PREVALENCE OF PATHOGENIC SPECIES OF EIMERIA AT DUTCH DAIRY FARMS WITH CORRESPONDING RISK FACTORS
Balen, E.A. van
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With this research the prevalence of Eimeria oocysts excretions of calves at Dutch dairy farms was examined, by performing two McMasters on rectally obtained feces samples. This way the OPG count as well as the oocysts determination was determined. All farms which participated in this research were client at the University Veterinary practice for farm animals. Samples were collected in October-December 2012. In total 488 individual samples were collected of 66 farms. On every farm, calves were divided by pen and age into pens of age group I and II, which resulted in 143 pens in total. Age group I contained 42 completely analyzed pens with 144 individual samples, and age group II contained 49 completely analyzed pens with 166 individual samples. Of the 406 individual analyzed samples, 69.5% were positive on Eimeria pathogenic or apathogenic oocysts. The prevalence found of farms positive on at least pathogenic Eimeria oocysts was 87.9%, prevalence in age group I was 48.5% and in age group II 65.2%. Of the pathogenic Eimeria species, E.alabamensis was most common. Farm prevalence of E.alabamensis oocysts was 69.7%, prevalence in age group I was 34.9% and in age group II 45.5%. E.bovis was second most common found pathogenic Eimeria species, with a farm prevalence of 53%. Prevalence in age group I was 25.8% and in age group II 34.9%. Least found pathogenic Eimeria species was E.zuernii with a farm prevalence of 25.8%, prevalence in age group I was 10.6% and in age group II 18.2%. Prevalence’s of all pathogenic Eimeria species were higher in older calves (age group II), compared to younger calves (age group I). Although the OPG’s of all individual samples of calves in age group I didn’t differ significantly from calves in age group II, the OPG of individual samples of pens of age group I positive on oocysts of pathogenic Eimeria species were significantly higher compared to samples of age group II positive on oocysts of pathogenic Eimeria species. Also the OPG of individual samples of pens of age group I positive on oocysts of pathogenic Eimeria species were higher compared to pens of age group I positive on oocysts of apathogenic Eimeria oocysts. The same results were found for the mean OPG pen per and the highest OPG per pen. No association was found between the OPG count and the occurring problems per pen, nor between the oocysts determination and the occurring problems per pen. Because the OPG count of calves after weaning infected with pathogenic Eimeria oocysts is not higher compared to apathogenic oocysts, and no association is made between pathogenic Eimeria species and occurring problems nor for the OPG count and occurring problems, it is concluded that oocyst determination is necessary to find out if calves are infected with pathogenic or apathogenic Eimeria species. It is best to perform oocysts determination on pooled samples, because there was found a large range in OPG count between individual samples within pens. It was tried to identify risk factors for Eimeria infections, but no clear risk factors were found.