Suckling neonatal pigs (NP, 24 h old) do not exhibit elevated blood ketone bodies (KB). Mature swine have relatively high KB under certain conditions, suggesting an ontogeny of ketogenesis. Thus we evaluated the hypothesis that NP possess a relatively attenuated ketogenic capacity vs. weaned pigs (WP) and mature pigs (MP). Fasted animals were given an intraperitoneal dose of octanoate (C8), and plasma beta-hydroxybutyrate (beta-OHB) and C8 were monitored over 180 min. Newborn (NR, 24 h old) and mature rabbits (MR, > 1 yr old) were also compared. Linear regressions of plasma beta-OHB (microM) vs. plasma C8 (microM) were calculated for C8 < 1,000 microM. There was a significant linear relationship of beta-OHB regressed against C8 in all ages of pigs (P < 0.001) and in NR (P = 0.024). The slope for NP (0.08) was one to two orders of magnitude below slopes for older pigs (WP = 1.19 and MP = 0.78, P < 0.01 vs. NP), NR *6.97, P < 0.05), and MR (4.04, NS). The beta-OHB peak in NP (40.9 +/- 4.4 microM) was 1-8% of the maxima in other animals (P < 0.05) despite a C8 maximum (2.3 +/- 0.3 mM) similar to that of WP (1.9 +/- 0.7 mM) and MR (2.9 +/- 1.2 mM) (P > 0.05, NS). The data are consistent with the hypothesis that NP have a poor capacity for ketogenesis.
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