Studies on the Influence of Antibiotics and Methionine on Nitrogen Utilization and Basal Metabolism of the Growing Male Albino Rat

Abstract

The effects of methionine and of a mixture of streptomycin and choloromycetin on nitrogen metabolism, basal metabolic rate, and body composition of growing male albino rats were investigated, using a 2 × 2 factorial design and equalized food intake. The basal diet to which the above supplements were added was semi-purified and employed soybean oil meal as the sole protein source. No highly significant interactions between supplements were observed. The highly significant effects of adding methionine with or without antibiotics were to increase biological value of the dietary protein 36%, nitrogen balance 54%, body weight gain 20%, body nitrogen gain 25%, and body water gain 28%. The highly significant effects of adding antibiotics with or without methionine were to increase nitrogen balance 7.5%, apparent digestibility of protein 2.2%, true digestibility of protein 1.4%, and to decrease endogenous nitrogen excretion 16.8%.