Immune system stimulation and amino acid utilization in the growing pig

加拿大的猪肉产业是加拿大经济的重要贡献者。猪场每年的销售额估计为35亿美元，猪肉产业对加拿大出口的贡献每年超过28亿美元。因此，一个盈利和可持续的猪肉产业对国民经济和为加拿大人提供一致、安全和高质量的食品非常重要。猪的健康状况是影响猪肉生产效率、营养物质流失到环境和猪肉品质的一个重要决定因素。尽管有严格的生物安全措施，我们仍然面临着严重的亚临床疾病挑战在加拿大的商业养猪场。为了最大限度地减少由于疾病引起的免疫系统刺激的负面影响，一个潜在的重要方法是，在猪粮中添加超过在最低疾病环境中管理的猪所建立的推荐水平的营养物质。本研究的总体目的是确定饲粮中添加蛋氨酸、半胱氨酸和色氨酸是否会减少免疫系统刺激对生长猪营养物质利用的负面影响，并探讨这些氨基酸在免疫系统刺激过程中的代谢命运。将进行营养平衡和代谢研究，以量化免疫系统刺激和这些氨基酸的摄入对消化功能、猪体内氮和硫的保留、营养物质在环境中的损失以及与动物免疫反应有关的蛋白质和代谢物的产生的相互作用。通过尽量减少免疫系统刺激对营养物质利用和动物生产力的负面影响，并更密切地满足猪的营养需求，可以减少经济损失和环境影响。此外，可以减少饲料中抗生素的使用，这将进一步提高猪肉的安全性。在拟议的研究中探索的概念也对人类健康有直接影响，特别是对免疫挑战期间关键必需氨基酸的推荐摄入量的发展。

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.