Evaluation of energy sources with and without carnitine in newborn pig heart and liver

The oxidation rate of five energy substrates with and without exogenous addition of carnitine in the heart and liver of 15-h-old nonsuckled piglets was evaluated. Oxygen consumption (nmol O2.mg protein-1.min-1) in heart and liver for five substrates were: pyruvate, 0.248, 0.191; palmitoyl-CoA, 0.042, 0.034; palmitoyl-carnitine, 0.249, 0.111; isovalerate, 0.084, 0.059; acetoacetate, 0.166, 0.068, respectively. The addition of free carnitine doubled the rate of palmitoyl-CoA utilization in both heart and liver, but palmitoyl-CoA oxidation was always much lower than that of palmitoyl-carnitine. In livers of piglets from sows fed 8% fat, palmitoyl-carnitine oxidation was slower (P less than 0.03) than in piglets from sows fed 0% fat. Heart tissue metabolized isovalerate faster (P less than 0.02) when piglets were from sows fed fat compared with those from the nonfat group. A lysine x fat interaction was observed for piglet liver metabolism of isovalerate and acetoacetate, suggesting that a more metabolically developed pig results when sows are fed 0.48% lysine without supplemental fat during gestation. Carnitine did not seem to be the limiting factor for the oxidation of palmitoyl-CoA, and gestational dietary fat and lysine seemed to influence substrate metabolism in the newborn pig.