Amino acid utilization and peripheral tissue metabolism in ruminants fed full-fat canola-based diets

在高产反刍动物中，蛋白质可能是第一限制营养物质，因为这些动物无法仅从微生物蛋白中满足其对代谢蛋白（MP）的需求。MP的不足必须通过饮食中提供不可降解的摄入蛋白（UIP）来弥补，UIP与微生物蛋白一起提供供宿主动物吸收的氨基酸（AA）。在膳食中加入全脂油籽或油籽粕以增加膳食中UIP的供应已受到相当大的关注。在加拿大西部，人们对用全脂油菜籽喂养反刍动物很感兴趣，因为它能提供高质量的蛋白质，增加日粮的能量密度。此外，油菜籽还能提高反刍动物食用产品的不饱和脂肪酸（FA）含量。据报道，不饱和脂肪酸对人类心血管健康和降低癌症风险有有益作用。相对而言，很少有研究对处理或未处理的全脂油菜籽中蛋白质部分作为反刍动物AA来源的影响进行评估。我们的目标是：1)确定处理或未处理的全脂油菜籽对外周组织使用AA供应的影响；2)确定高产反刍动物蛋白质积累的极限氨基酸；3)确定策略添加限制AA对动物生产性能和外周组织蛋白质代谢的影响。本试验将以安装瘤胃和十二指肠瘘管的肉牛（作为反刍动物模型）为试验对象，进行一系列试验，以确定瘤胃蛋白质消化和十二指肠AA谱。外周组织代谢将使用组织活检技术进行研究。通过高产奶牛或速生肉牛的饲养试验，检验处理对动物生产性能和食用产品质量的影响。本研究将有助于进一步了解油菜籽饲粮对反刍动物氨基酸的利用。预期结果包括增加和更有效地利用全脂油菜籽作为反刍动物的饲料，并提高牛奶或肉类的营养特性。这将有助于保持畜牧业生产者的竞争优势，并增加加拿大油菜籽种植者的收入。

In high producing ruminants, protein may be the first limiting nutrient as these animals are unable to meet their requirements for metabolizable protein (MP) from microbial protein alone. The deficit in MP must be made up by the dietary provision of undegradable intake protein (UIP) which, together with microbial protein, provides amino acids (AA) for absorption by the host animal. The dietary inclusion of full fat oilseeds or oilseed meals to augment dietary UIP supply has received considerable attention. In western Canada,there is considerable interest in feeding full fat canola seed to ruminants because it provides high quality protein and increases the energy density of diets. In addition, canola seed can increase the unsaturated fatty acid (FA) content of ruminant edible products. Unsaturated FA have been reported to have beneficial effects on human cardiovascular health and to reduce the risk of cancer. Relatively little research has been done to evaluate the effects of the protein fraction in treated or untreated full fat canola seed as a source of AA for ruminants. Our objectives are: 1) to determine the effects of treated or untreated full fat canola seed on the supply of AA for peripheral tissue use; 2) to identify the limiting AA for protein accretion in high producing ruminants; and 3) to determine the effects of strategic supplementation with those limiting AA on animal performance and peripheral tissue protein metabolism. A series of experiments will be conducted with beef steers (as a model for ruminants) fitted with ruminal and duodenal cannulae to determine ruminal protein digestion and duodenal AA profiles. Peripheral tissue metabolism will be studied using tissue biopsy techniques. Feeding experiments with high yielding dairy cows or fast growing beef cattle will test treatment effects on animal performance and edible product quality. This research will enhance our understanding of AA utilization in ruminants fed canola based diets. Expected outcomes include increased and more efficient use of full fat canola seed as a feed for ruminants, and enhanced nutritional properties of milk or meat. This should help to maintain the competitive advantage of livestock producers as well as increase revenues for canola farmers in Canada.