Utilization of D-Tryptophan by Swine

Abstract

The degree of utilization of D-tryptophan by swine was studied using baby pigs fed rations deficient in tryptophan and supplemented with either the L- or DL-form of this amino acid. Growth and nitrogen retention were the principal criteria employed to estimate the efficiency of use of the unnatural isomer. Pigs maintained on a ration deficient in tryptophan lost weight, but at most showed only a slight negative nitrogen balance. When this ration was supplemented with 0.05 percent L- or 0.1 percent DL-tryptophan, the animals consumed the ration more readily, growth improved and definitive positive nitrogen retention was found. Averages favored the animals receiving DL-tryptophan, but differences were not sufficiently great to show statistical significance. These combined data support the view that partial utilization of D-tryptophan was effected.