No abstract

Two trials with sixty-five sows indicate that severe protein restriction during gestation and lactation significantly impairs subsequent reproductive efficiency. The percentage of sows exhibiting oestrus, the average number of days from weaning to oestrus, and the average ovulation rate and uterine weights were significantly lower in sows fed a low-protein diet. Conception rate and embryo survival to 28 days were not significantly affected. The detrimental effects from protein restriction were more severe in younger gilts. Oestrus, ovulation and fertility were induced in non-cyclic sows fed the low-protein diet by injecting pmsg and hcg. Varying the dietary protein intake of gilts and sows during gestation has resulted in small differences in the litter size and birth weight of pigs.

No abstract

Summary TWO experiments involving 372 barrows were conducted to evaluate the effects of orally administered diethylstilbestrol (DES) and methyltestosterone (MT) with varying levels of dietary protein.The DES-~-MT combinat/on significantly increased carcass leanness regardless of dietary protein level. No significant effects of dietary protein levels on carcass leanness were observed with the barrows used in this study. It appears carcass leanness was maximized at the dietary protein level of 12%.Daily gains were significantly reduced by DES-{-MT over all dietary protein levels. However, the amount of depression was reduced by adding the hormone to the diets at a heavier weight. Significant interactions were present between dietary protein levels and DES+MT on daily gain. Greater depression of gain occurred on the lower dietary protein levels when DES+MT was added to the diet.The effect of D,ES+MT on feed efficiency was inconsistent between experiments. A small significant effect of dietary protein level ori feed efficiency occurred in experiment 1. Feed efficiency appeared to be maximized at the 12% level in this study.