This study examined the effects of exogenous hCG administration on ovarian function and pregnancy rates in estrous-induced dairy goats during the transition into the breeding season. Eighty-six Toggenburg does received 60 mg of medroxyprogesterone acetate intravaginal sponge for 6 d plus 200 IU of equine chorionic gonadotropin and 30 μg of d-cloprostenol i.m. 24 h before sponge removal, and were then bred for 96 h. Seven days (D7) after first mating the does received either 1 mL of saline (the control group, n = 43) or 300 IU of hCG (the hCG-treated group, n = 43) i.m. Transrectal ovarian ultrasonography (B-mode and color Doppler) was performed on D7, D13, D17, and D21 and ultrasonographic pregnancy detection on D30. Pregnancy rate was higher (P < 0.05) in hCG-treated goats (90.7%; 39/43) than that in control animals (74.4%; 32/43). Accessory luteal structures (ALSs) were detected in 46.5% (20/43) of hCG-treated does. All hCG-treated does that had ALSs and 82.6% of goats without ALS post-treatment remained pregnant. The total luteal area increased (P < 0.05) from D7 to D13 in pregnant animals of both groups, whereas mean vascular area declined (P < 0.05) by D21 in all nonpregnant does. Serum progesterone concentrations increased (P < 0.05) on D21 in pregnant goats of both groups, but they were related to changes in luteal tissue content only in control does throughout the present study. Mean daily numbers of small- and medium-sized antral follicles decreased (P < 0.05) only in pregnant animals of both groups with a decline in medium follicle numbers occurring earlier in hCG-treated (D13) compared with control does (D17). To summarize, a single dose of hCG given on D7 after estrus was followed by a decrease in the number of medium-sized antral follicles in gestating hCG-treated does, induced the formation of ALSs in ~47% of all hCG-treated does, and significantly increased the pregnancy rate in estrous-induced Toggenburg goats in the transition to the breeding season.

本研究探讨了在发情诱导的奶山羊进入繁殖季节期间给予外源性 hCG 对卵巢功能和妊娠率的影响。 86 只 Toggenburg 确实接受了 60 mg 醋酸甲羟孕酮阴道海绵，持续 6 天，再加上 200 IU 马绒毛膜促性腺激素和 30 μg d-氯前列醇，在海绵取出前 24 小时内注射，然后饲养 96 小时。第一次交配后 7 天 (D7)，雌鹿接受 1 mL 生理盐水（对照组，n = 43）或 300 IU hCG（hCG 治疗组，n = 43），经直肠卵巢超声检查（B 型和D7、D13、D17 和 D21 进行彩色多普勒超声检查，D30 进行超声妊娠检测。 hCG 处理山羊的妊娠率(90.7%; 39/43) 高于对照动物 (74.4%; 32/43)。在 46.5% (20/43) 的 hCG 治疗组中检测到辅助黄体结构 (ALS)。所有经 hCG 治疗的患有 ALS 的母羊和 82.6% 未患 ALS 的山羊在治疗后仍然怀孕。两组妊娠动物的黄体总面积从 D7 到 D13 均有所增加 ( P < 0.05)，而所有非妊娠动物的平均血管面积在 D21 时均下降 ( P < 0.05)。两组怀孕山羊的血清孕酮浓度在 D21 时均有所增加（ P < 0.05），但在本研究中仅在对照中它们与黄体组织含量的变化有关。仅在两组怀孕动物中，中小型窦卵泡的平均每日数量减少（ P < 0.05），与对照组（D17）相比，hCG 治疗组（D13）中中等卵泡数量的减少发生得更早。 总而言之，发情后第 7 天给予单剂量 hCG，妊娠期 hCG 处理母兔中中等大小的窦卵泡数量减少，诱导约 47% 的 hCG 处理母兔形成 ALS，并显着提高了发情诱发的吐根堡山羊在向繁殖季节过渡期间的妊娠率。