Effects Of Different Lactobacillus Strains And Dosage Forms On Growth Performance And Immunity Of Broilers

The experiment was conducted to study the effects of two lactobacillus strains, L.graminis and L. gasseri, made in solid and liquid perparation respectively on growth performance and immune function of young chickens. It aimed to find one suitable state for each lactobacillus strain to make the preparation's function better and also provide a theoretical basis and technical support for the application of lactobacillus preparation in young broiler chickens.A total of 288 one-day-old broiler chickens were assigned randomly into 6 groups with 12 replications of 4 blocks: groupⅠwas the control (basal diets); groupⅡwas antibiotic (basal diets+0.01%flavomycin preparation); groupⅢwas L.graminis solid preparation (basal diets+0.2% L.graminis solid preparation); groupⅣwas L.graminis liquid preparation (basal diets+ L.graminis liquid preparation); groupⅤwas L. gasseri solid preparation (basal diets+0.2% L. gasseri solid preparation); groupⅥwas L gasseri liquid preparation (basal diets+ L gasseri liquid preparation). The experimental period was 28 days, and the growth performance of chicken, bacteria population in cecum and immune functions were determined.The results showed that:(1) Supplementation of lactobacillus preparation significantly increased daily weight gain and feed conversion ratio compared with the control group(P<0.05), and the liquid preparation was better than the solid dosage form state;(2) Additionally, supplementation of lactobacillus liquid preparation significantly increased lactobacillus amount and effectively inhibited population of E.coli in cecum compared with antibiotic group(P<0.05); No significant impact was observed from different lactobacillus dosage forms on growth performance and caecal microflora(P>0.05), but the effects of liquid preparation was better than the effects of solid preparation;(3) The effects of the immune function of broiler chickens:①No significant impact was observed from different lactobacillus dosage forms on immune organ index of the chicken(included thoracic gland, spleen and bursa of fabricius)(P>0.05), but immune organ index in the group of the liquid preparation were improved;②The concentration of immunoglobulin was improved by different lactobacillus dosage forms, the concentration of IgA was improved by the liquid preparation extreme significantly(P<0.01), and the concentration of IgG was improved by L.graminis liquid preparation in the second week(P<0.01);③The concentration of IL-2 was improved by different lactobacillus dosage forms, the concentration of IL-2 was improved by L.graminis liquid preparation in the whole experimental stage(P<0.05);④The concentration of SIgA was improved by different lactobacillus dosage forms, the concentration of SIgA was improved by L.graminis liquid preparation obviously in the second week(P<0.05), the concentration of SIgA was improved by L.graminis and L gasseri liquid preparation extreme obviously compared with antibiotic group in the fourth week(P<0.01);⑤Lymphocyte conversion ratio was reinforced by lactobacillus preparation, the effect of liquid preparation was better than the effect of solid preparation. Generally, the liquid preparation group was a little better than the solid preparation group on the immune function obviously;(4)The mucosal shape of small intestine was improved by the treatment of lactobacillus preparation, the height of intestinal villus and the thickness of intestinal wall were raised, the depth of crypt was reduced but there was no significant difference of mucosal shape between solid preparation group and liquid preparation group.Generally, both two forms of lactobacillus preparation could improve the growth performance and immune function of young broiler chickens and mucosal shape of small intestine, while the liquid preparation group got a better effects and the liquid preparation group of L.graminis obstained the best results.