The aim of this study was to test the hypothesis that toltrazuril administered at 4 weeks post-turnout reduces the infection intensity of Theileria orientalis Ikeda type in dairy calves and so prevents serious clinical disease in these animals at 2-3 months of age. Two groups of 40 dairy calves on two separate dairy farms in the Waikato were followed for 16 weeks post-turnout onto pasture. On each farm, 20 calves were randomly selected and orally treated with toltrazuril (15 mg/kg) at 4 weeks post-turnout, whilst the remaining 20 calves were left untreated. All 40 calves were blood sampled and weighed at 2, 4, 6, 8, 12, and 16 weeks post-turnout i.e. 6 samplings per calf. A random subset of 10 calves from each treatment group on each farm were faecal sampled at each visit. The blood samples were used to estimate the T. orientalis Ikeda type infection intensity and haematocrit for each calf and the faecal samples were used to estimate the number of coccidia oocysts per gram of faeces. Three linear mixed effects models, to evaluate the effect of toltrazuril treatment on infection intensity, haematocrit (HCT) and weight respectively were fitted to the data. No calves on either farm developed clinical theileriosis or coccidiosis and the three mixed effects linear models, controlling for the effect of farm and days from turnout, showed that there was no effect of treatment on infection intensity (p = 0.81), on HCT (p = 0.99) and on weight gain (p = 0.79). In conclusion, this study showed no evidence supporting the use of toltrazuril to control T. orientalis Ikeda type infection levels and prevent disease.

中文翻译：

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托曲唑治疗降低乳牛犊东方泰勒虫池田型感染强度的功效。

这项研究的目的是检验以下假设，即在服药后4周使用托他脲可降低乳牛犊中东方泰来菌池田型的感染强度，从而防止这些动物在2-3个月大时出现严重的临床疾病。在怀卡托的两个单独的奶牛场中，对两组40只奶牛犊进行了跟踪，结果发现它们在转入牧场后持续了16周。在每个农场中，随机选择20头犊牛，并在停产后4周用托曲唑（15 mg / kg）口服处理，而其余20头犊牛则未经处理。对所有40头小牛进行血液采样，并在投票后的2、4、6、8、12和16周称重，即每只小牛6次采样。在每次访视时从每个农场的每个治疗组随机抽取10头小牛的子集。血样用于估计T。每只小牛和粪便样本的东方东方池田型感染强度和血细胞比容用于估计每克粪便中球菌的卵囊数量。将三个线性混合效应模型拟合到数据中，以评估托曲唑的治疗对感染强度，血细胞比容（HCT）和体重的影响。农场中的小牛均未出现临床虫体病或球虫病，并且三种混合效应线性模型控制了农场的影响和投票的天数，表明治疗对感染强度（p = 0.81），HCT没有影响（p = 0.99）和体重增加（p = 0.79）。总之，这项研究表明没有证据支持使用托他珠利来控制东方锥虫池田型感染水平并预防疾病。