Ciordia H, McCampbell H C, Calvert G V, Plue R E
Am J Vet Res. 1984 Nov;45(11):2455-7.
A total of 469 cows and calves from 2 herds, each on 6 pastures, was used to evaluate the anthelmintic efficacy and animal-performance benefits of ivermectin given subcutaneously at a dosage of 200 micrograms/kg to nursing beef calves and their dams during a grazing season. Pastures were paired across the 2 herds. Three pasture groups from 1 herd were randomly assigned to either a nonmedicated control or to a medicated group. Treatment assignments were reversed in the other herd. The control groups comprised 110 cows and 108 calves, whereas 127 cows and 124 calves were treated with ivermectin (200 micrograms/kg). The cows were treated once, in late spring, and the calves were treated twice, once in late spring and again in midsummer. Cattle from one herd were weighed on days - 12, 21, 49, 77 (day of 2nd treatment for calves), and 105, and the other herd was weighed on days - 6, 23, 57, 86 (day of 2nd treatment for calves), and 113. Rectal fecal samples for nematode egg counts were obtained from approximately 25% of the cattle in each pasture on weighing days; usually, the same cattle were sampled each time. Calves treated with ivermectin gained (P less than 0.05) more weight than control calves up to the 2nd treatment date and up to the termination of the study. There was no significant difference between treated and control cows, with regard to weight gain over either interval. Treated calves had fewer positive fecal egg counts (P less than 0.01) and passed fewer eggs (P less than 0.05) after both treatments than did control calves. There were no differences in either number of eggs or number of negative cows between treatment groups. Adverse reactions attributable to treatment were not seen.
在一个放牧季节，从两个牛群中选取了总共469头母牛和小牛，每个牛群分布在6个牧场，用于评估皮下注射剂量为200微克/千克的伊维菌素对哺乳肉牛犊及其母牛的驱虫效果和对动物生长性能的益处。两个牛群的牧场两两配对。将其中一个牛群的三个牧场组随机分配到非用药对照组或用药组。另一个牛群的处理分配则相反。对照组包括110头母牛和108头小牛，而127头母牛和124头小牛接受了伊维菌素（200微克/千克）治疗。母牛在春末接受一次治疗，小牛接受两次治疗，一次在春末，一次在仲夏。一个牛群的牛在第 - 12、21、49、77天（小牛第二次治疗日）和105天称重，另一个牛群的牛在第 - 6、23、57、86天（小牛第二次治疗日）和113天称重。在称重日，从每个牧场约25%的牛中采集直肠粪便样本进行线虫虫卵计数；通常每次采样的是同一批牛。在第二次治疗日期之前以及直至研究结束，接受伊维菌素治疗的小牛比对照小牛增重更多（P小于0.05）。在任何一个时间段内，治疗组和对照组母牛的体重增加没有显著差异。两次治疗后，治疗组小牛的粪便阳性虫卵计数较少（P小于0.01），排出的虫卵也较少（P小于0.05）。各治疗组之间在虫卵数量或阴性母牛数量上均无差异。未观察到与治疗相关的不良反应。
