Efeito da sincronização da onda folicular e da ECG prévio a opu na maturação de oócitos e na produção in vitro de embriões em vacas Braford

Abstract

The objective of this dissertation was to evaluate the effect of follicular wave synchronization and eCG prior to OPU in Braford donors on the acquisition of oocyte competence, the rate of extrusion of first polar body and mitochondrial reorganization, and in vitro produced blastocysts. 48 months old or more non-lactating and non-gestating Braford females were submitted to three sessions of follicular aspiration at 14-day intervals on a crossover experimental design. To evaluate the effect of the eCG dose, donors were divided into three groups: no treatment prior to OPU (Control), follicular wave synchronization (Synchro), and follicular wave synchronization plus 800 IU of eCG (eCG800). On day 0 (D0), the donors received intramuscular (IM) administration of 2 mg of estradiol benzoate, 5 mg of dinoprost tromethamine and a device impregnated with 1 g of progesterone (P4) was inserted intravaginally. On day 3 (D3), the eCG800 group donors received 800 IU of eCG IM. On day 6 (D6), the P4 device was removed, and follicular aspiration of all donors was performed. The number of follicles per donor was counted and classified by size. The evaluation in experiment 1 was the number of aspirated follicles, the number of oocytes obtained, as well as the viable oocytes that were evaluated for competence development, nuclear, and cytoplasmic maturation per group. 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 and tendency if P > 0.05 and ≤ 0.10. Nonparametric data were evaluated by Dunn's test. The number of medium sized follicles at the time of OPU of the eCG800 group was higher than other treatments (P < 0.0001 and P = 0.004) in experiment 1 and 2, respectively. The blastocyst rate on D7 of eCG800 and Synchro group demonstrated superiority tendency (P = 0.075). The other variables (number of small, large, and total follicles at the time of OPU, number of aspirated follicles, oocytes, viable oocytes, blastocysts on D7 and excellent quality embryo per donor per OPU, rates of recovery, viability, oocyte competence, extrusion of first polar body, mitochondrial reorganization, extrusion of first polar body combined with mitochondrial reorganization cleavage and excellent quality embryo) showed no statistical difference. Based on presented results, it is concluded that the dose of 800 IU of eCG increased the proportion of medium follicles in relation to the control group, and among Synchro group tended to produce more blastocysts on D7.