Abstract
The purpose of the experiment in this paper was to study the effect of diets containing the named amino acids respectively in excess on the nutritional efficiency for young rats.
Each test diet had 1.0% or 0.6% dietary nitrogen level and contained respective amino acids, the amounts of which were thirty or forty fold to the tryptophan content.
(1) When fed on the diet with excessive L-threonine, the rats showed a growth depression, though the symptoms were less severe.The excretion of threonine in rat urine was remarkable, and reached forty percent against the threonine ingested.
(2) When fed on the 0.6% nitrogen level diet with excessive L-leucine, the rats showed a growth depression, while on the 1.0% nitrogen level diet, they showed no growth depression.
(3) When fed on the diets with excessive DL-isoleucine, rats showed a growth depression, the symptoms of which were not severe in this case also.The excretion of L-isoleucine in rat urine was comparatively abundant and reached ten percent against isoleucine ingested.
(4) When fed on the L-valine-excess diets having 0.6% dietary nitrogen level, rats showed a depression in the growth and in the nitrogen efficiency.
(5) When fed on the DL-tryptophan-excess diets and L-histidine-excess diets, rats showed a growth depression and their urinary ammonia-nitrogen content increased.
(6) When fed on the L-phenylalanine-excess diets, rats showed a growth depression.
(7) When fed on the diets with excessive L-arginine, no remarkable effect appeared in the rat growth.
