Luteinizing hormone releasing hormone and placental gonadotrophins for therapy of ovarian quiescence in cattle
1991
Kamomae, H. (National Inst. of Animal Health, Tsukuba, Ibaraki (Japan)) | Kaneda, Y. | Domeki, I. | Nakahara, T.
This study was conducted to develop an effective theraphy on ovarian quiescence in cattle. In ovarian quiescent cattle, luteinizing hormone releasing hormone analogue (LH-RH-A) induced ovulation indirectly about 36 hr after injection by releasing luteinizing hormone (LH). Human chorionic gonadotrophin (hCG) induced ovulation directly about 36 hr after injection without LH release. Pregnant mare serum gonadotrophin (PMSG) stimulated development, maturation and active estradiol-17beta (E2) secretion of follicles(s), so that the actively secreted E2 triggered ovulatory LH surge about 35 hr after injection. Consequently, PMSG induced ovulation about 72 hr after injection. After induced ovulation, hypoplastic and short-lived (Type I) corpus luteum (CL)developed (i.e. induced CL) on LH-RH-A treatment. Type I and well-developed but slightly short-lived (Type II) CL developed on hCG treatment, and Type I, Type II and well-developed and normal life span (Type III) CL did on PMSG treatment. The ovarian cyclic activity started at lower rates on each treatment with LH-RH-A, hCG and PMSG. For initiating the ovarian cyclic activity it was recognized that induced CL was functional enough to increase plasma progesterone level and that a follicle matured with active E2 secretion in accordance with regression of the CL. Therefore, to promote the ovarian cyclic activity PMSG was supplementally dosed at a low level in 6 days after LH-RH-A treatment. The PMSG treatment was expected to stimulate maturation and active E2 secretion of a follicle developing along with regression of the induced CL. This treatment induced the ovarian cyclic activity at a high rate
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