Waldner Cheryl, Wildman Brian K, Hill Bruce W, Fenton R Kent, Pittman Tom J, Schunicht Oliver C, Jim G Kee, Guichon P Timothy, Booker Calvin W
Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7K 5B4.
Can Vet J. 2004 Mar;45(3):218-24.
A study was conducted in Alberta to determine the seroprevalence of Neospora caninum in feedlot calves purchased from various auction markets throughout western Canada. Four feedlots (1 feedlot from each of the Airdrie and High River areas and 2 feedlots from the Strathmore area) were selected for sampling. At each feedlot, a random 10% sample of feedlot steer and bull calves entering the feedlot from September 2001 to December 2001 were enrolled in the study until there were a maximum of 500 animals enrolled per feedlot. Blood samples were collected from 1976 male animals at the time of entry to the 4 study feedlots. The animals represented 375 groups purchased from 70 sale points throughout British Columbia, Alberta, Saskatchewan, and Manitoba. Of the 1976 animals tested, 128 animals tested positive for antibodies to N. caninum. The prevalence and adjusted 95% confidence limits for N. caninum in beef calves on entrance to the feedlot in western Canada were 6.5% (95% CI, 5.1 to 8.2). There were no significant (P > or = 0.05) associations between the risk of treatment, the risk of designation as "chronic," and the risk of death and antibodies to N. caninum either before or after adjusting for feedlot, entry weight, entry date, and clustering of disease within lots at each feedlot. In addition, there was no significant (P > or = 0.05) association between serological status and feedlot entry weight or average daily gain. Note that there was no information available on feed conversion because the calves were mixed within existing commercial feedlot pens and the actual feed intake of each animal could not be determined. Adjustment for the concentration of antibodies to bovine viral diarrhea virus on arrival did not change any of the examined associations between N. caninum status and calf health or performance. The results of this study demonstrated that the prevalence of N. caninum in feedlot calves in western Canada was less than the prevalence reported in the United States. Additional studies are required to determine whether the inferior rate of gain and feed efficiency observed in the southern United States with animals testing positive for antibodies to N. caninum also occurs under the management conditions used in western Canada.
在艾伯塔省开展了一项研究，以确定从加拿大西部各个拍卖市场购买的饲养场小牛的犬新孢子虫血清阳性率。选择了四个饲养场（艾尔德里和高河市各一个饲养场，斯特拉斯莫尔地区两个饲养场）进行采样。在每个饲养场，从2001年9月至2001年12月进入饲养场的饲养场阉牛和公牛犊中随机抽取10%的样本纳入研究，每个饲养场最多纳入500只动物。在4个研究饲养场的动物入场时，从1976只雄性动物采集了血样。这些动物代表了从不列颠哥伦比亚省、艾伯塔省、萨斯喀彻温省和马尼托巴省的70个销售点购买的375组动物。在检测的1976只动物中，128只动物犬新孢子虫抗体检测呈阳性。加拿大西部饲养场肉牛犊入场时犬新孢子虫的流行率及调整后的95%置信区间为6.5%（95%CI，5.1至8.2）。在调整饲养场、入场体重、入场日期以及每个饲养场栏舍内疾病聚集情况之前或之后，治疗风险、被指定为“慢性”的风险以及死亡风险与犬新孢子虫抗体之间均无显著（P≥0.05）关联。此外，血清学状态与饲养场入场体重或平均日增重之间也无显著（P≥0.05）关联。请注意，由于小牛被混养在现有的商业饲养场围栏内，无法确定每只动物的实际采食量，因此没有关于饲料转化率的信息。对到达时牛病毒性腹泻病毒抗体浓度进行调整后，犬新孢子虫状态与小牛健康或性能之间的任何已检测关联均未改变。本研究结果表明，加拿大西部饲养场小牛的犬新孢子虫流行率低于美国报告的流行率。需要进一步研究以确定在美国南部观察到的犬新孢子虫抗体检测呈阳性的动物生长速度和饲料效率较低的情况在加拿大西部的管理条件下是否也会出现。
