Effect of hay type on cecal and fecal microbiome and fermentation parameters in horses

Abstract

The effect of hay type on the microbiome of the equine gastrointestinal tract is relatively unexplored. Our objective was to characterize the cecal and fecal microbiome of mature horses consuming alfalfa or Smooth Bromegrass (brome) hay. Six cecally cannulated horses were used in a split-plot design run as a crossover in two periods. The whole plot treatment was ad libitum access to brome or alfalfa hay fed over two 21-d acclimation periods with subplots of sampling location (cecum and rectum) and sampling hour. Each acclimation period was followed by a 24-h collection period where cecal and fecal samples were collected every 3 h for analysis of pH and volatile fatty acids (VFA). Fecal and cecal samples were pooled and sent to a commercial lab (MR DNA, Shallowater, TX) for the amplification of the V4 region of the 16S rRNA gene and sequenced using Illumina HiSeq. The main effects of hay on VFA, pH, and taxonomic abundances were analyzed using the MIXED procedure of SAS 9.4 with fixed effects of hay, hour, location, period, and all possible interactions and random effect of horse. Alpha and beta diversities were analyzed using the R Dame package. Horses fed alfalfa had greater fecal than cecal pH (P ≤ 0.05), whereas horses fed brome had greater cecal than fecal pH (P ≤ 0.05). Regardless of hay type, total VFA concentrations were greater (P ≤ 0.05) in the cecum than in feces, and alfalfa resulted in greater (P ≤ 0.05) VFA concentrations than brome in both sampling locations. Alpha diversity was greater (P ≤ 0.05) in fecal compared with cecal samples. Microbial community structure within each sampling location and hay type differed from one another (P ≤ 0.05). Bacteroidetes were greater (P ≤ 0.05) in the cecum compared with the rectum, regardless of hay type. Firmicutes and Firmicutes:Bacteroidetes were greater (P ≤ 0.05) in the feces compared with cecal samples of alfalfa-fed horses. In all, fermentation parameters and bacterial abundances were impacted by hay type and sampling location in the hindgut.

Feeding a Saccharomyces cerevisiae Fermentation Product (Olimond BB) Does Not Alter the Fecal Microbiota of Thoroughbred Racehorses

“…A similar duration of the feeding phase has been used in other studies on fecal microbiota [ 11 , 37 , 38 ]. The number of horses ( n = 11) was in the range of other studies (between six and seventeen [ 11 , 37 , 38 , 39 ]). Our design largely excluded random influences on the microbiota that can occur on each sample day despite identical experimental conditions [ 40 ].…”

Fecal microbiome of horses transitioning between warm-season and cool-season grass pasture within integrated rotational grazing systems

“…Groups of fibrolytic and butyrate-producing bacteria were differentially abundant across C–W transitions while separate and distinct groups containing ASV assigned to similar taxa and/or taxa with similar ascribed functions varied over the W–C transitions, suggesting functional redundancy and further reinforcing the overall stability of microbial communities during changes in pasture forages. While no differences were found in fecal pH, which is often cited as an indicator of bacterial activity in the hindgut [ 7 , 91 , 92 ], analyses of metabolites such as lactate and short-chain fatty acids or culture-based assays of functional communities (i.e. cellulytics, amylolytics, lactate-utilizers, etc.)…”

Variations in the fecal microbiota and their functions of Thoroughbred, Mongolian, and Hybrid horses

“…On the one hand, the host gut provides the necessary environmental conditions for microbial growth, such as nutrients, temperature, humidity, and pH ( 1 ). On the other hand, the gut microbiota convert complex carbohydrates into short-chain fatty acids (SCFAs) through fermentation, providing the host with essential nutrients and energy ( 2 ). Meanwhile, some beneficial microbes in the gut can also specifically bind to the mucosal epithelium to enhance the gut immune protection barrier, thus preventing the invasion of pathogenic microorganisms ( 3 ).…”