Exogenous progesterone enhances ova and embryo quality following superstimulation of the first follicular wave in Nelore (Bos indicus) donors

Three experiments were conducted to evaluate the effects of exogenous progesterone on superovulatory response and ova/embryo quality in Bos indicus donors superstimulated during the first follicular wave (FFW). We hypothesized that exogenous progesterone during gonadotropin treatments would improve ova and embryo quality. In Experiment 1, 18 Nelore cows were randomly allocated to three groups: (1) FFW; (2) FFW plus a progesterone-releasing device (FFW+P4); and (3) control (E2+P4). Cows in the FFW groups were superstimulated beginning at synchronized ovulation, whereas cows in the control group were superstimulated after synchronization of follicular wave emergence with estradiol plus progesterone (E2+P4). There were no differences in mean (± SD) numbers of transferable embryos between FFW+P4 (8.0 ± 4.5) and control (6.7 ± 4.8) groups, but both were higher (P = 0.006) than the FFW group (0.2 ± 0.4). In Experiment 2, FFW and FFW+P4 were compared in 20 Nelore donors; exogenous progesterone increased the number of transferable embryos (3.9 ± 3.4 vs. 1.3 ± 4.1, P = 0.003). In Experiment 3, FFW and FFW+P4 were compared in 10 Nelore donors except that cows were slaughtered 12 h after pLH (Lutropin-V®, Bioniche Animal Health, Belleville, ON, Canada) treatment. More mature cumulus oocyte complex (COC) (expanded cumulus cell layers) were collected in the FFW+P4 group than in the FFW group (21.8 ± 13.1 vs. 10.8±14.7; P = 0.003). In summary, superovulatory response was satisfactory when FSH (Folltropin-V®, Bioniche Animal Health) treatment was initiated at emergence of the first follicular wave in Nelore (Bos indicus) donors, and the hypothesis that administration of exogenous progesterone during the treatment will improve oocyte and embryo quality was supported.