratory problems, infertility

problems, or displaced abomasum increased

from 1996 to 2007. The percentage of cows

with diarrhea for more than 48 hours or milk

fever decreased from 1996 to 2007. The three

most common conditions identified by

producers in 2007 were clinical mastitis,

lameness, and infertility problems (16.5, 14.0,

and 12.9 percent of cows, respectively).

Percentage of cows by health problem 

Percent Cows* 

Problem 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Clinical mastitis 13.4 (0.3) 14.7 (0.3) 16.5 (0.5) 

Lameness 10.5 (0.3) 11.6 (0.3) 14.0 (0.4) 

Respiratory problems 2.5 (0.1) 2.7 (0.1) 3.3 (0.1) 

Retained placenta 

(more than 24 hours) 7.8 (0.2) 7.8 (0.2) 7.8 (0.2) 

Infertility problems 

(not pregnant 150 

days after calving) 

11.6 (0.3) 11.9 (0.3) 12.9 (0.3) 

Other reproductive 

problems (e.g., 

dystocia, metritis) 

NA 3.7 (0.2) 4.6 (0.3) 

Diarrhea for more 

than 48 hours 3.4 (0.2) 2.8 (0.2) 2.5 (0.2) 

Milk fever 5.9 (0.1) 5.2 (0.1) 4.9 (0.1) 

Displaced abomasum 2.8 (0.1) 3.5 (0.1) 3.5 (0.1) 

Neurological 

problems NA 0.3 (0.0) 0.3 (0.0) 

Other health-related 

problems 2.2 (0.2) 0.8 (0.1) 0.6 (0.1) 

*As a percentage of January 1 respective-year cow inventory on operations with any dairy cows.
USDA APHIS VS / 99

Section I: Population Estimates—E. Incidence of Disease or Illness
100 / Dairy 2007

Section I: Population Estimates—E. Incidence of Disease or Illness

2. Disease

confirmation

The timely recognition of signs of illness among

cattle and the timely diagnosis and treatment of

disease are significant in limiting the spread of

disease. Decreased milk production, cows with

fever, deaths, and/or abortions could indicate

that a new disease has been introduced into the

herd. On average in 2007, an operation would

have to have a 20.6 percent decrease in milk

production before a veterinarian would be

contacted for assistance or consultation. Large

operations had a lower threshold (12.9 percent

reduction) compared with small operations

(22.3 percent reduction). Operations reported

that a veterinarian would be contacted if

9.6 percent of cows exhibited a fever,

5.8 percent of cows died within a short period,

or 6.8 percent of cows aborted.

a. Operation average percentage change at which a veterinarian would be 

contacted for assistance, by potential problem sign and by herd size 

Operation Average Percent Change 

Herd Size (Number of Cows) 

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Potential 

Problem Sign Avg. 

Std. 

Error Avg. 

Std. 

Error Avg. 

Std. 

Error Avg. 

Std. 

Error 

Decline in total 

daily milk 

production 

22.3 (1.2) 18.0 (1.1) 12.9 (1.2) 20.6 (0.9) 

Milk cows 

exhibiting fever 

within a short time 

period 

10.7 (1.2) 7.3 (0.9) 6.0 (1.8) 9.6 (0.9) 

Milk cows dying 

within a short time 

period 

6.8 (1.1) 3.2 (0.7) 4.2 (1.9) 5.8 (0.8) 

Milk cows aborting 

within a short time 

period 

8.1 (1.1) 3.9 (0.7) 4.6 (1.8) 6.8 (0.8) 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 101

Section I: Population Estimates—E. Incidence of Disease or Illness

Operations in the West region would seek

veterinary assistance if daily milk production

declined by 14.1 percent, while operations in the

East region would do so at a 21.3 percent

decline. For the other three potential problem

signs, there were no regional differences in the

average percentage change at which operations

would seek assistance from a veterinarian.

b. Operation average percentage change at which a veterinarian would be 

contacted for assistance, by potential problem sign and by region 

Operation Average Percent Change 

Region 

West East 

Potential Problem Sign Average Std. Error Average Std. Error 

Decline in total daily 

milk production 14.1 (1.1) 21.3 (1.0) 

Milk cows exhibiting fever 

within a short time period 5.7 (1.3) 10.0 (0.9) 

Milk cows dying within a 

short time period 3.8 (1.3) 5.9 (0.9) 

Milk cows aborting within 

a short time period 4.5 (1.3) 7.0 (0.9) 

Source: NAHMS Dairy 2007. 
102 / Dairy 2007

Section I: Population Estimates—E. Incidence of Disease or Illness

Laboratory testing is essential in determining the

cause of many diseases and allows for the

implementation of appropriate preventive or

control measures. More than one of five

operations in 2007 (22.7 percent) reported that

Johne’s disease was confirmed via laboratory

testing. A lower percentage of small operations

(17.4 percent) received a laboratory diagnosis

for Johne’s disease compared with medium and

large operations (35.0 and 34.1 percent,

respectively). Less than 10 percent of all

operations reported a laboratory confirmation

for the other listed diseases. Salmonella was

more frequently diagnosed via laboratory testing

on large operations than on medium and small

operations.

c. Percentage of operations in which the following diseases in cattle on the 

operation were confirmed via laboratory testing during the previous 12 

months, by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Disease Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Bovine leukosis 

virus (BLV) 5.7 (1.9) 12.4 (2.9) 7.8 (2.9) 7.5 (1.5) 

Bovine viral 

diarrhea (BVD) 1.1 (0.7) 5.9 (2.0) 9.6 (3.3) 2.8 (0.7) 

Leptospirosis 1.4 (0.8) 2.4 (1.1) 9.7 (3.8) 2.1 (0.7) 

Neospora 3.9 (1.6) 1.0 (0.6) 14.4 (4.4) 3.9 (1.1) 

Salmonella 5.1 (1.8) 10.8 (2.3) 30.9 (5.9) 8.1 (1.4) 

Mycobacterium 

avium subspecies

paratuberculosis

(Johne’s disease) 

17.4 (3.0) 35.0 (3.9) 34.1 (4.8) 22.7 (2.3) 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 103

Section I: Population Estimates—E. Incidence of Disease or Illness
104 / Dairy 2007

Section I: Population Estimates—E. Incidence of Disease or Illness

During the previous 12 months, there were no

differences by region in the percentages of

operations reporting laboratory confirmation for

the listed diseases.

d. Percentage of operations in which the following diseases in cattle on the 

operation were confirmed via laboratory testing during the previous 12 

months, by region 

Percent Operations 

Region 

West East 

Disease Percent Std. Error Percent Std. Error 

Bovine leukosis virus (BLV) 4.3 (2.0) 7.8 (1.7) 

Bovine viral diarrhea (BVD) 5.3 (2.3) 2.5 (0.7) 

Leptospirosis 5.2 (2.4) 1.9 (0.7) 

Neospora 10.8 (3.5) 3.2 (1.2) 

Salmonella 17.2 (4.2) 7.3 (1.5) 

Mycobacterium avium 

subspecies paratuberculosis 

(Johne’s disease) 

12.8 (3.2) 23.6 (2.5) 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 105

Section I: Population Estimates—E. Incidence of Disease or Illness

Bovine leukosis virus (BLV) was most

frequently diagnosed via blood samples

(88.5 percent of operations) in 2007. Blood, ear

notches, tissues at necropsy, and aborted fetuses

were the most frequently used samples for

diagnosing BVD. Leptospirosis and Johne’s

disease were most frequently diagnosed via

blood samples (69.6 and 70.3 percent of

operations, respectively). Neospora was

confirmed using aborted fetuses, blood, and

tissues at necropsy. Salmonella was most

frequently confirmed using fecal samples

(49.3 percent of operations).

e. For operations in which disease was confirmed via laboratory testing, 

percentage of operations by diagnostic samples used to confirm disease, and 

by confirmed disease 

Percent Operations 

Confirmed Disease 

Bovine 

Leukosis 

Virus (BLV) 

Bovine 

Viral 

Diarrhea 

(BVD) 

Leptospirosis Neospora Salmonella Johne’s 

Disease 

Diagnostic 

Sample Pct. 

Std. 

Err. Pct. 

Std. 

Err. Pct. 

Std. 

Err. Pct. 

Std. 

Err. Pct. 

Std. 

Err. Pct. 

Std. 

Err. 

Aborted 

fetus NA 13.9 (6.7) 22.8 (11.2) 59.0 (14.2) 7.9 (4.9) NA 

Blood 88.5 (4.8) 47.5 (12.9) 69.6 (12.5) 40.6 (14.2) 16.9 (5.5) 70.3 (5.3) 

Ear notch NA 41.3 (12.5) NA NA NA NA 

Feces NA 7.5 (4.4) NA NA 49.3 (9.1) 36.4 (5.5) 

Milk NA 0.6 (0.4) NA NA 20.0 (9.9) 12.4 (3.5) 

Tissues at 

necropsy 

6.3 (3.5) 15.7 (7.9) 10.3 (7.4) 18.5 (10.1) 15.4 (4.7) 0.1 (0.1) 

Urine NA NA 8.8 (5.4) NA NA NA 

Other 15.5 (6.3) 3.0 (2.9) 0.0 (--) 9.0 (8.5) 5.0 (4.2) 1.7 (1.6) 

Source: NAHMS Dairy 2007.
106 / Dairy 2007

Section I: Population Estimates—E. Incidence of Disease or Illness

3. Milk cultures Milk cultures can identify the most prevalent

cause of clinical mastitis, help direct mastitis

therapy, and screen purchased animals or

milking strings for contagious mastitis

pathogens.

A lower percentage of small operations

performed individual cow, bulk-tank milk, string

sample, or any cultures compared with medium

and large operations. A higher percentage of

large operations performed bulk-tank milk or

string-sample cultures compared with medium

and small operations. More than one-half of

operations (52.9 percent) had performed milk

cultures during the previous 12 months. More

than 8 of 10 large operations (82.6 percent) had

performed any culture, compared with about 7

of 10 medium operations (68.4 percent) and 4 of

10 small operations (44.5 percent).

a. Percentage of operations by source of milk cultures performed during the 

previous 12 months, and by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Milk Culture 

Source Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Individual cows 36.0 (3.6) 55.4 (4.2) 64.6 (5.3) 42.6 (2.7) 

Bulk-tank milk 25.1 (3.3) 46.4 (4.1) 75.8 (5.1) 33.6 (2.5) 

String samples 0.0 (--) 2.6 (0.8) 19.2 (3.9) 1.9 (0.3) 

Any culture 44.5 (3.8) 68.4 (3.9) 82.6 (4.6) 52.9 (2.8) 

Source: NAHMS Dairy 2007.
USDA APHIS VS / 107

Section I: Population Estimates—E. Incidence of Disease or Illness
108 / Dairy 2007

Section I: Population Estimates—E. Incidence of Disease or Illness

A higher percentage of operations in the West

region performed bulk-tank milk or stringsample cultures compared with operations in the

East region.

b. Percentage of operations by source of milk cultures performed during the 

previous 12 months, and by region 

Percent Operations 

Region 

West East 

Milk Culture Source Percent Std. Error Percent Std. Error 

Individual cows 43.4 (5.3) 42.6 (2.9) 

Bulk-tank milk 60.6 (5.1) 31.0 (2.7) 

String samples 11.0 (3.0) 1.0 (0.2) 

Any culture 65.1 (5.0) 51.7 (3.1) 

Source: NAHMS Dairy 2007.

For operations that performed milk cultures

during the previous 12 months, a higher

percentage of large operations than small

operations performed on-farm cultures (20.8 and

4.2 percent, respectively). A higher percentage

of medium operations (45.5 percent) had

cultures performed at a State or university

diagnostic laboratory compared with small

operations (24.1 percent). There were no herdsize differences in the percentage of operations

that used a commercial laboratory; about 4 of 10

operations (41.5 percent) used a commercial

laboratory to culture milk. Almost 50 percent of

operations that performed milk cultures

(49.2 percent) used a private veterinary

laboratory or clinic, with no differences across

herd sizes.
USDA APHIS VS / 109

Section I: Population Estimates—E. Incidence of Disease or Illness

c. For the 52.9 percent of operations that performed milk cultures during the 

previous 12 months, percentage of operations by facility used to perform 

cultures and by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Facility Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

On-farm, by farm 

personnel 4.2 (2.0) 14.0 (3.8) 20.8 (4.8) 9.0 (1.8) 

State or university 

diagnostic 

laboratory 

24.1 (4.9) 45.5 (5.0) 31.2 (4.4) 31.8 (3.3) 

Commercial 

laboratory 38.9 (5.6) 45.3 (5.0) 43.8 (6.0) 41.5 (3.6) 

Private veterinary 

laboratory 

(veterinary clinic) 

50.5 (5.7) 43.2 (5.1) 60.8 (6.3) 49.2 (3.7) 

Source: NAHMS Dairy 2007.

d. For the 52.9 percent of operations that performed milk cultures during the 

previous 12 months, percentage of operations by facility used to perform 

cultures and by region 

Percent Operations 

Region 

West East 

Facility Percent Std. Error Percent Std. Error 

On-farm, by farm personnel 13.0 (4.6) 8.5 (1.9) 

State or university 

diagnostic laboratory 13.0 (4.2) 34.0 (3.7) 

Commercial laboratory 59.2 (6.4) 39.4 (4.0) 

Private veterinary laboratory 

(veterinary clinic) 52.5 (6.6) 48.8 (4.1) 

Source: NAHMS Dairy 2007.

The only regional difference in the percentage

of operations that used a specific facility to

perform milk cultures was observed for State or

university diagnostic laboratory, which was used

by 13.0 percent of operations in the West region

compared with 34.0 percent in the East region.
110 / Dairy 2007

Section I: Population Estimates—E. Incidence of Disease or Illness

Milk was cultured most often from cows with

chronic clinical disease and from clinical cases

that did not respond to treatment (59.1 and

54.0 percent of operations, respectively). A

higher percentage of large operations performed

cultures on milk from individual fresh cows and

from all clinical cases compared with medium

and small operations.

e. For the 42.6 percent of operations that performed cultures on milk from 

individual cows during the previous 12 months, percentage of operations by 

cow type and by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Cow Type Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Fresh cows 8.0 (3.5) 14.9 (3.8) 47.2 (6.6) 13.9 (2.5) 

All clinical cases 22.2 (5.4) 35.4 (5.5) 65.4 (6.4) 30.5 (3.7) 

Chronic clinical 

cases 54.8 (6.4) 64.5 (5.3) 67.0 (7.6) 59.1 (4.2) 

Clinical cases that 

did not respond to 

treatment 

50.1 (6.5) 61.1 (5.6) 53.5 (7.9) 54.0 (4.3) 

High somatic cell 

count cows 37.9 (5.7) 49.6 (5.8) 31.5 (6.2) 41.1 (3.9) 

Other 11.0 (4.8) 7.0 (2.5) 8.6 (4.4) 9.5 (3.0) 

Source: NAHMS Dairy 2007.
USDA APHIS VS / 111

Section I: Population Estimates—E. Incidence of Disease or Illness

A higher percentage of operations in the West

region performed cultures on milk from

individual fresh cows and all clinical cases

(49.8 and 60.7 percent, respectively) compared

with operations in the East region (10.5 and

27.7 percent, respectively).

f. For the 42.6 percent of operations that performed cultures on milk from 

individual cows during the previous 12 months, percentage of operations by 

cow type and by region 

Percent Operations 

Region 

West East 

Cow Type Percent Std. Error Percent Std. Error 

Fresh cows 49.8 (7.9) 10.5 (2.6) 

All clinical cases 60.7 (8.3) 27.7 (4.0) 

Chronic clinical cases 55.4 (8.5) 59.4 (4.5) 

Clinical cases that did not 

respond to treatment 43.9 (8.1) 54.9 (4.7) 

High somatic cell count cows 46.6 (8.2) 40.6 (4.1) 

Other 4.8 (2.6) 9.9 (3.2) 

Source: NAHMS Dairy 2007.
112 / Dairy 2007

Section I: Population Estimates—E. Incidence of Disease or Illness

Similar percentages of all operations that

performed milk cultures during the previous

12 months detected Staphylococcus aureus, E.

coli/Klebsiella/other gram-negative, or

environmental strep (Strep. spp.). A higher

percentage of large operations (21.4 percent)

identified Mycoplasma compared with medium

and small operations (3.8 and 4.0 percent,

respectively). A lower percentage of small

operations identified E. coli/Klebsiella/other

gram-negative or coagulase-negative staph

(Staph. spp. non-aureus) organisms compared

with large operations.

g. For the 52.9 percent of operations that performed milk cultures during the 

previous 12 months, percentage of operations by organism identified and by 

herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Organism Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Strep. agalactiae 29.4 (5.4) 42.2 (5.0) 35.6 (5.7) 34.4 (3.6) 

Staph. aureus 50.5 (6.1) 51.4 (5.1) 64.4 (6.1) 52.3 (3.9) 

Mycoplasma 4.0 (3.2) 3.8 (1.9) 21.4 (4.7) 5.7 (1.9) 

E. coli/Klebsiella/ 

other gram-negative 41.8 (5.9) 64.3 (4.8) 78.9 (5.4) 53.3 (3.8) 

Coagulase-negative 

staph (Staph. spp. 

non-aureus) 

25.3 (5.5) 37.6 (4.8) 63.4 (6.0) 33.5 (3.5) 

Environmental strep 

(Strep. spp. nonagalactiae) 52.4 (6.1) 67.0 (4.8) 78.3 (5.1) 60.1 (3.8) 

Source: NAHMS Dairy 2007.
USDA APHIS VS / 113

Section I: Population Estimates—E. Incidence of Disease or Illness

Mycoplasma was isolated from a higher

percentage of operations in the West region

(17.7 percent) than in the East region

(4.2 percent).

h. For the 52.9 percent of operations that performed milk cultures during the 

previous 12 months, percentage of operations by organism identified and by 

region 

Percent Operations 

Region 

West East 

Organism Percent Std. Error Percent Std. Error 

Strep. agalactiae 37.3 (6.2) 34.0 (3.9) 

Staph. aureus 53.5 (6.4) 52.1 (4.3) 

Mycoplasma 17.7 (4.5) 4.2 (2.1) 

E. coli/Klebsiella/other 

gram-negative 67.0 (6.3) 51.6 (4.2) 

Coagulase-negative staph 

(Staph. spp. non-aureus) 46.5 (6.5) 31.9 (3.9) 

Environmental strep (Strep. 

spp. non-agalactiae) 62.7 (6.5) 59.8 (4.2) 

Source: NAHMS Dairy 2007.
114 / Dairy 2007

Section I: Population Estimates—E. Incidence of Disease or Illness
USDA APHIS VS / 115

Section I: Population Estimates—E. Incidence of Disease or Illness

4. Abortions Abortion is a term generally used to describe the

expulsion of a dead fetus at 45 to 265 days of

gestation (Virginia Cooperative Extension,

2009). Abortions in cattle can be due to a

variety of conditions: congenital problems with

the calf that cause spontaneous abortions;

disease processes that cause sporadic abortions;

and infectious diseases such as Campylobacter

or brucellosis, which can cause economically

damaging abortion “storms.” Determining the

cause of abortions can help diagnose health

problems in the herd, lead to the reduction or

prevention of additional abortions, and result in

the birth of more healthy calves.

The percentage of operations in which at least

one abortion occurred increased from 1996 to

2007.

a. Percentage of operations that had at least one cow or heifer abort 

Percent Operations 

Dairy 1996 Std. Error Dairy 2002 Std. Error Dairy 2007 Std. Error 

66.3 (1.2) 72.9 (1.3) 86.6 (2.2) 

Optimally, no more than 2 percent of cows and

heifers should abort each year, although up to

5 percent is considered acceptable. The abortion

percentage for cows and heifers combined

increased from 3.5 percent in 1996 to

4.5 percent in 2007.

b. Percentage of heifers and cows* that aborted, by herd size 

Percent Heifers/Cows 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Study Year Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

1996 3.2 (0.1) 3.3 (0.1) 4.3 (0.3) 3.5 (0.1) 

2002 3.6 (0.1) 3.4 (0.1) 4.9 (0.3) 4.0 (0.1) 

2007 3.7 (0.1) 3.7 (0.1) 5.3 (0.3) 4.5 (0.2) 

*As a percentage of cow inventory on January 1 of each respective year on operations with any dairy cows. 
116 / Dairy 2007

Section I: Population Estimates—E. Incidence of Disease or Illness

The percentages of operations by abortion

percentages were similar across study years.

c. Percentage of operations1 by abortion percentage 

Percent Operations 

Percent Abortions2

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Less than 2.0 42.7 (1.3) 39.3 (1.3) 38.2 (1.4) 

2.0 to 4.9 36.2 (1.2) 34.6 (1.2) 34.3 (1.3) 

5.0 to 9.9 16.2 (0.9) 20.3 (1.1) 20.6 (1.1) 

10.0 to 14.9 3.2 (0.5) 4.7 (0.7) 4.9 (0.6) 

15.0 or more 1.7 (0.4) 1.1 (0.3) 2.0 (0.4) 

Total 100.0 100.0 100.0 

1

Operations with any dairy cows 

2

As a percentage of cow inventory at time of interview. 

Determining the cause of abortion can be

difficult. In many cases, the event that caused

the fetus to die occurred days to weeks before

the actual abortion. Frequently, the cause of an

abortion is not detectable, or the fetus is too

decomposed to evaluate or is never found at all.

A diagnosis is determined in 50 percent or less

of abortion samples submitted to diagnostic

laboratories. To improve the chances of

diagnosing the cause of an abortion, a detailed

history and the proper diagnostic specimens

should be submitted to the laboratory. Specific

samples recommended for submission include

sera from the dam, the entire fetus, or specific

tissues and placenta.

d. For the 86.6 percent of operations 

that had any cows or heifers abort, 

percentage of operations that 

submitted any samples for 

diagnosis 

Percent Operations Standard Error 

12.4 (1.7) 

Source: NAHMS Dairy 2007.

About one of eight operations (12.4 percent)

submitted samples to determine the cause of

abortion in 2007.
USDA APHIS VS / 117

Section I: Population Estimates—E. Incidence of Disease or Illness

For operations that submitted samples,

70.2 percent submitted serum from the dam and

32.7 percent submitted the placenta.

e. For operations that submitted 

samples to determine cause of 

abortion, percentage of operations 

by type of sample submitted 

Sample 

Type 

Percent 

Operations 

Standard 

Error 

Placenta 32.7 (6.9) 

Entire 

fetus 53.8 (7.6) 

Serum of 

dam 70.2 (6.6) 

Other 4.0 (3.2) 

Source: NAHMS Dairy 2007.

The majority of operations that reported any

abortions but did not submit samples for

diagnosis (69.6 percent) did not perceive

abortion as a problem on their operation.

f. For any aborted fetuses that were not submitted for diagnosis, percentage of 

operations by reason for not submitting fetus 

Reason Percent Operations Standard Error 

Cost 2.5 (1.0) 

Lack of information obtained from 

previous abortion submissions 6.6 (1.3) 

Inconvenience 7.0 (1.7) 

Abortion not perceived 

as a problem on the operation 69.6 (2.7) 

Other 14.3 (2.0) 

Total 100.0 

Source: NAHMS Dairy 2007.
118 / Dairy 2007

Section I: Population Estimates—E. Incidence of Disease or Illness

Although only 12.4 percent of operations that

reported any abortions submitted samples for

diagnosis, more than 8 of 10 operations

(82.0 percent) would submit aborted fetuses for

diagnosis if testing was performed at no cost,

and 48.5 percent of aborted fetuses would be

submitted for diagnosis.

g. Percentage of operations that would submit aborted fetuses to a veterinary 

diagnostic laboratory if testing was performed at no cost, and percentage of 

aborted fetuses that would be submitted 

Percent 

Operations

Standard 

Error 

Operation 

Average Percent 

Aborted Fetuses 

Standard 

Error 

82.0 (2.3) 48.5 (4.9) 

Source: NAHMS Dairy 2007.

Photo courtesy of Keith Weller, ARS.
USDA APHIS VS / 119

Section I: Population Estimates—F. Mortality, Necropsy, and Carcass Disposal

F. Mortality, Necropsy, and Carcass Disposal

1. Mortality

The percentages of preweaned and weaned

heifer calves that died decreased from 1996 to

2007. The percentage of preweaned heifer

calves that died decreased from 10.8 percent in

1996 to 7.8 percent in 2007. Weaned heifer calf

deaths increased from 2.2 percent in 1991 to

2.8 percent in 2002 and then decreased to

1.8 percent in 2007.

A lower percentage of small operations had any

deaths in each of the cattle classes compared

with medium and larger operations. All large

herds had at least one death in each cattle class,

which was expected since these operations have

more animals at risk.

b. Number of preweaned and weaned heifer deaths*, as a percentage of heifers 

born alive... 

...or moved onto 

the operation 

NDHEP 1991 Dairy 1996 Dairy 2002 Dairy 2007 

Heifer 

Class Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Preweaned 8.4 (0.4) 10.8 (0.4) 10.5 (0.3) 7.8 (0.2) 

Weaned 2.2 (0.1) 2.4 (0.1) 2.8 (0.1) 1.8 (0.1) 

*Operations with any dairy cows.

a. Percentage of operations that had at least one death* in the following cattle 

classes, by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Cattle Class Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Preweaned 

heifers 59.8 (1.8) 100.0 (0.0) 100.0 (0.0) 69.9 (1.4) 

Weaned 

heifers 29.9 (1.6) 73.1 (2.3) 100.0 (0.0) 41.6 (1.3) 

Cows 76.5 (1.5) 99.1 (0.4) 100.0 (0.0) 82.6 (1.1) 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007.
120 / Dairy 2007

Section I: Population Estimates—F. Mortality, Necropsy, and Carcass Disposal

Scours/diarrhea accounted for more than

50 percent of preweaned heifer deaths in each

study year since 1991, while respiratory

problems accounted for 21 to 25 percent of

deaths during the same period.

c. Percentage of preweaned heifer deaths*, by cause 

Percent Deaths 

Cause 

NDHEP 

1991 

Std. 

Error 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Scours/ 

diarrhea 52.2 (2.6) 60.5 (1.2) 62.1 (1.1) 56.5 (1.3) 

Respiratory 

problems 21.3 (1.6) 24.5 (1.0) 21.3 (0.9) 22.5 (0.9) 

Joint or navel 

problems 2.2 (0.7) 1.0 (0.1) 1.7 (0.2) 1.6 (0.3) 

Lameness 

or injury NA 0.6 (0.1) 0.5 (0.1) 1.7 (0.3) 

Lack of 

coordination/ 

severe 

depression 

NA 0.4 (0.1) 0.4 (0.1) 0.3 (0.1) 

Poison NA 0.3 (0.1) 0.1 (0.0) 0.0 (0.0) 

Calving 

problems NA NA 4.1 (0.6) 5.3 (0.7) 

Trauma 2.4 (0.8) NA NA NA 

Other known 11.7 (1.8) 6.4 (1.1) 2.9 (0.4) 4.3 (0.7) 

Unknown 10.2 (1.4) 6.3 (0.9) 6.9 (0.8) 7.8 (0.9) 

Total 100.0 100.0 100.0 100.0 

*Operations with any dairy cows 
USDA APHIS VS / 121

Section I: Population Estimates—F. Mortality, Necropsy, and Carcass Disposal
122 / Dairy 2007

Section I: Population Estimates—F. Mortality, Necropsy, and Carcass Disposal

The percentage of weaned heifer deaths caused

by respiratory problems increased from

34.8 percent of deaths in 1991 to 46.5 percent in

2007. Weaned heifer deaths caused by lameness

or injury increased from 4.0 percent of deaths in

1996 to 12.8 percent in 2007.

d. Percentage of weaned heifer deaths*, by cause 

Percent Deaths 

Cause 

NDHEP 

1991 

Std. 

Error 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Scours/ 

diarrhea 18.4 (2.6) 14.1 (1.6) 12.3 (1.0) 12.6 (1.0) 

Respiratory 

problems 34.8 (3.5) 44.8 (2.1) 50.4 (1.6) 46.5 (1.7) 

Joint or navel 

problems 1.0 (0.4) 1.2 (0.5) 1.4 (0.3) 1.0 (0.3) 

Lameness 

or injury NA 4.0 (0.5) 6.4 (0.6) 12.8 (1.0) 

Lack of 

coordination/ 

severe 

depression 

NA 0.5 (0.1) 0.3 (0.1) 0.7 (0.2) 

Poison NA 1.2 (0.3) 1.1 (0.4) 1.9 (0.9) 

Trauma 6.7 (0.9) NA NA NA 

Other known 20.8 (2.0) 15.8 (2.4) 12.1 (1.2) 9.9 (1.0) 

Unknown 18.3 (2.1) 18.4 (1.4) 16.0 (1.1) 14.6 (1.2) 

Total 100.0 100.0 100.0 100.0 

*Operations with any dairy cows. 
USDA APHIS VS / 123

Section I: Population Estimates—F. Mortality, Necropsy, and Carcass Disposal
124 / Dairy 2007

Section I: Population Estimates—F. Mortality, Necropsy, and Carcass Disposal

The percentage of cows that died increased

across herd sizes from 1996 to 2007. The

overall percentage of cows that died increased

from 3.8 percent in 1996 to 5.7 percent in 2007.

e. Percentage of cows deaths*, as a percentage of January 1 inventory, by herd 

size 

Percent Cows 

Herd Size 

(Number of Cows) 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Small (fewer than 100) 3.6 (0.1) 4.4 (0.1) 4.8 (0.1) 

Medium (100 to 499) 3.9 (0.1) 5.0 (0.1) 5.8 (0.2) 

Large (500 or more) 4.0 (0.2) 4.9 (0.1) 6.1 (0.2) 

All operations 3.8 (0.1) 4.8 (0.1) 5.7 (0.1) 

*Operations with any dairy cows. 
USDA APHIS VS / 125

Section I: Population Estimates—F. Mortality, Necropsy, and Carcass Disposal

The percentage of cow deaths due to lameness

or injury increased from 12.7 percent in 1996 to

20.0 percent in 2007. Conversely, the

percentage of cow deaths due to calving

problems and other known reasons decreased

from 1996 to 2007.

f. Percentage of cow deaths*, by cause 

Percent Deaths 

Cause 

Dairy 

1996 

Std. 

Error 

Dairy 

2002 

Std. 

Error 

Dairy 

2007 

Std. 

Error 

Scours, diarrhea, or other 

digestive problems 9.0 (1.0) 8.6 (0.5) 10.4 (0.5) 

Respiratory problems 9.6 (0.7) 10.3 (0.5) 11.3 (0.7) 

Poison 0.9 (0.2) 0.4 (0.1) 0.4 (0.1) 

Put down due to 

lameness or injury 12.7 (0.7) 13.9 (0.6) 20.0 (0.8) 

Lack of coordination or 

severe depression 1.4 (0.2) 1.4 (0.2) 1.0 (0.1) 

Mastitis 16.3 (0.8) 17.1 (0.6) 16.5 (0.7) 

Calving problems 18.3 (0.7) 17.4 (0.7) 15.2 (0.7) 

Other known reasons 17.0 (0.9) 11.1 (0.6) 10.2 (0.8) 

Unknown reasons 14.8 (0.8) 19.8 (0.9) 15.0 (1.1) 

Total 100.0 100.0 100.0 

*Operations with any dairy cows. 
126 / Dairy 2007

Section I: Population Estimates—F. Mortality, Necropsy, and Carcass Disposal

2. Necropsy Determining the cause of death is important in

preventing future deaths and improving the

health of the herd. A relatively low percentage

of operations performed necropsies on dead

preweaned heifers, weaned heifers, or cows

(8.0, 7.1, and 13.0 percent, respectively) to

determine cause of death. With the exception of

weaned heifers, the percentage of operations

that performed any necropsy for a particular

cattle class increased as herd size increased.

Less than 1 of 10 small operations (8.4 percent)

performed necropsies on cows, while 3 of

10 large operations (33.3 percent) performed

necropsies.

a. For operations* that had at least one death in the following cattle classes, 

percentage of operations that performed necropsies to determine the cause of 

death, by herd size 

Percent Operations 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Cattle Class Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Preweaned 

heifers 4.4 (0.9) 11.9 (1.4) 22.6 (2.5) 8.0 (0.7) 

Weaned 

heifers 5.8 (1.4) 6.9 (1.2) 13.5 (2.1) 7.1 (0.9) 

Cows 8.4 (1.0) 20.2 (1.8) 33.3 (2.7) 13.0 (0.9) 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007. 
USDA APHIS VS / 127

Section I: Population Estimates—F. Mortality, Necropsy, and Carcass Disposal

About 4 percent of animals that died within any

cattle class were necropsied to determine the

cause of death. There were no substantial

differences in the percentages of deaths

necropsied among cattle classes or herd sizes.

b. For operations* that had at least one death in the following cattle classes, 

percentage of preweaned heifer deaths, weaned heifer deaths, and cow deaths 

in which necropsies were performed to determine cause of death, by herd size 

Percent Deaths Necropsied 

Herd Size (Number of Cows)

Small 

(Fewer than 100) 

Medium 

(100-499) 

Large 

(500 or More) 

All 

Operations 

Cattle Class Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error Pct. 

Std. 

Error 

Preweaned 

heifers 1.8 (0.4) 4.7 (1.1) 3.8 (0.5) 3.5 (0.4) 

Weaned 

heifers 3.9 (1.0) 4.8 (1.5) 3.7 (0.7) 4.1 (0.6) 

Cows 4.4 (0.7) 6.0 (0.9) 3.5 (0.4) 4.4 (0.4) 

*Operations with any dairy cows. 

Source: NAHMS Dairy 2007. 
128 / Dairy 2007

Section I: Population Estimates—F. Mortality, Necropsy, and Carcass Disposal

3. Carcass disposal Prompt removal and disposal of dead animals

from pens before other animals, rodents, or

birds have contact with them reduces the risk

that disease agents from the carcasses will be

spread to other animals.

The percentage of operations that used

rendering to dispose of dead calves decreased

from 43.8 percent in 2002 to 36.5 percent in

2007, while the percentage of operations that

composted dead calves increased from 10.1 to

24.2 percent during the same period.

a. Percentage of operations* by primary method used to dispose of dead calves 

Percent Operations 

Disposal Method Dairy 2002 Std. Error Dairy 2007 Std. Error 

Buried 35.3 (1.3) 32.6 (1.3) 

Burned/incinerated 2.8 (0.4) 2.0 (0.4) 

Rendered 43.8 (1.3) 36.5 (1.3) 

Composted 10.1 (0.8) 24.2 (1.2) 

Landfill 2.4 (0.4) 1.7 (0.3) 

Other 5.6 (0.6) 3.0 (0.5) 

Total 100.0 100.0 

*Operations with any dairy cows. 
USDA APHIS VS / 129

Section I: Population Estimates—F. Mortality, Necropsy, and Carcass Disposal

Although rendering remained the primary

method of dead-cow disposal, the percentage of

operations that used this method decreased from

62.4 percent in 2002 to 56.9 percent in 2007.

Conversely, the use of composting increased

from 6.9 percent of operations in 2002 to

16.8 percent in 2007. These changes in deadcow disposal are similar to those observed in

disposing of dead calves.

b. Percentage of operations* by primary method used to dispose of dead cows 

Percent Operations 

Disposal Method Dairy 2002 Std. Error Dairy 2007 Std. Error 

Buried 22.7 (1.1) 20.3 (1.1) 

Burned/incinerated 2.2 (0.4) 1.8 (0.4) 

Rendered 62.4 (1.2) 56.9 (1.3) 

Composted 6.9 (0.7) 16.8 (1.0) 

Landfill 1.9 (0.3) 1.7 (0.3) 

Other 3.9 (0.5) 2.5 (0.4) 

Total 100.0 100.0 

*Operations with any dairy cows. 
130 / Dairy 2007

Section II: Methodology

Section II: Me Section II: Methodology Dair hodology Dairy 2007

A. Needs Assessment

NAHMS develops study objectives by exploring

existing literature and contacting industry

members about their informational needs and

priorities during a needs-assessment phase. The

objective of the needs assessment for the

NAHMS Dairy 2007 study was to collect

information from U.S. dairy producers and other

dairy specialists about what they perceived to be

the most important dairy health and productivity

issues. A driving force of the needs assessment

was the desire of NAHMS researchers to receive

as much input as possible from a variety of

producers, industry experts and representatives,

veterinarians, extension specialists, universities,

and dairy organizations. Information was

collected via focus groups and through a Needs

Assessment Survey.

Focus group teleconferences and meetings were

held to help determine the focus of the study:

Teleconference, March 30, 2006

National Johne’s Working Group

Meeting, Louisville, KY, April 2, 2006

National Johne’s Working Group

National Institute for Animal Agriculture

Meeting, Louisville, KY, April 3, 2006

National Milk Producers Federation

Animal Health Committee

Teleconference, December 15, 2006

Bovine Alliance on Management and Nutrition

In addition, a Needs Assessment Survey was

designed to ascertain the top three management

issues, diseases/disorders, and producer

incentives from producers, veterinarians,

extension personnel, university researchers, and

allied industry groups. The survey, created in

SurveyMonkey, was available online from early

February through late April 2006 and was

promoted via electronic newsletters, magazines,

and Web sites. Organizations and magazines

promoting the study included Vance

Publishing’s “Dairy Herd Management–Dairy

Alert,” “Dairy Today,” “Hoard’s Dairyman,”

NMC, “Journal of the American Veterinary

Medical Association,” and the American

Association of Bovine Practitioners. E-mail

messages requesting input were also sent to

cooperative members of the National Milk

Producers Federation as well as State and

Federal personnel. A total of 313 people

completed the survey questionnaire.

Respondents to the Needs Assessment Survey

represented

• University/extension personnel—23 percent,

• Producers—22 percent,

• Veterinarians/consultants—20 percent,

• Federal or State government personnel—

15 percent,

• Nutritionists—8 percent,

• Allied industry personnel—8 percent, and

• Other—4 percent.

Note: For methodology documentation for studies in 1991, 1996, and 2002, see previous study reports.

Also see Appendices III and IV for an overview.
USDA APHIS VS / 131

Section II: Methodology

CEAH Focus Group meeting

Fort Collins, CO, May 18, 2006

Draft objectives for the Dairy 2007 study were

based on input from teleconferences, face-toface meetings, and the online survey, and were

developed prior to the focus group meeting.

Attendees included producers, university/

extension personnel, veterinarians, and

government personnel. The day-long meeting

culminated in the formulation of eight

objectives for the study:

 1. Describe trends in dairy cattle health and

 management practices.

 2. Evaluate management factors related to

 cow comfort and removal rates.

 3. Describe dairy calf health and nutrition

 from birth to weaning and evaluate heifer

 disease-prevention practices.

 4. Estimate the prevalence of herds infected

 with bovine viral diarrhea virus (BVD).

 5. Describe current milking procedures and

 estimate the prevalence of contagious

 mastitis pathogens.

 6. Estimate the herd-level prevalence and

 associated costs of Mycobacterium avium

 subspecies paratuberculosis

 (Johne’s disease).

 7. Describe current biosecurity practices and

 determine producer motivation for

 implementing or not implementing

 biosecurity practices.

 8. Determine the prevalence of specific food-

 safety pathogens and describe

 antimicrobial resistance patterns.

B. Sampling and Estimation

1. State selection The preliminary selection of States to be

included in the study was done in February 2006

using the National Agricultural Statistics Service

(NASS) January 27, 2006, “Cattle Report.” A

goal for NAHMS national studies is to include

States that account for at least

70 percent of the animals and producer

population in the United States. The initial

review of States identified 16 major States

representing 82.0 percent of the U.S. milk cow

inventory and 79.3 percent of U.S. operations

with milk cows (dairy herds). The States were

California, Idaho, Indiana, Iowa, Kentucky,

Michigan, Minnesota, Missouri, New Mexico,

New York, Ohio, Pennsylvania, Texas, Vermont,

Washington, and Wisconsin.

A memo identifying these 16 States was

provided in March 2006 to the USDA–APHIS–

VS–CEAH Director and, in turn, the VS

Regional Directors. Each Regional Director

sought input from the respective States about

being included in or excluded from the study.

Virginia expressed interest in participating and

was included, bringing the total number of

States to 17.
132 / Dairy 2007

Section II: Methodology

2. Operation

selection

The list sampling frame was provided by NASS.

Within each State a stratified random sample

was selected. The size indicator was the number

of milk cows for each operation. NASS selected

a sample of dairy producers in each State for

making the January 1 cattle estimates. The list

sample from the January 2006 survey was used

as the screening sample. Among producers

reporting 1 or more milk cows on January 1,

2006, a total of 3,554 operations were selected

from the sample for contact in January 2007

during Phase I.

Operations with 30 or more dairy cows that had

participated in Phase I were invited to

participate in data collection for Phase II of the

study. A total of 1,077 operations agreed via

written consent to be contacted by veterinary

medical officers to determine whether to

complete Phase II.

3. Population

inferences

a. Phase I: General Dairy Management

Report

Inferences cover the population of dairy

producers with at least 1 milk cow in the

17 participating States. As of January 1, 2007,

these States accounted for 82.5 percent

(7,536,000 head) of U.S. milk cows and 79.5

percent (59,640) of U.S. operations with milk

cows. (See Appendix II, p 139, for respective

data on individual States.) All respondent data

were statistically weighted to reflect the

population from which they were selected. The

inverse of the probability of selection for each

operation was the initial selection weight. This

selection weight was adjusted for nonresponse

within each State and size group to allow for

inferences back to the original population from

which the sample was selected.

b. Phase II: VS Initial and Second Visits

Inferences cover the population of dairy

producers with 30 or more milk cows in the

17 participating States. For operations eligible

for Phase II data collection (those with 30 or

more dairy cows), weights were adjusted to

account for operations that did not want to

continue to Phase II. In addition, weights were

adjusted for nonresponse to the questionnaire in

each visit. The 17-State target population of

operations with 30 or more dairy cows

represented 82.5 percent of U.S. dairy cows and

84.7 percent of U.S. dairy operations with 30 or

more milk cows (Appendix II).
USDA APHIS VS / 133

Section II: Methodology

C. Data Collection

1. Phase I: General Dairy Management

Report

From January 1 to 31, 2007, NASS enumerators

administered the General Dairy Management

Report questionnaire. The interview took

slightly over 1 hour.

2. Phase II: VS Initial Visit

From February 26 to April 30, 2007, Federal

and State veterinary medical officers (VMOs)

and/or animal health technicians (AHTs)

collected data from producers during an

interview that lasted approximately 2 hours.

3. Phase II: VS Second Visit

From May 1 to August 31, 2007, Federal and

State VMOs and/or AHTs collected data from

producers during an interview that lasted

approximately 2 hours.

D. Data Analysis

Validation a. Phase I: Validation—General Dairy

Management Report

Initial data entry and validation for the General

Dairy Management Report were performed in

individual NASS State offices. Data were

entered into a SAS data set. NAHMS national

staff performed additional data validation on the

entire data set after data from all States were

combined.

b. Phase II: Validation—VS Initial and

Second Visit Questionnaires

After completing the VS Initial and Second Visit

questionnaires, data collectors sent them to their

respective State NAHMS Coordinators, who

reviewed the questionnaire responses for

accuracy and sent them to NAHMS. Data entry

and validation were completed by NAHMS staff

using SAS.
134 / Dairy 2007

Section II: Methodology

E. Sample Evaluation

The purpose of this section is to provide various

performance measurement parameters.

Historically, the term “response rate” has been

used as a catch-all parameter, but there are many

ways to define and calculate response rates.

Therefore, the table below presents an

evaluation based on a number of measurement

parameters, which are defined with an “x” (see

table on next page) in categories that contribute

to the measurement.

1. Phase I: General Dairy Management

Report (GDMR)

A total of 3,554 operations were selected for the

survey. Of these operations, 3,304

(93.0 percent) were contacted. There were

2,519 operations that provided usable inventory

information (70.9 percent of the total selected

and 76.2 percent of those contacted). In

addition, there were 2,194 operations

(61.7 percent) that provided “complete”

information for the questionnaire. Of the 2,067

operations that provided complete information

and were eligible to participate in Phase II of the

study, 1,077 (52.1 percent) consented to be

contacted for consideration/discussion about

further participation.
USDA APHIS VS / 135

Section II: Methodology

Measurement Parameter

Response 

Category 

Number 

Operations 

Percent 

Operations Contacts Usable1 Complete2

Survey complete 

and VMO consent 1,077 30.3 x x x 

Survey complete, 

refused VMO 

consent 

990 27.9 x x x 

Survey complete, 

ineligible3

 for VMO 127 3.6 x x x 

No dairy cows on 

January 1, 2007 214 6.0 x x 

Out of business 111 3.1 x x 

Out of scope 

(prison, research 

farm, etc.) 

6 0.2 

Refusal of GDMR 785 22.1 x 

Office hold (NASS 

elected not to 

contact) 

126 3.5 

Inaccessible 118 3.3 

Total 3,554 100.0 3,304 2,519 2,194 

Percent of total 

operations 93.0 70.9 61.7 

Percent of total 

operations 

weighted4

94.0 74.1 59.6 

1

Usable operation—respondent provided answers to inventory questions for the operation (either zero or 

positive number on hand). 

2

Survey complete operation—respondent provided answers to all or nearly all questions. 

3

Ineligible—fewer than 30 head of milk cows on January 1, 2007. 

4

Weighted response—the rate was calculated using the initial selection weights. 
136 / Dairy 2007

Section II: Methodology

2. Phase II: VS Initial Visit

There were 1,077 operations that provided

consent during Phase I to be contacted by a

VMO for Phase II. Of these 1,077 operations,

582 (54.0 percent) agreed to continue in Phase

II of the study and completed the VS Initial Visit

Questionnaire; 380 (35.3 percent) refused to

participate. Approximately 10 percent of the

1,077 operations were not contacted, and

0.4 percent were ineligible because they had no

dairy cows at the time they were contacted by

the VMO during Phase II.

Measurement Parameter

Response Category 

Number 

Operations 

Percent 

Operations Contacts Usable1 Complete2

Survey complete 582 54.0 x x x 

Survey refused 380 35.3 x 

Not contacted 111 10.3 

Ineligible3 4 0.4 x x 

Total 1,077 100.0 966 586 582 

Percent of total 

operations 89.7 54.4 54.0 

Percent of total 

operations weighted4 87.5 50.8 50.4 

1

Usable operation—respondent provided answers to inventory questions for the operation (either zero or 

positive number on hand). 

2

Survey complete operation—respondent provided answers to all or nearly all questions. 

3

Ineligible—no dairy cows at time of interview, which occurred from February 26 through April 30, 2007 

4

Weighted response—the rate was calculated using the turnover weights. 
USDA APHIS VS / 137

Section II: Methodology

3. Phase II: VS Second Visit

Of the 582 operations that completed the VS

Initial Visit Questionnaire, 519 (including one

operation that did not complete the VS Initial

Visit on time) completed the VS Second Visit

Questionnaire; 47 (8.1 percent) refused to

participate. Approximately 3 percent of the

583 operations were not contacted, and

0.3 percent were ineligible because they had no

dairy cows at the time of the VS Second Visit.

Measurement Parameter

Response Category 

Number 

Operations 

Percent 

Operations Contacts Usable1 Complete2

Survey complete 519 89.0 x x x 

Survey refused 47 8.1 x 

Not contacted 15 2.6 

Ineligible3 2 0.3 x x 

Total 583 100.0 568 521 519 

Percent of total 

operations 97.4 89.4 89.0 

Percent of total 

operations weighted4 98.1 90.6 90.3 

1

Usable operation—respondent provided answers to inventory questions for the operation (either zero or 

positive number on hand). 

2

Survey complete operation—respondent provided answers to all or nearly all questions. 

3

Ineligible—no dairy cows at time of interview, which occurred from May 1 through August 31, 2007. 

4

Weighted response—the rate was calculated using the turnover weights. 
138 / Dairy 2007

Appendix I: Sample Profile

Appendix I: Sample Profile

Dairy 2007

A. Responding Operations

1. Number of responding operations, by herd size

Phase I: General 

Dairy Management 

Report 

Phase II: VS 

Initial Visit 

Phase II: VS 

Second Visit 

Herd Size 

(Number of Cows) Number of Responding Operations 

Fewer than 100 1,028 233 211 

100 to 499 691 215 188 

500 or more 475 134 120 

Total 2,194 582 519 

2. Number of responding operations, by region

Phase I: General 

Dairy Management 

Report 

Phase II: VS 

Initial Visit 

Phase II: VS 

Second Visit 

Region Number of Responding Operations 

West 426 108 93 

East 1,768 474 426 

Total 2,194 582 519 
USDA APHIS VS / 139

Appendix II: U.S. Milk Cow Population and Operations

Appendix II: U.S. Milk Co .S. Milk Cow

Population and Oper opulation and Operations

Number of milk cows on January 1, 2007* 

Number of Milk Cows, 

January 1, 2007 

(Thousand Head)

Number of Operations 

2007 Average Herd Size 

Region State 

Milk cows 

on 

operations 

with 1 or 

more head 

Milk cows 

on 

operations 

with 30 or 

more head 

Operations 

with 1 or 

more head 

Operations 

with 30 or 

more head 

Operations 

with 1 or 

more head 

Operations 

with 30 or 

more head 

West 

California 1,790 1,788.2 2,200 1,920 813.6 931.4 

Idaho 502 501.0 800 620 627.5 808.1 

New Mexico 360 358.9 450 180 800.0 1,993.9 

Texas 347 344.2 1,300 660 266.9 521.5 

Washington 235 234.3 790 540 297.5 433.9 

 Total 3,234 3,226.6 5,540 3,920 583.8 823.1 

East 

Indiana 166 154.4 2,100 1,150 79.0 134.3 

Iowa 210 203.7 2,400 1,870 87.5 108.9 

Kentucky 93 86.5 2,000 1,180 46.5 73.3 

Michigan 327 320.5 2,700 1,910 121.1 167.8 

Minnesota 455 441.3 5,400 4,800 84.3 91.9 

Missouri 114 108.3 2,600 1,400 43.8 77.4 

New York 628 612.3 6,400 5,100 98.1 120.1 

Ohio 274 252.1 4,300 2,400 63.7 105.0 

Pennsylvania 550 536.3 8,700 7,000 63.2 76.6 

Vermont 140 137.2 1,300 1,100 107.7 124.7 

Virginia 100 97.0 1,300 820 76.9 118.3 

Wisconsin 1,245 1,213.9 14,900 12,800 83.6 94.8 

 Total 4,302 4,163.5 54,100 41,530 79.5 100.3 

Total (17 States) 7,536 7,390.1 59,640 45,450 126.4 162.6 

Percent of U.S. 82.5 82.5 79.5 84.7 

Total U.S. (50 States) 9,132.0 8,958.5 74,980 53,680 121.8 166.9 

*Source: NASS Cattle report, February 1, 2008, and NASS Farms, Land in Farms, and Livestock Operations 2007 Summary report, 

February 1, 2008. An operation is any place having one or more head of milk cows, excluding cows used to nurse calves, on hand at 

any time during the year. 
140 / Dairy 2007

Appendix III: Methodology Overview, Phase I

Appendix III: Me Appendix III: Methodology hodology

Overview, Phase I (1 , Phase I (1991–2007)

NAHMS Dairy Studies 

1991 1996 2002 2007 

Data collection dates 

4/1991-

7/1992 

1/1-1/26 

1996 

12/31/2001-

2/12/2002 

1/1-1/31 

2007 

Minimum number of dairy cattle 30 1 1 1 

Number of States 28 20 21 17 

Data collectors National Agricultural Statistics Service enumerators 

States as a percentage of U.S. population coverage 

Operations 76.3 80.4 83.0 79.5 

Cows 81.3 83.1 85.7 82.5 

Respondent Sample profile (herd size) 

Small (fewer than 100 cows) 931 1,480 1,131 1,028 

Medium (100-499 cows) 705 873 820 691 

Large (500 or more cows) 175 189 510 475 

Response category 

Survey complete 1,811 2,542 2,461 2,194 

Percent of total 54.1 56.3 63.5 61.7 

No milk cows 

NA 

646 227 214 

Out of business/ 

no milk sold in 1995 179 183 111 

Out of scope 

(prison, research farm, etc.) 16 45 6 

Refused 969 821 785 

Did not contact NA 2 126 

Inaccessible 164 137 118 

Total 3,346 4,516 3,876 3,554 
USDA APHIS VS / 141

Appendix IV: Methodology Overview, Phase II

Appendix IV Appendix IV: Methodology hodology

Overview, Phase II V , Phase II VS Initial V S Initial Visit

(1996–200 996–2007)

NAHMS Dairy Studies 

1996 2002 2007 

Data collection dates 2/20-5/24 2/25-4/30 2/26-4/30 

Minimum number of dairy cattle 30 30 30 

Number of States 20 21 17 

Data collectors State and Federal VMOs and AHTs 

Participating States as a percentage of U.S. population coverage

Operations 85.6 86.6 84.7 

Cows 82.7 85.5 82.5 

Respondent Sample profile (herd size)

Small (fewer than 100 cows) 630 400 233 

Medium (100-499 cows) 502 392 215 

Large (500 or more cows) 87 221 134 

Response category

Survey complete 1,219 1,013 582 

Percent of total 76.0 70.4 54.0 

Refused 340 335 380 

Did not contact 16 76 111 

Ineligible 29 14 4 

Total 1,604 1,438 1,077 
142 / Dairy 2007

Appendix V: Study Objectives and Related Outputs

Appendix V: Study Objectives and

Related Outputs

1. Describe trends in dairy cattle health and

management practices

• Part II: Changes in the U.S. Dairy Cattle

Industry 1991–2007, March 2008

• Part V: Changes in Dairy Cattle Health and

Management in the United States, 1996–

2007, July 2009

2. Evaluate management factors related to cow

comfort and removal rates

• Dairy Facilities and Cow Comfort on U.S.

Dairy Operations, 2007, Interpretive

Report, expected spring 2010

3. Describe dairy calf health and nutrition from

birth to weaning and evaluate heifer disease

prevention practices

• Part I: Reference of Dairy Cattle Health and

Management Practices in the United States,

2007, October 2007

• Off-Site Heifer Raising on U.S. Dairy

Operations, 2007, info sheet, November

2007

• Colostrum Feeding and Management on

U.S. dairy Operations, 1991–2007, info

sheet, March 2008

• Part IV: Reference of Dairy Cattle Health

and Management Practices in the United

States, 2007, February 2009

• Calf Health and Management Practices on

U.S. Dairy Operations, 2007, Interpretive

Report, February 2010

• Calving Management on U.S. Dairy

Operations, 2007, info sheet, January 2009

• Passive Transfer Status of Heifer Calves on

U.S. Dairies, 1991–2007, info sheet, March

2010

4. Estimate the prevalence of herds infected with

bovine viral diarrhea virus (BVD)

• Bovine Viral Diarrhea (BVD) Detection in

Bulk Tank Milk and BVD Management

Practices in the United States, 1996–2007,

info sheet, October 2008

5. Describe current milking procedures and

estimate the prevalence of contagious mastitis

pathogens

• Part III: Reference of Dairy Cattle Health

and Management Practices in the United

States, 2007, September 2008

• Milking Procedures on U.S. Dairy

Operations, 2007, info sheet, October 2008

6. Estimate the herd-level prevalence and

associated costs of Mycobacterium avium

subspecies paratuberculosis

• Johne’s Disease on U.S. Dairies, 1991–2007

info sheet, April 2008

7. Describe current biosecurity practices and

determine producer motivation for

implementing or not implementing biosecurity

practices

• Part I: Reference of Dairy Cattle Health and

Management Practices in the United States,

2007, October 2007

• Part III: Reference of Dairy Cattle Health

and Management Practices in the United

States, 2007, September 2008

• Biosecurity Practices on U.S. Dairy

Operations, 1991–2007, Interpretive

Report, May 2010
USDA APHIS VS / 143

Appendix V: Study Objectives and Related Outputs

8. Determine the prevalence of specific foodsafety pathogens and describe antimicrobial

resistance patterns

• Antibiotic Use on U.S. Dairy Operations,

2002-07, info sheet, October 2008

• Listeria and Salmonella in Bulk Tank Milk

on U.S. Dairy Operations, 2002–07, info

sheet, June 2009

• Salmonella and Campylobacter on U.S.

Dairy Operations, 2002–07, info sheet, July

2009

• Food Safety Pathogens Isolated from U.S.

Dairy Operations, 2007, Interpretive

Report, expected spring 2010

• Prevalence of Coxiella burnetti on U.S.

Dairy Operations, 2007, info sheet,

expected spring 2010

Additional informational sheets

• Dairy Cattle Identification Practices in the

United States, 2007, info sheet, November

2007

• Reproduction Practices on U.S. Dairy

Operations, 2007, info sheet, February 2009

• Bovine Leukosis Virus (BLV) on U.S. Dairy

Operations, 2007, info sheet, October 2008

• Injection Practices on U.S. Dairy

Operations, 2007, info sheet, February 2009

• Methicillin-Resistant Staphylococcus aureus

(MRSA) Isolation from Bulk Tank Milk in

the United States, 2007, info sheet,

expected spring 2010
144 / Dairy 2007

Appendix VI: References

Appendix VI: References

Bovine Alliance on Management and Nutrition.

Biosecurity on Dairies. 2001a.

http://nahms.aphis.usda.gov/dairy/bamn/

BAMNBiosDairy01.pdf

Accessed October 10, 2009

Bovine Alliance on Management and Nutrition.

A Guide to Colostrum and Colostrum

Management for Dairy Calves, revised, 2001b.

http://www.aphis.usda.gov/vs/ceah/ncahs/

nahms/dairy/bamn/BAMNColostrum.pdf

Accessed December 2009

Center for Food Security and Public Health,

Iowa State University. Biological Risk

Management, Overview for Producers.

http://www.cfsph.iastate.edu/BRM/default.htm

Accessed October 10, 2009

Center for Food Security and Public Health,

Iowa State University. General Prevention

Practices for Beef and Dairy Producers.

http://www.cfsph.iastate.edu/BRMforProducers/

English/GeneralPrevention/GenPrevPrac.pdf

Accessed October 10, 2009

Dargatz DA, Garry FB, Traub-Dargatz JL. An

introduction to biosecurity of cattle operations.

Vet Clin North Am Food Anim Pract 2002;

18:1–5.

Godden S, McMartin S, Feirtag J, Stabel J, Bey

R, Goyal S, Metzger L, Fetrow J, Wells S,

Chester-Jones H. Heat-treatment of bovine

colostrum II: effects of heating duration on

pathogen viability and immunoglobulin G. J

Dairy Sci 2006; 89(9):3476–3483.

Kirk JH. Pathogens in Manure – Strategies to

Prevent Infections. University of California,

Davis. 2003.

http://www.vetmed.ucdavis.edu/vetext/INF-DA/

Pathog-manure-prevent.pdf

Accessed October 10, 2009

McCluskey BJ. Biosecurity for arthropod-borne

diseases. Vet Clin North Am Food Animal Pract

2002; 18:99–114.

McGuirk SM, Collins M. Managing the

production, storage, and delivery of colostrum.

Vet Clin North Am Food Animal Pract 2004;

20:593–603.

Nielsen SS, Bjerre H, Toft N. Colostrum and

milk as risk factors for infection with

Mycobacterium avium subspecies

paratuberculosis in dairy cattle. Dairy Sci 2008;

91:4610–4615.

New York State Cattle Health Assurance

Program: Herd Expansion Module.

http://nyschap.vet.cornell.edu/module/

herdexpansion/herdexpansion.asp

Accessed October 10, 2009

Villarroel A, Dargatz DA, Lane VM, McCluskey

BJ, Salman MD. Suggested outline of potential

critical control points for biosecurity and

biocontainment on large dairy farms. J Am Vet

Med Assoc 2007; 230(6):808–819.
USDA APHIS VS / 145

Appendix VI: References

Virginia Cooperative Extension. Abortions in

Dairy Cattle—I: Common Causes of Abortions.

2009. Publication 404-288. http://amser.org/

index.php?P=AMSER--

ResourceFrame&resourceId=5586

Accessed October 10, 2009.

Wells SJ. Biosecurity on dairy operations:

hazards and risks. J Dairy Sci 2000;

83(10):2380–2386.