| At present,the raw materials of plant protein are in short supply and the price of soybean meal is high.Xanthoceras sorifolia Bunge（XsB）is one of the endemic woody oil species in China and it is cultivated in many areas of China.The protein content of the seed kernel after oil treatment was the same as that of soybean meal,and it also contained 18 kinds of amino acids.However,there are few reports on the application of XsB meal in animal production.In view of this,soybean meal of diets was replaced by XsB meal to study the effect of XsB meal on the production performance,cecal short-chain fatty acids and microbiota composition of Arbor Acres（AA）broilers,and the fermentation characteristics of broilers caecum bacteria on XsB meal in vitro.The experiment is divided into the following three sections:1 Effects of Xanthoceras sorbifolia Bunge meal substituting soybean meal on production performance of AA broilersThe purpose of this experiment was to investigate the effects of XsB meal substituting to soybean meal on growth performance,slaughter performance,nutrient utilization and breast meat composition in Arbor Acres（AA）broilers.A total of 192 21-day-old AA broilers were randomly divided into three groups,with 8 replicates in each group and 8 chicken in each replicate.Broilers in the control group were fed basic diet,while the broilers from group I and the group II were fed diets with 50%and 100%XsB meal substituting soybean meal for 21 days,respectively.During the experiment,daily feed intake and body weight were recorded weekly,and fecal samples were collected at 41 days of age to determine the apparent nutrient utilization.At 42 days of age,slaughter performance was recorded and breast meat composition was determined.The results showed that:1)the XsB meal substituting soybean meal significantly reduced the final body weight,average daily gain and average daily feed intake in broilers from 21 to 42 days of age（P<0.05）.2)The leg muscle yield of broilers in the group I was significantly higher than that in the control group（P<0.05）;and the dressing percentage and eviscerated percentage in the group Ⅱ were significantly lower than that in the control group（P<0.05）.3)XsB meal substituting soybean meal significantly reduced the utilization of crude ash in broilers（P<0.05）,and the utilization of crude protein in the group Ⅱ was significantly lower than that in the control group（P<0.05）.4)XsB meal substituting soybean meal significantly reduced the content of crude fat in broilers’ breast muscle（P<0.05）.In summary,XsB meal substituting soybean meal in diets lhad negative effects on the growth and slaughter performance,apparent nutrients utilization and crude fat of breast muscle in broilers from 21 to 42 days.Therefore,it is recommended that the replacement of soybean meal with XsB meal should be less than 50%in the diets of broilers（in the diets should be less than 14%）.2 Effects of Xanthoceras sorbifolia Bunge meal substituting soybean meal on short-chain fatty acids status,cecal microbiota composition and function of AA broilersThe purpose of this experiment was to investigate the effects of XsB meal substituting to soybean meal on short-chain fatty acids status,microbiota composition and function of cecal digesta in AA broilers（the material and methods were consistent with the first experiment）.At the end of the experiment,broilers were slaughtered and caecal chyme samples of broilers were sampled to determine the levels of short-chain fatty acids,microbiota composition and function of cecal digesta in broilers.The results showed that:1)compared with the control group,the propionic acid content in cecal digesta of broilers in the group I was significantly reduced（P<0.05）;the contents of acetic acid,propionic acid,butyric acid and total short-chain fatty acids in cecal digesta of broilers in the group Ⅱ were significantly reduced（P<0.05）.2)XsB meal substituting of soybean meal significantly reduced the relative abundance of[Eubacterium]coprostanoligenes group and Tyzzerella in cecal digesta of broilers（P<0.05）;the relative abundance of Barnesiaellaceaeuncultured in the group Ⅱ was significantly reduced（P<0.05）,and Coprobacter and Oscillibacter were significantly increased（P<0.05）.3)50%and 100%XsB meal substituting soybean meal significantly increased the abundance of carotenoid synthesis and mismatch repair system functional genes of microbiota in cecal digesta,respectively（P<0.05）.In summary,100%XsB meal substituting soybean meal changed the structure of cecal microbiota and reduced the levels of cecal SCFAs in broilers;while the substitution of 50%soybean meal by XsB meal had little influence on the above indexes.3 Effects of fermentation characteristics of cecal microbiota in AA broilers on Xanthoceras sorifolia Bunge meal in vitroThe purpose of this experiment was to investigate fermentation characteristics of AA broilers caecum bacteria on soybean meal and XsB meal,basal diets and diets of the groupⅠ and Ⅱ in vitro（the material was consistent with chapter 2）.The cecal chyme of broiler was taken as inoculum,and then incubated with 1 g soybean meal,XsB meal,basal diets or the diets of group Ⅰ and Ⅱ in the fermentation flask,respectively.The fermentation flasks were kept at 37℃ for 72 h.The gas production（GP）during the experiment and concentrations of short-chain fatty acids（SCFAs）,ammonia nitrogen（NH3-N）,microbial crude protein（MCP）and total protein（TP）in the medium after fermentation were measured.The results showed that:1)the total GP,asymptotic GP,the time to reach the rate of maximum GP and the rate of maximum GP of XsB meal fermentation were significantly lower than those of soybean meal（P<0.05）;the time to reach half of the asymptotic GP and the rate of maximum GP in the group Ⅱ were significantly increased compared to basal diets and the group Ⅰ（P<0.05）.2)The concentrations of acetic acid,propionic acid and total SCFAs in the medium of XsB meal fermentation were significantly lower than those in soybean meal（P<0.05）;the concentrations of acetic acid and total SCFAs in the medium of experimental diets were significantly decreased compared to basal diets（P<0.05）.3)the concentrations of TP in the medium of XsB meal was markedly higher than soybean meal（P<0.05）.In summary,the GP efficiency,producing ability of SCFAs and TP degradation in XsB meal and experimental diets fermentation were lower than those in the soybean meal and the basal diets in vitro,respectively.It suggested that XsB meal and its related diets were difficult to degrade by cecal microbiota of AA broilers. |
