Submitted to: Theriogenology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/1998
Publication Date: N/A
Interpretive Summary: The utilization of the Beltsville sperm sexing technology in several important agricultural species is the goal of our research at the present time. The pig presents a particular challenge in that it requires large numbers of sperm to obtain pregnancies via regular artificial insemination. Therefore, in vitro fertilization of in vitro matured eggs presents an opportunity to use small numbers of sperm to obtain sexed embryos that are then transferred to recipient animals. This study demonstrates the effectiveness of using sexed sperm to fertilize in vitro matured pig eggs with X and Y sorted sperm populations. There were 8 sows farrowing in this study out of 27 that served as recipients. Three had litters that were 100 percent male. Five litters were born that totaled 33 pigs, all except one of which was female (97%). These studies have demonstrated the clear feasibility of using sexed sperm in conjunction with in vitro fertilization nso as to be able to apply sexed semen to improved productivity in the pig. Scientists will use this information to establish sperm sexing for practical use.
Technical Abstract: The present study examined the ability to establish pregnancies after transfer of pig embryos derived from in vitro fertilization (IVF) of in vitro matured (IVM) oocytes by X- and Y-chromosome bearing spermatozoa sorted by flow cytometry. Cumulus oocyte complexes were cultured in BSA- free NCSU 23 medium containing porcine follicular fluid, cysteine, epidermal growth factor, LH and FSH for 22 h and then oocytes were culture without hormonal supplements for an additional 22 h. Boar semen was collected and prepared at USDA, Beltsville, MD by flow cytometric sorting of X- and Y-chromosome bearing sperm. After IVM, cumulus-free oocytes were co-incubated with sorted X or Y spermatozoa for 6-7 h in modified Tris- buffered medium containing 2.5 mM caffeine and 0.4% BSA. After IVF, putative embryos were transferred to NCSU 23 medium containing 0.4% BSA for culture. A portion of oocytes were fixed 12 h after IVF and others were cultured up to 96 h. At 96 h after IVF, 8-cell to morula stage embryos fro each gender were surgically transferred to the uterus of recipient gilts. Insemination of IVM pig oocytes with X- or Y-bearing sperm did not influence the rate of penetration, polyspermy, male pronuclear formation or mean number of sperm per oocyte. No difference was observed between cleavage rates at 48 h after IVF. Transfer of embryos derived from X bearing sperm to 18 recipients resulted in 5 pregnancies and delivery of 23 females and 1 male piglet. Similarly, transfer of embryos derived from Y bearing sperm to recipients resulted in 3 pregnancies with 9 male piglets delivered. The results show that X and Y bearing spermatozoa sorted using USDA sperm sexing technology can be successfully used in an IVM-IVF system to obtain piglets of a predetermined sex.