Among the topics at the SDSU Extension Seedstock Symposium will be a discussion on disease susceptibility, its effect on the cattle industry, and how highly or lowly inheritable they may be.
Dr. James Reecy, an Iowa State University professor, says “Environmental and genetic factors impact disease susceptibility/resistance in all species. The combined impact of environment and genetics need to be optimized to improve the resistance to any given virus, bacteria or stress that causes disease.”
Bovine respiratory disease (BRD or BRDC) will be discussed as an example, because it cost the beef industry $6.92 million in 2005. For perspective, the number two factor resulting in cattle losses was roughly half, at $3.67 million.
Breeding resistance to diseases is a popular topic and has been shown to work; examples include nematode infection, mastitis, cattle ticks and enhanced immune responsiveness.
Dr. Reecy says “Selection for disease resistance can be implemented in a number of ways, including the observation of the disease. Challenge all animals, challenge relatives to breeding stock, observe pathogen products and finally examine biological & immune response.”
Breed differences in resistance and sensitivity to BRD have shown large differences in morbidity and mortality across the breeds. Dr. Reecy will discuss the differences and the genetic correlation between disease resistance and other traits usually used in beef cattle evaluation and selection – growth, carcass weights, palatability, daily gain, and energy intake.