Background As a domesticated species vital to humans, horses are raised worldwide as a source of mechanical energy for sports, leisure, food production, and transportation. The gut microbiota plays an important role in the health, diseases, athletic performance, and behaviour of horses. Results Here, using approximately 2.2 Tb of metagenomic sequencing data from gut samples from 242 horses, including 110 samples from the caecum and 132 samples from the rectum (faeces), we assembled 4142 microbial metagenome-assembled genomes (MAG), 4015 (96.93%) of which appear to correspond to new species. From long-read data, we successfully assembled 13 circular whole-chromosome bacterial genomes representing novel species. The MAG contained over 313,568 predicted carbohydrate-active enzymes (CAZy), over 59.77% of which had low similarity match in CAZy public databases. High abundance and diversity of antibiotic resistance genes (ARG) were identified in the MAG, likely showing the wide use of antibiotics in the management of horse. The abundances of at least 36 MAG (e.g. MAG belonging to Lachnospiraceae, Oscillospiraceae, and Ruminococcus) were higher in racehorses than in nonracehorses. These MAG enriched in racehorses contained every gene in a major pathway for producing acetate and butyrate by fibre fermentation, presenting potential for greater amount of short-chain fatty acids available to fuel athletic performance. Conclusion Overall, we assembled 4142 MAG from short- and long-read sequence data in the horse gut. Our dataset represents an exhaustive microbial genome catalogue for the horse gut microbiome and provides a valuable resource for discovery of performance-enhancing microbes and studies of horse gut microbiome.

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With the rapid development of high-throughput sequencing technology, the amount of metagenomic data (including both 16S and whole-genome sequencing data) in public repositories is increasing exponentially. However, owing to the large and decentralized nature of the data, it is still difficult for users to mine, compare, and analyze the data. The animal metagenome database (AnimalMetagenome DB) integrates metagenomic sequencing data with host information, making it easier for users to find data of interest. The AnimalMetagenome DB is designed to contain all public metagenomic data from animals, and the data are divided into domestic and wild animal categories. Users can browse, search, and download animal metagenomic data of interest based on different attributes of the metadata such as animal species, sample site, study purpose, and DNA extraction method. The AnimalMetagenome DB version 1.0 includes metadata for 82,097 metagenomes from 4 domestic animals (pigs, bovines, horses, and sheep) and 540 wild animals. These metagenomes cover 15 years of experiments, 73 countries, 1,044 studies, 63,214 amplicon sequencing data, and 10,672 whole genome sequencing data. All data in the database are hosted and available in figshare 10.6084/m9.figshare.19728619.

CRAMdb (a database for composition and roles of animal microbiome) is a comprehensive resource of curated and consistently annotated metagenomes for non-human animals. It focuses on the composition and roles of the microbiome in various animal species. The main goal of the CRAMdb is to facilitate the reuse of animal metagenomic data, and enable cross-host and cross-phenotype comparisons. To this end, we consistently annotated microbiomes (including 16S, 18S, ITS and metagenomics sequencing data) of 516 animals from 475 projects spanning 43 phenotype pairs to construct the database that is equipped with 9430 bacteria, 278 archaea, 2216 fungi and 458 viruses. CRAMdb provides two main contents: microbiome composition data, illustrating the landscape of the microbiota (bacteria, archaea, fungi, and viruses) in various animal species, and microbiome association data, revealing the relationships between the microbiota and various phenotypes across different animal species. More importantly, users can quickly compare the composition of the microbiota of interest cross-host or body site and the associated taxa that differ between phenotype pairs cross-host or cross-phenotype. CRAMdb is freely available at (http://www.ehbio.com/CRAMdb).