| This experiment chose 817 broilers which had local characteristics as test object,to evaluate the effects of Saccharomyces cerevisiae culture on the growth performance,nutrient apparent metabolic rate,gut microbes,intestinal morphology and related immune cells of broilers,through adding different levels of Saccharomyces cerevisiae culture into the basal diet and making comparison with antibiotics.The trial included three parts.A total of 600 healthy one-day-old 817 birds with similar weight were randomly divided into 5 groups with 6 replicates per group and 20 chicks per replicate.The chicks in control group were fed with the basal diet,while the antibiotics group was fed with the basal diet added into 20 mg/kg sulfuric acid colistin and 2.6 mg/kg flavomycin.Those experimental groups(Group ?,?,?)were fed the basal diet supplemented with 2.5,5.0 and 7.5 g/kg yeast culture,respectively.The experiment lasted for.60 days.On d35 of feeding trials,a total of 60 broilers and 2 bird per replicate were selected randomly to carry out muck metabolic experiment.(1)Results of feeding trial,metabolic trial,slaughter performance,organ indexs and serum indexs were as follows:1)During days 1 to 21 of the trial,ADG,ADFI and body weight on 21 d in groups ?,? increased significantly than those in control group(P<0.05),but no significant difference were observed in antibiotics group(P>0.05).From 22 to 60 days of age and all the trial period,ADG and body weight on 60 d in group ? were significantly higher than those in control group and ADFI was also higher than those in antibiotics group(P<0.05).Compared with the control group,there were no significantly differences in feed conversion ratio and survival rate among experimental groups(P>0.05),while a downward trend of the two indexes were found during the overall period(P=0.055).2)Compared with the control group,groups ?,? could improve the apparent metabolic rate of total phosphorus(P<0.05),and the effects were comparable to those of antibiotics group(P>0.05),while no difference were found in the apparent metabolic rate of CP and calcium(P>0.05).3)There were no significant differences in semi-eviscerated rate,eviscerated rate,rate of leg muscle among all the treatment groups except a decreased tendency in the rate of chest muscle(P>0.05).The rate of abdominal fat of group ?was the lowest among all the treatment groups and lower significantly than group ?(P<0.05),but it had no difference with the rest of three groups(P>0.05).4)Compared with control group and antibiotics group,no difference were found in the indexs of cardiac,liver and thymus(P>0.05)besides an increased tendency in spleen index(P=0.071)of groups ?,?,?.Bursa of fabricius index of group ?,? were obviously lower than antibiotics group,although did not reach a significant level(P>0.05).5)Compared with control group and antibiotic group,no significant differences were observed of groups ?,?,? in total protein(TP),total bilirubin(TBIL),alkaline phosphatase(ALP),uric acid(UA)of serum(P>0.05)except an increased tendency of total three iodine thyroid original glycine(TT3)(P=0.057).The total thyroid hormone(TT4)of groups ?,? was significantly lower than the control group and achieved the effect of antibiotics group as well as group ?(P>0.05).Thus,Saccharomyces cerevisiae culture can improve the growth performance of 817 broilers by regulating serum indexs,improving nutrient apparent availability and reducing feed-weight ratio.And Saccharomyces cerevisiae culture can improve the rate of lean meat by decreasing abdominal fat ratio,strengthen the immunity levels by increasing the spleen index.The appropriate adding dose of the culture is 5.0 g/kg.(2)Results of gut microbes,intestinal morphology and related immune cells were as flowers:1)Compared with the control group,group ? could decrease the number of E.coli obviously in the cecum(P<0.05)and achieve the feeding effect of antibiotics group(P>0.05).Compared with the control group and antibiotics group,there were significant differences in the content of Lactic acid bacteria in the cecum of group ? as well as the number of Bifidobacteria in the jejunum of group?(P<0.05).2)Compared with the control group,villus height and the ratio of villus height and crypt depth increased significantly of group ?,? in duodenum(P<0.05).Crypt depth of groupIII in duodenum was significantly lower than control group and antibiotic group(P<0.05)and its ratio of villus height and crypt depth were significantly higher than that of control group in duodenum and jejunum(P<0.05),which effects were equal to the antibiotics group(P>0.05).In addition,the crypt depth of group ? in jejunum and ileum decreased significantly(P<0.05).Compared with control group and antibiotic group,the ratio of villus height and crypt depth of the other groups had an increased tendency in ileum(P=0.084).3)The number of lymphocyte and SIgA positive expression area of group ?,? were significantly higher than control group in duodenum(P<0.05)and approximately equal to the antibiotics group(P>0.05).Compared with control group and antibiotic group,the number of mast cells of group II,III had a downward trend(P=0.076).In jejunum,the number of goblet cells and lymphocytes of group III were significantly higher than that of control group(P<0.05)and the area of SIgA positive expression was significantly higher than control group and antibiotic group(P<0.05).The number of mast cells of group? in jejunum is lower than the control group(P<0.05),but had no significant difference when compared with antibiotics group(P>0.05).Groups ?,?,? made the number of lymphocytes increase obviously than the control group in the ileum(P<0.05),and which effects was equal to antibiotics group,while the other indexs among all the groups had no significant difference(P>0.05).Thus,Saccharomyces cerevisiae culture by promoting the proliferation of Lactic acid bacteria and Bifidobacterium and inhibiting the proliferation of E.coli,to optimize the structure of intestinal microbial flora;by improving the ratio of villus height and crypt depth in duodenum,jejunum and ileum to improve the intestinal structure;by improving the goblet cells,lymphocytes and SIgA positive area to enhance the intestinal immmne.The suitable adding dose of Saccharomyces cerevisiae culture is 5.0 g/kg.In conclusion:Adding 5.0 g/kg of Saccharomyces cerevisiae culture into the basal diet of 817 broilers can significantly improve the growth performance,slaughter performance,intestinal flora,intestinal morphology and immunity function,and the promote effect is superior to antibiotics group. |
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