Effects of Gasterophilus pecorum infestation on the intestinal microbiota of the rewilded Przewalski's horses in China.

Horse botflies have been a threat to the Przewalski's horses in the Kalamaili Nature Reserve in Xinjiang of China since their reintroduction to the original range. As larvae of these parasites could infest the intestine of a horse for months, they could interact with and alter the structure and composition of its intestinal microbiota, affecting adversely its health. Nonetheless, there are no such studies on the rewilded Przewalski's horses yet. For the first time, this study characterizes the composition of the intestinal microbiota of 7 rewilded Przewalski's horses infected severely by Gasterophilus pecorum following and prior to their anthelmintic treatment. Bioinformatics analyses of the sequence data obtained by amplicon high throughput sequencing of bacterial 16S rRNA genes showed that G. pecorum infestation significantly increased the richness of the intestinal microbial community but not its diversity. Firmicutes and Bacteroidetes were found the dominant phyla as in other animals, and the parasitic infestation decreased the F/B ratio largely by over 50%. Large reduction in relative abundances of the two genera Streptococcus and Lactobacillus observed with G. pecorum infestation suggested possible changes in colic and digestion related conditions of the infected horses. Variations on the relative abundance of the genus groups known to be pathogenic or symbiotic showed that adverse impact of the G. pecorum infestation could be associated with reduction of the symbiotic genera Lactobacillus and Bifidobacterium that are probiotics and able to promote immunity against parasitic infection.

Effect of Gender Bias on Equine Fecal Microbiota.

Many studies on human intestinal microbiota indicate that gender difference is one of the key factors influencing microbial community composition. To date, the degree of influence that gender has on equid intestinal microbiota has not been reported. Thus, microbiota was analyzed in feces of seven female Przewalski's horses (FRPHs) and seven male Przewalski's horses (MRPHs) in this study, determining which microbiota characteristics respond to gender biases. The microbial community composition and structure were explored by 16S rRNA sequencing, followed by diversity analysis and difference analysis. Female Przewalski's horses showed higher Shannon diversity than MRPHs, no difference in Simpson diversity, and displayed difference in beta diversity. Although gender had little effect on the overall microbiota, it significantly changed the dominant microbial community in each classification level. Male Przewalski's horses contained significantly higher amounts of microorganisms related with diseases, including spirochetes (phylum), deltaproteobacteria (class), fibrobacteria (class), spirochaetia (class), desulfovibrionales (order), fibrobacterales (order), spirochaetales (order), and spirochaetaceae (family). Female Przewalski's horses showed less than MRPHs in the top 10 genera. To our knowledge, this study is the first to document the gender-related intestinal microbiota profile in equines and discovered notable differences between the gender, which suggests that gender should be considered as a biological variable in future microbiota studies.