Nitrogen Metabolism in Wethers as Affected by Dietary Protein Solubility and Amino Acid Profile1

Abstract
Four yearling crossbred wethers were used in a 4 X 4 latin square design to compare diets varying in protein solubility and amino acid profile. Four isonitrogenous (15% CP) diets with amino acid profiles resembling the protein of either hominy or soybean meal and protein solubilities of either 13 or 35% were formulated from common feedstuffs using linear programming methods. Water consumption, urine volume, urinary nitrogen excretion and rumen ammonia and butyrate concentrations were higher (P<.01) for wethers receiving rations in which 35% of the dietary protein was soluble. While apparent nitrogen digestibility did not differ among diets, diets with an amino acid profile similar to soybean meal resulted in a lower dietary (P<.01) and a higher nondietary (P<.01) fecal N, when expressed as a percent of total fecal nitrogen, being excreted and a higher (P<.01) percent true digestible nitrogen. Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science.