A detailed study was performed to compare the in vivo ileal digestibility and modulatory effects in fecal microbiota of novel galacto-oligosaccharides (GOS) derived from lactulose [GOS-Lu; degree of polymerization (DP) $2, 14.0% trisaccharides] and commercial GOS derived from lactose (GOS-La; DP $3, 35.1% trisaccharides) in growing rats (5 wk old). Rats were fed either a control diet or diets containing 1% (wt:wt) of GOS-Lu or GOS-La for 14 d. Quantitative analysis of carbohydrates from...