1Unité de Neuro-Gastroentérologie & Nutrition, INRA UMR 1054, 180 chemin de Tournefeuille, BP 3, 31931 Toulouse cedex 9, France.
Animal. 2008 Oct;2(10):1496-500. doi: 10.1017/S1751731108002425.
Standard artificial insemination (AI) using a speculum in dairy goats does not result in acceptable fertility rates in nulliparous does. An explanation might be the difficulties to pass the cervical canal in nulliparous females with the insemination gun, increasing the time needed for semen deposition. Nulliparous Alpine dairy goats were used to evaluate whether time interval from insertion to withdrawal of the speculum is a factor influencing pregnancy rates to first AI with frozenthawed semen. Oestrus was synchronized using fluorogestone acetate intravaginal sponges (FGA, 40 mg) for 11 days, associated with 50 mg i.m. of cloprostenol and 250 IU i.m. eCG 48 ± 2 h before sponge removal. In the first experiment (n = 52; 3 herds), the average duration of the AI procedure was 42 ± 10 s, with a median of 39 s. AI performed in less than 39 s resulted in higher pregnancy rates (75%, n = 28) than AI lasting for more than 39 s (46%, n = 24). In the second experiment, does (n = 325; 5 herds) were randomly assigned into two treatment groups according to a short (20 s) or long (60 s) AI procedure. We showed that the duration of AI affected fertility after a first insemination, and that pregnancy rate was significantly improved using a short-duration AI (61.2%; n = 169) compared with a long-duration AI (44.2%; n = 156). We have previously shown in the ewe that genital stimulation during AI enhanced uterine motility. Other authors reported a negative correlation between increased uterine motility at the time of AI and fertility rates in small ruminants. The results of this study suggest that rapid semen deposition may limit the reflex activation of uterine contractions provoked by the speculum and the movement of the insemination gun, and thus ameliorates reproductive performance to first AI in nulliparous goats.
标准的人工授精（AI）在奶牛山羊中使用窥器，无法使初产母羊获得可接受的受孕率。原因可能是输精枪难以穿过初产母羊的宫颈管，导致精液沉积所需的时间增加。本研究旨在评估初产阿尔卑斯奶山羊的产道从插入到撤出窥器的时间间隔是否是影响冷冻精液首次 AI 受孕率的因素。通过阴道内放置氟孕酮海绵（FGA，40mg）对发情进行同步处理，持续 11 天，同时在海绵取出前 48 ± 2 小时肌肉内注射氯前列烯醇 50mg 和促性腺激素释放激素 250IU。在第一个实验中（n=52；3 个畜群），AI 过程的平均持续时间为 42 ± 10s，中位数为 39s。在 39s 以内完成的 AI 受孕率较高（75%，n=28），而持续时间超过 39s 的 AI 受孕率较低（46%，n=24）。在第二个实验中，根据 AI 过程的长短（20s 或 60s），将母羊（n=325；5 个畜群）随机分配到两组处理中。我们发现，AI 的持续时间会影响首次授精后的受孕率，与长 AI （44.2%，n=156）相比，短 AI（61.2%，n=169）显著提高了妊娠率。我们之前在绵羊中表明，AI 期间的生殖道刺激可增强子宫蠕动。其他作者报道称，在小反刍动物中，AI 时子宫蠕动增加与受孕率呈负相关。本研究结果表明，快速的精液沉积可能会限制窥器和输精枪运动引起的子宫收缩反射性激活，从而改善初产母羊的首次 AI 繁殖性能。
