In vivo embryo production in bovine donors with low and high antral follicle counts superovulated with low and high FSH doses

Abstract

This study evaluated the embryo yield in Bos indicus donors with low and high antral follicle counts (AFCs) subjected to a multiple ovulation and embryo transfer (MOET) program using low and high FSH doses for superovulation. Donors (n = 16) underwent a presynchronization E2/P4-based protocol 30 days (D-30) before starting the MOET program. After AFC evaluation (D-26), donors with low (n = 8; ≤ 15 follicles; mean = 10.00 ± 0.91 follicles) and high AFCs (n = 8; ≥ 25 follicles; mean = 36.13 ± 6.05 follicles) underwent a first program involving a dose of 150 IU of FSH (low-dose). Then, 45 days later, all donors underwent a second program involving a dose of 300 IU of FSH (high-dose). MOET was performed using a conventional timed superstimulation protocol with decreasing FSH applications at 12 h intervals, and uterine flushing was performed 7 days after ovulation induction. Data were analyzed by two models employing ANOVA and Tukey's test in a procedure for an adjusted mixed effect model (P ≤ 0.05). The first model contemplated a split-plot scheme and second model considered the treatment effect. An effect of AFC was observed only for the number of corpora lutea (CLs), which was higher (P = 0.01) in donors with high AFCs than in those with low AFCs. For all other variables monitored, donors with low AFCs showed similar reproductive performance to high-AFC donors (P > 0.1). In general, the 300 IU of FSH dose resulted in significantly greater (P < 0.01) numbers of CL, total structures, and viable and freezable embryos than the 150 IU dose. There was no interaction of AFC*FSH (P > 0.05). However, a significant treatment effect was observed, which showed that donors with a high AFC treated with a high FSH dose presented the greatest mean numbers of CL (P = 0.002), total structures (P = 0.002), viable embryos (P = 0.04) and freezable embryos (P = 0.004). However, donors with a low AFC treated with 300 IU of FSH exhibited similar embryo yield to that of the high-AFC group treated with 300 IU of FSH (P > 0.1). In conclusion, the embryo yield was not influenced by the AFC category but was influenced by the FSH dose. Furthermore, the significant treatment effect revealed that high-AFC donors superovulated with the highest FSH dose presented the best performance in terms of embryo yield.