| This study was conducted to investigate the effects of source and composition, storage temperature and time of digestive enzymes on the digestive ability of simulated intestinal fluid, which will provide a reference for the preparation of simulated intestinal fluid. This experiment included the following three trials:1) based on collectoin of in vivo intestinal fluid using the cannula technique, development of a method for crude purification of in vivo intestinal fluid into intestinal fluid dry powder.2) effects of source and the contribution of digestive enzyme activities on the digestive ability of simulated duck intestinal fluid to feed.3) the appropriate storage temperature and time to ensure the digestive ability of simulated digestive fluid kid for ducks.The objective of trial1was to develop a crude purification method for the digestive enzymes of in vivo intestinal fluid, which will provide a material for the preparation simulated intestinal fluid. A two-sample completely randomized design was adopted. The duck intestinal fluid was treated with ammonium sulfate precipitation (method of ammonium sulfate) or low-temperature dried (method of freeze-dried) to concentration, then dialyzed and freeze-dried into intestinal fluid dry powder, respectively. The proximate content, recovery rate of true protein and digestive enzymes activities of intestinal fluid dry powder was compared the method of ammonium sulfate and the method of freeze-dried. Then the effect of fat extract on the digestive enzymes activities of intestinal fluid dry powder purified by these two methods was conducted as above experiment design. The results showed as follows:1) the recovery rate of enzyme activity was67.02%-88.21%and53.27%-65.26%using the method of concentration-dialysis-freeze-dried and (NH4)2SO4-dialysis-freeze-dried to purify the in vivo intestinal fluidof duck. The average activity of digestive enzymes purified using the method of concentration-dialysis-freeze-dried was24.92%higher than that of (NH4)2SO4-dialysis-freeze-dried.2) fat-extracted can increase the digestive enzyme activities of intestinal fluid dry powder,and the digestive enzyme activities and their recovery rate using the method of concentration-dialysis-freeze-dried-extract fat were higher than that of (NH4)2SO4-dialysis-freeze-dried-extract fat.The objective of trial2was conducted to investigate the effects of production batches and the digestive enzyme activities contribution of intestinal fluid dry powder on the digestive ability of the simulated duck intestinal fluid to corn, soybean meal and wheat bran, which will provide a reference for the appropriate amount of intestinal fluid dry powder in the simulated intestinal fluid. A nested design was adopted with batches of intestinal fluid dry powder as independent variable and the percentage of digestive enzymes activities of intestinal fluid dry powder in simulated intestinal fluid as nested variable. There were3treatments of batch1,2,3in the independent variable, and4treatments of0%(shared),25%,50%,75%in the nested variable. The dry matter digestibility (DMD) and enzymatic hydrolysate gross energy (EHGE) of corn, soybean meal and wheat bran were measured by in vitro digestion using ten simulated intestinal fluid, respectively. The results showed as follows:1) there were no significant effects of simulated intestinal fluid prepared with3batches of intestinal fluid dry powder on the apparent dry matter digestibility (ADMD), true dry matter digestibility (TDMD) and apparent enzymatic hydrolysate gross energy (AEHGE), true enzymatic hydrolysate gross energy (TEHGE) of corn and wheat bran measured using in vitro digestion (P>0.05). No significant differences in the ADMD, AEHGE and TEHGE (P>0.05), but significant difference in the TDMD (from71.75%to72.24%, P<0.05) of soybean meal digested by simulated intestinal fluid prepared with3batches of intestinal fluid dry powder were observed.2) in the same batch of intestinal fluid dry powder, the ADMD and AEHGE of corn, soybean meal and wheat bran digested by3simulated intestinal fluid significantly decreased on account of the contribution of the digestive enzyme activities from intestinal fluid dry powder to the simulated intestinal fluid changed from25%to75%, but the TDMD of corn, soybean meal and wheat bran were stable (the max absolute difference was0.88%, and relative difference was0.88%). The TEHGE of these3feeds digested by simulated intestinal fluid were stable (max absolute difference was0.17MJ/kg, and relative difference was0.90%) under the contribution of the digestive enzyme activities from intestinal fluid dry powder to the simulated intestinal fluid changed from25%to50%. In conclusion, the digestive abilities of simulated intestinal fluid prepared with3batches of intestinal fluid dry powder were equal. The digestive abilities of simulated intestinal fluid was stable under the contribution of the digestive enzyme activities from intestinal fluid dry powder to the simulated intestinal fluid changed from25%to50%.The objective of trial3was conducted to investigate the effects of store temperature and time of the digestive enzyme on the digestive ability of the simulated duck intestinal fluid to study the difference of the simulated intestinal fluid at different storage conditions,, which will provide a technological specification of the store condition for simulated digestive fluid kid. A2×6factorial completely randomized design with2store temperature and6store time was adopted. There were2treatments of4℃and room temperature in the store temperature, and6treatments of0month,1month,2months,3months,4months,5months,6months in the store time. The activities of trypsin, chymotrypsin and amylase and the DMD and EHGE of corn, soybean meal and wheat bran were measured for the simulated intestinal fluid at different store temperature and time. The results showed as follows:1) There were significant difference in the activities of trypsin, chymotrypsin and amylase of simulated intestinal fluid stored in different store temperature and time (P<0.05). The digestive enzymes activities of simulated intestinal fluid stored at4℃were significant higher than that stored at room temperature (P<0.05). The activities of digestive enzymes decreased with more store time.2) The store temperature and time influenced the DMD and EHGE of corn, soybean meal and wheat bran. But the TDMD and TEHGE of these feeds were stable.3) At4℃, the store time of simulated intestinal fluid influenced the ADMD and AEHGE of corn, soybean meal and wheat bran. But the TDMD (the max absolute difference was0.87%, and relative difference was0.51%) and TEHGE (the max absolute difference was0.19MJ/kg, and relative difference was0.62%) of these feeds were stable. At room temperature, the store time of simulated intestinal fluid influenced on the ADMD and AEHGE of corn, soybean meal and wheat bran. But the TDMD (the max absolute difference was0.68%, and relative difference was0.40%) and TEHGE (the max absolute difference was0.28MJ/kg, and relative difference was1.44%) of these feeds were stable. In conclusion, the digestive abilities of simulated intestinal fluid were stable when it has stored for5months at4℃and room temperature, which indicated that the digestibility of simulated intestinal fluid was stable in5months. |
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