Effects of xylanase supplementation on ruminal digestibility in fistulated non-lactating dairy cows fed rice straw

The effect of xylanase product on ruminal disappearance and rumen fermentation of rice straw based diet was evaluated in fistulated non-lactating dairy cows. Three fistulated non-lactating dairy cows were used in 3×3 Latin squares design; the trial consisted of 3 periods of 21 d in each period. Treatments were: (1) control, (2) 10 g xylanase/cow/d, and (3) 20 g xylanase/cow/d. The commercial xylanase enzyme (endo-1, 4-beta-xylanase, EC 3.2.1.8) which was a fibrolytic enzyme powder (Porzyme® 93010; Danisco Animal Nutrition) was used in this study. Diets offered as 3 kg/d of concentrate containing 17% CP together with ad libitum rice straw and clean water. Enzyme did not change dry matter intake, ruminal pH and NH3-N concentrations. DM and ADF potential disappearance fraction, DM and ADF total disappearance were unaffected by the enzyme supplementation. However, NDF potential disappearance fraction, NDF total disappearance were increased when the enzyme was added at a high dose. Hemicellulose degradability in 0, 3, 6, 12, 24, 48, 72 and 96 h were unaffected by supplementation of xylanase. Total volatile fatty acids concentration, molar proportion of acetate, propionate and butyrate and ratio of acetate: propionate at each hour of incubation were unaffected by xylanase.