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

Veterinary Services 

Centers for Epidemiology and Animal Health December 2009 

_________________________________________________________________________________________________________________________ 

Parasite Control Practices on 

U.S. Cow-calf Operations, 

2007–08 

Internal parasites can reduce the reproductive 

performance of the cow herd, reduce weaning 

weights of calves, and negatively impact animal 

health by causing symptoms such as anemia or 

diarrhea, and by causing immunosuppression 

which makes animals more susceptible to other 

types of infections. 

The U.S. Department of Agriculture’s National 

Animal Health Monitoring System (NAHMS) 

conducted the Beef 2007–08 study, which focused 

on beef cow-calf health and management practices 

in 24 States.* These States represented 

79.6 percent of U.S. cow-calf operations and 

87.8 percent of U.S. beef cows. An objective of the 

Beef 2007–08 study was to describe deworming 

practices and the use of dewormers on U.S. cowcalf operations. 

From January 14 through March 31, 2008, 567 

cow-calf operations responded to a survey 

conducted by NAHMS regarding the operations’ 

previous evaluations of fecal samples for parasite 

eggs and deworming practices, including why 

dewormers were used and the frequency of 

administration. 

Parasite testing 

During the previous 3 years, only 5.7 percent of 

operations performed any testing of fecal samples 

to evaluate the parasite burden in their cattle. The 

percentages of operations that did any fecal testing 

during the previous 3 years to evaluate parasite 

burden were not statistically different across herd 

sizes and regions (figures 1, 2). 

 

*States/Regions

West: California, Colorado, Idaho, Montana, New Mexico, Oregon, 

Wyoming 

Central: Iowa, Kansas, Missouri, Nebraska, North Dakota, South 

Dakota 

Southeast: Alabama, Arkansas, Florida, Georgia, Kentucky, 

Louisiana, Mississippi, Oklahoma, Tennessee, Texas, Virginia 

0

10

20

Percent

Figure 1. Percentage of Operations that Performed Any Fecal 

Testing During the Previous 3 Years to Evaluate Parasite Burden in

Their Cattle, by Herd Size

1-49 50-99 100-199 200 or more All operations

Herd Size (Number of Beef Cows)

3.8

10.0

8.8

12.1

5.7

 

0

5

10

Percent

Figure 2. Percentage of Operations that Performed Any Fecal 

Testing During the Previous 3 Years to Evaluate Parasite Burden in

Their Cattle, by Region

West Central Southeast

Region

3.8

5.3

7.7

5.1
United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

Deworming frequency 

 For operations that had unweaned calves or 

weaned stocker calves, more than one-half usually 

dewormed these animals one or more times per 

year (53.7 and 54.1 percent, respectively). About 7 

of 10 operations (69.5 percent) dewormed 

replacement heifers 1 or more times per year, and 

over 8 of 10 operations (81.7 percent) dewormed 

cows 1 or more times per year (table 1). 

 

Table 1. Percentage of Operations by 

Frequency that the Following Classes of Cattle 

were Usually Dewormed

Percent Operations 

Frequency 

Cattle Class Never 

Occasionally* Once a 

Year 

More 

than 

Once a 

Year Total

Unweaned 

calves 38.3 8.0 31.1 22.6 100.0

Replacement 

heifers 

weaned but 

not yet 

calved 24.9 5.6 29.4 40.1 100.0

Weaned 

stocker 

calves 41.3 4.6 28.9 25.2 100.0

Cows 13.2 5.1 38.2 43.5 100.0

*Less than once a year. 

 For operations that dewormed cattle or calves 

at least occasionally, a regular schedule was the 

primary factor used to determine when to deworm 

cattle and calves on the majority of operations 

(85.1 percent), as shown in figure 3. The 

appearance of cattle was the primary method used 

for assessing the effectiveness of the deworming 

program on the majority of operations (82.3 

percent). 

0

20

40

60

80

100

Percent

Figure 3. For Operations that Dewormed Cattle or Calves at Least

Occasionally, Percentage of Operations by Primary Factor used to

Determine when to Treat Cattle for Internal Parasites (Worms)

When the

cattle look 

rough

Fecal

consistency

Regular

schedule

Fecal tests Other

Primary Factor

10.1

1.5

85.1

0.6 2.7

Choice of deworming products 

 For operations that dewormed cattle or calves 

at least occasionally, about 9 of 10 (91.1 percent) 

listed efficacy as important or very important when 

choosing a deworming product. Additionally, over 8 

of 10 operations (83.8 percent) cited ease of 

application as important or very important. Tradition 

was relatively unimportant in choosing a deworming 

product; only 33.8 percent of operations cited 

tradition as important or very important in choosing 

a deworming product (table 2). 

Table 2. For Operations that Dewormed Cattle 

or Calves at Least Occasionally, Percentage of 

Operations by Reason for Choosing Deworming 

Product, and by Importance Level of Reason 

Percent Operations 

Level of Importance 

Reason 

Not 

Important 

Slightly 

Important 

Important 

Very 

Important Total

Price 19.6 24.4 35.6 20.4 100.0

Tradition 48.3 17.9 24.0 9.8 100.0

Efficacy 4.8 4.1 28.4 62.7 100.0

Recommended 

by others 23.2 19.1 38.9 18.8 100.0

Ease of 

application or 

administration 9.9 6.3 34.3 49.5 100.0

Other 97.1 0.0 2.2 0.7 100.0
United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture 

Summary 

 Few cow-calf operations (5.7 percent) tested 

fecal samples during the previous 3 years to 

evaluate parasite burdens in their cattle. 

 Most operations (86.8 percent) dewormed their 

cows at least occasionally. For operations that 

dewormed cattle or calves at least occasionally, 

appearance of the cattle was by far the most 

common means of assessing the effectiveness of 

the deworming program. 

 Efficacy and ease of application/administration 

were the attributes most frequently cited as being 

important or very important in choosing a 

deworming product. 

________________________________ 

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: NAHMS@aphis.usda.gov 

http://nahms.aphis.usda.gov 

#N571.1209 

____________________________________ 

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