Utilization of the D-isomers of arginine and histidine by chicks and rats

Young chicks and rats were fed crystalline amino acid diets deficient in either arginine or histidine, and the growth-promoting capacity of the D-isomers of these two amino acids was examined. D-arginine had no growth-promoting activity in either chicks or rats. D-histidine had minimal growth-promoting activity (about 20%) in chicks and no bio-activity in rats.