Abbreviations: aNDF, neutral detergent fiber after -amylase treatment; A:P, molar ratio of acetate to propionate; CP, crude protein; DM, dry matter; HPLC, high-performance liquid chromatography; iBut, isobutyrate; iVal, isovalerate; IVaNDFD, in vitro aNDF digestibility; Mol frac, molar fraction; NFC, non-fiber carbohydrate; qPCR, quantitative polymerase chain reaction; RPS, relative population ...