Effects of fructooligosaccharides (FOS) addition and time after feeding on the tissue weight of cecum (A); concentration of IgA in saliva (B); and IgA flow rate in saliva per weight of submandibular gland tissue (C). n = 6 per group at each time. Symbols and vertical bars represent means and standard errors, respectively. There were interactions between FOS addition and intake period in the weight of cecal tissue, concentration of IgA, and IgA flow rate of saliva per weight of submandibular gland tissue (p < 0.0001, 0.03, and 0.0009, respectively, two-way ANOVA). * p < 0.05 versus control group at each week using Tukey’s multiple comparison.