DECREASED DIETARY-PROTEIN OR ENERGY-INTAKE AND PLASMA GROWTH-HORMONE LEVELS OF PREGNANT PIG, ITS FETUSES AND DEVELOPING PROGENY

The effects of low protein diets on plasma growth hormone [GH] were studied in pregnant pigs, fetuses and the developing progeny. Pregnant pigs were fed 18%, 3% or 0.5% protein diet throughout the gestation period. At 10, 13 and 15 wk of gestation, fetuses were removed from the uterus after the dam had been bled to death. Plasma samples were used for GH determinations. In a 2nd experiment, 2 day old pigs from another set of pregnant pigs fed the diet containing 18%, 3% or 0.5% protein during gestation were cross-fostered to control nursing dams and weaned at 4 wk of age to a standard diet. Plasma obtained at regular intervals was used for GH determination. Plasma GH was significantly higher in dams fed 0.5% protein after wk 13 of gestation. High GH (10 times the dam GH level) was observed in all fetuses irrespective of maternal dietary manipulation. Offspring of severely protein deprived pigs (0.5% protein) had significantly elevated GH levels up to 12 wk of age in spite of cross fostering to a control dam after birth. There is probably little or no effect of maternal protein restriction on fetal GH levels. The persistent high GH levels in the progeny of severely malnourished pigs indicate a possible impairment of the production, release or catabolism of GH and/or its releasing factor.