Improved understanding of nitrogen (N) nutrition for growing pigs to increase flexibility in feed formulation, reduce N losses into the environment and improve gut health

加拿大猪肉产业为人类健康提供了高质量的蛋白质和其他营养素，每年为加拿大经济贡献超过90亿美元，为国际贸易平衡贡献超过30亿美元。为了使猪肉行业保持全球竞争力，需要解决饲料成本和营养物质流失到环境中的问题。猪肉生产的这两个方面与生长猪的蛋白质（氨基酸和氮）利用密切相关。 本项目的总体目标是更好地了解生长猪的氮（N）利用，并更准确地确定生长猪对日粮N和氨基酸摄入量的反应。随着纯化氨基酸的可用性增加，猪日粮中常规蛋白质来源的使用减少，从而降低了氮向环境中的损失以及日粮蛋白质和氮含量。后者可能会限制氮的摄入量内源性生产的氨基酸由猪本身，因此，猪的生产力。 此外，需要更好地了解暂时低于氨基酸和氮需求量饲养猪的长期后果。具有高（肌肉）生长潜力的现代猪在一段时间的氨基酸摄入限制后更有可能表现出完全的补偿性生长。 可以探索补偿性生长以（1）增加氨基酸和N利用的效率，（2）改善对肠道中有害蛋白质发酵敏感的年轻生长猪的肠道健康，以及（3）通过减少年轻生长猪中昂贵蛋白质的摄入来降低饲养成本。这些概念将在营养代谢研究中探讨。新的饲养策略将在生长性能研究中进行评估，其中评估生产和营养利用效率以及胴体和肉质特性。这些信息将使我们能够进一步优化实际的饲养策略，降低饲料成本，改善生长猪的肠道健康和营养利用效率。 饲料蛋白占饲料成本的25%以上。饲料成本仅降低1%，就意味着加拿大猪肉行业每年可获得超过2000万美元的收益。

The Canadian pork industry provides a source of high quality protein and other nutrients for human health, while contributing annually more than $9B to the Canadian economy and more than $3B to the international trade balance. For the pork industry to remain globally competitive feed costs and nutrient losses into the environment need to be addressed. These two aspects of pork production are closely associated with protein (amino acids and nitrogen) utilization in growing pigs. The overall aim of this project is to better understand nitrogen (N) utilization in growing pigs, and to more accurately define the response of growing pigs to dietary N and amino acid intake. With increased availability of purified amino acids, usage of conventional protein sources in pig diets is reduced, lowering N losses into the environment and dietary protein and N content. The latter may limit N intake for endogenous production of amino acids by pigs themselves and, therefore, productivity of pigs. Also, long-term consequences of feeding pigs temporarily below requirements for amino acids and N needs better understanding. Modern pigs with high (muscle) growth potentials are more likely to demonstrate complete compensatory growth following a period of amino acid intake restriction. Compensatory growth may be explored to (1) increase the efficiency of amino acid and N utilization, (2) improve gut health in young growing pigs that are susceptible to harmful protein fermentation in the gut, and (3) reduce feeding costs by reducing the intake of expensive protein in young growing pigs. These concepts will be explored in nutrient metabolism studies. Novel feeding strategies will then be evaluated in growth performance studies, in which production and nutrient utilization efficiencies, as well as carcass and meat quality characteristics are evaluated. This information will allow us to further optimize practical feeding strategies, to reduce feed costs, improve gut health and nutrient utilization efficiencies in growing pigs. Feed protein represents more than 25% of feed costs. A mere 1% reduction in feed costs represents more than $20,000,000 per year for the Canadian pork industry.