In order to know the influence of age on the supplement of polished rice with lysine and threonine weaning male rats were fed on a 90% rice diet supplemented with or without 0.4% L-lysien hydrochloride and 0.24% DL-threonine (diets 2 and 1) from weaning to 15-week-old. Rats fed on diet 2 showed higher growth rate, higher ratio of retained nitrogen to absorbed nitrogen, and higher ratio of urinary allantoin to urinary urea than those of rats fed on diet 1 throughout the periods. When rats of about 20-week-old were fed on diets 1 and 2, the ratio of retained nitrogen to absorbed nitrogen, biological value, true digestibility and net protein utilization did not differ among rats of both dietary groups. By the depletion-repletion technique, increase in body weights of adult rats fed on an 85% rice diet supplemented with 0.2% L-lysien hydrochloride and 0.24% DL-threonine was found significantly greater than those of adult rats fed on an 85% rice diet.
Growth rate of young rats and ratio of retained nitrogen in absorbed nitrogen were capable of measuring the effect of supplement of a diet containing 85% of polished rice with 0.2% L-lysine hydrochloride and 0.24% DL-threonine. Although weaning male rats grew at approximately the same rate when they were fed on diet C (a 85% polished rice diet supplemented with 0.2% L-lysine hydrochloride and 0.24% DL-threonine) and diet D (the same diet as diet C except that double amount of L-lysine hydrochloride was added), ratio of retained nitrogen to absorbed nitrogen and ratio of urinary allantoin to urinary urea of rats fed on diet D were significantly higher than those of rats fed on diet C.
Cation exchange chromatographic method proposed by S. Katz and D.G. Comb was modified for determination of 5'-ribonucleotides. By using Dowcx-50 (H+) column, 1.0×13.0cm2, authentic 5'-ribonucleotides, AMP, GMP, IMP, ATP, and acid-soluble ribonucleotides in the muscles of both carp and scallop were separated quantitatively and determined. The method was applied successfully to the determination of the quantities as small as 100μg of individual 5'-ribonucleotides.