Effect of Methionine Deficiency on the Utilization of Energy by the Chick

Abstract

The effects of a moderate deficiency of sulfur amino acids in the diet of young chicks on energy utilization were studied. The deficient diet (sulfur amino acids 2.6% of protein) did not significantly retard growth, but produced lowered gross efficiency of gains as compared with the adequate diet (sulfur amino acids 4% of protein). No differences in efficiency of energy metabolism were observed based on determinations of metabolizable energy, productive energy, heat production and tissue gains. Chicks fed the methionine-deficient diet, however, had greater gains in tissue fat but lower gains of protein. As a consequence, the higher caloric intake of chicks fed the methionine-deficient diet did not produce additional weight gain. The differences in gross efficiency and in body composition produced by the methionine-deficient and methionine-adequate diets were shown to be due entirely to the differences in food intake.