Floyd J G, Ott R S, Hixon J E, Veeramachaneni D N, Willms C L, Parrett D F
Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana 61801.
Am J Vet Res. 1994 Apr;55(4):556-60.
At initiation of a 140-day postweaning weight gain test, Angus bulls were assigned in equal numbers (n = 5) to 1 of 3 treatment groups to determine effects of implantation with zeranol, an estrogenic growth promotant, on selected reproductive characteristics. The bulls, whose age (mean +/- SD) was 233 +/- 20 days at initiation of the test (day 0), were implanted with 36 mg of zeranol on day 0, on days 0 and 60, or were not implanted. At day 140, scrotal circumference and testicular consistency were unaffected by zeranol implantation. Zeranol implantation did not affect the morphologic characteristics of semen samples collected by electroejaculation on day 139. There was no effect of zeranol treatment on paired weights of testes, epididymides, or vesicular glands from bulls at slaughter 47 to 68 days after day 140. Microscopic lesions associated with estrogenic exposure were not observed in accessory sex glands or epididymides of any bull. Histopathologic changes in the seminiferous epithelium were not induced by zeranol treatment. Implantation with zeranol did not affect body weight or hip weight at day 140 or carcass weight at slaughter. Plasma concentration of luteinizing hormone was increased (P = 0.04), whereas testosterone concentration tended to be less (P = 0.08) in both groups of zeranol-implanted bulls after administration of gonadotropin-releasing hormone on day 140.
在一项为期140天的断奶后体重增加试验开始时，将安格斯公牛平均分成3组（每组n = 5），以确定植入雌激素生长促进剂玉米赤霉醇对选定生殖特征的影响。试验开始时（第0天）公牛的年龄（平均值±标准差）为233±20天，在第0天、第0天和第60天分别给公牛植入36毫克玉米赤霉醇，或不进行植入。在第140天，玉米赤霉醇植入对阴囊周长和睾丸质地没有影响。玉米赤霉醇植入不影响第139天通过电刺激采集的精液样本的形态特征。在第140天后47至68天屠宰时，玉米赤霉醇处理对公牛的睾丸、附睾或精囊的配对重量没有影响。在任何公牛的副性腺或附睾中均未观察到与雌激素暴露相关的微观病变。玉米赤霉醇处理未诱导生精上皮的组织病理学变化。植入玉米赤霉醇不影响第140天的体重或髋部重量，也不影响屠宰时的胴体重量。在第140天给予促性腺激素释放激素后，两组植入玉米赤霉醇的公牛的促黄体生成素血浆浓度均升高（P = 0.04），而睾酮浓度则趋于降低（P = 0.08）。
