Submitted to: Asian Australasian Journal of Animal Sciences
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/15/2014
Publication Date: 2/28/2014
Publication URL: http://handle.nal.usda.gov/10113/59028
Citation: Lee, K.W., Lillehoj, H.S., Jang, S.I., Lee, S.H., Bautista, D.A., Siragusa, G. 2014. Effect of Bacillus subtilis-based direct-fed microbials on immune status in broiler chickens raised on fresh or used litter. Asian Australasian Journal of Animal Sciences. 26(11):1592-7. doi: 10.5713/ajas.2013.13178. Interpretive Summary: Direct-fed microbials (DFMs) are beneficial live microorganisms, which when administered in adequate amounts; confer a health benefit on the host by balancing its intestinal microbes. In many poultry production facilities, DFMs of some type are commonly used to balance gut bacteria and to enhance gut health. Because of increasing information on the role of gut bacteria in the development of host gut immune system, understanding how DFMs interact with beneficial, symbiotic gut bacteria to influence host immune response to pathogens is important. In this report, ARS scientists collaborated with scientists from private industry to investigate the role of DFMs in young chickens that have an immature immune system. The results showed that dietary DFMs clearly enhanced gut health and improved host immune response to pathogens such as Clostridium perfringens. These results further imply the potential application of probiotics such as Bacillus subtillus in chicken diet to modulate immunity and to reduce negative consequence of infectious diseases in growing chickens. This information will help field veterinarians to develop novel strategies to reduce economic losses due to infectious disease.
Technical Abstract: The type of dietary direct-fed microbials (DFMs) or poultry litter could directly influence the composition of gut microbiota. Gut microbiota play an important role in shaping the developing immune system and maintaining homeostasis of the mature immune system in mammal and chickens. The present study was carried out to investigate the interaction between litter, DFMs and immunity in broiler chickens exposed to a field-simulated environment. The immune status of broiler chickens was assessed by serum antibodies against Eimeria spp. and Clostridium spp. and intestinal cytokine mRNA expression. The current experimental design had a 3 × 2 factorial arrangement of treatments with three types of litter: 1) fresh litter and used litter obtained, 2) from a farm with no disease outbreak (used litter) and 3) a farm with the histories of gangrenous dermatitis outbreak (GD litter), and two dietary treatments, with or without DFMs. It was found that either DFM addition or type of litter significantly affected anticoccidial antibody levels of broiler chickens. In general, dietary DFMs increased the anticoccidial antibodies in the fresh-litter raised chickens, but lowered the levels in the GD-litter raised chickens. Serum antibodies against Clostridium perfringens a-toxin were significantly (p<0.05) higher in chickens raised on GD litter compared with those raised on fresh litter. Cytokine mRNA expression was significantly (p<0.05) altered by either the type of litter or DFMs. Of interest, dietary DFMs lowered interferon ', interleukin 2, and IL-8 (CXCLi2) cytokine mRNA expression in chickens raised on fresh litter whereas in GD-litter raised chickens, DFMs increased the cytokines. In conclusion, dietary DFMs can modulate various immune parameters of broiler chickens, but the DFM-mediated effects were dependent upon the type of litter on which the chickens were raised.