Bell S L, Perry K W, Rowlinson P
Faculty of Agriculture and Biological Sciences, Department of Agriculture, University of Newcastle upon Tyne, Newcastle upon Tyne, UK.
Vet Parasitol. 1996 Apr;62(3-4):275-90. doi: 10.1016/0304-4017(95)00872-1.
The efficacy of albendazole in an intraruminal controlled-release device against gastrointestinal nematodes in calves was evaluated under field conditions. Calf productivity was monitored during the first and second grazing seasons. Two groups of parasite-naive Holstein Friesian heifer calves were grazed from May to October on adjacent, similarly contaminated paddocks. One group was given a Captec bolus at turnout, the group was left untreated. Pasture larval counts peaked on the paddock grazed by the untreated calves at 23,000 1 kg-1 dry matter in October. This precipitated clinical parasitic gastro-enteritis in the untreated calves with a mean peak faecal egg count of 335 epg, high blood pepsinogen and gastrin concentrations and a mean worm burden of 79,614 at 100 days post-turnout. Pasture larval counts on the paddock grazed by the treated calves remained less than 3000 1 kg-1 DM and the mean faecal egg count was zero until mid-August, peaking at 146 eggs per gram of faeces (epg) in October. The treated calves had body liveweight advantage of 19 kg at the end of September. During the second grazing season the first season untreated calves were refractory to infection. The first season treated calves showed signs of parasitic gastro-enteritis, although not to the extent exhibited by a group of first season parasite-naive tracer calves which were grazed on the same paddock.
在野外条件下评估了瘤胃控释装置中阿苯达唑对犊牛胃肠道线虫的疗效。在第一个和第二个放牧季节监测犊牛的生产性能。两组未感染寄生虫的荷斯坦弗里生小母牛犊牛于5月至10月在相邻且污染程度相似的围场上放牧。一组在放牧开始时给予Captec丸剂，另一组不进行处理。10月，未处理犊牛放牧的围场上的牧草幼虫数量达到峰值，为每千克干物质23000条。这导致未处理犊牛发生临床寄生虫性胃肠炎，平均粪便虫卵计数峰值为每克335个，血胃蛋白酶原和胃泌素浓度较高，放牧开始100天时平均虫负荷为79614条。处理犊牛放牧的围场上的牧草幼虫数量保持在每千克干物质少于3000条，直到8月中旬平均粪便虫卵计数为零，10月达到每克粪便146个虫卵（epg）的峰值。9月底，处理过的犊牛体重优势为19千克。在第二个放牧季节，第一季未处理的犊牛对感染具有抵抗力。第一季处理过的犊牛出现了寄生虫性胃肠炎的症状，尽管程度不如在同一围场上放牧的一组第一季未感染寄生虫的示踪犊牛。
