EMULSIFICATION AND FATTY-ACID CHAIN-LENGTH AFFECT THE UTILIZATION OF MEDIUM-CHAIN TRIGLYCERIDES BY NEONATAL PIGS

Three experiments were conducted using 52 pigs between 22 and 35 h of birth to determine the effects of emulsification and fatty-acid chain length on utilization of medium-chain triglycerides (MCT). After a 4-h period during which feed was withheld, pigs were force-fed 6 mL of nonemulsified (NE) MCT or 20 mL of a 30% (vol/vol) Tween 80-(polyoxy-ethylene [20] sorbitan monooleate) MCT emulsion, marking time 0, and serial blood samples were drawn throughout 8 h for analysis of medium-chain fatty acid (MCFA) concentrations by HPLC. In Exp. 1, pigs received either NE or emulsified Tri-C4, -C5, -C6, or -C7. The emulsified treatments were discontinued due to deaths caused by coma resulting from high concentrations (up to 12 mM of plasma MCFA. Concentrations in pigs fed emulsified MCT were 2.5-fold higher than those in pigs fed NE MCT. In pigs fed NE MCT, concentrations of even-chain-length MCFA were higher than those of odd-chain-length MCFA ( P < .001), with a tendency for C6 to be higher than C4 ( P < .1). In Exp. 2 and 3, pigs received an equimolar mixture of MCT in either emulsified or NE form. In Exp. 2, the mixture contained Tri-C4 through Tri-C7; whereas, in Exp. 3 the mixture contained Tri-C4, -C6, -C8, and -C10. A three-way interaction (emulsion x fatty acid x sample time; P < .05) was observed in both experiments. In Exp. 2, MCFA concentrations reached higher levels (P < .05) and rose more quickly in pigs fed emulsified MCT than in those fed nonemulsified MCT, but they also decreased more rapidly. In both experiments, the plasma C6 concentrations were highest among all chain lengths tested. Collectively, these studies suggest that emulsification alters the digestion/absorption kinetics of MCT. Furthermore, C6 may be the optimal chain length for maximizing the rate and extent of MCT utilization by newborn pigs.