The effect of overheat or overheat-xylose processing on chemical composition and in vitro non-linear first order matter (DM) and crude protein (CP) disappearance of three samples of guar meal (GM) was evaluated. Samples were intact GM, verheat processed GM (GMhp, GM was heated at 100 °C for 45 minute using air-forced oven) and overheat-xylose processed GM (GMhx, xylose was included in GM to give a final concentration of 10 g/kg DM, then was heat processed at 100 °C for 45 minute using air-forced oven). The model was: D(t)= D(i).exp (-kd. time)+ I; Where, D(t) is residual DM at any time, , D(i) potentially digestible fraction , kd is fractional rate constant of digestion (h-1) and, I is indigestible fraction. Results of the nonlinear first order disappearance kinetic of DM indicated that the DM of GM and GMhp was completely degradable after 24 h of incubation. The fractional rate constant (kd) of DM disappearance was significantly (P< 0.05) influenced by overheat or overheatxylose processing.
