Abstract: Experiments were designed to investigate the factors of influencing superovulation in Wagyu.These factors included season, times of repeated superovulation and paternal line.All donors received 120 mg NIH of Folltropin-V in a conatant dose, twice daily IM schedule over 4 days.The results showed that:①There were no difference of the mean number of embryos (7.1, 7.8, 8.3 and 7.7) and of transferable embryos (5.2, 4.7, 5.2 and 5.2) in the spring, summer, autumn and winter(P>0.05).The mean number of untransferable embryos (3.2 and 3.1) in summer and autumn were significantly higher than in spring (1.9) (P<0.05).②Repeated superovulation (1 to 10)was applied to superovulation of Wagyu.There were no difference among the mean number of embryos (7.5 to 9.3), of transferable embryos (4.6 to 6.1) and of untransferable embryos (2.7 to 3.4) (P>0.05).③The mean number of recovered embryos in the WESFA0107 line (11.1)was significantly higher than in the GOSFZ0302、BYWFA0015、BYWFY0342、BYWFY0350 and TFWFW06290 lines (P<0.05).The mean number of recovered transferable embryos in the WESFA0107 line (6.2)was significantly higher than in the BYWFY0350 line (3.6)(P<0.05).The mean number of recovered degenerate embryos in the WESFA0107 line (3.3) was significantly higher than in the BYWFA0015, BYWFY0350 and TFWFW06290 lines (1.8, 1.1 and 1.7) (P<0.05).The mean number of recovered unfertilized ova in the WESFA0107 line (1.6)was significantly higher than other lines (P<0.05).The mean numbers of recovered embryos and transferable embryos in the BYWFY0350 line (5.3 and 3.6) were the least among the paternal lines.In summary, avoiding hot seasons, repeated superovulation and selecting dornors of appropriate paternal line could enhance the production of embryo in Wagyu.

Key words: Wagyu; superovulation; season; embryo