Fontenot M E, Miller J E, Peña M T, Larsen M, Gillespie A
Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA.
Vet Parasitol. 2003 Dec 30;118(3-4):203-13. doi: 10.1016/j.vetpar.2003.10.017.
Gastrointestinal nematodes are of concern in sheep production because of production and economic losses. Control of these nematodes is primarily based on the use of anthelmintic treatment and pasture management. The almost exclusive use of anthelmintic treatment has resulted in development of anthelmintic resistance which has led to the need for other parasite control options to be explored. The blood sucking abomasal parasitic nematode Haemonchus contortus causes severe losses in small ruminant production in the warm, humid sub-tropic and tropics. This study evaluated the effectiveness of a nematode trapping fungus, Duddingtonia flagrans, in reducing availability of parasitic nematode larvae, specifically H. contortus, on pasture. Chlamydospores of D. flagrans were mixed with a supplement feed which was fed daily to a group of crossbred ewes for the duration of the summer grazing season. A control group was fed the same supplement feed without chlamydospores. A reduction in infective larval numbers was observed in fecal cultures of the fungus-fed group. Herbage samples from the pasture grazed by the fungus-fed group also showed a reduction in infective larvae. There were no significant (P > 0.05) differences in overall fecal egg count, packed cell volume or animal weight between fungus-fed and control groups. Tracer animals were placed on the study pastures at the end of the study to assess pasture infectivity. Although tracer animals were only two per group, those that grazed with the fungus-fed group had substantially reduced (96.8%) nematode burdens as compared to those from the control group pasture. Results demonstrated that the fungus did have activity against nematode larvae in the feces which reduced pasture infectivity and subsequently nematode burdens in tracer animals. This study showed that D. flagrans, fed daily to grazing ewes, was an effective biological control agent in reducing a predominantly H. contortus larval population on pasture.
由于生产和经济损失，胃肠道线虫在绵羊生产中备受关注。这些线虫的控制主要基于驱虫治疗和牧场管理。几乎完全依赖驱虫治疗已导致驱虫抗性的产生，这使得有必要探索其他寄生虫控制方法。吸血性皱胃寄生线虫捻转血矛线虫在温暖、潮湿的亚热带和热带地区给小反刍动物生产造成严重损失。本研究评估了捕食线虫真菌——达丁顿菌在减少牧场上寄生线虫幼虫，特别是捻转血矛线虫幼虫数量方面的有效性。将达丁顿菌的厚垣孢子与补充饲料混合，在夏季放牧季节期间每天喂给一组杂交母羊。对照组饲喂不含厚垣孢子的相同补充饲料。在喂食真菌组的粪便培养物中观察到感染性幼虫数量减少。来自喂食真菌组所放牧牧场的牧草样本也显示感染性幼虫数量减少。在喂食真菌组和对照组之间，总粪蛋计数、红细胞压积或动物体重方面没有显著（P>0.05）差异。在研究结束时，将示踪动物放置在研究牧场上以评估牧场的感染性。尽管每组仅两只示踪动物，但与对照组牧场的示踪动物相比，与喂食真菌组一起放牧的示踪动物的线虫负荷大幅降低（96.8%）。结果表明，该真菌确实对线虫幼虫在粪便中的活动有抑制作用，从而降低了牧场的感染性，并随后减少了示踪动物的线虫负荷。这项研究表明，每天喂给放牧母羊的达丁顿菌是一种有效的生物控制剂，可减少牧场上主要为捻转血矛线虫的幼虫数量。
