Superovulation induced by one-shot administration of FSH in aluminum hydroxide gel in Japanese Black cattle, 2: Dosage of FSH and use of newly-developed gel

In the present study, we tried to determine a recommended dosage of FSH in one-shot administration of FSH in aluminum hydroxide gel in Japanese Black cattle and to use newly-developed gel as a substitute for the gel. In experiment 1, 30AU and 25AU FSH were administered to 15 and 13 Japanese Black cattle, respectively, by one intramuscular injection (one-shot 30AU FSH and one-shot 25AU FSH). The hormone was used as a mixture with 5ml aluminum hydroxide gel (3mg/ml). In experiment 2, FSH was administered to 8 Japanese Black cattle by one-shot 25AU FSH used newly-developed gel (Kawasaki Mitaka Pharmaceutical Co., Ltd.) and repeated intramuscular administrations (repeated FSH), and their effects were compared. For repeated FSH, the hormone dissolved in saline was used in decreasing doses (5, 5, 3, 3, 2 and 2 (20AU in total)) twice a day (morning and evening) for three days. PGFsub(2alpha) analogue (750micro g) was administered twice 48 and 56 hours after one-shot FSH or the first injection of repeated FSH. Artificial insemination was performed on the animals during their metestrus. 7days after the artificial insemination embryos were collected, and corpora lutea and large ovarian follicles were examined. In experiment 1, corpora lutea, large ovarian follicles, collected embryos and transferable embryos counted 7.0+-4.8 (mean+-S.D), 1.7+-1.0, 5.2+-14.7 and 3.5+-4.2 in number per cow in one-shot 30AU FSH, and 7.2+-6.4, 1.0+-0.8, 5.8+-6.0 and 4.8+-5.4 in one-shot 25AU FSH. There was no significant difference between the means in any of the examined items. Collected embryos were better in quality in one-shot 25AU FSH than in one-shot 30AU FSH. In experiment 2, corpora lutea, large ovarian follicles, collected embryos and transferable embryos counted 7.9+-6.6, 3.6+-4.8, 6.1+-5.8 and 4.5+-4.4 in one-shot FSH, and 9.4+-6.3, 5.1+-5.4, 6.0+-3.5 and 2.6+-3.0 in repeated FSH. There was no significant difference between the means in any of the examined items. Collected embryos were better in quality in one-shot FSH than in repeated FSH. These results suggest that we can reduce the dose of FSH to 25AU in one-shot administration of FSH for superovulation treatment of Japanese Black cattle, and newly-developed gel can be used as a substitute for conventional aluminum hydroxide gel.