摘要
Background: Artificial insemination (AI) can serve as a powerful tool to the sheep owners for making rapid genetic progress of their flock. The AI in sheep is mostly performed using fresh semen with two reasons i) lambing rate following trans-cervical AI with frozen semen is limited by the inability of frozen-thawed sperm to transit the cervix and ii) the need of circumventing the cervical barrier through laparoscope aided intrauterine AI. Therefore, AI with frozen-thawed semen is not as widespread in sheep as it is in other domestic species. However, to get maximum benefits through the use of AI, frozen-thawed semen is a prerequisite because instead of high fertility, the short shelf life of fresh semen coupled with a limitation on the number of insemination doses achievable per unit time restricts the widespread use of individual sires. Therefore, in order to enhance lambing rate, a total of 240 trans-cervical artificial inseminations with frozen-thawed semen were performed in Bharat Merino ewes during autumn season either once in the evening (G-I, 10 h after onset of estrus, n = 100) or twice (G-II, 14 h and 22 h after onset of estrus, n = 140) i.e. once in the morning and again in the evening. Results: The pregnancy rate (proportion of pregnant ewes confirmed by ultrasonography at day 40) and lambing rate (proportion of ewes lambed) were higher in G-II as compared to G-I (26.4 vs 20% and 19.3 vs 10%, respectively). The difference in lambing rates was statistically (P < 0.05) significant. The depth of insemination within cervico-uterine tract had no significant effect on pregnancy and lambing rates. Conclusions: The results indicate that lambing rate in sheep following TCAI with frozen-thawed semen was significantly influenced by time of inseminations. Two inseminations after 14 and 22 h of onset of estrus enhanced the lambing rates of Bharat Merino sheep as compare to single insemination after 10 h of onset of estrus. The TCAI technique with frozen-thawed ram semen is promising and may serve as a valuable tool for genetic improvement of sheep breeds. Research efforts are going on worldwide to overcome the poor fertility following TCAI with frozen-thawed semen.
摘要译文
背景：人工授精（AI）可以为羊主提供强大的工具，使他们的羊群快速遗传。绵羊的AI大多使用新鲜的精液进行，原因有两个：i）经冷冻精液经宫颈的AI的产羔率受到冷冻解冻的精子无法通过子宫颈的限制，并且ii）需要通过腹腔镜辅助子宫内AI。因此，具有冷冻解冻精液的人工授精在绵羊中的流行程度不及其他家养品种。但是，为了通过使用AI获得最大利益，冷冻融化的精液是先决条件，因为代替高生育力，新鲜精液的保质期短，并且每单位时间可获得的授精剂量受到限制，这限制了其广泛使用。个体父本。因此，为了提高产羔率，秋季在巴拉特美利奴羊母羊中进行了总共240次经冷冻的精液经颈宫颈人工授精，晚上一次（GI，发情发生后10小时，n = 100）或两次（发情后14 h和22 h，G = II，n = 140），即早上一次，晚上一次。结果：与G-I相比，G-II的妊娠率（第40天经超声检查证实的母羊所占比例）和产羔率（被母羊所占的比例）更高（分别为26.4％和20％，19.3％和10％）。 ）。产羔率差异有统计学意义（P <0.05）。子宫颈-子宫内的授精深度对怀孕和产羔率没有显着影响。结论：结果表明，TCAI后冷冻解冻精液的绵羊羔羊产卵率受授精时间的影响很大。与发情10小时后单次授精相比，发情14和22小时后两次授精提高了巴拉特美利奴羊的产羔率。冷冻融化的公羊精液的TCAI技术很有前途，可以作为绵羊品种遗传改良的有价值的工具。为了克服TCAI后使用冷冻解冻精液造成的不良生育能力，全球正在开展研究工作。
Kumar; Davendra;Naqvi; Syed Mohammed Khursheed;. Effect of time and depth of insemination on fertility of Bharat Merino sheep inseminated trans-cervical with frozen-thawed semen[J]. Journal of Animal Science and Technology, 2014,56(3)