Effects Of Inulin On Growth Performance,Productions Of The Major Odor-causing Compounds,and The Intestinal Microbiota Of Broilers

Inulin,which was derived from D-fructose molecules by((1 → 2)glycosidic linkages,was mainly derived from the roots of Jerusalem artichoke and chicory.The aim of this experiment was to investigate the effects of different levels of inulin on the growth performance and main odor compounds of broilers in order to determine the optimum level of inulin and to explore the microbial biology of reducing the amount of odor compounds in broilers mechanism.Three hundred one-day-old AA+ broilers were selected and randomly distributed into 5 treatment groups with 6 replicates per treatment,each replicate consisting of 10 broilers.Broilers in the experimental groups were fed basal diets containing 0(Control),0.05%,0.15%,0.25%and 0.50%inulin,respectively.2 weeks was the experimental period.Every broiler was breeded under the identical settings and they were fed the same food and water during the experiment.The contents of major odor compounds in 6 weeks old excreta,cecum and rectum of broilers were determined by repeated units.The PCR-DGGE was used to analysis the microflora structure and the diversity of the content in cecum and rectum digesta of 6 weeks old broilers,the qPCR was used to analysis total bacteria counts,Escherichia coli counts,Lactobacilli counts,Bifidobacteria counts and Clostridium Perfringens counts in cecum and rectum digesta.The results showed that:(1)The dietary inulin supplementation had no significant effects on growth performance of broilers(P>0.05);but the average daily feed intake and material weight ratio of 0.50%inulin were the lowest.There was significant linear relationship between dietary supplementation of inulin and the average daily feed intake of 4 to 6 and 1 to 6 weeks of age and material weight ratio of 1 to 6 weeks of age(P<0.05);(2)The lactic acid concentration in excreta of broilers fed diet with 0.50%inulin was significantly higher than that in control group(+31.07%),and the excreta pH values decreased significantly(P<0.05).The lactic acid concentration in excreta was higher significantly compared with those in cecal and rectal digesta(P<0.05);The indole concentration in excreta of broilers fed diet with 0.50%inulin was significantly decreased(-50.76%),and the skatole concentration was significantly lower(P<0.05);The indole concentration in excreta showed a significant positive correlation with the concentration of indole and skatole in rectal digesta,and indole in cecal digesta(P<0.05).The pH in excreta and the concentration of lactic acid in cecal digesta showed a significant negative correlation(P<0.05);(3)The dietary inulin supplementation had no significant effects on the microflora diversity of the content in cecum and rectum digesta(P>0.05);the Evenness of cecum and the Shannon-Wiener Index of rectum of broilers fed diet with 0.50%inulin decreased significantly(P<0.05),the Shannon-Wiener Index of rectum of 0.25%inulin decreased significantly(P<0.05);Clustering analysis showed that there was little effect on similarity coefficient between control group samples and 0.50%inulin group;principal component analysis showed that the control group had the biggest discreteness samples with 0.50%inulin group;according to some of the dominant bands of DGGE after tapping,the result showed that 0.50%inulin may inhibit the growth of Bacteroides thetaiotaomicron of Bacteroidetes,promote the proliferation of Firmcutes Intestinimonas;0.05%,0.15%and 0.25%inulin may inhibit the growth of Christensenellaminuta;(4)0.05%inulin significantly increased the count of Lactobacilli in broilers(P<0.05);0.15%inulin significantly reduced the count of total bacteria of cecum and rectum(P<0.01);0.50%inulin significantly reduced the count of total bacteria and Escherichia coli of rectum and increased the number of cecal and bifidobacteria(P<0.01).The concentration of indole in intestinal tract and the count of lactic acid bacteria showed a significant negative correlation(P<0.05).In summary,0.50%inulin has the best effect on reducing odor compounds in the excreta and intestinal.It could be speculated that Bacteroides thetaiotaomicron of Bacteroidetes,Firmcutes Intestinimonas Christensenella minuta and Intestinimonas sp.may have an important effect in intestinal odor compounds produced in broliers.