Study On The Determination Of The Nutrient Apparent Digestibility Coefficient For Lateolabras Japonica Using Simulative Digestion System

Using biological method?in vivo method?determine the feed digestibility is long,the results vary greatly,and have no unified method to measuring the digestibility single feed ingredient.But using in vitro bionic digestion method can effectively evaluate the quality of different feeds or ingredients,the time is short,and can save a lot of manpower,material resources and financial resources.At present,using the simulative digestion system to evaluate the quality of feed was generally applied in livestock and poultry,but had no related research reports in aquaculture.In the present study,the pH,ion concentration and endogenous digestive enzyme activity of digestive tract of the sea bass Lateolabras japonica were determined,and then through the simulation of the digestive physiology environment in sea bass,developing a set of normalization reagents of simulative digestion enzyme and buffer,finally verifying the simulative digestion effect by the SDS-?simulative digestion system.The feasibility of assaying the digestibility of dry matter and crude protein of sea bass feeds or ingredients using the SDS-??was evaluated by comparing the in vitro and in vivo nutrient digestibility.The primary results and conclusion are as follows:1.The pH value of the gastric,foregut and hindgut of sea bass is 2.1².5,6.0⁶.5 and6.5⁷.0 respectively.The pepsin activity in the sea bass gastric fluid was 67.66U/ml;in the foregut digestive fluid,the chymotrypsin activity was 68.03U/ml,the trypsin activity was189.33U/ml,the amylase activity was 56.81U/ml;in the hindgut digestive fluid,the chymotrypsin activity was 62.36U/ml,the trypsin activity was 249.04U/ml,the amylase activity was 50.69U/ml.In the sea bass gastric fluid,NaCl concentration was 18.51mmol/L,KCl concentration was 10.53mmol/L;in the foregut fluid,Na₂HPO₄ concentration was357.12mmol/L,NaH₂PO₄ concentration was 187.23mmol/L,NaCl concentration was98.73mmol/L,KCl concentration was 9.74mmol/L;in the hindgut fluid,Na₂HPO₄concentration was 352.33mmol/L,NaH₂PO₄ concentration was 199.14mmol/L,NaCl concentration was 100.35 mmol/L,KCl concentration was 5.56mmol/L.2.The optimum time of gastric,foregut and hindgut simulative digestion was 4h,6h and6h respectively.3.Using the self-made simulative digestion enzyme solution to digest feedstuff in the simulative digestion system,the digestibility of which are close to the digestibility in vivo.It indicated that the simulative digestion enzyme solution can be used for simulative digestion system to rapid evaluating the feed nutritional value of sea bass.This study is the first time using the simulative digestion system to evaluating the feed nutritional value in aquaculture.The results can provide reliable experimental datas for the simulative digestion in vitro of sea bass,and provide the basis for other marine stomach fish simulative digestion in vitro.