The Glutamic Acid and Arginine Requirement for High Growth Rate of Rats Fed Amino Acid Diets

Abstract

Rat feeding experiments were conducted to study the influence of glutamic acid and arginine on growth rate, efficiency of food utilization and carcass composition of rats fed amino acid diets. When the concentrations of glutamic acid and arginine were varied simultaneously, results show that each partially supplied the requirement for the other but that both were required in substantial amounts for highest growth rates. Weight gains exceeding 5 g/day were obtained only at dietary levels of 0.8% or more of arginine·HCl and 4% or more of glutamic acid. Glutamine was more effective than glutamic acid but α-ketoglutarate was inhibitory. Diets composed of L-amino acids supported greater weight gains than those containing some racemic mixtures, but did not alter the requirement for glutamic acid and arginine. Performance with the best amino acid diets was equal to that provided by the protein (supplemented gluten) control diet with weight gains of approximately 45 g/week. The evidence is discussed supporting the hypothesis that arginine and glutamic acid function to alleviate the potential ammonia toxicity arising from the feeding of large amounts of amino acids.