Involvement of Food Intake and Amino Acid Catabolism in the Branched-Chain Amino Acid Antagonism in Chicks

Publisher Website
Google Scholar
Abstract
The role of food intake and branched-chain amino acid (BCAA) catabolism in the branched-chain amino acid antagonism was investigated. A diet containing crystalline amino acids as the sole source of amino acids was formulated to contain adequate levels of all required nutrients. The basal diet contained 0.60% isoleucine, 0.82% valine and 1.2% leucine. Increasing dietary leucine to 5.0% resulted in reduced food consumption, weight gain, and efficiency of food utilization. These effects were prevented by increasing dietary isoleucine and valine to 0.80 and 1.07%, respectively. When l-[1-14C]isoleucine or l[1-14C]valine were included in the diet, the amount of 14CO2 exhaled was increased within 24 hours of feeding the 5% leucine diet. The excretion of 14C was unaffected by leucine. It was determined by force feeding that approximately 70% of the reduced growth rate in chicks fed the leucine-supplemented diet ad libitum could be accounted for by reduced food intake. A portion of the growth depression may be due to increased BCAA catabolism, limiting the availability of valine and isoleucine for growth.