Reproductive and metabolic response and body changes in ewes fed with two energy levels

Objective. To evaluate the reproductive response, metabolic state and body changes in Dorper and Katahdin ewes supplemented with 2 energy levels prior to insemination. Materials and methods. The animals used in this experiment were 14 Katahdin and 13 Dorper ewes distributed in two treatments, in which estrus had been synchronized. Fourteen days prior to synchronization of estrus, the ewes were distributed in two treatments according to the energy level of the diet, T1:2.0 and T2:2.5 Mcal kg-1 of ME. Feeding consisted of 14 days of adaptation and 14 of feeding with integral diet. At the start and finish of each study, measurements were made of backfat thickness, area of the ribeye, body weight, and glucose and insulin concentrations. The principal reproductive parameters were measured, such as response to estrus, percentage of gestation and prolificity. Analyses of variance were made along with ji-squared tests to determine the effect of the energy level and genotype. Results. The genotype and energy level did not affect any of the variables measured, although it was found that with both energy levels there was an increase in glucose concentrations, as well as an increase in weight, body fat and area of the rib-eye. Conclusions. Because there was no difference in the reproductive parameters and body changes with feeding in the 2 energy levels, it is preferable to use the feed with 2.0 Mcal kg-1 of ME, given that it reduces costs.