Effect of Treatment With Gonadoreline at the Embryo Transfer on Pregnancy Outcomes in Bovine.

Abstract

The aim of this study was to assess whether administration of the gonadotropin-releasing hormone (GnRH) agonist gonadorelin would increase conception rates at 30 (P / ET 30) and 60 (P / ET 60) days of gestation and reduce pregnancy losses (PL) in embryo recipients and what would be the correlation between the animal category and the season of the year in which the embryo transfer would occur. The experiment was conducted on 11 commercial farms in the state of Minas Gerais, Brazil. Recipients were randomly divided into groups: treated (n = 624), cows that received 0.1 mg gonadorelin on the day of FTET, and control (n = 687), untreated cows. All embryos were produced in vitro from oocyte donors of different races. Recipients were classified as heifers, dry cows or lactating cows. Higher conception rate was observed at 30 days (p = 0.03) and 60 days (p = 0.01) in the treated group (45.8%; 43.0%, respectively). Dry and lactating cows had less pregnancy loss (p = 0.001) compared to heifers (2.70% and 2.47% vs 10.42%, respectively). During spring/summer, there was less P/FTET at 30 days (0.024). Embryo transfer carried out in the warmer seasons of the year reduced the pregnancy rate to 60 days and increased pregnancy loss. As an implication, the use of the GnRH analogue can be used as a tool to increase fertility in embryo recipients.