Jabbar G, Umberger S H, Lewis G S
Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061-0306.
J Anim Sci. 1994 Dec;72(12):3049-54. doi: 10.2527/1994.72123049x.
Two commercially available progestogen products for cattle, melengestrol acetate (MGA) and norgestomet (SMB), were evaluated for their ability to induce synchronized estrus in anovulatory ewes. Seasonally anestrous ewes (n = 232) were randomly assigned to one of seven treatments: 1) control (C); 2) MGA only (OMGA; .3 mg of MGA/d); 3) MGA+zeranol (RMGA; 2.5 mg of zeranol); 4) MGA+PG-600 (PMGA; 400 IU of PMSG + 200 IU of hCG in a 5-mL dose); 5) SMB only (OSMB); 6) SMB + zeranol (RSMB); and 7) SMB + PG-600 (PSMB). Treatments were initiated 10 d before breeding. Immediately preceding progestogen treatment, RMGA and RSMB ewes were given a single i.m. injection of zeranol. Concomitant to progestogen removal, PMGA and PSMB ewes were given a single i.m. injection of PG-600. On May 4, 1992, all treatment groups were combined into one breeding group for a 30-d breeding period. Mating at synchronized estrus was greater (P < .001) for progestogen-treated ewes. Within progestogen treatments, more (P < .001) SMB ewes than MGA ewes were marked within the first 5 d of breeding. Overall, there were no treatment differences in estrus response for the 30-d breeding period. Progestogen-treated ewes had a shorter (P < .001) mean interval from ram introduction to lambing. Fertility and prolificacy were not different for C, MGA, or SMB ewes. Ewes primed with zeranol before MGA or SMB treatment had fertility and intervals from ram introduction to lambing similar to those of ewes receiving an injection of PG-600 after progestogen treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
对两种市售的牛用孕激素产品——醋酸美仑孕酮（MGA）和诺孕美特（SMB）诱导无排卵母羊同期发情的能力进行了评估。季节性乏情母羊（n = 232）被随机分配到七种处理之一：1）对照组（C）；2）仅用MGA（OMGA；0.3 mg MGA/天）；3）MGA+玉米赤霉醇（RMGA；2.5 mg玉米赤霉醇）；4）MGA+PG - 600（PMGA；5 mL剂量中含400 IU孕马血清促性腺激素+200 IU人绒毛膜促性腺激素）；5）仅用SMB（OSMB）；6）SMB+玉米赤霉醇（RSMB）；7）SMB+PG - 600（PSMB）。处理在配种前10天开始。在孕激素处理前，RMGA和RSMB组母羊经肌肉注射一次玉米赤霉醇。在去除孕激素的同时，PMGA和PSMB组母羊经肌肉注射一次PG - 600。1992年5月4日，所有处理组合并为一个配种组，进行为期30天的配种期。孕激素处理的母羊在同期发情时的交配率更高（P < 0.001）。在孕激素处理组中，在配种的前5天内，被标记的SMB组母羊比MGA组母羊更多（P < 0.001）。总体而言在30天的配种期内发情反应上各处理间无差异。孕激素处理的母羊从引入公羊到产羔的平均间隔更短（P < 0.001）。对照组、MGA组或SMB组母羊的繁殖力和产仔数无差异。在MGA或SMB处理前用玉米赤霉醇预处理的母羊，其繁殖力以及从引入公羊到产羔的间隔与在孕激素处理后注射PG - 600的母羊相似。（摘要截短至250字）
