Fig. 2

Measurement of bacterial community composition (beta diversity) of the faecal bacterial microbiota for the effect of treatment (fed control horses [black shapes] versus feed withheld, FW [grey shapes]) and time period category (see Fig. 6 for definitions). The principle coordinate analysis (PCoA) plot shows weighted (a, relative proportions of commonly present 16S rRNA bacterial sequences) and unweighted (b, presence-absence information of 16S rRNA bacterial sequences) UniFrac distances between samples. Samples that are more similar are located more closely to one another, and dissimilar samples are further apart. Note that the grey solid squares (FW horses during the late withheld time period) and grey plus-signs (FW horses during the early refed time period) are spread out away from the cluster with the black shapes (fed control horses during all time periods) and grey circles, triangles, and non-sold square (FW horses during the fed, early withheld, and late refed time periods, respectively). Pairwise comparisons of weighted data showed that there was no significant difference between groups during the fed time period. Significant differences were observed between groups during the early withheld (P = 0.021) and the late withheld, early refed, and late refed time period (P = 0.001)