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Update on Disease Susceptibility

Update on Disease Susceptibility. Department of Animal Sciences Colorado State University. The economics industry concern for cattle health: Bovine Respiratory Disease. 1997 estimates put prevention and treatment of disease in the feedlot at >$3 billion (Griffin, 1997)

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Update on Disease Susceptibility

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  1. Update on Disease Susceptibility Department of Animal Sciences Colorado State University

  2. The economics industry concern for cattle health: Bovine Respiratory Disease • 1997 estimates put prevention and treatment of disease in the feedlot at >$3 billion (Griffin, 1997) • ~1.1 million cattle with an estimated value of over $692 million were lost to respiratory causes in 2005 (USDA, 2006). • ~16 pounds reduction in hot carcass weight for animals treated in 1st 40 days (Snowder et al., 2007) • Lung damage (yes/no) – 34 pounds of carcass weight (Engler, 2007)

  3. Feedlot morbidity/mortality rates McAllister, 2010

  4. BRD incidence rate • Over 14% of all feedlot placements develop BRD (USDA, 2001) • 5 times the prevalence of the next highest reported disease

  5. Genetics of Feedlot Health Project • Funded by Pfizer, Inc. (Pfizer Animal Genetics) • Hypothesis: • Susceptibility/resistance to disease is, in part, genetically controlled and that genetic control can be characterized by DNA markers. This genetic control is likely manifest through two mechanisms: • The animal’s ability to cope with stress and therefore reduce the risk of becoming sick. • The variation among animals relative to their immunological ability to counteract disease challenges.

  6. Study Background • Steers from a single ranch source were shipped to cooperating commercial feedlot in Lamar, CO • Split over 2 years • Calves vaccinated on ranch 2x each year • No arrival vaccination first year • Arrival vaccination in second year

  7. Relationships Ability to cope with stress Immunological response Disease Challenge Treated Individual Phenotypes Collected

  8. Animal Data • Phenotypes characterizing morbidity/mortality • Sick (yes/no) • Time to recovery/mortality • Treatment records • Treatment protocol, body temperatures, weight change • Visual scores for nasal and eye discharge, cough, and depression; and respiration rate • Lung lesion scores • Mortality information • Necropsy results, bacteriology, etc

  9. Animal Data • Phenotypes characterizing exposure, stress and immune response • BVD I&II, PI3, IBR, BRSV exposure • Circulating cortisol and IL levels • IgG levels

  10. Animal Data • Phenotypes characterizing performance • Weights—arrival and re-implant • Carcass performance • HCW, MS, QG, REA, BF • Ultrasound through the feeding period • Arrival with 2 additional observations at re-implant • Temperament measures • Flight speed • Chute score

  11. BRD Treatment Rates • Year 1 –45% treated • Year 2—7.1% treated

  12. Treatment rates over time

  13. Characterization of disease

  14. Treatment versus Lung Damage In comparison to literature reports (Loneragan, Whittum, Thompson)

  15. Treatment Effects on Carcass Performance

  16. Treatment Effects on Carcass Performance by Number of Treatments

  17. As expected: “Treatment” influences performance

  18. From the perspective of a feedlot trial… • What is predictive? • Does ranch treatment influence feedlot performance?

  19. Source treatment effects on probability of feedlot treatment • Highly significant effects of ranch treatment on probability of feedlot treatment (P<.001) • Receiving weight had no effect on probability of treatment in the feedlot.

  20. Remember…. • Hypothesis: • Susceptibility/resistance to disease is, in part, genetically controlled and that genetic control can be characterized by DNA markers. • Is there genetic variation for traits in this study?

  21. Heritabilities What about the “health” traits?

  22. Compared to other studies • Treatment (yes/no) • On the higher end of literature estimates. • Snowder et al., 2006 was .18 on the underlying scale

  23. Is susceptibility related to other performance characteristics? McAllister, 2010

  24. Summary • Treatment for BRD influences animal performance in the feedlot. • Genetic variation exists for susceptibility to BRD.

  25. Ongoing Investigation • Can we better distinguish between “sick” versus “healthy” individuals in our statistical analyses? • What is the true “trait of interest”? • What proportion of genetic variance can we explain with SNP data?

  26. Acknowledgements • Pfizer Animal Genetics • Guy Loneragan, West Texas A&M University • Hana Van Campen, CSU • Kraig Peel, CSU • Bob Weaber, University of Missouri • Christopher Chase, South Dakota State University • Janeen Salak-Johnson, University of Illinois • John Pollak, Cornell University (MARC) • John Wagner, CSU-Southeast Colorado Research Center • Tony Bryant, Five Rivers Ranch Cattle Feeding • Graduate Students! • Brian Brigham • Chase McAllister • Scott Speidel • Amanda Pepper • Gabriela Marquez • Cory Pendley • Brandon Meiwes • Leanne Matthews • Megan Rolf • Ed Creason • Many others…

  27. Questions?

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