Abstract: The possibility of intraspecific and interspecific fertilization between buffalo and cattle was explored in this study. Buffalo and bovine oocytes matured in vitro for 22 to 24 h were fertilized by injection of buffalo or bovine frozen-thawed spermatozoa. At 16 to 18 h after injection,a portion of ICSI 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 no difference in the two pronuclear formation rate (47.73% and 36.67%),cleavage rate (68.00% and 72.64%) and blastocyst development(16.44% and 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 with the embryos from those (45.28%,71.31% and 33.70%,P＞0.05) of bovine oocytes fertilized with buffalo sperm (interspecies). This results indicated that: ① Buffalo oocytes fertilized with bovine sperm and bovine oocytes fertilized with buffalo sperm could develop to blastocysts, ②The developmental capacity of bovine oocytes was higher than buffalo oocytes as evidenced by their proportion cleaved and developed to blastocysts after intraspecific and interspecific fertilization by ICSI.

Key words: buffalo; cattle; ICSI; intraspecies; interspecies; embryo