Development of Appropriate Fibrolytic Enzyme Combination for Maize Stover and Its Effect on Rumen Fermentation in Sheep

In vitro studies were undertaken to develop an appropriate fibrolytic enzymes cocktail comprising of cellulase, xylanase and ${\beta}$-D-glucanase for maize stover with an aim to increase its nutrient utilization in sheep. Cellulase and xylanase added individually to ground maize stover at an increasing dose rates (0, 100, 200, 400, 800, 1,600, 3,200, 6,400, 12,800, 25,600, 32,000, 38,400, and 44,800 IU/g DM), increased (p<0.01) the in vitro dry matter digestibility and in vitro sugar release. The doses selected for studying the combination effect of enzymes were 6,400 to 32,000 IU/g of cellulase and 12,800 to 44,800 IU/g of xylanase. At cellulase concentration of 6,400 IU/g, IVDMD % was higher (p<0.01) at higher xylanase doses (25,600 to 44,800 IU/g). While at cellulase doses (12,800 to 32,000 IU/g), IVDMD % was higher at lower xylanase doses (12,800 and 25,600 IU/g) compared to higher xylanase doses (32,000 to 44,800 IU/g). At cellulase concentration of the 6,400 to 32,000 IU/g, the amount of sugar released increased (p<0.01) with increasing levels of xylanase concentrations except for the concentration of 44,800 IU/g. No effect of ${\beta}$-D-glucanase (100 to 300 IU/g) was observed at lower cellulase-xylanase dose (cellulase-xylanase 12,800 to 12,800 IU/g). Based on the IVDMD, the enzyme combination cellulase-xylanase 12,800 to 12,800 IU/g was selected to study its effect on feed intake and rumen fermentation pattern, conducted on 12 rams (6 to 8 months; $20.34{\pm}2.369$ kg body weight) fed 50% maize stover based TMR. The total volatile fatty acids (p<0.01) and ammonia-N concentration was higher in enzyme supplemented group, while no effect was observed on dry matter intake, ruminal pH and total nitrogen concentration.