The impact of anthelmintic treatment on gut bacterial and fungal communities in diagnosed parasite-free sika deer Cervus nippon.

The gut microbiota, including both bacterial and fungal communities, plays vital roles in the gut homeostasis of animals, and antibiotics can lead to disorders of these microbial communities. The use of anthelmintic treatment to control parasitic infection has long been a standard practice, although its impact on the gut microbiota of healthy sika deer is relatively unknown. This study used next-generation sequencing based on 16S/18S/ITS rRNA genes to investigate the shifts in fecal bacterial and fungal communities in parasite-free sika deer after treatment with fenbendazole and ivermectin tablets. The α-diversity of both bacterial and fungal communities was significantly decreased (P < 0.05) after treatment, as were the bacterial genus Bacteroides and fungal genus Candida (P < 0.05). The results of β-diversity, LEfSe analysis, core community's analysis, taxonomic composition, and functional prediction of fungal and bacterial communities confirmed the substantial impacts of anthelmintic treatment on the function and structure of the intestinal microbiota of sika deer. Nevertheless, many lines of evidence, including β-diversity, LEfSe analysis and functional prediction analysis, suggested that the anthelmintics exerted more significant influences on fungal communities than on bacterial communities, suggesting that more attention should be paid to the changes in fungal communities of sika deer under anthelmintic treatment. The present study provides evidence to support the assumption that anthelmintic drugs modify the gut microbiota of deer and serves as the first trial to test the potential effects of anthelmintics on mycobiota in ruminants using high-throughput sequencing techniques. Key Points • Anthelmintic treatment showed significant effects on the gut microbiota of sika deer. • Fungi were more strongly affected by anthelmintic treatment than bacteria. • The profile of mycobiota provides essential data that were previously absent.