193 Comparison of Superovulatory Responses to Single Subcutaneous FSH Injection and Twice-Daily Intramuscular FSH Injection Protocols in Japanese Black Cows

The conventional superovulation treatment using follicle-stimulating hormone (FSH) comprises 2 intramuscular injections per day for 3 to 4 days. This conventional method requires frequent handling of donors—which may cause increasing stress in donors—and high labour costs. Therefore, to alleviate these issues, a treatment protocol using a single FSH injection under on-farm conditions is needed. The objective of this study was to evaluate the feasibility of the single subcutaneous FSH injection protocol (Sugawara et al. 2017 Reprod. Fertil. Dev. 29, 209), compared with with the traditional twice-daily intramuscular FSH injection protocol, in Japanese Black cows. Japanese Black cows (n = 13) were superovulated using 2 treatments in a crossover design. All cows received an intravaginal progesterone device (CIDR) at random stages of the oestrous cycle (Day 0), and 2 mg of oestradiol benzoate on Day 1 (24 h after CIDR insertion). On Day 6, for the group receiving a single subcutaneous FSH injection (single-FSH), 20 armor units (AU) of pFSH dissolved in 30 mL of saline was subcutaneously injected in the neck region and 0.5 mg of prostaglandin F2a was intramuscularly injected simultaneously. For the control group, FSH administration was initiated at Day 6. A total dose of 20 AU of FSH was administered in 3 days (with decreasing doses of 5, 3, and 2 AU, respectively, per injection) with 2 intramuscular injections per day; 0.5 mg of prostaglandin F2a was injected 48 h after the first FSH injection. For both groups, CIDR was removed 60 h after FSH injection and AI was done 42 to 48 h after CIDR removal. Embryo collections were performed 7 days after AI. Data were analysed using t-test for the mean numbers of collected ova/embryos and transferable embryos, and chi-squared test for the proportion of transferable embryos. There were no significant differences in the mean numbers (single-FSH v. control) of ova/embryos collected (17.1 ± 12.1 v. 17.8 ± 9.3), or transferable embryos (8.4 ± 9.3 v. 10.3 ± 8.7), and proportion of transferable embryos (45.0 ± 34.0 v. 56.6 ± 36.5). These results showed that although a slightly higher number and proportion of transferable embryos were obtained in the control group, a superovulation treatment protocol involving a single subcutaneous FSH injection can be effectively used for Japanese Black cows, under on-farm conditions.