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Case-control study to determine herd-level risk factors for bovine respiratory disease in nursing beef calves on cow-calf operations

Amelia R. Woolums DVM, MVSc, PhD1, Roy D. Berghaus DVM, PhD2, David R. Smith DVM, PhD3, Russell F. Daly DVM, MS4, Gerald L. Stokka DVM, MS5, Brad J. White DVM, MS6, Tucker Avra DVM7, Ali T. Daniel DVM8, and Matt Jenerette DVM9
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  • 1 Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602.
  • | 2 Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA 30602.
  • | 3 Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762.
  • | 4 Department of Veterinary & Biomedical Sciences, College of Agriculture & Biological Sciences, South Dakota State University, Brookings, SD 57007.
  • | 5 Department of Animal Sciences, College of Agriculture, Food Systems, & Natural Resources, North Dakota State University, Fargo, ND 58102.
  • | 6 Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506.
  • | 7 Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602.
  • | 8 Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602.
  • | 9 Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602.

Abstract

OBJECTIVE To determine herd-level risk factors for bovine respiratory disease (BRD) in nursing beef calves.

DESIGN Matched case-control study.

SAMPLE 84 cow-calf operations in Nebraska, North Dakota, and South Dakota.

PROCEDURES Case herds were herds that treated at least 5% of the calf crop for BRD prior to weaning. Control herds were herds that treated < 0.5% of the calf crop for BRD prior to weaning. Each case herd was matched with 2 control herds on the basis of veterinary practice and enrollment year. Herd owners or managers were interviewed by telephone, and characteristics and practices associated with case status were determined by multivariable conditional logistic regression.

RESULTS 30 case herds and 54 control herds were evaluated. Increasing herd size, frequent pasture movement for intensive grass management (intensive grazing), and use of estrus-synchronization programs were significantly associated with herd status. The odds of being a case herd for herds with 150 to 499 cows was 7.9 times and that for herds with ≥ 500 cows was 12 times, compared with the odds of being a case herd for herds with < 150 cows. The odds of being a case herd for herds that used intensive grazing was 3.3 times that for herds that did not use intensive grazing. The odds of being a case herd for herds that used an estrus-synchronization program was 4.5 times that for herds that did not use an estrus-synchronization program.

CONCLUSIONS AND CLINICAL RELEVANCE Management practices can be associated with an increase in the BRD incidence in nursing beef calves. Modification of management practices may decrease BRD incidence in nursing calves for herds in which it is a problem.

Abstract

OBJECTIVE To determine herd-level risk factors for bovine respiratory disease (BRD) in nursing beef calves.

DESIGN Matched case-control study.

SAMPLE 84 cow-calf operations in Nebraska, North Dakota, and South Dakota.

PROCEDURES Case herds were herds that treated at least 5% of the calf crop for BRD prior to weaning. Control herds were herds that treated < 0.5% of the calf crop for BRD prior to weaning. Each case herd was matched with 2 control herds on the basis of veterinary practice and enrollment year. Herd owners or managers were interviewed by telephone, and characteristics and practices associated with case status were determined by multivariable conditional logistic regression.

RESULTS 30 case herds and 54 control herds were evaluated. Increasing herd size, frequent pasture movement for intensive grass management (intensive grazing), and use of estrus-synchronization programs were significantly associated with herd status. The odds of being a case herd for herds with 150 to 499 cows was 7.9 times and that for herds with ≥ 500 cows was 12 times, compared with the odds of being a case herd for herds with < 150 cows. The odds of being a case herd for herds that used intensive grazing was 3.3 times that for herds that did not use intensive grazing. The odds of being a case herd for herds that used an estrus-synchronization program was 4.5 times that for herds that did not use an estrus-synchronization program.

CONCLUSIONS AND CLINICAL RELEVANCE Management practices can be associated with an increase in the BRD incidence in nursing beef calves. Modification of management practices may decrease BRD incidence in nursing calves for herds in which it is a problem.

Supplementary Materials

    • Supplementary Appendix s1 (PDF 30 kb)

Contributor Notes

Dr. Woolums's present address is Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762.

Address correspondence to Dr. Woolums (amelia.woolums@msstate.edu).