Effect of Dietary Energy Levels upon Reproduction and the Relation of Endometrial Phosphatase Activity to Embryo Survival in Gilts

Abstract

The effects of high and low levels of dietary energy upon some reproductive phenomena were studied in three experiments utilizing Duroc gilts. Energy intake was regulated by varying the crude fiber content of the experimental diets. Restricting energy intake reduced not only daily gain and weight at first estrus, but also delayed the onset of estrus. Gilts fed a low-energy diet containing 52% alfalfa meal had a slightly higher ovulation rate and a higher embryo survival rate, averaging 1.36 more viable embryos at 25 days of gestation, than did gilts fed a high-energy diet containing 10% alfalfa meal. In the third experiment the embryo survival rate in gilts fed a low-energy diet containing only 10% alfalfa meal was intermediate to the other diets. The relationship of phosphatase activity in the endometrium to diet and embryo survival were determined in one experiment. The effect of level of dietary energy upon alkaline phosphatase activity was not significant. There was a significant negative correlation ( −.35) between alkaline phosphatase activity in the endometrium and number of viable embryos at 25 days of gestation. The negative relationship was more pronounced on the low-energy diets. At 25 days of gestation acid phosphatase activity in the endometrium was higher than alkaline phosphatase. Differences in acid phosphatase activity between diets were not significant. A positive but nonsignificant correlation between acid phosphatase activity and number of viable embryos was found.