LAUSR

ABSTRACT Some antioxidants and growth factors play an important role in promoting oocyte maturation and embryo development in many mammalian species, but there is little information about the yak (Bos grunniens). Therefore, the objective of this study was to evaluate Cys, insulin-like growth factor-1 (IGF-1) and epidermis growth factor (EGF) on yak oocyte maturation, cleavage and blastocyst rates after in vitro fertilized with Jersey sperm. A single or different combination of Cys, EGF and IGF-1 was added to in vitro maturation (IVM) and in vitro culture (IVC) media. The results showed that a single addition of Cys and IGF-1 increased oocyte maturation and blastocyst rates (p < .05), but did not increase cleavage rate; EGF or IGF-1 + EGF increased oocyte maturation, cleavage and blastocyst rates (p < .05) compared with the control. A combination of IGF-1 + EGF + Cys could have a beneficial effect (p < .05). These results indicated that supplementation of IVM and IVC media with Cys, IGF-1, EGF and their combinations could improve in vitro production efficiency of yak-cattle crossbred embryos.