| The study was conducted to explore the effects of Atractylis Macroceohala Koidz.Polysaccharide(PAM)and Bacillus subtilis by adding to the basal diet on growth performance,intestinal development,cecal microbe and immune function of growing laying hens to determine the feasibility and appropriate amounts of PAM and Bacillus subtilis and provid scientific basis for the application of PAM and Bacillus subtilis in poultry.A total of healthy 480 growing laying hens were randomly divided into 12 groups,with 4 replicates per group and 10 hens per replicate.A 4×3 completely random experiment was designed,the experimental diets were supplemented with PAM and Bacillus subtilis in the basal diet,the PAM levels were 0,0.2%,0.4%and 0.6%,and Bacillus subtilis levels were 0,250 mg/kg and 500 mg/kg,respectively.The study lasted for 7 wk including 1 wk of adaptation and 6 wk of the main experimental period.The results showed as follows:(1)Dietary PAM had no significant effects on the average feed intake(ADFI)and tibia length of growing laying hens(P>0.05),but had significant effects on the final body weight(BW),average daily gain(ADG),and feed-to-weight ratio(F/G)(P<0.05).Dietary addition of 250mg/kg and 500mg/kg Bacillus subtilis had no significant effects on BW,ADFI,F/G and tibia length(P>0.05),but significantly increased ADG(P<0.05).Interaction between the PAM and Bacillus subtilis had no significant effects on the ADFI and tibia length of growing laying hens(P>0.05),but had significant effects on the BW,ADG,and F/G(P<0.05).(2)Adding 0.2%,0.4%and 0.6%PAM in the diet had no significant effects on relative intestinal length of growing laying hens(P>0.05).The effects of the relative intestinal length was not significant by adding 250mg/kg and 500mg/kg Bacillus subtilis in the diet(P>0.05).Interaction between the PAM and Bacillus subtilis had no significant effects on the relative intestinal length(P>0.05).(3)Dietary PAM had no significant effects on the morphological structure of duodenum,crypt depth of jejunum,and crypt depth and villus height/crypt depth(V/C)of ileum of growing laying hens(P>0.05),while significantly increased the villus height and V/C of the jejunum(P<0.05),and had the tendency of increasing villus height of the ileum(P=0.063).Dietary Bacillus subtilis had no significant effects on the morphological structure of duodenum,villus height of jejunum and the villus height and crypt depth of ileum(P>0.05),but had significant effects on crypt depth and V/C of jejunum and V/C of ileum(P<0.05).Interaction between the PAM and Bacillus subtilis had no significant effects on the morphological structure of duodenum and the crypt depth and V/C of ileum and the crypt depth of jejunum(P>0.05),but significantly increased the V/C of jejunum(P<0.05),had the tendency of increasing the villus height of the jejunum(P=0.059)and the villus height of ileum(P=0.051).(4)Dietary PAM had no significant effects on the lipase activity of duodenum of growing laying hens(P>0.05),and there was a tendency to increase amylase activity(P=0.078).Adding 250 mg/kg and 500 mg/kg Bacillus subtilis in diet had no significant effects on the lipase activity of duodenum(P>0.05)but significantly increased amylase activity(P<0.05).Interaction between the PAM and Bacillus subtilis significantly increased the lipase activity and amylase activity of duodenum(P<0.05)..(5)Dietary PAM had no significant effects on the apparent digestibility of dietary phosphorus and energy of growing laying hens(P>0.05),had the tendency of increasing the apparent digestibility of calcium(P=0.086);Supplement of 250mg/kg and 500mg/kg Bacillus subtilis had no significant effects on the apparent digestibility of dietary calcium,phosphorus and energy(P>0.05);Interaction between the PAM and Bacillus subtilis had no significant effects on the apparent digestibility of dietary calcium,phosphorus and energy(P>0.05).(6)Adding 0.2%,0.4%and 0.6%PAM to the diet could significantly reduce the content of E.coli of cecum(P<0.05),significantly increased the content of bifidobacterium and lactobacillus(P<0.05).Dietary Bacillus subtilis had no significant effect on the content of E.coli of cecum(P>0.05),but 500mg/kg Bacillus subtilis could significantly increase the content of bifidobacterium and lactobacillus of cecum(P<0.05.Interaction between the PAM and Bacillus subtilis had tendency of reducing the content of E.coli and increasing the content of lactobacillus(P>0.05),but had significant effects on the content of bifidobacterium of cecum(P<0.05).(7)Dietary PAM had no significant effect on serum IgM content and immune organ index of growing laying hens(P>0.05),but significantly increased serum IgA and IgG content(P<0.05).Adding Bacillus subtilis to the diet had no significant effects on the serum IgA content and immune organ index(P>0.05),but significantly increased the serum IgG and IgM content(P<0.05).Interaction between the PAM and Bacillus subtilis had no significant effects on the serum IgA,IgM content and immune organ index(P>0.05),while significantly affected the serum IgG content(P<0.05).In a word,it is showed that the additive combination of 0.4%PAM and 250mg/kg(5×10~9cfu/kg)Bacillus subtilis in the diet could better promote the growth of growing laying hens,improve the structure of the small intestine,promote organism to digest the nutrients,and regulate the microecological balance of the intestine and improve the immunity. |
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