319 SUPEROVULATORY RESPONSE IN JAPANESE BLACK CATTLE BY A SINGLE SUBCUTANEOUS ADMINISTRATION OF PURE FOLLICLE-STIMULATING HORMONE DISSOLVED IN SALINE

The objective of this study was to evaluate the superovulatory response to a single SC administration of pFSH (Antrin R-10) dissolved in saline in Japanese Black cattle. Forty Japanese Black cows were divided into 5 groups. All cows received a progesterone releasing intravaginal device (PRID) at a random stage of the oestrous cycle except the day of oestrus (Day 0). Superovulatory treatments were initiated on Day 4 with single SC administration of 20 AU pFSH dissolved in 10 mL of saline (Group A) or 50 mL of saline (Group B), or 30 AU pFSH dissolved in 10 mL of saline (Group C) or 50 mL of saline (Group D). Conventional superovulatory treatment (Group E) was also initiated on Day 4 with 20 AU pFSH in decreasing doses in IM administration twice a day for 3 days (5/5, 3/3, and 2/2 in the am/pm). Each administration was carried out in the neck region. For oestrus induction, all animals were treated with prostaglandin F2α (750 μg of cloprostenol) on Day 4, and then the PRID was removed on Day 6 in the morning. The GnRH (10 μg of buserelin) was administrated at 31 h after PRID removal to induce ovulations. The cows were artificially inseminated at 24 h after GnRH treatment, and embryos were recovered 7 days after the insemination. Blood samples were collected at 0, 2, 4, 6, 8, 10, 24, 31, 48, 55, 72, and 79 h after the first pFSH administration, and serum pFSH concentration was measured using time-resolved fluorescence immunoassay. Percentage data were arcsine transformed before analysis, and one-way ANOVA was used for statistical analysis (P 0.05) differences among groups in the number of corpus luteum, total number of ova/embryos, number of transferable embryos, and percentage of transferable embryos. The concentrations of pFSH in serum increased in all groups 2 h after each administration and reached a peak at 8 h in Groups A and C, at 10 h in Groups B, D, and E, and then in all groups it decreased gradually. The concentrations of pFSH in serum decreased to the base level (the level at 0 h) in Group A at 55 h and in Group C at 72 h after the first pFSH administration. At 79 h, serum pFSH was still detected in Groups B, D, and E. These results suggest that the single SC administration of 20 AU pFSH that is the same dose as the conventional treatment is able to induce a superovulatory response comparable to that of conventional treatment in Japanese Black cattle. Table 1.Superovulatory responses (mean ± SE) in different treatment groups