Effect of Low Dose of hCG on Induction of Fertile Estrus in Shiba Goats Pretreated Intravaginally with Progesterone during the Early Postpartum Nursing Period.

Abstract

Abstract. The present study was conducted to determine the effect of a low dose of human chorionic gonadotropin (hCG) on the induction of fertile estrus in Shiba goats pretreated intravaginally with progesterone during the early postpartum period. Nursing Shiba goats (n=13) around 3 weeks after the parturition were pretreated with a controlled internal drug release dispenser (CIDR) containing 0.3 g of progesterone for 7 day, and 60 µg of cloprostenol 24 hr before CIDR removal. Goats in Group I (n=6) received subcutaneous injections of a low dose of hCG (1 IU/kg) after the removal of CIDR at 12-h intervals until the occurrence of estrus. Goats in Group II (n=7, control) received subcutaneous injections of saline instead of hCG. The rate of estrus induction in Group I (83.3%) tended to be higher than that in Group II (42.9%), although the difference was not significant (P=0.14). Time from the removal of CIDR to the beginning of estrus in Group I was significantly shorter than that in Group II (P<0.05). A prominent peak of estradiol-17β concentration in plasma was observed with a maximum value at 30 h after the removal of CIDR in Group I, while two relatively small rises were detected with a maximum value at 48 h in Group II. The pregnancy rate in Group I (83.3%) was significantly higher (P<0.05) than in Group II (28.6%). These results suggest that the injections of low dose hCG after the treatment with CIDR promote follicular maturation and fertile estrus induction in the goats during the early postpartum nursing period. Key words: Low dose hCG, Estrus induction, Goat, Postpartum nursing period, Estradiol-17β (J. Reprod. Dev. 48: [497][498][499][500][501][502][503][504] 2002) hiba goats originated from a Japanese native dwarf breed and are known to be continuous breeders [1]. The Shiba and other dwarf goats have b een u s ed fo r va ri o us r es ear c h es , s u ch as r epr od uct ive phys io logy and pat ho log y of ruminant [2,3], physiology of fetus [4], cloning of animals [5], and thus recent demand for the goat has been expanding. In order to improve the reproductive efficiency of the Shiba goat, the interval from parturition to conception needs to be shortened. In cattle, ovaries are acyclic in the early postpartum period mainly due to the inadequacy of pulsatile release of luteinizing hormone (LH), but not follicle-stimulating hormone (FSH), due to calf nursing and/or negative energy balance [6]. Therefore, it is thought that treatment with hormones possessing LH activity might mature antral follicles and induce fertile estrus in acyclic animals during the early postpartum period.It has been reported that, in immature rats, a low

Comparison of Plasma Concentrations of Estradiol-17.BETA. and Progesterone, and Conception in Dairy Cows with Cystic Ovarian Diseases between Ovsynch and Ovsynch plus CIDR Timed AI Protocols

“…The concentration of estradiol-17β in blood plasma was measured by RIA as described previously [13][14][15][16]20]. The concentration of progesterone in blood plasma was measured by RIA using the processed standard curve as described previously [13][14][15][16]20].…”

“…The concentration of progesterone in blood plasma was measured by RIA using the processed standard curve as described previously [13][14][15][16]20]. Anti-estradiol-17β-6-BSA serum (GDN no.…”

Effect of Suckling on Embryo Production by Repeated Ovum Pick-Up Before and After Timed Artificial Insemination in Early Postpartum Japanese Black Cows

“…It has also been shown that suckling delays postpartum ovarian resumption in Japanese Black cows [25]. Another explanation for why more culture-competent oocytes were collected in the weaned group might be that normal growth of follicles and oocytes requires normal gonadotropin secretion and that gonadotropin secretion is inhibited in early postpartum suckled beef cows [26][27][28][29]. Since normal follicular and oocyte growth is probably necessary for normal development of blastocysts in vitro, the effects of suckling on the plasma FSH and LH profiles and follicular profiles (number and size) around the time of OPU in Japanese Black cows should be clarified in future research.…”

Ovsynch Plus CIDR Protocol for Timed Embryo Transfer in Suckled Postpartum Japanese Black Beef Cows

“…The concentration of progesterone in blood plasma was measured by RIA as described previously, [12,19] using the processed standard curve. Anti-progesterone-11-BSA serum (GDN no.…”

“…The concentration of estradiol-17β in the plasma was measured by RIA, as described previously [12,19]. Before the samples were assayed, the accuracy of the assay was estimated using the processed standard curve.…”