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

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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.