Desempenho reprodutivo de ovelhas alimentadas com dietas contendo diferentes níveis de energia no terço inicial da prenhez

Abstract

The aim of this study was to evaluate the pregnancy rate as a function of diet energy levels in early pregnancy and of blood glucose, as well as the embryo loss as a function of body condition and blood glucose. After estrus synchronization and breeding, 120 Santa Inês female sheep were distributed in four treatments, using total feed, from 0 to 50 days of pregnancy, to evaluate the pregnancy rate as a function of the levels of energy in diet and blood glucose, as well as embryo loss as a function of body condition (BC) and glucose level. Total Digestible Nutrients (TDN) levels in the diets were: 59.68%; 66.28%; 72.93%; and 79.39%. On the breeding day and each 10 days, five mL of blood were collected for immediate glucose determination and to evaluate blood progesterone level. From the 25° day after breeding, ultrasound exams were made each five days for pregnancy follow-up, aiming at evaluating embryo loss. The embryo loss rate was correlated with the energy levels of the treatments and the glucose level; before day 20, pregnancy was confirmed by the blood progesterone level. The females that had more than 1 ng/mL were considered pregnant at day 20. The embryo loss was not affected (P_0.05) by blood glucose of the ewes on the day of breeding. The pregnant rate was not affected (P<0.05) by the BC of the ewes in the moment of breeding, with a higher rate of pregnancy in the ewes with BC equal to 3 points (score from 1 to 5). The glucose lowered with weight and BC gain, the heavier ewes and with better BC with high probability of embryo loss. There was a linear weigh gain in the ewes, from 0 to 50 days after breeding, as a function of the increase in the feed energy level. It is recommended to breed ewes with a higher blood glucose and BC of about three points and diet of 59.68% TDN, in the first 50 days of pregnancy.