Lactobacillus: Strain and Supplemental Level on Growth Performance,Immune Function and Intestinal Structure of Broilers

The experiment was conducted to study the effects of homology Lactobacillus preparation with different strains and supplemental levels in diets on growth performance,immune function and intestinal structure of broilers.The objective of this study was to compare the application effects of different strains and to find the suitable supplemental level in diets of broilers.A total of 288 one-day-old healthy AA broilers were randomly assigned to 6 groups with 4 replicates per group and 12 broilers per replicate.The number of live lactic acid bacteria in Lactobacillus preparation was between 5×108 CFU/g and 6×108 CFU/g.The experimental treatments were divided as follows: group Ⅰ,the control,basal diet;group Ⅱ,the antibiotic,basal diet+0.01% flavomycin;group Ⅲ,basal diet+0.2% L.graminis preparation;group Ⅳ,basal diet+1.0% L.graminis preparation;group Ⅴ,basal diet+0.2% L.gasseri preparation;group Ⅵ,basal diet+1.0% L.gasseri preparation.The number of live lactic acid bacteria in Lactobacillus preparation was equivalent between group Ⅲ and group Ⅴ,and between group Ⅳ and group Ⅵ,and they were 1×106 and 5×106 CFU/g,respectively.The experiment lasted for 28 days.The results showed as follows: 1) the supplementation of Lactobacillus in the diet could improve growth performance of broilers to some degree.Supplementation of 0.2% and 1.0% Lactobacillus in the diet could both increase the average daily gain and decrease feed/gain of broilers aged from 1 to 28 days(P0.05).There was no significant difference between different strains at the same supplemental level(P0.05),but the effects of 1.0% groups were better than those of 0.2% groups in the same strain(P0.05).2) The contents of IgG and IgA in serum of broilers in Lactobacillus groups were improved to some degree,except for IgA content in 1.0% groups at week 4,they were higher than those in the control group at week 2 and 4(P0.05),but there were no significant differences among 0.2% groups and the control group,and between different strains at the same supplemental level(P0.05).3) At week 2 and 4,T lymphocytes proliferative response in peripheral blood of broilers in 1.0% groups was significantly higher than that in the control group(P0.05),except for the control group,there were no significant differences among the other groups(P0.05).4) About the height of small intestinal villi of broilers fed with Lactobacillus,only 1.0% L.graminis preparation group at week 2,0.2% and 1.0% L.graminis preparation groups and 1.0% L.gasseri preparation group at week 4 were significantly higher than the control group(P0.05);about crypt depth,1.0% groups were significantly lower than the control group at week 2(P0.05),and 0.2% and 1.0% L.graminis preparation groups were significantly lower than 0.2% L.gasseri preparation group at week 4(P0.05).In conclusion,homology Lactobacillus can effectively improve growth performance,immune function and intestinal structure of broilers.For the same strain,the effects of 1.0% supplementation are better than those of 0.2% supplementation,and the effects of L.graminis supplementation are better than those of L.gasseri supplementation.