Abstract: Estrous cow serum, which is supplemented in the medium of animal oocytes maturation and embryos culture in vitro, maybe can enhance the rate of oocytes maturation and embryos development. In this study, sheep oocytes collected from slaughterhouse-derived ovaries were used as experimental material, the effects of estrous cow serum on maturation and parthenogenesis of sheep oocytes in vitro was explortion. The results showed that 10% the first day estrous cow serum, which was supplemented in sheep oocytes maturation medium, could enhance the rates of oocytes maturation and parthenogenetic embryos cleavage. Moveover, after cultured 72 h in vitro, if 10% the seventh day estrous cow serum was supplemented in cultrue medium, sheep parthenogenetic embryos were endowed with higher ability developing into morulae and blastocysts. This study indicated that estrous cow serum can enhance the rate of maturation and parthenogenesis of sheep oocytes in vitro.

Key words: oocyte; estrous cow serum; parthenogenetic embryos; maturation in vitro; sheep