Hawkins J A, Evans R R, Newby T J, Delivorias M H, Tyler T D
Vet Parasitol. 1985 Mar;17(3):229-38. doi: 10.1016/0304-4017(85)90035-4.
The efficacy of a morantel sustained release bolus (MSRB) for control of gastrointestinal nematodes in yearling steers was evaluated over a 6-month grazing period commencing on 26 March 1982. Three groups of 15 steers were allotted to the following treatments: Group 1 -- one MSRB at start of trial; Group 2 -- one therapeutic dose of thiabendazole at start of trial; Group 3 -- untreated control. The treatment groups were grazed separately. Parasite egg counts (EPG), herbage larval counts, pepsinogen levels and weight gains were monitored. Every other month, sets of 2 parasite-free tracer calves were placed in the pasture grazed by each treatment group and allowed to graze for 3 weeks before being subsequently necropsied for worm counts. At the end of the trial, 6 animals from each group were also necropsied for worm counts. The MSRB treatment resulted in significantly lower egg counts, fewer infective larvae on pasture, lower pepsinogen levels and lower worm burdens in tracer calves than was the case for the untreated group, but generally the levels were not significantly different from those associated with the thiabendazole treatment. The mean weight gain for the MSRB treated steers showed a significant advantage (70.9 lb) over the untreated animals, but was not significantly different from those which received thiabendazole. Total worm counts at the end of the trial were not different from any treatment group.
1982年3月26日开始，在为期6个月的放牧期内，评估了莫仑太尔缓释丸剂（MSRB）对一岁公牛胃肠道线虫的防治效果。将三组各15头公牛分配至以下处理组：第1组——试验开始时投喂一粒MSRB；第2组——试验开始时投喂一剂治疗剂量的噻苯达唑；第3组——未处理的对照组。各处理组分开放牧。监测寄生虫卵计数（每克粪便虫卵数，EPG）、牧草幼虫计数、胃蛋白酶原水平和体重增加情况。每隔一个月，将两组无寄生虫的示踪小牛放入各处理组放牧的牧场中，让它们放牧3周，随后进行剖检以计数蠕虫。试验结束时，每组也剖检6只动物以计数蠕虫。与未处理组相比，MSRB处理组的虫卵计数显著降低、牧场上的感染性幼虫数量减少、胃蛋白酶原水平降低，示踪小牛体内的蠕虫负荷也降低，但总体而言，这些水平与噻苯达唑处理组无显著差异。MSRB处理的公牛平均体重增加比未处理的动物有显著优势（70.9磅），但与接受噻苯达唑治疗的公牛无显著差异。试验结束时各处理组的蠕虫总数无差异。
