Borgsteede F H, van der Linden J N, Cornelissen J B, Gaasenbeek C P, Ascher F
Institute for Animal Science and Health, Lelystad, The Netherlands.
Vet Rec. 1998 Jun 20;142(25):696-9. doi: 10.1136/vr.142.25.696.
The effect of three intraruminal sustained-release devices (SRD) against Dictyocaulus viviparus infection was tested in five groups of six calves. Group 1 served as untreated controls, and groups 2, 3 and 4 were dosed with a levamisole SRD, a fenbendazole SRD, and an ivermectin SRD, respectively. Group 5 was vaccinated against lungworm and received a levamisole SRD. The calves were turned out on May 28 and the devices given seven days later. All the calves received trickle infections with a total of 200 lungworm larvae between 9 and 34 days after turnout. They were housed on October 28, challenged with 5000 lungworm larvae and slaughtered three weeks later. No clinical signs of parasitic bronchitis were observed during the study. The treated groups gained significantly more weight (P < 0.05) than the controls, but did not differ among themselves. Larvae were first detected in the faeces of the control group between 25 and 32 days after the first infection, and had a group mean of 21 larvae per gram (lpg) after 60 to 80 days, after which the lpg gradually decreased. In group 2, larvae were detected near the end of the grazing season and never exceeded a group mean of 1.5 lpg. In group 3, a very low larval output was observed after housing (group mean 0.1 lpg). Groups 4 and 5 never became patent. The results of an ELISA followed the pattern of larval output; optical densities above the cut-off value were recorded in groups 1, 2 and 3. On the basis of worm recoveries after challenge, group 1 was immune. Group 4 had significantly more lungworms than group 2. There were no significant differences in worm numbers between groups 2, 3 and 5, but the worms in group 5 were retarded in growth (P < 0.05).
在五组每组六头犊牛中测试了三种瘤胃内缓释装置（SRD）对胎生网尾线虫感染的效果。第1组作为未处理的对照组，第2、3和4组分别用左旋咪唑SRD、芬苯达唑SRD和伊维菌素SRD给药。第5组接种了抗肺线虫疫苗并接受了左旋咪唑SRD。犊牛于5月28日放牧，7天后放置装置。所有犊牛在放牧后9至34天内接受了总共200条肺线虫幼虫的连续感染。它们于10月28日圈养，用5000条肺线虫幼虫进行攻毒，三周后屠宰。在研究期间未观察到寄生性支气管炎的临床症状。处理组的体重显著高于对照组（P<0.05），但处理组之间没有差异。在第一次感染后25至32天在对照组粪便中首次检测到幼虫，60至80天后每组平均每克粪便中有21条幼虫（lpg），此后lpg逐渐下降。在第2组中，在放牧季节结束时检测到幼虫，且从未超过每组平均1.5 lpg。在第3组中，圈养后观察到幼虫排出量非常低（每组平均0.1 lpg）。第4组和第5组从未出现虫体排出现象。ELISA结果与幼虫排出模式一致；第1、2和3组记录到高于临界值的光密度。根据攻毒后的虫体回收情况，第1组具有免疫力。第4组的肺线虫数量显著多于第2组。第2、3和5组之间的虫体数量没有显著差异，但第5组的虫体生长受到抑制（P<0.05）。
