An observational study of Eimeria species in housed cattle on Dutch dairy farms.

The prevalence of oocysts of Eimeria species in calves (n = 334), yearlings (n = 254) and cows (n = 1314) was determined on 38 Dutch dairy farms. Twelve species of Eimeria were identified in faecal specimens by sucrose-flotation. The prevalences of Eimeria spp. differed markedly in the different age classes on individual farms as well as between farms. The overall prevalence of Eimeria oocysts in faecal specimens was 46% for calves, 43% for yearlings and 16% for cows. The number of oocysts excreted was generally low in cows and yearlings, whereas high numbers of oocysts per gram of faeces (OPG) were exclusively observed in calves. No cases of clinical coccidiosis were observed in this survey. Linear regression analysis showed that there is significant reduction in the OPG levels (P < 0.05) in calves infected with Eimeria, aged between 7 and 38 weeks. Finally, the data are discussed in relation to management practices and the acquisition of immunity.