Efeito Da Fase Embrionária Sobre a Taxa De Prenhez De Vacas Nelore

Abstract

The present report aims to analyze pregnancy rate according to the stage of embryo development at the moment of embryo transfer. All embryos had seven days of development in vitro and came from Nelore breed (Bos taurus indicus) oocyte donors. The study was performed in Uberaba, Minas Gerais, from August to October 2016. The recipient females were under the same sanitary, nutritional and hormonal protocol. In total, 443 animals of different breeds and ages have been selected. These females were used as receptors in fixed-time embryo transfer programs. Pregnancy rates of 31.95%, 42.27%, 48.16% and 56.66% were obtained for early blastocyst, blastocyst, expanded blastocyst and hatched blastocyst, respectively. The mean pregnancy rate was 44.46%. According to the obtained results, it has been possible to observe that expanded and hatched blastocysts result in better pregnancy rates in fixed-time embryo transfer.