Different doses of pFSH are effective to promote follicular growth, superovulatory response, and embryo yield in White Dorper ewes

This study evaluated the effect of 250, 333, or 400 IU of a commercial porcine stimulating-follicle hormone (pFSH) on follicular growth, superovulatory (SOV) response, and embryo yield in White Dorper sheep. Ewes received an induced-ovulation protocol (D0 = progesterone (P4) device insertion) and superovulation starting 60 h before P4 withdrawal (D9), which consisted of six decreasing doses of 250 IU (G250; n = 15), 333 IU (G333; n = 15), or 400 IU (G400; n = 14) of pFSH. Ewes also received 50 µg of gonadotropin-releasing hormone (GnRH) analog on D10 and 300 IU of hCG on D13. Ewes were mated and submitted to non-surgical embryo recovery (NSER). Ultrasound evaluations were performed on D6, D7, D8, D9, and D16. The overall responding donor rate (≥3 CL) was 86.4% (38/44). The mean number of large follicles was higher (P < 0.05) in all groups on D8 (6.2 ± 0.9, 7.7 ± 0.9, and 8.3 ± 1.1) and D9 (11.1 ± 0.6, 10.4 ± 1.0, and 11.5 ± 0.9). Non-surgical embryo recovery procedures were successfully performed in 60.5% (23/38) of females. The CL count in successfully flushed ewes was greater (P < 0.05) in G333 (12.7 ± 2.3) and G400 (12.0 ± 1.3) than in G250 (6.0 ± 1.1). The recovery rate (44.4%, 57.3%, and 50.0%) and numbers of transferable embryos (2.3 ± 1.1, 6.1 ± 2.6, and 4.5 ± 1.3) did not differ (P > 0.05) among groups. All protocols were efficient in promoting follicular growth and adequate superovulatory response and embryo yield.