| Direct fed microbial (DFM) or probiotics are live microbial supplements, which are intentionally administered to animals and human to beneficially improve intestinal function by affecting the composition of the GI microflora. Supplementation of DFM/probiotics have demonstrated to have very promising effects on promoting resistance to diseases, reducing allergic responses, alleviating gut disorders and boosting immunity. The mechanisms, however, are still unclear. Regulation of the composition of microbial communities in the GI tract is a multi-factorial process in which any or all of these numerous forces may come into play. Therefore, it is important to use well defined strains of probiotic bacteria and appropriate biomarkers to evaluate their effects on a specific animal model. Primalac(TM) is a defined bacteria consortium, which has been reported to modulate GI tract structure and energy metabolism in this laboratory. This study is to investigate the mechanisms, by which DFM communicate with GI tract so as to affect histology, immune function, and energy metabolism using the rapidly growing broiler chick model.;The present studies demonstrated a faster rate of antigen specific IgG production and an increase in total sIgA secretion, suggesting a stimulation of Th2 type response. These effects may be attributed to more energy that has been repartitioned to immune system following DFM supplementation. DFM supplementation also has demonstrated a protective effect on GI epithelia, especially to esophagus and crop, and a stimulatory effect on the growth of small intestine, ileal villi as well as microvilli. The increased mucous secretion which may be induced by increased number of bacterial colonization observed may contribute to these beneficial effects. The stimulated Th2 immune function may also help protect epithelium from damage either by pathogens or inflammation. To further understand the molecular mechanisms which may be involved in DFM-mediated changes in the gut, we assayed both ileum and cecum tissues for differences in gene expression using a focus oligo nucleotide array. Analysis of gene array networks identified the IL-27 pathway as the most likely one that may be associated with DFM-mediated changes in the host gene expression in both ileum and cecum.;In summary, it is likely that supplementation of DFM Primalac(TM) can stimulate the development of immune system by modulation of energy repartition and induce protective effects on the GI tract development which result in improved gut morphology and function. |
