Serum cortisol concentration and rectal temperature at time of ovum pick up in cows and their relationship with subsequent in vitro embryo development and pregnancy

Abstract

The aim of this trial was to evaluate serum cortisol concentrations and rectal temperature at time of ovum pick up (OPU) in IVF oocyte donors and establish correlations between serum cortisol, rectal temperature, amount of recovered oocytes, cleavage rate, blastocyst rate and pregnancy rate. Red Angus donor cows (n = 30) kept on Brachiaria decumbens pasture with water and mineral ad libitum were used on this trial. Four days before OPU (D-4), cows had all their >6 mm follicles aspirated aiming to induce a new follicular recruitment. On D0, cows were checked for rectal temperature and blood samples were collected for cortisol analysis. A total of 577 oocytes were recovered and 91.3% (527/577) were considered viable and matured in vitro. Cleavage rate was 84.63% (446/527) and 189 embryos reached at least the morula stage, which were transferred to recipient heifers previously synchronized, producing 93 pregnancies. Data were analyzed by logistic regression. Cows with higher serum cortisol concentrations at time of OPU tended to have lower proportion of viable oocyte recovered (P<0.1) and had lower proportion of pregnancies/recovered oocytes and pregnancies/transferred embryos (P<0.05). Rectal temperature did not affect analised parameters. This data suggest that increasing on serum cortisol concentrations may affect negatively the amount of pregnancies produced by donor in IVF programs, although no negative effects on in vitro embryo development were detected.