| The artifical intestinal fluid containing main enzymes and activities similar to the intestinal fluid of ducks was designed according to the digestive enzymes activities range of intestinal fluid under normal physiological condition. The enzymic method determining metabolizable energy of ducks feedstuffs with pepsin-artifical intestinal fluid was established. It would provide modern technique for effect energy determination in nutrient requirements of water poultry.The first part was conducted to the T type cannula design for collecting enough intestinal fluid without stress. The cannula continuously collecting digesta and method of digesta collection were selected according to the intestinal cannula used in pig, cattle, and sheep. The results showed that there were little damage on cannulated intestine and adherence between intestine and abdomen fat after cannulation. The body weight of cannulated ducks recovered in 15 days after operation, and average collection volume was about 20.2ml/h.The second part was mainly conducted to digestive enzymes activities range of intestinal fluid under normal nutrition condition, the representative intestinal fluid collection scheme by simple T-cannula, and the effects of diet energy and protein contents on the activities of digestive enzymes activities in the jejunum fluid were studied. The results showed that there was diurnal rhythm of digestive enzymes activities in the intestinal fluid of ducks under ad libitum access to diets and water. The representative intestinal fluid sample was collected for 1h every three hours from 9:30 to 18:30 on 1st , 3rd, and 5th days of collection period. The effect of diet energy content on digestive enzymes activities was not significant ,but the protein content changed amylase, trypsin and chymotrypsin activity. The range of amylase, typsin, chymotrypsin, lipase, sucrase and maltase activities in the intestinal fluid of ducks was 308.26-408.15U/ml, 74.51-101.77U/ml, 32.14-48.20U/ml, 0.79-1.22U/ml, 5.27-5.41U/ml, and 24.57-30.32U/ml respectively under normal production conditon.The third part was conducted to the optimum hydrolyzation condition of pepsin- artifical intestinal fluid enzymic method for determining metabolizable energy of ducks feedstuffs. The results showed pepsin concentration and enzymes variety and activities in artifical intestinal fluid of the enzymic method were identical with the main digestive enzymes in the stomach-intestine of ducks. The optimum hydrolyzation time was 3h, and temperature was 38℃ in pepsin enzymic hydrolyzation, the optimum pH was 6.6 and hydrolyzation time was 22h in artifical intestinal fluid enzymic hydrolyzation.The fourth part was conducted to study the mathematical model predicting corn metabolizable energy of ducks with enzymic hydrolyzate gross energy (EHGE). The models were AME=2.639+0.897 X EHGE (CF<2.8), AME=3.890+0.788 X EHGE (CF>2.8) (RSD=0.166MJ/Kg), and TME=3.625+0.905×EHGE(CF<2.8), TME=4.950+0.792×EHGE (CF>2.8) (RSD=0.166MJ/Kg). The range of difference between AME predicted with enzymic method and determined with biological method was about -0.353 MJ/Kg 0.343 MJ/Kg, and TME was -0.371 MJ/Kg 0.335 MJ/Kg respectively. The precision of enzymic method prediction was equal to biological method, and better man chemical method for metabolizable energy prediction.In the fifth part, the precision and repeatability of corn metabolizable energy predicted withenzymic method were tested. The results showed that there were high precision and good repeatability of corn metabolizable energy estimated with enzymic method, hi six corns, the range of difference between AME predicted with enzymic method and determined with force feeding-empting method was about -0.057 MJ/Kg -0.303 MJ/Kg, and TME was -0.065 MJ/Kg -0.294 MJ/Kg respectively. The metabolizable energy determined with enzymic method could be used for predicting biological metabolizable energy.
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