Sawyer G J
Aust Vet J. 1987 Feb;64(2):46-8. doi: 10.1111/j.1751-0813.1987.tb16127.x.
Male and female Hereford and Hereford cross beef calves between 2.5 and 4.5 months of age were implanted with 36 mg zeranol, 24 mg oestradiol 17 beta or left untreated, and then weighed every 4 to 5 weeks. Calves treated with zeranol or oestradiol 17 beta gained 9.6 kg (8.2%) and 12.9 kg (11.0%) more weight respectively than untreated calves. Steer calves gained more weight than heifer calves. There was no response to either growth promotant in heifers or in zeranol-treated steers beyond 35 days after implantation, and the only significant further gains in the next 31 days were made by steers treated with oestradiol 17 beta. After this time growth of treated and control calves was similar. The lack of a continued response to the growth promotants was not associated with significantly lower growth rates in any weighing interval.
选取年龄在2.5至4.5个月之间的雄性和雌性赫里福德牛以及赫里福德杂交肉牛犊，分别给它们植入36毫克的玉米赤霉醇、24毫克的17β - 雌二醇，或者不做处理，然后每4至5周称重一次。接受玉米赤霉醇或17β - 雌二醇处理的牛犊，体重分别比未处理的牛犊多增加了9.6千克（8.2%）和12.9千克（11.0%）。公牛犊比母牛犊增重更多。在植入激素35天后，母牛犊以及接受玉米赤霉醇处理的公牛犊对这两种生长促进剂均无反应，在接下来的31天里，唯一显著的进一步增重是由接受17β - 雌二醇处理的公牛犊实现的。在此之后，处理组和对照组牛犊的生长情况相似。对生长促进剂缺乏持续反应，与任何称重间隔期内显著较低的生长速率无关。
