Immune system stimulation and amino acid utilization in the growing pig

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The Canadian pork industry is an important contributor to the Canadian economy. Farm gate sales are estimated at $3.5 billion per year and the contribution of the pork industry to Canadian exports exceeds $2.8 billion per year. A profitable and sustainable pork industry is thus important to the national economy and to provide consistent, safe and high quality food to Canadians. An important determinant of pork production efficiency, nutrient losses into the environment, and pork meat quality is the health status of pigs on commercial farms. In spite of strict bio-security measures, we are still faced with serious sub-clinical disease challenges on commercial swine operations in Canada. A potentially important means to minimize the negative impact of immune system stimulation, due to disease, is the fortification of swine diets with nutrients at levels exceeding recommendations that have been established in pigs that are managed in a minimum-disease environment. The overall aim of the proposed research is to establish whether the supply of additional dietary methionine, cysteine and tryptophan will reduce the negative impact of immune system stimulation on nutrient utilization in growing pigs, and to explore the metabolic fate of these amino acids during immune system stimulation. Nutrient balance and metabolism studies will be conducted to quantify interactive effects of immune system stimulation and intake of these amino acids on digestive function, nitrogen and sulfur retention in the pig's body, nutrient losses into the environment, and production of proteins and metabolites that are involved in the animal's immune response. By minimizing the negative impact of immune system stimulation on nutrient utilization and animal productivity, and by more closely meeting the pigs' nutrient requirements, the economic losses and environmental impact can be reduced. Moreover, the use in-feed antibiotics can be reduced, which will further enhance pork meat safety. The concepts that are explored in the proposed research have direct implications for human health as well, in particular towards the development of recommended intakes of key essential amino acids during an immune challenge.