Effects of pastures' re-wetting on endoparasites in cattle in northern Germany

The influence of re-wetting of pastures on the occurrence of important endoparasites in cattle was monitored over the course of three years. The study was conducted on a peninsula at the German North-Sea Coast. The cattle were stabled from November to April. During summer season, they were kept on pastures included in a nature protection program differentiating between three states of re-wetting. Faecal samples from randomly selected animals were analysed with routine diagnostic methods for the occurrence of Eimeria spp., nematode and trematode eggs and lungworm larvae. Samples were taken three times per year: before turning out, in the middle of the grazing season and at the end. After a diagnostic and plausibility check, a total of 692 samples could be used for statistical analysis. The overall prevalence was 29.5% for Eimeria spp. and 42.2% for nematodes. Eggs of the liver fluke and lungworm larvae were only detected at very low levels. Statistical analyses were performed with a generalized linear model including the fixed effects wetting status, farm, year, and if it was the first summer on pasture for the animal. Significant influences on nematodes were detected for the stage of re-wetting, while Eimeria spp. were significantly affected by the grazing period. These findings indicate that the important parasites liver fluke and lungworm have not hitherto been affected at all by re-wetting measures. Furthermore, the prevalence of nematodes and Eimeria spp. did not increase. In conclusion, no clinical signs for parasitic diseases and no significantly elevated infection levels were shown after the third year of re-wetting, but even longer observations are essential to evaluate long-term consequences.