Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2010
Publication Date: 4/5/2010
Citation: Lee, K.W., Lee, S.H., Lillehoj, H.S., Li, G.X., Jang, S.I., Park, M.S., Kim, D.K., Lillehoj, E.P., Neumann, A.P., Rehberger, T.G., Siragusa, G.R., Babu, U.S. 2010. Effects of Direct-Fed Microbials on Growth Performance, Gut Morphometry, and Immune Characteristics in Broiler Chickens. Poultry Science. 89:203-216. Interpretive Summary: Development of safe and effective alternative methods is becoming a priority for poultry industry due to increasing concerns about increasing drug-resistance of poultry pathogens. Although drugs have been traditionally used to control many diseases of poultry, the results of recent ARS study indicate a potential non-drug application of dietary strategy to control mucosal pathogens of poultry. In this report, ARS scientists in collaboration with scientists at Danisco, University of Maryland and U.S.FDA investigated immunostimulating effects of direct-fed microbial (DFM) food supplements. Feeding broiler chickens with DFM-supplemented diets altered intestinal morphometric measurements with increased villus height and crypt depth compared with non-DFM fed controls. Certain DFM supplementation enhanced innate immunity and improved various aspects of host intestinal immune response. These results provide a rational scientific basis to utilize DFMs as immunomodulating agents in poultry production to reduce the use of antibiotics.
Technical Abstract: This study was conducted to compare growth performance, gut morphometry, and parameters of local and systemic immunity in broiler chickens fed for 22 consecutive days with a diet supplemented with one of eight Bacillus spp. as a direct-fed microbial (DFM), a commercial product incorporating three DFMs , or a non-supplemented diet. DFMs did not significantly modify body weight gain and most failed to affect serum antibody levels in response to immunization with a recombinant Eimeria protein. However, altered intestinal morphometric measurements were readily apparent in DFM-fed chickens as revealed by increased villus height and crypt depth compared with non-DFM fed controls. In addition, serum levels of a-1-acid glycoprotein as an inflammatory marker were reduced in DFM-fed birds, while splenic lymphocyte proliferation, intestine intraepithelial lymphocyte (IEL) subpopulations, and cytokine mRNA levels in IELs were increased, decreased, or unchanged compared with controls depending on the DFM used. These results provide a rational scientific basis for future studies to investigate DFMs as immunomodulating agents to enhance host protective immunity against enteric pathogens in broilers chickens.