The Technique Of β-mannanase Evaluation By Digestion In Vitro

The Study is based on the effects of theβ-mannanase with different activities for the performance and utilization of nutrients in the corn-soybean meal based diets for broilers, and in the same time, the evaluation and prediction for theβ-mannanase have been researched with a two step invitro method simulating digestion.Basic properties (including the optimal reaction time and optimal substrate concentration,optimal pH and pH stability,optimal temperature and temperature stability) ofβ-mannanase were studied by the method of reductive sugar(3, 5-Dinitrosalicylic acid; DNS).The result showed that the optimal reaction time of theβ-mannanase was 15min. The optimal substrate concentration was 1.25%. The optimal pH of theβ-mannanase was 6.0. It had the best pH stability at pH6.0 and it had a good stability between pH4.5-7 when incubated at 40℃for 30min.The optimal active temperature of the enzyme was 50℃.When keep in the water with the temperature of 40～90℃for 30min separately, the enzyme activity was reduced when the temperature rise .It had a good stability when the temperature was below 60℃.This experiment established a digestion device in vitro to imitate digestion in broiler and its related parameters being studied. Diets were digested in two-step in-vitro method, the parameters were determined by the maximal digestibility of DM. The results indicated that the most suitable parameters were that the pH is 3.0 and 6.3 separately; the concentration of pepsin is 70mg/mL, the addition of pancreatin is 50mg, and the time assemble of digestion in stomach and small intestine step is 75min and 200min separately, the volumes of dialysate is 400ml.This experiment were conducted to investigated the effects ofβ-mannanase addition on the corn-soybean meal diet in vitro based on the results of experiment two. The results indicated that theβ-mannanase added into basal diets at the levels of 0.01%-0.08% can increase the digestibility of DM, CP and energy in vitro, the digestibility of DM, CP and energy in vitro had strong correlation with the performance and utilization of nutrients in broilers. The model is advantage to the evaluation and prediction ofβ-mannanase application broilers diets.