Short Communication
Effect of Gender Bias on Equine Fecal Microbiota

https://doi.org/10.1016/j.jevs.2020.103355Get rights and content

Highlights

  • Intestinal microbiota can mirror the states of hosts.

  • The intestinal microbial community of Przewalski’s horses was explored by high-throughput sequencing.

  • The differences of intestinal microbial community composition and diversity between genders were discovered.

  • Gender should be considered as a biological variable in future microbiota studies for horses.

Abstract

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.

Introduction

Intestinal microbiota is defined as an assemblage of microorganisms living in the gastrointestinal tract, which can be identified by marker genes [1]. The commensal intestinal microorganisms are usually harmless to the host [2], but can result in development of diseases when influenced by environmental factors [3,4]. Equine intestinal microbiota plays an important role in maintaining health, such as digestion [5] and immunity [2]. Because of their small stomachs, to sustain enough energy, equines require constant gathering of food to compensate; therefore, intestinal microbiota is especially necessary to aid digestion [5]. Thus, it is vital to identify factors affecting the intestinal microbiota of equine. However, the microbial community in equine intestines has received less attention compared with human-related research. A study published in 2020 reviewed the current knowledge about the factors influencing equine intestinal microbiota, including nutrition and management, medication, age, disease, stress [6], was short of gender data. In fact, gender bias has been regarded as an important factor disturbing the intestinal microbial community, which has been proven in humans and mice [7,8].

Gender difference is prevalent in the human and animal populations. Studies in the human intestine have provided insight into the influence of gender on the intestinal microbial community. Sinha et al. (2019) indicated that the intestinal microbial community composition is vastly different between females and males; females showed a greater microbial diversity than males [9]. Female groups were enriched in the genus of Bifidobacterium from Actinobacteria and less Veillonellaceae [10]. Another study showed that the genera of Bifidobacterium, Ruminococcus, and Akkermansia were more abundant in females, and the genera of Prevotella, Megamonas, and Fusobacterium were more abundant in males [11]. As the human intestinal microbiota is highly associated with disease development, understanding the gender-related microbiota can help to differentially prescribe medicine between females and males [9]. Studies of animal gender–related intestinal microbiota were mainly conducted in mice and showed that female mice had higher microbial diversity and richness than male mice [12] and also the phyla of actinobacteria and tenericutes were less in the female group [13]. These results indicated that the gender-related microbial difference not only occurs in the human intestine, but also in animals. Until now, studies have not yet been conducted on equine. Therefore, we hope to identify the change of equine intestinal microbial community composition and structure associated with gender bias in this study.

Section snippets

Materials and Methods

This study was carried out in accordance with the Chinese laws, regulations of the Beijing Forestry University, and guidelines of animal research [14]. The experimental protocol was reviewed and approved by the Institution of Animal Care and the Ethics Committee of Beijing Forestry University. The management authority of the Kalamaili Nature Reserve approved the collection of Przewalski’s horse fecal samples.

Seven female Przewalski’s horses (FRPHs) and seven male Przewalski’s horses (MRPHs)

Results and Discussions

A total of 856,779 sequencing reads were obtained from the samples, with a length of 358,014,436 bp. A total of 2,890 OTUs were identified and classified into 23 phyla, 35 classes, 79 orders, 137 families, and 302 genera.

Conclusions

The present study represents the first to determine the difference of intestinal microbiota between female and male equid, which was shown in alpha diversity, beta diversity, and relative abundance in each taxonomic unit.

Acknowledgments

The authors sincerely thank all rangers, breeders, and staff members at the Kalamaili Nature Reserve. This project is funded by the China Postdoctoral Science Foundation (2020TQ0047) and the National Natural Science Foundation of China (NSFC No. 31670538).

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    Animal welfare/ethical statement: This study was carried out in accordance with the Chinese laws, regulations of the Beijing Forestry University, and guidelines of animal research. The experimental protocol was reviewed and approved by the Institution of Animal Care and the Ethics Committee of Beijing Forestry University. The management authority of the Kalamaili Nature Reserve approved the collection of Przewalski’s horse fecal samples.

    Conflict of interest statement: The authors declared that they have no conflicts of interest to this work.

    1

    Dini Hu and Yuzhu Chao contribute equally to this work.

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