It is probable that reduced pregnancy rates in ewes after fixed time artificial insemination (FTAI) is attributable, in part, to the reduced number of normal spermatozoa that colonize the oviduct. Administration of oxytocin stimulates both cervical dilation and uterine/oviductal contractility. The hypothesis that oxytocin can enhance sperm transport into the uteri and the oviducts, and thereby increase pregnancy rates, was tested in the present study. Oestrus was synchronized in 199 multiparous Kazak ewes using intravaginal flurogestone-impregnated sponge. The sponge was left in the vagina for 12 days followed with an injection of 330 IU of eCG at sponge removal. Each ewe was intracervically inseminated twice at 50 hr and 62 hr after the removal of sponges using an insemination catheter containing 0.25 ml of diluted semen. Semen was collected from seven Texel rams and all the ejaculates were pooled and diluted in ultra-high temperature-treated commercial skimmed milk without (Control group, 0.05 ml of saline per mL milk, n = 144) or with oxytocin supplement (Oxytocin group, 0.5 U of oxytocin per ml milk, n = 55). Pregnancy status was determined by transabdominal ultrasound examination 45 days after insemination. Lambing performance was recorded at delivery. Significant differences were observed between the Oxytocin group and the Control group in terms of the pregnancy rate and the fecundity rate (85.5% and 92.7% versus 68.8% and 72.9%, respectively). In conclusion, low dose oxytocin supplementation of semen extender significantly increased pregnancy and fecundity rates in oestrus-synchronized Kazak ewes after FTAI.

中文翻译：

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哈萨克母羊固定时间人工授精后催产素提高妊娠率

固定时间人工授精 (FTAI) 后母羊的妊娠率降低可能部分归因于定植输卵管的正常精子数量减少。催产素的施用刺激宫颈扩张和子宫/输卵管收缩。本研究检验了催产素可以促进精子进入子宫和输卵管从而提高妊娠率的假设。使用阴道内氟孕酮浸渍海绵使 199 只经产哈萨克母羊同步发情。将海绵留在阴道内 12 天，然后在取出海绵时注射 330 IU 的心电图。在取出海绵后的 50 小时和 62 小时，使用含有 0.25 毫升稀释精液的授精导管对每只母羊进行两次宫颈内授精。n  = 144）或使用催产素补充剂（催产素组，每毫升牛奶 0.5 U 催产素，n  = 55）。受精后 45 天通过经腹超声检查确定妊娠状态。在交付时记录羔羊性能。在妊娠率和生育率方面，催产素组和对照组之间观察到显着差异（分别为 85.5% 和 92.7% 对 68.8% 和 72.9%）。总之，在 FTAI 后，低剂量的精液补充剂补充催产素显着提高了发情同步的哈萨克母羊的妊娠率和繁殖率。