Effects Of Compound Probiotics On Growth,Immunity Indices And Intestinal Flora In Broilers

In order to investigate the nutritional manipulation effects of different combinations of probiotics on AA broilers,the single-factor test and the response surface experiments design was carried out.The compound freeze-dried protectant agert added to the sludge of Bacillus subtilis,Saccharomyces cerevisiae and Lactobacillus acidophilus to improve the lyophilization survival rate.The addition proportion of Bacillus subtilis,Saccharomyces cerevisiae,Lactobacillus acidophilus and Bifidobacterium lactis was explored by the simulating digestive fluid test of gastroin intestinal.The feeding experiments was conducted witha single-factor complete randomized design,320 healthy 1-day-old male AA broilers were randomly divided into 4groups with 4 replicates in each group and 20 broilers per replicate.Group I was control group and feeding basal diet.Group II was added 1 000 mg/kg compound probiotics to basal diet with a ratio of 2:1:1:1(Bacillus subtilis containing antimicrobial peptide:Saccharomyces cerevisiae:Lactobacillus acidophilus:Bifidobacterium lactis),group III was added 1 000 mg/kg compound probiotics to basal diet with a ratio of 1:2:1:1(Bacillus subtilis containing antimicrobial peptide:Saccharomyces cerevisiae:Lactobacillus acidophilus:Bifidobacterium lactis),group IV was added 1 000 mg/kg compound probiotics to basal diet with a ratio of 1:1:1.5:1.5(Bacillus subtilis containing antimicrobial peptide:Saccharomyces cerevisiae:Lactobacillus acidophilus:Bifidobacterium lactis).The trial period was 42 days.The serum biochemical index,immune index,intestinal mucosa morphology and intestinal microflora of AA broiler were determined to discussed the optimum ratio of compound probiotics,which provided the data reference for the practical application of compound probiotics in the broiler industrial chain.The experimental results were showed as follows:(1)Optimum formula of freeze-dried protectant for Bacillus subtilis is skim milk powder7.13%,trehalose 6.16%,monosodium glutamate 0.93%.Optimum formula of freeze-dried protectant for Saccharomyces cerevisiae is maltodextrin 8.74%,trehalose 3.93%,sorbitol 4.22%.Optimum formula of freeze-dried protectant for Lactobacillus acidophilus is skim milk powder9.52%,monosodium glutamate 1.92%,D-sodium isoascorbate 2.17%.According to the results of the tolerance test of simulated gastroin intestinal digestive fluid,the dosages are as follows:Bacillus subtilis 9.0×10~8 cfu/g,Saccharomyces 4.0×10~8 cfu/g,cerevisiae Lactobacillus acidophilus 1.0×10~100 cfu/g,Bifidobacterium lactis 1.0×10~100 cfu/g.(2)The compound probiotics could improve the growth performance,slaughter performance and nutrient metabolic rate of broilers.At 1 to 42 days of age,the average daily feed intake and average daily gain of broilers in group III were the highest,and the ratio of feed to gain was the lowest,which were significantly different from group I(P<0.05).The Dressing percentage,Semi-eviscerated yield,Eviscerated yield and Leg muscle yield of group II,group III and group IV is higher than that of group I(P>0.05);The breast muscle percentage in groups III and IV was significantly higher than that in group I(P<0.05).The CF and P nutrient apparent digestibility of each group was not significant(P>0.05);The DM,CP,EE and Ca nutrient apparent digestibility of group II,group III and group IV was significantly higher than that of group I(P<0.05).(3)The compound probiotics could improve the serum biochemical indexes levels and immune index of broilers.At the age of 21 days,the TP,ALB,ALT and BUN of each group was not significant(P>0.05).At the age of 42 days,the ALB,ALT and BUN of each group was not significant(P>0.05);The TP of group II,group III and group IV was significantly higher than that of group I(P<0.05).At 21 and 42 days of age,the spleen index,thymus index,Bursa index and IgG of each group was not significant(P>0.05).The IgA of group III was significantly higher than that of group I(P<0.05).(4)The compound probiotics could improve the intestinal mucosa morphological structure and intestinal microflora.The intestinal mucosa morphological structure of group II,group III and group IV is higher than that of group I(P>0.05).At the age of 7 days,Escherichia coli of group I is significantly higher than that of group II,group III and group IV(P<0.05);Salmonella of groups I and II is significantly higher than that of group IV(P<0.05);Lactobacillus of group IV is significantly higher than that of groups I(P<0.05).At the age of 14 days,Salmonella of group IV is significantly higher than that of group I,group II and group III(P<0.05).At the age of 21days,Lactobacillus of group IV is significantly higher than that of groups I(P<0.05).At the age of 28 days,Escherichia coli of group I is significantly higher than that of groups III and IV(P<0.05).At the age of 42 days,Escherichia coli of group I is significantly higher than that of groups III(P<0.05).In conclusion,adding compound probiotics in diet can increase the growth performance,nutrient apparent digestibility and immunologic function,improve slaughter performance,intestinal mucosa morphological structure and intestinal microflora,and supplemented with 1000 mg/kg proportions of 1:2:1:1(Bacillus subtilis containing antimicrobial peptide:Saccharomyces cerevisiae:Lactobacillus acidophilus:Bifidobacterium lactis)compound probiotics can reach the best effects.