In two experiments, 144 neonatal pigs were force-fed 12 ml of triglyceride containing fatty acids of even (C8, C10) or odd (C7, C9) medium-chain length (even-MCT, odd-MCT, respectively) or long- (greater than or equal to C16) chain length (LCT). Pigs were individually caged for measurement of urinary N excretion and(or) blood metabolites over 24 h. In Exp. 1, pigs were force-fed immediately after birth and were not allowed to suckle. Supplementation with triglyceride decreased 24-h N excretion compared with control animals given 12 ml of water, suggesting decreased breakdown of body protein and improved energy status. Blood glucose increased over 24 h in all pigs (P less than .05), but more in pigs given MCT (1.38 mM) than in those given LCT (.61 mM) or in controls (.85 mM) and more in animals given even-MCT (1.87 mM) than in those given odd-MCT (1.14 mM). In Exp. 2, pigs were allowed to suckle and were force-fed at 6, 18 or 48 h of age. An apparent improvement in utilization of even-MCT was observed between 6 and 18 h, as evidenced by a twofold vs a sixfold increase in 3-OH-butyrate (BHBA) concentration 1 h after dosing and a twofold vs 12-fold increase in plasma fatty acid concentration. This was not seen in pigs given odd-MCT. The BHBA response with odd-MCT was approximately half that observed with even-MCT in pigs 18 and 48 h old, but not in pigs 6 h old. No change in BHBA concentration (P greater than .1) was observed in pigs after force-feeding LCT at either 6, 18 or 48 h of age. Collectively, these data suggest that MCT may be better utilized than LCT and that there may be a differences in the utilization of even-MCT vs odd-MCT, depending on the age of the neonate. This could be related to chain length effects on digestion and absorption because plasma decanoate concentration changed very little, even though it composed 25% of the even-MCT supplement.