Recombinant FSH as an alternative to pituitary-extracted FSH for superovulation and embryo production in sheep.

The aim of this study was to compare recombinant bovine FSH (rbFSH) with a conventional multiple-dose purified porcine FSH (pFSH) for in vivo embryo production in sheep. Forty multiparous Santa Inês ewes were randomly assigned to two groups: the GPUR group received 333 IU of pFSH in six decreasing doses at 12-hour intervals; the GREC group received a single 100 μg dose of rbFSH. Both groups underwent SOV following a short estrous synchronization protocol and were naturally mated. Estrus tended to last longer in GPUR than GREC ewes (44.5 ± 3.9 h vs. 35.6 ± 3.9 h; P = 0.08). No significant differences were observed between GPUR and GREC groups regarding estrus incidence (100% - GPUR vs. 95% - GREC), interval to estrus onset (66.9 ± 2.3 h - GPUR vs. 65.0 ± 2.4 h - GREC), number of CL (8.3 ± 1.1 - GPUR vs. 6.3 ± 1.1 - GREC), recovered structures (3.1 ± 0.8 - GPUR vs. 1.9 ± 0.9 - GREC), or viable embryos (1.2 ± 0.8 - GPUR vs. 1.7 ± 0.8 - GREC) whereas, the use of rbFSH reduced the incidence of anovulatory follicles (1.3 ± 0.5 - GPUR vs. 0.3 ± 0.5 - GREC; P = 0.04). The use of rbFSH did not result in differences in ovarian stimulation response in hair sheep, although rbFSH reduced the incidence of anovulatory follicles. Considering that it greatly simplifies on-farm procedures, it may represent a practical alternative for use in SOV in sheep.