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Abstract：
The purpose of this study is to compare five protocols of estrous synchronization for Hu ewes to obtain the most effective and economical protocol, to apply the advantageous scheme in large-scale sheep farming. Healthy multiparous Hu ewes (n = 150) were randomly divided into five groups, and all ewes were administered fluorogestone acetate (FGA, 45 mg) vaginal sponge. The sponges of the first three groups (Groups I, II, and III) were removed on the 11th day, and 0.1 mg of PGF2α was injected intramuscularly on the ninth day. Group I received 6 μg of gonadotropin-releasing hormone (GnRH) by intramuscular injection at 36th h after withdrawal of the sponge. Group II was injected 330 IU of pregnant mare serum gonadotropin (PMSG) on the ninth day. The combination of 6 μg of GnRH and 330 IU of PMSG was treated in Group III at the same time as Group I and Group II. The sponges of the latter two groups (Groups IV and V) were removed on the 13th day, and 330 IU of PMSG was injected intramuscularly simultaneously. PGF2α (0.1 mg) was administered on the 12th day in Group IV. All ewes were detected for estrus at 24, 36, 48, 60, and 72 h after the sponge removal. The loss of sponge and vaginitis was recorded when the sponge was withdrawn. Cervical artificial insemination (AI) was performed with fresh semen of Dorper rams diluted with skimmed milk. After 30 days of insemination, the conception was detected with a veterinary B-ultrasound scanner. The lambing status of all ewes and the cost of drugs for estrous synchronization in each group were recorded. The results showed the following: (1) on the whole, the average percentage of estrous ewes in the period of 24-36 h and 36-48 h after removal was significantly higher than other three periods and that of the period of 60-72 h was significantly lower than the first three periods after removal; (2) there was no significant difference in percentages of estrous ewes in any of the five time periods, sponge loss rate, vaginitis rate, total percentage of estrous ewes, conception rate, single lambing rate, twinning rate, and multiple lambing rate of ewes among five protocols; (3) total percentage of estrous ewes and conception rate were more than or equal to 80% in the Groups II and III, and the twinning lamb rate of the Group II protocol was 70%; (4) there was no difference in lambing rate of ewes among Groups II, III, IV, and V; (5) the Group III had the highest drug cost of 22.5 CNY. In conclusion, considering the lambing rate, twinning lamb rate, and drug cost for estrous synchronization, Group II was the most advisable for application and promotion in large-scale sheep farms among these five protocols of estrus synchronization.
摘要：
这项研究的目的是比较五个方案的发情同步的胡母羊，以获得最有效和经济的协议，将有利方案应用于规模化养羊。健康的多胎Hu母羊（n=150）随机分为五组，所有母羊都服用醋酸氟代石酮(FGA，45mg)阴道海绵。前三组的海绵(第一组，II,和III)在第11天被移除，第9天肌肉注射PGF2α0.1mg。在取出海绵后第36小时，第一组通过肌肉注射接受6μg促性腺激素释放激素（GnRH）。在第9天，第II组注射了330IU的孕马血清促性腺激素（PMSG）。在第III组中与第I组和第II组同时处理6μgGnRH和330IUPMSG的组合。后两组(IV组和V组)的海绵在第13天取出,同时肌肉注射330IU的PMSG。第IV组于第12天给予PGF2α(0.1mg)。在取出海绵后24、36、48、60和72h检测到所有母羊的发情。当取出海绵时记录海绵和阴道炎的损失。用脱脂乳稀释的Dorper公羊新鲜精液进行子宫颈人工授精（AI）。授精30天后,受孕是用兽医B超扫描仪检测到的。记录每组所有母羊的羔羊状况和发情同步药物的费用。结果表明:(1)总体上,去除后24-36h和36-48h的发情母羊平均百分比显著高于其他三个时期，60-72h的发情母羊平均百分比显著低于去除后的前三个时期；(2)五个时期中任何一个时期的发情母羊百分比没有显著差异，海绵损失率，阴道炎率，发情母羊的总百分比，受孕率，单羔羊率，孪生率，五个方案中母羊的多次产仔率；（3）第二和第三组中发情母羊的总百分比和受胎率大于或等于80％，第二组方案的孪生羔羊率为70％；（4）第二组母羊的产仔率没有差异，III,IV,和V；（5）第三组的药物成本最高，为22.5元。总之,考虑到羔羊率，孪生羔羊率，和动情同步的药物费用，在这五个发情同步方案中，第二组最适合在大型养羊场中应用和推广。
