Gestação de embriões bovinos produzidos in vitro oriundos de raças de corte e leite

Abstract

The in vitro production of bovine embryos is a relevant biotechnology applied to assisted reproduction, presenting itself as an effective tool in the enhancement of reproductive efficiency and in the generation of genetically superior animals. This biotechnique enables the use of females with reproductive alterations that prevent their reproduction, of senile and prepubescent animals. However, the variability in the success of in vitro embryo transfers is one of the major impasses for its expansion, since, in order to obtain satisfactory pregnancy rates through in vitro production, some factors need to be observed, considering their influence on the result of the technique. Therefore, the objective of this study was to evaluate the influence of factors such as the time of embryo transfer, the stage of development and quality of transferred embryos, embryo processing, the ovary ipsilateral to the corpus luteum and the size of the corpus luteum, on the pregnancy rate of recipients who received in vitro-produced bovine embryos from beef and dairy breeds. The study was carried out with retrospective data from 419 transfers of in vitro produced bovine embryos, 245 from beef breeds and 174 from dairy breeds. The data were provided by a private company specialized in Animal Reproduction. The study included data obtained from February to November 2021, from three beef cattle raising properties and 13 properties with activity focused on dairy cattle. The pregnancy rate was calculated considering the effects of time of embryo transfer, stage of embryonic development, embryo quality and processing, ovary ipsilateral to the corpus luteum, and corpus luteum size. The size of the corpus luteum was also evaluated according to its occurrence in the left or right ovary. The size of the corpus luteum was also evaluated according to its occurrence in the left or right ovary. Mean percentages were compared using the Frequency Scatter Test (Chi-square), using the SAS statistical package version 9.2, considering 5% significance (p<0.05). The 419 transfers of embryos produced in vitro performed, resulted in 29.04% of pregnancy. Considering that, there were no influences of the time of embryo transfer to recipients, stage of embryo development, ovary ipsilateral to the corpus luteum and size of the corpus luteum on the pregnancy rate of recipients after embryo transfer of in vitro production embryos from beef and dairy breeds. However, the quality and processing of in vitro production embryos exerted effects on the pregnancy rate after embryo transfer of beef and dairy breed embryos.