Effects Of The Dietary Soybean Oligosaccharide,Stachyose And Raffinose On The Concentrations Of Odor-causing Compounds And Microbial Structure In Ceca Of Broilers

Soybean oligosaccharides are produced by the processing of soybean and soybean by-products.The main components are stachyose,raffinose,saccharose and etc.The purpose of this experiment was to study effects of the dietary soybean oligosaccharide,stachyose and raffinose supplementation on the concentrations of odor-causing compounds and microbial structure in ceca of broilers.So as to explore the effects of soybean oligosaccharides and its functional components on the production of odor-causing compounds and the microbiological mechanism in broilers.In this experiment,300 one-day-age Arbor Acres(AA+)broiler chicks were selected by single-factor randomized experimental design,and randomly divided into 5groups,and each group had 6 replicates and 10 chickens in each replicate.Broilers in the positive control group were fed with corn-soybean meal diet.Broilers in the negative control group were fed with corn-nonsoybean meal diet.Broilers in the other 3 test groups were fed with the corn-nonsoybean meal diet supplemented with 0.6% of soybean oligosaccharide,stachyose and raffinose respectively.The dietary nutrition level and feeding management condition of each group remained the same.The experiment was divided into 2 periods,lasted49 days.The first period sustained 28 days and the second period 21 days.Broilers were free to eat and drink during the whole experiment.After feeding experiment,metabolism test was carried out by endogenous indicator method.On the 49 day,one chicken was selected from each replicate,Chicken blood was collected from the sub-wing vein,and serum was separated from blood.Then these chickens were slaughtered,and samples of cecal contents were collected and determined.The experiment results showed that:(1)Production performance and nutrient apparent metabolic rate: the average daily gain(ADG)and average daily feed intake(ADFI)of positive control broilers were significantly higher than other groups.The feed-to-gain ratio(F/G)was significantly lower than other groups(P<0.01).The ADG of broilers aged 1～49 days was significantly higher than that of soybean oligosaccharide and raffinose groups(P<0.05).The F/G of soybean oligosaccharide and stachyose groups was significantly lower than that of raffinose group(P<0.01).The metabolic rates of energy and dry matter were significantly different among the three groups(P<0.01),and the effects order was positive control >raffinose >stachyose >soybean oligosaccharide >negative control.The metabolic rate of protein in the positive control group was significantly higher than the other groups(P<0.01),and that in the stachyose and raffinose groups was significantly higher than the negative control group(P<0.05).(2)Nonspecific immune function: there was no significant difference in serum immunoglobulin(Ig A,Ig M,Ig G),complement protein 3 and lysozyme among the five groups(P>0.05).(3)Cecal odor-causing compound concentration: compared with the negative control group,the cecal indole concentration of soybean oligosaccharide,stachyose and raffinose groups decreased by 9.25%,15.06% and 8.58%,respectively(P<0.01).Compared with the negative control group,the skatole decreased by 42.38%,45.14% and 14.12%,respectively.In addition,the volatile fatty acid concentration was significantly higher than that of the negative control group(P<0.01).(4)Microbial structure in ceca: the shannon index of cecal microflora in positive control group was significantly higher than the raffinose group(P<0.05).There was no significant difference among the other groups for Shannon index(P>0.05).There was no significant difference in colony chao index(P>0.05)and simpson index(P>0.05).The number of unknown bacteria in the control group was significantly higher than the raffinose group(P<0.05).In the other bacteria,the number of unknown bacteria in the raffinose group was significantly higher than that in the positive control group(P<0.05).Compared with the negative control group,soybean oligosaccharide and stachyose significantly increased the proportion of Firmicutes(P<0.05),there was no significant difference in the proportion of microflora at genera among the five groups(P>0.05).(5)The positive control group had the highest microflora similarities with the stachyose group,and had the lowest similarities with soybean oligosaccharide and the negative control group.In conclusion,broilers were fed the corn-nonsoybean meal diet with addition of 0.6%soybean oligosaccharide,stachyose and raffinose,the cecal indole and skatole concentrationswere significantly reduced.In addition,the cecal fermentation model(increased the concentration of volatile fatty acids in the ceca,and the content of lactic acid reduced)was improved.The effect of the oligosaccharides supplementation on reducing concentrations of cecal odor-causing compounds was mainly related to the improvement of the cecal microbial structure(diversity,similarity and proportion of bacteria).Under the condition of this experiment,the effect of stachyose was the best,followed by the soybean oligosaccharide,and it was not recommended to add the raffinose.