Veterinary Services 

Centers for Epidemiology and Animal Health June 2003

_________________________________________________________________________________________________________________________ 

Highlights of NAHMS Dairy 

2002: Part II: Changes in the 

U.S. Dairy Industry 

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 from December 31, 2001, to February 12, 

2002. 

 The following highlights were excerpted from 

the report released in May 2003: Dairy 2002 Part II: 

Changes in the United States Dairy Industry, 1991-

2002. Part II identifies changes in the dairy industry 

from 1991 to 2002, and specifically addresses 

changes identified from three NAHMS dairy 

studies: 1991 NDHEP, Dairy ’96, and Dairy 2002. 

• Almost one in two dairy operations has 

disappeared since 1991, with roughly a 4- to 

5-percent decrease per year. Combined 

with the relatively slower decline in milk cow 

numbers, the result is nearly a 73 percent 

increase in average herd size. 

• From 1991 to 2001, total annual U.S. milk 

production increased 11.9 percent. This 

increase was achieved with a concurrent 

7.2 percent decline in number of milk cows 

and a 20.7 percent increase in milk 

production per cow. 

• Between 1991 and 1996 there was a sharp 

decline in the percentage of operations that 

reported using Dairy Herd Improvement 

Association (DHIA) record-keeping systems. 

However, the percentage of operations 

using DHIA record-keeping systems 

remained the same between 1996 and 2001 

(Figure 1). 

• Overall, a higher percentage of operations 

fed a total mixed ration in 2001 (47.0 

percent of operations) than in 1995 (35.6 

percent of operations). 

• Overall, the use of bovine somatotropin 

(bST) increased between 1995 and 2001, 

(9.4 percent and 15.2 percent of operations, 

respectively). The overall percentage of 

cows that were given bST during the current 

lactation (at the time of the interview) also 

increased between 1995 and 2001(10.1 

percent and 22.3 percent, respectively). 

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Figure 1. Percent of Operations by Type of Individual 

Record-Keeping System Used 

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• From 1995 to 2001, rolling herd average 

milk production (cow average) increased 

2,012 pounds (Figure 2). 

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Figure 2. Rolling Herd Average Milk Production 

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• There was essentially no change from 1995 

to 2001 in the overall mortality of 

preweaned heifer calves born alive (10.8 

percent and 10.5 percent of heifer calves, 

respectively). There was no change in heifer 

calf mortality due to scours/diarrhea 

between 1995 and 2001 (6.5 percent 

reported for both years). 

• Basically, no change occurred between 

1991 and 2001 in the percentage of 

operations that allowed calves to receive 

colostrum at first nursing. Approximately 

one-third of operations still use this practice. 

• More operations were separating maternity 

housing from housing used for lactating 

cows between 1995 and 2001 (45.4 percent 

and 53.1 percent, respectively. 

• Overall, a substantial decline occurred 

between 1995 and 2001 in the percentage 

of operations that, before bringing cattle onfarm, tested cattle for brucellosis (31.0 

percent and 15.9 percent of operations, 

respectively) and tuberculosis (23.4 percent 

and 12.4 percent, respectively) (Figure 3). 

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Figure 3. Percent of Operations* by Testing Normally 

Required by the Operations 

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*For operations that brought cattle onto the farm. 

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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

#N397.0603 

________________________________________________________ 

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