Effect of prior follicular wave synchronization and eCG on ovum pick-up and in vitro embryo production in Braford cows.

Abstract

The aim of this study was to evaluate the effect of follicular wave synchronization and equine chorionic gonadotropin (eCG) prior to ovum pick-up (OPU) in Braford cows on the oocyte competence, maturation rate, and in vitro embryo production. Cows (n = 27) were divided into three groups on a crossover model: no treatment prior to OPU (Control), follicular wave synchronization (Synchro), and synchronization plus 800IU of eCG (eCG800). Donors of the groups Synchro and eCG800 were synchronized with 2 mg of estradiol benzoate (EB), prostaglandin F2α analogue (PGF2α) and intravaginal device with 1g of progesterone (P4) on D0. On day 3, eCG800 group donors received 800IU of eCG. On day 6, OPU was performed, and the number of follicles were counted and classified by diameter in small, medium, and large. In experiment 1, the viable oocytes were evaluated for competence development, nuclear maturation, and mitochondrial reorganization. In experiment 2, oocytes were matured, fertilized, and cultured in vitro to blastocyst stage. All analysis was performed by ANOVA, and the differences were compared by Tukey's test with significance P ≤ 0.05. The use of 800 IU of eCG increased (P < 0.05) the number of medium and large follicles compared to the Syncro group. The oocyte recovery, viability, nuclear or cytoplasmic maturation, cleavage, and grade 1 embryos rate did not differ among groups (P > 0.05). The blastocyst rate on D7 showed tendency (P = 0.075) to improve from Control (17±6.08%) to Synchro (23.8±8.95%) to eCG800 (37.3±6.51%). The dose of 800 IU of eCG 72 h before OPU increased the proportion and number of medium and large follicles in relation to the Control and Synchro groups, without affecting oocyte competence and tending to produce more blastocysts on D7.