Influence of short-term concentrate diet adaptation (low starch [LS] = 0.6% BW/d; high starch [HS] = 1.2% BW/d, as-fed basis) on equine cecum over 7 d. (A) Cecal fermentation is described by pH, total VFA concentration (mM), and molar proportion of VFA. (B) Microbiome response at the phyla level is described by the relative abundance of bacterial phyla present at greater than 1% of 16S rRNA sequences. (C) Microbiome response at the family level is described by relative abundance of bacterial families present at greater than 0.1% of 16S rRNA sequences. Symbols on the y-axis in Fig. 2A, 2B, and 2C denote the following effects treatment (**P < 0.05; *0.1 > P > 0.05), day (##P < 0.05; #0.1 > P > 0.05), treatment × day (‡0.1 > P > 0.05), and period (¶¶P < 0.05; ¶0.1 > P > 0.05). Error bars represent a pooled SEM.