LAUSR

Anecdotal evidence suggests that weaning/stocker weights, ADG, and carcass weights have increased for Southeast cattle over the last 30 years. Simultaneously, morbidity and mortality have not improved, and according to some reports, have significantly increased. Albeit, over the last 30 years, there have been several new vaccines and antibiotics introduced into the beef cattle market. Ceteris paribus, there appears to be a discrepancy related to prevailing theories that placing heavier cattle into stocker and feedlot operations reduces the incidence of morbidity and mortality. But, has there truly been an increase in weaning weights or placement weights of stocker/feedlot calves over the last 30 years? Perhaps, even with greater genetic selection by cow/calf producers for improved weaning weights and pre-weaning ADG, the genetic potential of these animals is not being realized until the stocker/feedlot sector. Indeed, Engler et al. (2014) reported that hot carcass weight (HCW) increased 4.9 lbs per year from 2001 to 2013 while others have reported no actual increase in weaning weights during this period. Undoubtedly HCW have increased, but the contributing factors are multifaceted including genetic selection for increased lean deposition, better nutritional programs, and the expanded variety of growth promoting implants, ionophores, and beta agonists. Likewise, morbidity and mortality are multifaceted manifestations affected by a variety of inputs including genetics, nutrition, environmental stressors, immunocompetence, and the prevalence and genetic diversity of pathogens. Therefore, while genetic selection for increased pre-weaning performance may be more prevalent, cow/calf producers may not be reaping the full potential of their calves due to management practices that do not capitalize on the genetic potential of the pre-weaned calf. Placing more emphasis on genetic selection for pre-weaning growth may have inadvertently resulted in calves that are less resistant to the stresses and strains associated with post-weaning production systems.