Seasonal Shifts in Diet and Gut Microbiota of the American Bison (\u3ci\u3eBison bison\u3c/i\u3e)

North American bison (Bison bison) are becoming increasingly important to both grassland management and commercial ranching. However, a lack of quantitative data on their diet constrains conservation efforts and the ability to predict bison effects on grasslands. In particular, we know little about the seasonality of the bison diet, the degree to which bison supplement their diet with eudicots, and how changes in diet influence gut microbial communities, all of which play important roles in ungulate performance. To address these knowledge gaps, we quantified seasonal patterns in bison diet and gut microbial community composition for a bison herd in Kansas using DNA sequencing-based analyses of both chloroplast and microbial DNA contained in fecal matter. Across the 11 sampling dates that spanned 166 days, we found that diet shifted continuously over the growing season, allowing bison to take advantage of the seasonal availability of high-protein plant species. Bison consumed more woody shrubs in spring and fall than in summer, when forb and grass intake predominated. In examining gut microbiota, the bacterial phylum Tenericutes shifted significantly in relative abundance over the growing season. This work suggests that North American bison can continuously adjust their diet with a high reliance on non-grasses throughout the year. In addition, we find evidence for seasonal patterns in gut community composition that are likely driven by the observed dietary changes

Seasonal Shifts in Diet and Gut Microbiota of the American Bison (\u3ci\u3eBison bison\u3c/i\u3e)

North American bison (Bison bison) are becoming increasingly important to both grassland management and commercial ranching. However, a lack of quantitative data on their diet constrains conservation efforts and the ability to predict bison effects on grasslands. In particular, we know little about the seasonality of the bison diet, the degree to which bison supplement their diet with eudicots, and how changes in diet influence gut microbial communities, all of which play important roles in ungulate performance. To address these knowledge gaps, we quantified seasonal patterns in bison diet and gut microbial community composition for a bison herd in Kansas using DNA sequencing-based analyses of both chloroplast and microbial DNA contained in fecal matter. Across the 11 sampling dates that spanned 166 days, we found that diet shifted continuously over the growing season, allowing bison to take advantage of the seasonal availability of high-protein plant species. Bison consumed more woody shrubs in spring and fall than in summer, when forb and grass intake predominated. In examining gut microbiota, the bacterial phylum Tenericutes shifted significantly in relative abundance over the growing season. This work suggests that North American bison can continuously adjust their diet with a high reliance on non-grasses throughout the year. In addition, we find evidence for seasonal patterns in gut community composition that are likely driven by the observed dietary changes

Microbial community composition along the digestive tract in forage- and grain-fed bison

Abstract Background Diversity and composition of microbial communities was compared across the 13 major sections of the digestive tract (esophagus, reticulum, rumen, omasum, abomasum, duodenum, jejunum, ileum, cecum, ascending colon, transverse colon, descending colon, and rectum) in two captive populations of American bison (Bison bison), one of which was finished on forage, the other on grain. Results Microbial diversity fell to its lowest levels in the small intestine, with Bacteroidetes reaching their lowest relative abundance in that region, while Firmicutes and Euryarchaeota attained their highest relative abundances there. Gammaproteobacteria were most abundant in the esophagus, small intestine, and colon. The forage-finished bison population exhibited higher overall levels of diversity, as well as a higher relative abundance of Bacteroidetes in most gut sections. The grain-finished bison population exhibited elevated levels of Firmicutes and Gammaproteobacteria. Within each population, different sections of the digestive tract exhibited divergent microbial community composition, although it was essentially the same among sections within a given region of the digestive tract. Shannon diversity was lowest in the midgut. For each section of the digestive tract, the two bison populations differed significantly in microbial community composition. Conclusions Similarities among sections indicate that the esophagus, reticulum, rumen, omasum, and abomasum may all be considered to house the foregut microbiota; the duodenum, jejunum, and ileum may all be considered to house the small intestine or midgut microbiota; and the cecum, ascending colon, transverse colon, descending colon, and rectum may all be considered to house the hindgut microbiota. Acid from the stomach, bile from the gall bladder, digestive enzymes from the pancreas, and the relatively low retention time of the small intestine may have caused the midgut’s low microbial diversity. Differences in microbial community composition between populations may have been most strongly influenced by differences in diet (forage or grain). The clinical condition of the animals used in the present study was not evaluated, so further research is needed to establish whether the microbial profiles of some bison in this study are indeed indicative of dysbiosis, a predisposing factor to ruminal acidosis and its sequelae

Gut Microbiota, and Management of American Bison (Bison bison) in Conservation and Commercial Herds of the Great Plains

Because American bison (Bison bison) are important to both conservation and ranching, I inquired as to the diet and gut microbiota of these animals, and the implications of these factors for sound management. I found that bison in Kansas browsed more in spring and fall, and consumed more forbs during summer, but graminoids formed a consistently low proportion of the diet. In Colorado, the bison diet was dominated by graminoids, followed by forbs, then browse. This pattern remained consistent for 18 months, despite a brief increase in forbs and decrease in graminoids when the herd’s pasture was enlarged. Comparisons among sites from May-August showed significant differences, with bison in Montana and Kansas consuming more forbs and browse than those in Colorado during certain months. Thus, the diet of bison was temporospatially variable and sometimes deviated significantly from grazing, possibly due to 1) plants that are high in protein and low in toxins; 2) large body size dictating less forage selectivity; 3) a lack migration; and 4) broad niche breadth. The present study suggests that bison may benefit from access to forbs and browse in addition to grasses. I also compared gut microbiota along the digestive tract between grass-finished and grain-finished bison. Location had the greatest effect, with sections of the foregut, the hindgut, and to a lesser degree the midgut being statistically similar. I also found a significant effect of diet on gut microbiota throughout the digestive tract, with the grain-finished bison exhibiting higher relative abundances of the bacterial phyla Firmicutes and Proteobacteria. Finally, my analysis of the natural and human history of the Great Plains shows that bison and other animals, as well as new energy sources, have the potential to foster both ecological and economic sustainability in the region to a greater degree than the system currently in place

Summary list of data tables

<p>List summarizing the 14 data tables used in our molecular study of bison diet and gut microbiome at Konza Biological Station in 2011.</p

Zipped file of all 14 Konza data tables

<p>Compressed zip file of the 14 data tables used in our molecular study of bison diet and microbioime at Konza Biological Station in the growing season of 2011.</p

PCO1 for plants by growth habit

<p>Primary axis values from principal coordinates analysis (PCoA) for plants by growth habit.</p

Relative abundance of plants by growth habit

<p>Relative abundance of plant growth habits over time as indicated by the trnL gene.</p

Relative abundance of microbial phyla

<p>Relative abundance of microbial phyla over time as indicated by 16S rRNA genes.</p

Konza_microbe.7z

This ~5-GB zipped file contains the mapping file and Illumina FASTQ files from our study on the gut microbiome of free-ranging bison at the Konza Prairie Biological Station in Kansas (Bergmann et al. 2015):<div><br></div><div>Bergmann GT, Craine JM, Robeson MS II, Fierer N (2015) Seasonal Shifts in Diet and Gut Microbiota of the American Bison (<em>Bison bison</em>). PLoS ONE 10(11): e0142409. doi:10.1371/journal.pone.0142409</div