Efeitos da raça do embrião, da estação do ano e do tipo do embrião na perda gestacional de receptoras bovinas

Abstract

Reproduction is a fundamental process for maintaining the life and evolution of species. Among the various existing biotechniques, in vitro embryo production (IVP) has been widely used to accelerate the genetic improvement of beef cattle and the objective of this study was to evaluate the effects of embryo breed, season and embryo type on the rate of pregnancy loss in bovine recipients. 759 embryo pregnancies of the Girolando, Senepol, Sindi and Simmental breeds were evaluated. The data were provided by a commercial PIVE company from Uberlândia, Minas Gerais, Brazil. The pregnancy diagnosis was made 30 and 60 days after estrus. A pregnancy loss was considered when the recipient diagnosed as pregnant in the first examination was not pregnant in the second examination. The data were analyzed using logistic regression, with the effects of embryo breed, embryo types (fresh vs. vitrified) and time of year at the time of ET (spring/summer vs. autumn/winter) included in the model. No effect of embryo breed on the pregnancy loss rate was detected, however the loss rate was higher in the Senepol breed, followed by Girolando, Sindi and Simmental, respectively. There was also no effect of the time of year at the time of ET or the type of embryo on the rate of pregnancy loss. Numerically, fresh embryos had a higher rate of pregnancy loss compared to devitrified embryos. It is concluded that under the conditions of the present study, no effects of the breed of the embryo, the season at the time of transfer and the type of embryo were detected on the rate of pregnancy loss.