Oxidation of alanine and beta-hydroxybutyrate in late gestation by zinc-restricted rats.

The day 21 response of the Long-Evans pregnant rat to marginal dietary zinc intake was investigated in this experiment. Day 20 and 21 food intakes of zinc-restricted dams were below the control group amounts and indicated that dietary nitrogen and energy did not meet gestation requirements. Intravenous injections of tracer doses of [14C]alanine provided evidence for decreased oxidation of the carbon chain of alanine when zinc-restricted were compared to control dams. The plasma pool size of beta-hydroxybutyrate and the rate of 14CO2 production following injection of the radioactively labeled ketone body indicated that substantial increases in the oxidation of beta-hydroxybutyrate were induced by restricted zinc feeding. Maternal plasma concentrations of alanine were marginally reduced, beta-hydroxybutyrate increased, and glucose unchanged by the suboptimal zinc diet. Litter weights at day 21 were moderately depressed (-11%) by maternal zinc-restriction, suggesting that the chronic effects of mild dietary zinc deficiency are most apparent near term in this animal model.