Effect of non-fiber carbohydrates on in vitro first order kinetics disappearance of cellulose

An in vitro experiment was conducted to determine the effect of supplemental non-fiber carbohydrate (NFC) on the disappearance kinetics of cellulose (Ce) by mixed ruminal microorganisms. Non-supplemented or NFC supplemented cellulose (467 mg NFC/g cellulose as sucrose (CeSu) or starch (CeSt) or a 1:1 mixture of sucrose + starch (CeSuSt)) were incubated for 24، 48، and 96 h at 39°C. After each incubation time، pH، ammonia-N concentration and cellulose disappearance were measured. The disappearance kinetics rate of all samples was determined using first order exponential model of D (t) = D (i). exp (-k. time) + I; where D (t) is potentially digestible fraction; D (i) is potentially digestible residues; k is digestion rate of cellulose (h-1) and I is indigestible fraction. In this experiment، inclusion of NFC to the rumen fluid medium resulted in a significant depression (P<0. 01) in the extent of cellulose disappearance. The disappearance rate constant of cellulose was significantly higher (P<0. 05) in non-supplemented samples as compared with those treatments containing NFC. The indigestible fraction of cellulose was significantly higher (P<0. 05) for treatments containing sucrose or sucrose + starch as the source of supplemental NFC as compared with nonsupplemented cellulose. However، when starch was added، the indigestible fraction of cellulose was similar to those of non-supplemented samples. The inclusion of NFC resulted in a significant reduction (P<0. 01) in pH of the medium، but had no significant effect (P>0. 05) on ammonia-N concentration