IMPACT OF SUPPLEMENTAL LYSINE OR TRYPTOPHAN ON PREGNANCY COURSE AND OUTCOME IN RATS

The purpose of this study was to examine the impact of supplemental lysine and tryptophan on pregnancy course and outcome in rats. From day 0 until day 20 of pregnancy, rats received one of the following diets ad libitum: lysine at 50% (L-50), 100% (L-100) or 500% (L-500) excess over controls (C); or tryptophan at 500% (T-500), 1,000% (T-1000) or 2,500% (T-2,500) excess. One group of rats received a control diet ad libitum and each treatment group had a matched pair-fed group receiving a control diet. No congenital malformations were observed in any of the fetuses. Groups L-50, L-100, T-500 and T-1,000 showed no significant differences in maternal weight gain or fetal condition compared to the controls. L-500 had a comparatively lower maternal weight gain and fetuses of significantly smaller weight and length than any other group, although their food consumption was above "C" level. T-2,500 had a significantly lower maternal weight gain than all groups, although its pair-fed control consumed less diet and did not have a significantly decreased maternal weight gain. T-2,500 had the lowest total fetal weight of any group. In summary, variable levels of lysine or tryptophan supplementation did not cause recognizable fetal malformations. However, diets highly supplemented with lysine or tryptophan may affect pregnancy through a decrease in maternal weight gain and fetal size.