A Preliminary Study On The Intraspecific And Interspecific Fertilization Between Buffalo And Cattle By Intracytoplasmic Sperm Injection

Factors affecting the fertilization of buffalo and bovine oocytes by sperm injection were examined, and the possibility of intraspecific fertilization between buffalo and cattle was also explored in this study. Buffalo and bovine oocytes matured in vitro for 22-24h were fertilized by injection of buffalo or bovine frozen-thawed spermatozoa. At 16-18h after injection, a portion of oocytes were fixed in acetic ethanol to examine the pronuclear formation, others were cultured in vitro to evaluate their cleavage rate and embryonic developmental ability. There was not difference in the two pronuclear formation rate (47.73% vs 36.67%), cleavage rate (68% vs 72.63%) and blastocyst development (16.44% vs 22.39%) of buffalo oocytes fertilized with buffalo (intraspecies) and bovine sperm (interspecies). (p>0.05). The two pronuclear formation rate (60.00%), cleavage rate (73.33%) and blastocyst rate (28.57%) of bovine oocytes fertilized with bovine sperm (intraspecies) were also not different from those (45.28%, 71.31% and 33.70% respectively, p>0.05) of bovine oocytes fertilized with buffalo sperm (interspecies). Treatment of buffalo sperm with 100ug/mL lysophosphatide did not affect the percentage of buffalo oocytes cleaved (80.41% vs 87.25%, p>0.05) and developed to blastocysts (6.7% vs 10.78%, p>0.05) after ICS1. Sixty-four percent of blastocysts derived from bovine oocytes fertilized with buffalo sperm survived and 30.6% of them hatched after freezing thawing, which was similar to the hatching rate (34.78%, p>0.05) of blastocysts unfrozen.In conclusions, 1) buffalo oocytes fertilized with bovine sperm and bovine oocytes fertilized with buffalo sperm can develop to blastocysts, which are proved to be freezable; 2) the developmental capacity of bovine oocytes is higher than baffalo oocytes as evidenced by their proportion cleaved and developed to blastocysts after intraspecific and interspecific fertilization by ICSI; 3) treatment of buffao sperm with lysophosphatide does not affect its ICSI efficiency.