Williams J C, Knox J W, Marbury K S, Kimball M D, Scheide S W, Snider T G
Department of Veterinary Science, LSU Agricultural Center, Baton Rouge 70803.
Res Vet Sci. 1988 Jul;45(1):31-40.
Three groups of 17 beef calves were used to evaluate effects of strategic anthelmintic treatment on safe (group 1) and contaminated (group 2) pasture in comparison with minimal treatment at weaning and contaminated pasture (group 3). The investigation extended from weaning in November 1982 to the following August. Results of faecal egg counts, herbage larval counts, plasma pepsinogen and tracer calf worm counts in autumn and spring indicated minimal levels of infection on safe pastures provided in November and April (group 1). A decided weight gain advantage for group 1 was achieved from November to April, but the rate of gain was not consistent after April and transfer to the second safe pasture. Final average weights in late August were: group 1, 368 kg; group 2, 336 kg; group 3, 262 kg. All were significantly different (P less than 0.05). Worm counts from representative yearlings in September revealed low to moderate levels of Ostertagia ostertagi in group 1. In contrast group 2 cattle had large, almost exclusively O ostertagi infections; group 3 cattle had exceedingly high levels of Trichostrongylus axei infection and moderate to high levels of O ostertagi. Marginal evidence of type 2 ostertagiasis was observed in individual animals of group 2 and group 3.
使用三组每组17头肉用犊牛，来评估与断奶时进行最少驱虫处理并在污染牧场饲养（第3组）相比，针对性驱虫处理对安全牧场（第1组）和污染牧场（第2组）的影响。调查从1982年11月断奶开始，持续到次年8月。秋季和春季粪便虫卵计数、牧草幼虫计数、血浆胃蛋白酶原以及追踪犊牛的蠕虫计数结果表明，11月和4月提供的安全牧场感染水平最低（第1组）。从11月到4月，第1组犊牛体重增加明显占优，但4月之后转移到第二个安全牧场后，增重速度并不一致。8月末的最终平均体重为：第1组368千克；第2组336千克；第3组262千克。各组之间均存在显著差异（P小于0.05）。9月对具有代表性的一岁犊牛进行的蠕虫计数显示，第1组奥氏奥斯特线虫感染水平低至中等。相比之下，第2组牛感染的奥氏奥斯特线虫数量多，几乎全是这种感染；第3组牛的阿克塞尔毛圆线虫感染水平极高，奥氏奥斯特线虫感染水平中等至高等。在第2组和第3组的个别动物中观察到了2型奥斯特线虫病的边缘证据。
