Impact of Selection of Beef Cattle for Performance Traits on Performance Efficiency and Health

There is speculation that selection for ‘economic’ traits (growth, milk, and carcass traits) result in reduced immune function and increased susceptibility to disease, with morbidity occurring later in the finishing period than typical morbidity patterns. Our Long-Term Goals: The results of this project is to provide a foundation for further investigations into the effects of genetic selection on animal health and wellbeing and offer a biological basis for alternate selection criteria and genetic based tools for health and welfare based selection. The hypothesis of this work is that focused selection of beef cattle for economic traits in elite herds has reduced robustness and resilience to stressors in the beef production chain. Our Objectives were to: 1. Determine the effects of selection focused on economic traits on phenotypic expression of immune competence and stress responsiveness of growing steers. 2. Examine the impacts of seasonal changes in climate and dietary resources provided to the dam on phenotypic expression of immune competence and stress responsiveness of their offspring