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Evaluating Dietary Amino Acid Adequacy In Horses Using Isotopic Techniques, Sara L. Tanner

Theses and Dissertations--Animal and Food Sciences

Little is known about amino acid (AA) requirements in horses despite muscle mass accretion being of importance to an athletic species. Isotope methods for determining AA requirements and whole-body protein synthesis (WBPS) had not been previously used in growing horses. The first study herein was the first to apply isotope methods to determine WBPS in growing horses. In the study, weanling colts received two different levels of crude protein. Whole-body protein kinetics indicated that WBPS was greater when the weanlings were fed the diet with a greater crude protein content (P<0.05). The second study sought to determine a lysine requirement for yearling horses using the indicator AA oxidation (IAAO) method. Despite using six dietary levels of lysine; three above and three below the current recommendation, no breakpoint could be determined. Phenylalanine kinetics were not affected by lysine level (P>0.05), but plasma lysine increased linearly with lysine intake …