| The relationships of maternal nutrition, blood volume, and uterine blood flow to porcine fetal development and ornithine decarboxylase activity were investigated in domesticated pigs that normally experience 40% fetal loss. Yorkshire pigs were subjected to prolonged inanition (40 days; 0 kcal/day; water only) from days 50 to 90 of pregnancy and either hysterectomized on day 90 or realimentated to a full diet and allowed to advance to parturition; controls received a full diet (7,028 kcal/day) until hysterectomy at day 90 or throughout gestation. Although a marked decline in body weight (31 kg) occurred in gilts subjected to inanition, fetal survival rates, and litter weight and size were similar (P > .05) in starved and full-fed animals. Blood hemoglobin, packed cell volume, plasma protein, erythrocyte and leukocyte populations during inanition were maintained at levels similar (P > .05) to controls with the exception of shifts in concentration caused by abrupt plasma volume changes. Plasma volume (r = .65) and blood volume (r = .58) were highly correlated (P < .0001) with body weight in inanition and control dams throughout the period of inanition and realimentation. Uterine blood flow during late pregnancy was similar (P > .05) in all dams and remained constant (P > .05) with time in spite of a 13-fold increase in fetal weight, and regardless of marked fluctuations in plasma and blood volume. Uterine blood flow was highly correlated (P < .02) with day 90 litter size (r = .82) and fetal weight (r = .86). Maternal liver ornithine decarboxylase activity decreased (P < .01) during inanition, but increased (P < .01) 10-fold upon realimentation of the gilts. Day 90 fetal brain ornithine decarboxylase activity was increased (P .05) in inanition and control dams. Ornithine decarboxylase activity of day 90 fetal liver was decreased (P < .05) and day 90 fetal liver weights were reduced (P < .05) in inanition gilts. Severe maternal nutrient deprivation during late pregnancy in the pig results in a marked decline in maternal body weight, plasma volume, blood volume, and liver ornithine decarboxylase activity; however, maternal uterine blood flow and fetal brain ornithine decarboxylase activity are maintained at levels that allow normal fetal survival, growth, and development. |
