Abstract: The study aimed to analyze the effects of different developmental stages (young and postpartum Wagyu), synchronization methods, follicle-stimulating hormone (FSH) dosage and superovulation times on superovulation efficiency and embryo production in Australian Wagyu beef. In this experiment, 38 young Wagyu (16-20 months old) and 42 postpartum Wagyu (first born) were selected for superovulation treatment. The number of total embryos, usable embryos, different grades embryos and the unavailable embryos were counted respectively, and then the data of superovulation efficiency and embryo production of each experimental group were compared and analyzed. The results showed that: 1) The rate of efficient superovulation in postpartum Wagyu ((95.46±2.58)%) was significantly higher than that in heifer((77.55±6.02)%, P<0.05), and the number of total embryos (12.30 vs 10.37), usable embryos (8.97 vs 7.66) and grade A degree embryos (3.86 vs 2.50) were also higher than those in heifer (P>0.05)； 2) There was no significant difference in the rate of efficient superovulation among different simultaneous treatments (spontaneous estrus, PG and implanted CIDR) before superovulation, but the average usable embryos per donor bovine in spontaneous estrus group (11.22±2.33) was significantly higher than that in PG group (6.09±1.05) (P<0.05); 3) Different doses of FSH could significantly affect the rate of efficient superovulation of donor and the number of average unavailable embryos per donor. The rate of efficient superovulation of heifer in 120 mg FSH group ((55.56±17.57)%) was significantly lower than that in 200 mg FSH group ((88.00±6.63)%) and 220 mg FSH group ((73.33±11.82)%) (P<0.05). The number of average unavailable embryos per donor of postpartum beefs in 220 mg FSH group (2.28±0.65) was significantly lower than that in 250 mg FSH group (5.00±1.38) (P<0.05); 4) The superovulation times significantly affected the rate of efficient superovulation of heifer and the number of average unavailable embryos per donor of postpartum beefs. The first rate of efficient superovulation of heifer ((70.27±7.62)%) was significantly lower than that of the second superovulation (100%) (P<0.05). The number of unavailable embryos recovered in the second superovulation(4.44±0.92) was significantly higher than that in the first superovulation (2.39±0.40) (P<0.05). Therefore, under the existing level of production management in North China, the superovulation donor should select the parturient cow, and the total dose of superovulation FSH should be 240 mg, which will provide technical and theoretical basis for the high efficiency production of embryos and the establishment of core groups in Wagyu.

Key words: Australian Wagyu beef, superovulation, FSH, embryo production