The Horse Gut Microbiome Responds in a Highly Individualized Manner to Forage Lignification

Although contributions of the equine gut microbiome to forage utilization are well recognized, impact alfalfa (Medicago sativa L.) lignification on remains unknown; thus, we characterized microbial communities in when feeding reduced lignin (RL) and conventional (CON) hays adult stock-type horses. Dietary treatments were fed six horses a crossover study. Experimental periods consisted 9-day dietary adaptation phase followed by 5-day total fecal collection phase, during which housed individual box stalls manure was removed continuous 24-hour basis. At 12-hour intervals, mixed, frozen, processed for V4, 16S rRNA amplicon MiSeq sequencing. Reduced did not shift composition equally across all horses; however, each subject’s responded hay content an individualized manner, mostly, terms beta diversity. Amplicon sequence variants affiliated Akkermansia, Fibrobacter succinogenes, Treponema, Paludibacter fluctuated significantly RL fed, with abundance patterns unique horse. Horse-specific associations between traits characteristics digested CON or also observed, mainly regards dry matter digestibility mean particle size. These results indicate that horse responds manner changes amount acid detergent hay, potentially impacting several feed characteristics. The implications these horse-specific responses lignification, metabolic health performance, remain be elucidated.