Characterization of in situ fibre digestion of several fibrous foods

The disappearance of neutral-detergent fibre (NDF) from six fibrous foods ( lucerne hay, NaOH-treated barley straw olive leaves, paprika meal, soya-bea n hulls and sunflower hulls) when incubated in the rumen of sheep in nylon bags was investigated. Source of fibre, time of incubation and its interact ion had a significant (P < 0.001) effect on NDF degradation. Stepwise regre ssion analysis showed that the best single predictor for NDF degradation ra te was the hemicellulose fraction of NDF (HEMndf). The variables selected t o predict potential degradability and degradability of NDF at 72 h were the proportions of acid-detergent lignin in NDF (ADL(ndf), first step) and of acid-detergent cutin in ADL (ADC(adl), second step). For NDF degradability at 12 h, the variables selected were the proportions of HEMndf, ADL(ndf) an d ADC(adl), in the first, second and third step, respectively. The results showed that ADC is an important component to understand NDF degradability a t both 12 and 72 h.