ABSTRACT
To reduce labor for superovulation treatment by twice-daily intramuscular (im) administration of FSH for more than 3 to 4 days, we investigated the superovulatory responses of Japanese Black cows to porcine FSH (pFSH) used as a single subcutaneous (sc) administration at two different doses in two different volumes of saline. In experiment 1, 20 Armour units (AU) of pFSH dissolved in either 10 mL (treatment A; n = 14) or 50 mL (treatment B; n = 14) of saline was administered subcutaneously in the neck region. In experiment 2, 30 AU of pFSH dissolved in either 10 mL (treatment C; n = 15) or 50 mL (treatment D; n = 15) of saline was administered subcutaneously in the neck region. The control animals in experiment 1 (n = 14) and experiment 2 (n = 15) received 20 AU of pFSH administered intramuscularly twice daily in decreasing doses for more than 3 days. In experiment 1, mean (±SEM) numbers of CL (15.4 ± 2.5, 18.1 ± 3.4, and 17.2 ± 2.6), total number of ova and embryos (12.9 ± 1.4, 15.9 ± 3.5, and 16.2 ± 2.8), and transferable embryos (7.5 ± 2.0, 10.4 ± 2.8, and 8.0 ± 2.1) did not differ among treatments A, B, and control. In experiment 2, mean (±SEM) numbers of CL (20.5 ± 4.3, 20.4 ± 2.7, and 20.1 ± 3.4), total number of ova and embryos (21.7 ± 4.2, 17.3 ± 3.4, and 16.5 ± 3.2), and transferable embryos (8.1 ± 1.6, 9.3 ± 2.2, and 9.5 ± 1.9) did not differ among treatments C, D, and control. Although there were no differences in serum pFSH concentrations among the three treatments at each of the time points in experiment 1, in experiment 2, the serum pFSH concentration at 6 and 8 hours after pFSH administration in treatment C (3.1 ± 0.8, 2.7 ± 0.5 ng/mL, mean ± SEM) was significantly greater (P < 0.05) than in the control (0.7 ± 0.1, 1.1 ± 0.2 ng/mL). At 10 hours after administration, the pFSH concentration had decreased and there were no differences among the three treatments at subsequent time points. These results suggest that increasing the volume of saline or the dose of pFSH does not affect the absorption pattern of pFSH administered as a single sc administration. In conclusions, single sc administration of pFSH at a dose of 20 or 30 AU dissolved in 10 or 50 mL of saline is able to induce a superovulatory response comparable with that obtained by twice-daily im administration in Japanese Black cows.
