Effects Of Wheat Bran Fermented With High Xylanase-producing Bacillus Cereus On The Intestinal Microflora Of Broiler Chickens

The aim of this study was to isolate bacillus in soil that had xylanase in extracellular secretion,and to analyse the effect of fermented wheat bran on performance,intestinal enzyme activity and intestinal microflora of broilers.Spores were isolated from soil by water bath in high temperature and further incubated for single colony.3,5-dinitrosalicylic acid(DNS)was used to rank the level of xylanase secretion.Universal primers were used for the amplification of 16 S r DNA sequences in genome before T-A cloning and aligment with BLAST for species identification.180 broilers in 21 d were selected and randomly devided into control check(CK),wheat bran group(WB)and fermented wheat bran group(FWB),with 6 repeats in each group and 10 broilers in each repeat.Based on complete feed in CK,5% of wheat bran and fermented wheat bran were added into WB and FWB respectively with the constant avian metabolic energy.The contrast feeding test sustained from 21 to 42 d with free intake of diets and water overall process.The growth performance and feed consumption in each repeat were recorded;one representative broiler was selected in each repeat and killed for the collection of intestinal contents of duodenum,jejunum,ileum and cecum with sterile operation.The differences of cellulase,pectinase,amylase,xylanase and microflora diversity were measured and analyzed.The results were shown as follows:(1)The strain W3 isolated from soil had 56.91 U/m L in xylanase after fermentation with wheat bran in 96 h,which was identified as Bacillus cereus by 16 S r DNA homologous comparison;(2)The content of hemicellulose in wheat bran after 72 h fermentation with W3 had trend to decrease(P=0.078),with no significant changes in other nutrients;(3)No obvious difference in average daily feed intake(ADFI),average daily weight gain(ADWG)or feed conversion ratio(FCR)was observed among CK,WB and FWB group(P>0.05);(4)Compared with duodenum of CK,the activity of amylase in FWB conspicuously raised from 7.65 U/m L to 19.60 U/m L(P<0.05),while the acitivity of xylanase raised from10.68 U/m L to 17.34 U/m L(P=0.071).There was no significant difference in other intestinal segments(P>0.05);(5)The Sobs and Chao1 indexs in Alpha diversity analysis of FWB in cecum were remarkably increased compared with those in CK(P<0.05).The amount of bifidobacteriaceae colonized in cecum of WB(14.38%)was promoted notably compared with CK(0.51%)and FWB(0.94%)(P<0.05);(6)PCo A in Beta analysis showed highly marked differences of microflora among CK,WB,and FWB both in duodenum and cecum(P<0.01).Based on the results above,the wheat bran fermented with high xylanase producing Bacillus cereus W3 strain has the ability to enhance digestive enzyme acitivity,improve the digestion and absorption of cellulose feedstuff and optimize the structure of intestinal microflora on broilers.