【摘要】 试验旨在探究来曲唑（LE）组合同步排卵（Ovsynch）程序对绵羊同期发情效果的影响。试验一：在繁殖季节，将30只经产蒙古羊随机分为3组，每组10只，Ovsynch组按特定程序注射溶剂、促性腺激素释放激素（GnRH）和前列腺素F_2α(PGF_2α),LE低、高剂量组先连续2 d注射不同剂量（0.125,0.25 mg/kg）LE，再按Ovsynch程序处理。所有母羊在最后一次注射GnRH12 h后用公羊试情。发情母羊在发情后12,24 h各进行1次人工授精（AI）。试验二：将20只经产蒙古羊随机分为Ovsynch组和LE高剂量组。激素处理方案同试验一的LE高剂量组，所有母羊分别在第2次注射GnRH后16,24 h进行定时人工授精（FTAI）。结果表明：在第1次注射GnRH前，用高剂量（0.25 mg/kg）LE处理2 d，母羊血清中雌二醇（E2）浓度显著降低（P<0.05），母羊第1次注射GnRH时卵巢上的最大卵泡直径显著增加（P<0.05），第1次注射GnRH诱发的排卵率提高，使相同处理母羊发情时间相对更同步；另外，LE预处理也显示出提高Ovsynch程序中母羊妊娠率和产羔率的趋势（P>0.05）。综上所述，LE处理有增加Ovsynch程序第1次注射GnRH的排卵率和第2次注射GnRH后发情同步性的趋势，能够在一定程度上提高母羊繁殖性能。更多还原

【Abstract】 This experiment aims to explore the effects of letrozole（LE） combined with the synchronization of ovulation（Ovsynch） program on estrus synchronization in ewes. In experiment 1, 30 multiparous Mongolian ewes in breeding season were randomly divided into three groups, each containing 10. The Ovsynch group received sequential injections of solvent, gonadotropin-releasing hormone（GnRH） and prostaglandin F_2α(PGF_2α) according to a standardized protocol, and the low and high LE treatment groups were administered with doses of LE（0. 125 mg/kg and 0. 25 mg/kg）, respectively, for two consecutive days prior to undergoing the same Ovsynch treatment regimen. Twelve hours after the last injection of GnRH, ewes in all groups were teased with rams. Ewes in estrus would receive artificial insemination（AI） once at 12 hours and once at 24 hours in heat,respectively. In experiment 2, 20 multiparous Mongolian sheep were randomly divided into the Ovsynch group and the high LE treatment group. The hormone treatment protocol was the same as that of the high LE treatment group in experiment 1. All ewes underwent fixed-time artificial insemination（FTAI） at 16 and 24 hours after the second injection of GnRH, respectively. The results showed that pretreatment with a high dose of LE（0. 25 mg/kg） for two days before the first GnRH injection significantly reduced serum estradiol（E2） concentrations（P<0. 05）, increased the diameter of the largest ovarian follicle at the time of the first GnRH injection（P<0. 05）, enhanced the ovulation rate induced by the first GnRH injection, and led to more synchronized estrus onset among ewes receiving the same protocol. Moreover,LE pretreatment also increased the pregnancy and lambing rates of ewes in the Ovsynch program（P>0. 05）. In conclusion, LE treatment could make differences in estrus synchronization of ewes in increasing the ovulation rate after the first GnRH injection and improving estrus synchrony following the second GnRH injection in the Ovsynch protocol, thereby contributing to improved reproductive performance in ewes to some extent.更多还原