Carnevale E M, Maclellan L J, Coutinho da Silva M A, Checura C M, Scoggin C F, Squires E L
Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, CO 80523, USA.
Anim Reprod Sci. 2001 Dec 3;68(3-4):305-14. doi: 10.1016/s0378-4320(01)00167-1.
Insemination of recipients for oocyte transfer and gamete intrafallopian transfer (GIFT) in five experiments were reviewed, and factors that affected pregnancy rates were ascertained. Oocytes were transferred into recipients that were (1) cyclic and ovulated at the approximate time of oocyte transfer, (2) cyclic with aspiration of the preovulatory follicle, and (3) noncyclic and treated with hormones. Recipients were inseminated before, after, or before and after transfer. Intrauterine and intraoviductal inseminations were done. Pregnancy rates were not different between cyclic and noncyclic recipients (8/15, 53% and 37/93, 39%). The highest numerical pregnancy rates resulted when recipients were inseminated with fresh semen from fertile stallions before oocyte transfer or inseminated with cooled transported semen before and after oocyte transfer. Oxytocin was administered to recipients before oocyte transfer when fluid was imaged within the uterus. Administration of oxytocin to recipients at the time of oocyte transfer resulted in significantly higher pregnancy rates than when oxytocin was not administered (17/26, 65% and 28/86, 33%). Intraoviductal and intrauterine inseminations of recipients during oocyte transfer resulted in similar embryo development rates when fresh semen was used (12/22, 55% and 14/26, 55%). However, embryo development rates significantly reduced when frozen (1/21, 5%) versus fresh sperm were inseminated into the oviduct. Results suggest that insemination of a recipient before and after transfer could be beneficial when semen quality is not optimal; however, a single insemination before transfer was adequate when fresh semen from fertile stallions was used. Absence of a preovulatory follicle did not appear to affect pregnancy rates in the present experiments. The transfer of sperm and oocytes (GIFT) into the oviduct was successful and repeatable as an assisted reproductive technique in the equine.
