Ascorbic acid synthesis in fetal and neonatal pigs and in pregnant and postpartum sows

The ontogeny of ascorbic acid synthesis and its concentration in fetal pigs from mid- to late gestation, and the effect of birth order and premature o r normal delivery ages were evaluated. In Experiment 1, fetal pigs were col lected from three sows at 60, 80, 100, 107 and 111 d of development. Liver L-gulono-gamma -lactone oxidase (GLO) activity and ascorbic acid concentrat ion were measured. High liver GLO activity in fetal liver occurred at 60 d but declined as pregnancy advanced (P < 0.01), whereas ascorbic acid concen tration increased (P < 0.01). Experiment 2 evaluated ascorbic acid synthesi s and concentration in neonates born early (1st and 2nd) or late (7th and 8 th) in the birthing sequence, or when born 2 d prematurely vs. the normal d elivery age. Rigs born early in the birthing sequence (P < 0.01) and those born at the natural delivery age (P < 0.05) had higher liver ascorbic acid concentrations, but liver GLO activity did not differ among groups. Sows we re killed at each period; liver GLO activity was constant during gestation but increased postpartum (P < 0.01). Liver ascorbic acid concentration was constant during gestation, except for a decline during late gestation, and increased postpartum (P < 0.05). These results suggest that more ascorbic a cid was transferred from the dam to the fetuses as pregnancy advanced, poss ibly suppressing fetal GLO activity. Thus, fetal liver GLO activity was the primary source of ascorbic acid during early fetal development, but more f etal ascorbic acid was transferred from the dam during later pregnancy.