LAUSR

The effectiveness of commonly used parasiticides decreases due to the drug resistance developed by many organisms. Therefore, the application of feed additives possessing antiparasitic properties may be helpful in limiting the burden of parasites. The aim of this research was to evaluate parasitological coefficients for endoparasites of regularly dewormed Arabian horses and Thoroughbreds, fed on a basal diet of oat and muesli with vegetable oils and/or without vitamin E. The observations revealed parasitic invasion in 25 of 27 examined horses. The most frequent in both breeds were Strongylidae—accounting for 86% of Thoroughbreds and 100% of Arabian horses. Strongyloididae were observed in 33% of individuals representing both breeds while botflies were found in one Arabian horse and one Thoroughbred. Mean EPG coefficients for strongylids and strongyloidids were higher in Thoroughbreds (530 vs. 529 and 43 vs. 29, respectively), although the differences were not statistically significant. The addition of pure linseed oil significantly reduced the number of Strongylidae in fecal samples. The results indicate that properly selected plant additives obtained from arable crops may be helpful in limiting the numbers of drug-resistant strongylids.