United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

Veterinary Services 

Centers for Epidemiology and Animal Health December 2003 

_________________________________________________________________________________________________________________________ 

Highlights of NAHMS Dairy 

2002: Part III

In 2002, the National Animal Health Monitoring 

System (NAHMS) conducted a study of dairy 

operations in the United States. The Dairy 2002 

study was conducted in 21 major dairy States*

 and 

was designed to provide information to both 

participants and industry from operations 

representing 82.8 percent of U.S. dairy operations 

and 85.5 percent of U.S. dairy cows. Data were 

collected between February 25 and April 30, 2002. 

 The following highlights were excerpted from 

the report released in December 2003: Dairy 2002 

Part III: Reference of Dairy Cattle Health and 

Health Management Practices in the United States, 

2002. 

• The highest percentage of producers (54.6 

percent) knew some basics about foot-andmouth disease. Anthrax was recognized by 

name only by most producers (54.0 percent). 

The industry’s awareness of Johne’s disease 

has increased over the last few years due to 

concentrated efforts to educate producers 

and control the disease (Figure 1).

Figure 1. Percentage of Operations by Level of Familiarity

with Johne's Disease (Paratuberculosis)

Had Not Heard

of Before

1.0%

Recognized

Name Only

11.4%

Knew Some

Basics

42.3%

Fairly Knowledgeable

45.3%

____________________ 

*

California, Colorado, Florida, Idaho, Illinois, Indiana, Iowa, Kentucky, 

Michigan, Minnesota, Missouri, New Mexico, New York, Ohio, 

Pennsylvania, Tennessee, Texas, Vermont, Virginia, Washington, 

Wisconsin 

• Disease exclusion management practices 

regarding visitors, employee travel, and cattle 

source also were evaluated by herd size. The 

percentage of operations using these 

practices at the time of the interview 

increased as herd size increased (Figure 2).

0

10

20

30

40

50

60

70

2 years previous

At time of interview

33.8

16.3

50.9

23.0

53.7

20.9

Small

(Less than 100)

Medium

(100-499)

Large

(500 or More)

Herd Size

Percent

Figure 2. Percent of Operations that Used Guidelines (at the

Time of the Interview and 2 Years Previously) that Determined 

Which Visitors were Allowed in Animal Areas, by Herd Size

• Dairy 2002 producers were asked to identify 

the category of bulk tank somatic cell count 

(BTSCC) that best described the average 

BTSCC for milk shipped during the 90 days 

prior to the interview. Overall, the highest 

percentage of operations (34.5 percent) had 

an average BTSCC of 200,000 to 299,000. 

The next highest averaged BTSCCs of 

100,000 to 199,000 (23.6 percent of 

operations) followed by 300,000 to 399,000 

(21.7 percent of operations). Only 2.4 percent 

of operations had an average BTSCC of less 

than 100,000, while 2.7 percent had an 

average BTSCC of 600,000 or more.
United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

• The percentage of lameness cases was 

similar across all herd sizes, with 20.4 

percent of cows and 8.1 percent of bred 

heifers (as a percentage of cow and bred 

heifer inventory) having a case of lameness 

during the 12 months prior to the interview.

• Over half of all lameness cases on U.S. dairy 

operations were attributed to digital dermatitis 

(hairy-heel warts). Producers reported that 

53.9 percent of lameness cases in cows and 

61.8 percent of lameness cases in bred 

heifers were due to digital dermatitis.

• Cull rates across the United States, which 

include cow deaths for Dairy Herd 

Improvement Association calculations, are 

generally reported to be between 30 and 35 

percent. For Dairy 2002, 24.9 percent of cows 

were reported culled in 2001. (This 

percentage does not include cow deaths.) 

Large operations culled a larger percentage 

of cows (27.6 percent) than medium or small 

operations (23.5 and 23.3 percent, 

respectively).

• Days in milk at time of culling is a predictor of 

forced versus unforced culls. Cows early in 

lactation are more likely to be forced culls, 

while later lactation animals are usually 

unforced culls. The majority of cows (60.3 

percent) were culled at 200 or more days in 

milk. Approximately a fourth of cull cows 

(24.1 percent) were culled from 50 to 199 

days in milk, while 15.6 percent were culled 

at less than 50 days in milk. Large and 

medium operations culled more cows (17.2 

and 16.7 percent, respectively) at less than 

50 days in milk compared to small operations 

(12.2 percent). Regional differences by days 

in milk at time of culling were negligible.

• Milkers can transfer mastitis-causing 

pathogens from their hands to the teats of 

noninfected cows. To help prevent pathogen 

transfer, it is recommended that milkers wear 

latex or nitrile gloves during milking. Only 

32.9 percent of operations reported that 

milkers wore gloves to milk all cows.

• Vaccines against coliform mastitis and 

Salmonella have been shown to decrease 

the incidence and severity of mastitis caused 

by gram-negative bacteria. The percentage of 

operations that reported giving coliform 

mastitis vaccines to a majority of cows during 

2001 was 35.8 percent, which accounted for 

57.1 percent of all cows. Only 10.4 percent of

operations representing 20.6 percent of cows 

administered Salmonella vaccine to the 

majority of cows.

• Mycoplasma is a contagious organism 

transferred from cow to cow that can cause 

mastitis. Diagnosis requires special culture 

techniques. There is no effective treatment. 

Only 8.7 percent of operations were fairly 

knowledgeable about the disease, while 22.9 

percent had never heard of it. Less than half 

of operations (46.6 percent) recognized 

Mycoplasma by name only.

• Over three-fourths of operations (76.6 

percent) did not use antibiotics in rations for 

weaned dairy heifers during the 12 months 

prior to the interview. Less than a fifth of 

operations (17.5 percent) included antibiotics 

in heifer rations, and 2.0 percent did not know 

if antibiotics were included in heifer rations. 

Judicious use of antibiotics helps prevent the 

development of pathogens resistant to 

antimicrobials.

• Overall, 75.2 percent of operations treated 

100.0 percent of cows with dry cow 

intramammary antibiotics at the time of 

drying-off. Almost 6 percent of operations did 

not treat any cows with this type of antibiotic 

at drying-off.

________________________________ 

For more information, contact: 

USDA:APHIS:VS:CEAH 

NRRC Building B, M.S. 2E7 

2150 Centre Avenue 

Fort Collins, CO 80526-8117 

970.494.7000 

E-mail: NAHMSweb@aphis.usda.gov 

www.aphis.usda.gov/vs/ceah/cahm

#N418.1203 

____________________________________ 

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