Utilization of medium-chain triglycerides by neonatal piglets: chain length of even- and odd-carbon fatty acids and apparent digestion/absorption and hepatic metabolism.

Jugular plasma concentrations of medium-chain fatty acids (MCFA) and whole blood concentrations of D-beta-hydroxybutyrate (BHBA) were measured in 1-d-old pigs at 0, 1, 2, 4 and 8 h after forcefeeding 12 mL of one of four triglycerides: tri-7:0, 8:0, 9:0 or 10:0. Both BHBA and MCFA were highest at 1 h. The MCFA measured at 1 h decreased (P less than 0.01) with increasing chain length. The BHBA was not different in pigs given tri-7:0, 8:0 or 9:0 but was lower (P less than 0.05) for pigs given tri-10:0. Isolated hepatocytes converted [1-14C] C7 or C9 to CO2 and acid soluble products more than 40% faster than cells given 8:0 or 10:0 and consumed 7% more O2. Even- and odd-MCFA were oxidized faster (P less than 0.01) than 18:1 (n-9). Theoretical calculations from fatty acid oxidation accounted for 96 to 142% of measured O2 consumption for the various fatty acids. In all instances, L-carnitine had no effect. Appearance of 14C in lipid products increased progressively with chain length from 7:0 to 18:1 (n-9). Collectively, these data suggest that changes in chain length within the medium-chain family may dramatically influence the rate and extent of digestion and/or absorption and metabolism of medium-chain triglycerides by neonates. This may be a consequence of increased hydrophobicity with increasing chain length or, for odd-chain fatty acids, a reflection of anaplerotic carbon effects from propionyl-CoA metabolism.