Addition of Duddingtonia flagrans chlamydospores to the concentrate feed can improve the successful of control measures against strongyle infection in horses

Abstract

The possibility to prevent strongyle infection in horses by adding chlamydospores of the nematophagous fungus Duddingtonia flagrans to the feed concentrate has been studied in four groups of Lusitano horses. Two groups were given a daily dosage of 5×10 5 chlamydospores of D. flagrans together with the feed concentrate during 9 weeks: group 1 (G-1) composed of 9 colts maintained under a pasture regime, and group 3 (G-3) composed of adult (3-4 yr) stabled horses with regular access to grazing paddocks located nearby the barn. The other two groups received feed concentrate without spores: group 2 (G-2) composed of 9 grazing foals, and group 4 (G-4) composed of 7 adult stabled horses. Prior to the beginning of the study, the grazing animals were dewormed with a single dose of pyrantel pamoate, and the adult horses (stabled) treated with a dose of ivermectin. The effect of the chlamydospores was assessed by the Faecal Egg Count Reduction (FECR) and the Egg Reappearance Period (ERP). Strongyle-eggs were found in the stools of G-2 and G-4 throughout the study. The egg-shedding was suppressed 1 week after deworming (WAD) in G-3, and 2 WAD in G-1. A 100% FECR value was observed in the G-1 from 2 to 4 WAD, and then reduced to 0%. The FECR values ranged from 100% to 90% in G-3. The ERP was 5 weeks in G-1 and G-3. Significant differences in the FECR were obtained between G-1 and G-2, as well as between G-3 and G-4. Our results demonstrate that addition of D. flagrans spores to the feed concentrate can be useful to reduce the possibility of infection in horses. Further studies are needed to determine the appropriate dosage and frequency of administration of the chlamydospores.