Despite aggressive heat stress abatement strategies, the U.S. swine industry loses ~$900 million annually. Sources of reduced revenue include: slower growth rates, inefficient feed utilization, increased health care costs, inconsistent market weights, mortality and altered carcass traits. Consequently, heat stress is currently one of the costliest issues in the U.S. pork industry and annually compromises the industry’s capacity to produce animal protein for human consumption. The effect of heat stress will likely become more of an issue for at least three additional reasons: 1) if the frequency of severe hot weather increases as predicted and 2) genetic selection continues to emphasize traditional economically important phenotypes as these (lean tissue accretion rates, piglets/sow etc.) are coupled with increased basal heat production, and 3) the inclusion of cheaper high fiber diets (digesting fiber generates increased more heat than other nutrients). Collectively, this presents two threats to profitability and sustainability: 1) the genetic propensity for lean growth accretion in contemporary commercial pigs is likely to make them more susceptible to heat stress, and 2) the need to use alternate feedstuffs containing higher fiber content is likely to create more heat stress in pigs. Therefore, there is an urgent need to describe the effects of management practices and genetics on heat stress induced losses in efficiency and profitability.
This project significantly improved our understanding of the interaction between heat stress, genetics and dietary fiber.