Coyne M J, Smith G, Johnstone C
Section of Animal Health Economics, School of Veterinary Medicine, University of Pennsylvania, New Bolton Center, Kennett Square 19348.
Am J Vet Res. 1991 Jul;52(7):1182-8.
Twenty-two Dorset Rambouillet lambs were moved to contaminated pasture on Apr 1, 1987. At regular intervals thereafter, pairs of lambs were withdrawn and euthanatized. Gastrointestinal parasites in the abomasum, small intestine, cecum, and large intestine were removed and counted. The last pair of lambs was euthanatized 8 months after original placement on the contaminated pasture. Fecal samples were taken at 3- to 4-week intervals throughout the grazing season and the fecal egg counts were used to estimate parasite fecundity (output of eggs per female parasite per day). The principal parasite genera found included Haemonchus spp, Trichostrongylus spp, and Nematodirus spp. In each of the genera examined, parasite fecundity remained the same irrespective of the intensity or duration of infection. Estimated average fecundities (eggs/female/day) were as follows: Haemonchus contortus, 6,582; Trichostrongylus spp, 262; Nematodirus spp, 40; and Oesophagostomum venulosum, 11,098.
1987年4月1日，22只多塞特·兰布耶羊羔被转移到受污染的牧场。此后定期将成对的羊羔撤离并实施安乐死。取出并计数真胃、小肠、盲肠和大肠中的胃肠寄生虫。最后一对羊羔在最初安置到受污染牧场8个月后被实施安乐死。在整个放牧季节，每隔3至4周采集粪便样本，并使用粪便虫卵计数来估计寄生虫繁殖力（每只雌虫每天的产卵量）。发现的主要寄生虫属包括血矛线虫属、毛圆线虫属和细颈线虫属。在所检查的每个属中，无论感染强度或持续时间如何，寄生虫繁殖力均保持不变。估计的平均繁殖力（卵/雌虫/天）如下：捻转血矛线虫，6582；毛圆线虫属，262；细颈线虫属，40；和微小奥斯特线虫，11098。
