showed a trendp = 0.07
Regarding the photoperiod effect, STD-fed rats did not show a photoperiod effect on fecal bacteria relative abundance at phylum level, whereas CAF-fed rats showed a trend towards decreased Firmicutes ( p = 0.07) and increased Bacteroidetes ( p = 0.08) relative abundance levels under L18 compared to both L6 and L12 ( Figure 3 d).