This study was conducted to assess effects of two hormonal treatments on ovarian follicular status, estrous synchrony and fertility in dairy goats during the non-breeding season when duration of progestogen device use varied by 12 h. In both experiments, does were administered 60 mg of medroxyprogesterone acetate via intravaginal devices, respectively, for 6 and 6.5 d (G6 and G6.5). At 24 or 36 h before device removal, 200 IU of eCG im and 30 μg d-cloprostenol im were administered. In Experiment 1 (n = 24), data related to sexual behavior and that were collected using ovarian ultrasonography were recorded, and in Experiment 2 (n = 83) fertility was assessed after Flexible Time Artificial Insemination (FxTAI). The interval from device removal to estrus was shorter (P < 0.05) after imposing the G6.5 treatment regimen. Diameter of largest and second-largest ovarian follicles and interval from device removal to ovulation were similar (P> 0.05) between groups. The does treated with the G6.5 hormonal regimen had greater estrous synchrony, associated with greater development of largest follicles at the time of device removal, which might have led to a lesser fertility rate (P > 0.05). Conversely, treatment with the G6 hormonal regimen resulted in a greater conception rate. In conclusion, increasing time the intravaginal device is inserted from 6 to 6.5 d resulted in greater estrous synchrony, advanced ovarian follicular development, abnormal CL function and lesser pregnancy rates in artificially inseminated dairy goats when there were treatments during the non-breeding season.

本研究旨在评估两种激素治疗对非繁殖季节奶山羊卵巢卵泡状态、发情同步性和生育力的影响，此时孕激素装置的使用持续时间相差 12 小时。在两个实验中，通过阴道内装置分别给予 60 mg 醋酸甲羟孕酮，持续 6 天和 6.5 天（G6 和 G6.5）。在装置移除前 24 或 36 小时，肌内注射 200 IU eCG 和 30 μg d-氯前列醇 im。在实验 1 ( n = 24) 中，记录了使用卵巢超声收集的与性行为相关的数据，在实验 2 ( n  = 83) 中，在弹性时间人工授精 (FxTAI) 后评估了生育能力。从装置移除到发情的间隔更短（P< 0.05) 在实施 G6.5 治疗方案后。组间最大和第二大卵泡直径和从装置取出到排卵的时间间隔相似（P > 0.05）。用 G6.5 激素方案治疗的雌性有更大的发情同步性，与装置移除时最大卵泡的更大发育相关，这可能导致较低的生育率（P> 0.05）。相反，用 G6 激素方案治疗导致更高的受孕率。总之，在非繁殖季节进行人工授精的奶山羊，将阴道内装置插入的时间从 6 天增加到 6.5 天会导致更大的发情同步性、先进的卵巢卵泡发育、CL 功能异常和较低的妊娠率。