Study On The Method To Predict The Metabalizable Energy And Digestible Amino Acid Of Ingredients In Yellow Chickens Using The Simulative Digestion System

In the study, the artifical intestinal fluid of yellow chickens was designed according to thenormal physiological parameters of digestive enzyme activities and electrolyte composition inthe duodenal, jejunal and ileal fluid. The digestibile energy and amino acids of16commonlyused feedstuffs of yellow chickens were determined by the bionic method, which based on theartifical intestinal fluid and simulative digestion system (SDS-П). The feasibility of determingthe digestibile energy and amino acids by the bionic method was evaluated by comparaing themeasurements with the values from traditional biological methods. On this basis, the additivity ofdigestibile energy and amino acids was further evaluated in order to establish an integrity, quiklyand accurate feedstuff evaluation system.The first part was conducted to determine the digestive enzyme activities and electrolytecomposition in the duodenal, jejunal and ileal fluid of yellow chicken undering the normalphysiological conditions, so as to providing direct data support for the bionic digestion. In thisexperiment, A2×3factorial and completely randomized design, which used2types of diets thatdiffered only in their protein source (a corn-soybean meal-miscellaneous meal (CSMD) and acorn-miscellaneous meal diet (CMD)) and3types of cannulated roosters (duodenal, jejunal, andileal cannulations), was adopted. The amylase, lipase, trypsin, and chymotrypsin activities and theelectrolyte composition in the duodenal, jejunal, and ileal fluid were determined. The resultsshowed that, the duodenal amylase activity and duodenal pH value was lower in the CMO groupthan the CSMD group, and a higher jejunal Mg²⁺concentration was observed in chickens thatwere fed the CMD, while the differences of the other means of duodenal, jejunal and ileal amylase,trypsin, chymotrypsin and lipase activities, and Na⁺, K⁺, CL-, and Ca²⁺concentrations between thetwo dietary groups were not significant.In the second part, the simulative digestion of gross energy (SDGE) of16commonly usedfeedstuffs of yellow chickens were determined in vitro, and the measurements were comparedwith the ture metabolizable energy (TME) from in vivo so as to evaluating the feasibility ofdeterming the digestibility of energy by the bionic method. The results showed that it was suitableto use corn starch as the basal diet in determining the TME of the protein feedstuff and it isreasonable to use the TME value of25-g treatment in feed formulation. The correlation coefficientbetween SDGE and TME values of16feedstuffs was0.98, the absolute differences betweenSDGE and TME values were generally below1.0MJ/kg and the estimation bias of SDGE for TMEwere within10%. The coefficient of variation of SDGE was between0.2to1.2%, while thecoefficient of variation of TME was between0.9to5.76%, indicating a higher precision of SDGE.In the third part, the simulative digestion of amino acids (SDAA) of16commonly usedfeedstuffs of yellow chickens were determined in vitro, and the measurements were comparedwith the true digestibility of amino acids (TDAA) in vivo so as to evaluating the feasibility of determing the digestibility of amino acids by the bionic method. The results showed that, there aresignificant differences of the endogenous amino acid losses between the fast,25-g protein-freedietary group and40g protein-free dietary group, and the coefficient of variation of theendogenous amino acid losses with and within batches were all very large. The absolutedifferences of amino acid digestibility values between in vitro and in vivo were mostly below10%,while the absolute differences of sulfur-containing amino acid were larger. Besides, the SDAA ofNo.12,13and16feedstuffs need to be further verified. The correlation coefficients of theseventeen digestible amino acids in the16feedstuffs between SDAA and TDAA was0.915to0.996, indicating an extremely significant correlation.The fourth part was conducted to check the additivity of metabolizable energy and digestibileamino acids in vitro and in vivo. The results showed that the determined SDGE values were100.3¹00.6%of predicted values, while the determined TME values were99.4¹01.1%ofpredicted values, indicating good additivity of both SDGE and TME values, but the SDGEshowed a better precision than TME. The determined SDAA values were76.1¹18.3%ofpredicted values, while the determined TDAA values were69.7¹21.9%of predicted values,indicating a better additivity of SDAA than TDAA.