The Effects Of Xylanase On The Nutrient Digestibility And Microfloar Of The Gastrointestinal Tract Of Broiler Chickens

The aim of this study was to investigate the effects of xylanse on the nutrientdigestibility and microfloar of gastrointestinal tract of broiler chickens and to provide somereferenced information for further exploration of reasonable application of enzyme inbroiler chickens production. The study included two parts and the general results werepresented as follows:In the first part: An experiment was designed to study the effects of wheat-based dietsupplemented with two xylanase preparations (foreign commercial xylanase EⅠand nativexylanase EⅡ)on the mean retention time(MRT)of digesta and the nutrient digestibility inthe segments of the gastrointestinal tract of broiler chickens. One hundred and sixty7-day-old broiler chickens were divided into five groups, namely, wheat based diets wassupplemented with 0.05% EⅠ(A1), 0.02% EⅠ(A2),0.02% EⅡ(B1),0.05% EⅡ(B2)and0%(C).The diets were fed between 7 and 22 days of age. The results showed that in allgroups, the MRT in jejunum and ileum were the longest. The MRT in proventriculus, colonand caeca were prolonged by xylanase supplementation, however, in other segments ofintestinal tract the MRT were shortened, but no significant effects were observed. Groups ofA1, A2, B1 and B2 reduced the total MRT by 15.2%, 6.4%, 13.6% and 13.8% respectively.Groups with xylanase supplemented made dry matter (DM) and crude protein(CP)digestibility increase significantly (P＜0.05). In all groups, the digestibility of DM andCP showed negative values in crop, proventriculus, duodenum and caeca and positivevalues in gizzard, jejunum, ileum and colon. There was a trend of increase from jejunum tocolon.In the second part: The study was conducted to examine the effects of wheat-baseddiet supplemented with xylanase on the microflora in the hindgut of broiler chickens. Onehundred and twenty 7-day-old broiler chickens were divided into two groups, namely,wheat-based diets was supplemented with 0% or 0.1% xylanase. The diets were fedbetween 7 and 21 days of age. Firstly, by traditional methods, examine the effect of xylanase on microbiota population, volatile fatty acid (VFA) and lactic acid concentrationin the hindgut of broiler chickens. The results showed that compared to the control group,0.1% xylanase addition group increased the counts of Lactobacillus and Bifidobacterium,reduced Escherichia coli population in caeca, but there was no significant difference(P＞0.05). Likewise, VFA and lactic acid concentration were increased by xylanasesupplementation, but no significant difference was observed exception of propionate andTVFA concentration in caeca (P＜0.05). Then, PCR and denaturing gradient geleletrophoresis (DGGE) were used to investigate the effects of wheat-based dietsupplemented with xylanase on the development of bacterial community in the hindgut ofbroiler chickens, the regions V6 to V8 of the 16S rDNA of ileum and caeca digesta bacteriawere amplified. DGGE profiles of the PCR amplification were compared by similarityanalysis. The results revealed that DGGE profiles from 0.1% xylanase addition group weremore complex than the control group, and there were more bands. However, the similarityof the DGGE profiles from the same group was not high, at most 80% in ileum and 85% incaeca.