ARTICLES

Maternal starvation and progesterone secretion, litter size, and growth in the pig

The relationships of maternal nutrition and progesterone secretion to prenatal fetal loss and neonatal survival and growth were investigated in domesticated pigs that normally experience 40% fetal loss. Yorkshire pigs were subjected to prolonged starvation (40 days; 0 kcal/day; water only) in either the middle third or last third of pregnancy and then gradually realimented to a full diet and allowed to advance to parturition; controls received a full diet (7,028 kcal/day) throughout gestation. Pregnancies were maintained in 74% of the pigs starved during either middle or late gestation compared to 100% in controls. In dams starved from days 30--70, progesterone levels remained similar to controls, but were maintained at lower levels during realimentation between days 72 and 99. Progesterone levels in dams starved days 50--90 and controls were similar from days 50 to 130. At parturition, litter size in starved dams (9.4) was similar to full-diet controls (8.0) although birth weight and neonatal growth of piglets were reduced markedly from dams starved in middle or late pregnancy. These results indicate that severe maternal nutrient deprivation during the middle or last third of gestation has little effect on ovarian progesterone secretion and is not a major limitation to fetal survival in this litter-bearing species. Maternal nutrient deprivation imposes a significant detrimental effect, however, on birth weight and neonatal growth to 80 days of age.