In vitro Estimation of Microbial Nitrogen Production and Ruminal Fermentation Responses to Levels and Applying Duration of a Commercial Enzyme Mixture

The objective of the present experiment was to quantify the gas production parameters, methane emission and microbial nitrogen production of a conventional total mixed ration including corn silage, alfalfa hay, wheat straw and concentrate (390, 110, 22 and 478 g/kg of diet DM, respectively) treated with different levels of Natuzyme® and pre-incubation time after enzyme administration. Two hundred fifty mg of milled and dried basal diet (n=4) was weighed into a 125 mL serum bottles for an in vitro gas production trial. A solution of a commercial enzyme blend (Natuzyme®) was added at 0, 12 and 24 h prior to starting the incubation (96 h) to make treatments of 0.84, 1.68 and 2.52 g/kg, respectively. No added enzyme bottles were considered as control. Half time of gas production (t1/2) was calculated. Then, another gas test was run for each treatment and terminated at t1/2 to measure gas volume, methane emission and solid residues. Dose rate of Natuzyme® did not make any significant differences in gas production parameters and fermentation responses except for microbial nitrogen production. Pre-treatment of the basal diet at 24 h incubation significantly (P