Nødtvedt Ane, Dohoo Ian, Sanchez Javier, Conboy Gary, DesCĵteaux Luc, Keefe Greg, Leslie Ken, Campbell John
Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown.
Can J Vet Res. 2002 Oct;66(4):249-57.
The epidemiology of bovine gastrointestinal nematodes was investigated through a 1-year (October 1999 to September 2000) longitudinal study in 38 Canadian dairy herds from 4 different provinces (Prince Edward Island, Quebec, Ontario, Saskatchewan). For each herd, fecal egg counts from 8 randomly selected animals were performed on a monthly or quarterly basis. Larval cultures were performed once, to determine the species breakdown of the parasites. All producers were interviewed regarding herd management practices. The observed fecal egg counts were low in this study, with a range from 0 to 419 nematode eggs per 5 g of feces. The mean count was 9.8 and the median was 1. Standard transformations failed to normalize the data, which followed an over-dispersed Poisson distribution. A zero inflated negative binomial model was applied to assess factors that would influence the fecal egg counts. Identified associations were: egg counts were lowest in the winter and highest in the late spring; first-lactation cattle had higher counts than older cows; if manure was spread mechanically on pastures used by lactating cattle the egg counts were higher; and if manure was spread on heifer-pastures, the adult cows had lower counts. In herds where pasture use was more extensive, the cattle had higher fecal egg counts. The difference in pasture exposure was found to be a main contributor to an observed difference in fecal egg counts among herds in the 4 provinces.
通过对来自加拿大4个不同省份（爱德华王子岛、魁北克、安大略、萨斯喀彻温省）的38个奶牛场进行为期1年（1999年10月至2000年9月）的纵向研究，调查了牛胃肠道线虫的流行病学情况。对于每个牛群，每月或每季度对8头随机选取的动物进行粪便虫卵计数。进行了一次幼虫培养，以确定寄生虫的种类分布。就牛群管理措施对所有养殖者进行了访谈。在本研究中观察到的粪便虫卵计数较低，每5克粪便中线虫卵的数量范围为0至419个。平均计数为9.8，中位数为1。标准变换未能使数据标准化，数据遵循过度分散的泊松分布。应用零膨胀负二项式模型来评估影响粪便虫卵计数的因素。确定的关联如下：虫卵计数在冬季最低，在春末最高；头胎奶牛的计数高于年龄较大的奶牛；如果粪便通过机械方式施用于泌乳牛使用的牧场，虫卵计数会更高；如果粪便施用于小母牛牧场，成年母牛的计数会更低。在牧场使用更为广泛的牛群中，牛的粪便虫卵计数更高。发现牧场暴露差异是4个省份牛群粪便虫卵计数观察到的差异的主要促成因素。
