Direct-Fed Microbials and Their Impact on the Intestinal Microflora and Immune System of Chickens

Direct-fed microbials (DFMs) are live microorganisms which confer a health benefit to the host. The mode of action of DFMs involves multiple mechanisms, including direct inhibition of enteric pathogens and indirectly through competitive exclusion of pathogens by the normal gut microbiota. Additionally, recent basic research efforts have focused on the effects of DFMs on promoting host immunity and on the complex interactions between the gut microflora and immune system development. This review will summarize the latest developments in DFM studies with particular emphasis on the underlying mechanisms of immune enhancement.