Involvement of Food Intake in the Lysine-Arginine Antagonism in Chicks

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Abstract
Studies were conducted to evaluate the involvement of food intake in the lysine-arginine antagonism. Diets were formulated to compensate for the metabolic consequences of excess dietary lysine: induction of renal arginase activity, depression of hepatic glycine transamidinase, and urinary losses of arginine. This was accomplished by inclusion of creatine in the basal diet, use of a moderate excess of lysine that did not increase urinary arginine excretion, and addition of the arginase depressors, α-aminoisobutyric acid (AIB) and L-threonine, to diets containing excess lysine. When chicks were fed diets containing excess lysine ad libitum, growth and efficiency of arginine retention were reduced. Supplementation of the diets with AIB and threonine markedly reduced the growth depression and restored efficiency of arginine utilization. When chicks were force-fed the diet containing excess lysine, growth was depressed, and body composition was altered. Inclusion of AIB and threonine in the diet containing excess lysine resulted in growth and body composition equivalent to levels of force-fed controls. In a second experiment the basal diet and basal supplemented with AIB and threonine were pair-fed to lysine-supplemented diets containing AIB and threonine. Body weight gains and body composition of all groups were similar. In other experiments, food intake increased within 24 hours (P < 0.05) and probably within 12 hours (P < 0.10) after removal of excess lysine from the diet. It is concluded that a portion of the lysine-arginine antagonism is due to a primary effect of lysine on regulation of food intake.