Aplicação de gonadorelina no momento da inovulação em tempo fixo de embrião bovino produzido in vitro

Abstract

The objective of this study was to evaluate the effect of gonadorelin at conception rates at 30 (DG30) and at 60 (DG60) days of gestation and on gestational loss rates (PGest) at recipients of bovine embryos produced in vitro. The experiment was carried out in 11 farms and the recipients were divided into: control group (n = 624) and treatment (n = 687). The variables were also analyzed: seasons of the year, farm, laboratory, recipient race, recipient category, embryo stage, embryo race, ovary structures and corpus luteum quality, as well as possible interactions. The protocol to synchronize the ovulation of the recipients was: D0: insertion of the intravaginal progesterone device and intramuscular application of 2.0mg of estradiol benzoate; D7: intramuscular application of 0.526mg of sodium cloprostenol; D9: intramuscular application of 0.526mg of sodium cloprostenol + 1mg of estradiol cypionate + withdrawal from the intravaginal device; D18: embryo innovulation + intramuscular application of 0.1mg gonadorelin or not. The data were evaluated by multivariate logistic regression using the GLIMMIX procedure of SAS version 9.2. In the final logistic regression model, some variables were removed based on the Wald criterion for P> 0.20. Treatment effect was detected on DG30 (P = 0.03), DG60 (P = 0.01) and trend on PGest (P = 0.09). The season affected DG30 (P = 0.04) and DG60 (P = 0.01). The farm variable had an effect on DG30 (P <0.0001) and DG60 (P <0.0001). There was a trend of effect of the recipient category on DG30 (P = 0.06) and DG60 (P = 0.06). There was no interaction between the evaluated variables. It is concluded that the application of gonadorelin at the time of the innovulation increased the conception rate in both DG30 and DG60.