A novel Lactobacillus plantarum strain P-8 activates beneficial immune response of broiler chickens

To investigate whether Lactobacillus plantarum P-8 may be used as an alternative to antibiotics in the broiler chicken diet, we compared P-8 and antibiotics for their immunobiotic properties and their effect on growth performance of broiler chickens in a 42-day trial. The results showed that P-8 provided similar benefits in weight gain, feed intake and feed efficiency as antibiotics did. Importantly, P-8 activated protective immune responses of the broilers while antibiotics lacked this effect. P-8 induced higher fecal secretory IgA (sIgA) levels on day 42 (P ≤ 0.027) and IgA+ lymphocytes in the jejunum and Peyer's patches (PP) (P < 0.001) compared to antibiotic treatment. Antibiotics reduced the IgA+ lymphocytes in jejunum and PP on day 42 compared to the control. P-8 increased CD3+ T cells in the small intestinal tissues in most test situations whereas antibiotics had fewer CD3+ cells in PP and cecal tonsil compared with the control broilers at the end of the trial. In addition, P-8 increased CD4+ T cells significantly in the intestinal tissues compared to both antibiotics and the control (P < 0.0052). Both Th1 and Th2 cytokine expression were enhanced by P-8 on day 14, consistent with the clinical trial results showing probiotic benefits in diseases. Antibiotics up- and down-regulated interleukin (IL)-2, IL-4 and IL-10 transcripts in an age-dependent manner, and showed anti-inflammatory potential. These data indicate that P-8 may provide protective immune response to broilers while maintaining similar growth performance and may be a potential alternative to antibiotics supplemented in chicken feeds.