Limiting amino acids in Colombian floury-2 corn for growth of young rats

One hundred and forty-four albino rats were used in two experiments to determine the amino acid inadequacies of Colombian floury-2 corn for growth, feed consumption, feed utilization and PER. The addition of 0.28 percent L-lysine and 0.04 percent L-tryptophan to a diet (9.4 percent protein) composed of Colombian floury-2 corn plus vitamins and minerals significantly improved performance in each experiment. There was a significant lyzine x tryptophan interaction in that the performance in all criteria was greater when both amino acids were added than when either was added alone. The addition of 0.12 percent DL-isoleucine alone or 0.08 percent DL-threonine alone or the two together resulted in no improvement above the basa unsupplemented diet. When lysine, threonine and tryptophan were added together there was a tendency for an improvement above that obtained with lysine and tryptophan together. When all four amino acids (lysine, tryptophan, threonine and isoleucine) were added, daily gain and daily feed were significantly greater (P less than .01) than in all other groups in experiment 1 and efficiency of feed utilization and PER tended to be higher than in other groups. It is suggested that the inferior performance reported for growing animals fed Colombian floury-2 corn compared to Colombian opaque-2 corn is related to the amino acid composition of the protein in the former and that the first and second limiting amino acids in Colombia floury-2 corn for growing rats are lysine and tryptophan, respectively. When these deficiencies are corrected an additional response is obtained by isoleucine and threonine supplementation eng