Prenatal Reproductive Performance in Gilts Fed Low Levels of Stilbestrol in a Legume-Free and an Alfalfa Ration

Abstract

In five dry-lot experiments, gilts were fed legume-free or 18% alfalfa, breeding-gestation rations containing levels of 0.29, 0.58 and 3.0 mcg. of stilbestrol per lb. A feeding period of 30 days preceded breeding. The gilts were slaughtered during gestation and observations made on the number of corpora lutea and live young. Lower ovulation rates were associated with the inclusion of the three levels of stilbestrol in the legume-free ration. The number of live young and percent corpora lutea represented as live embryos was consistently reduced when 0.29 and 0.58 mcg. of stilbestrol per lb. were included in the legume-free ration. The average number of live embryos and percent corpora lutea represented as live embryos observed in gilts fed 3.0 mcg. of stilbestrol per lb. of legume-free ration exceeded that of the control group in one experiment but were lower in the succeeding experiment. The addition of stilbestrol to the 18% alfalfa ration did not influence reproductive performance as measured. Corpora lutea and live young were positively correlated with weight of the gilts regardless of age.