Submitted to: Asian-Australasian Journal of Animal Sciences
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/30/2014
Publication Date: 6/1/2014
Publication URL: http://handle.nal.usda.gov/10113/58954
Citation: Lee, K.W., Lillehoj, H.S., Lee, S.H., Jang, S.I., Park, M.S., Bautista, D.A., Ritter, G.D., Lillehoj, E.P. 2014. Effect of dietary antimicrobials on immune status in broiler chickens. Asian-Australasian Journal of Animal Sciences. 25(3):382-92. doi: 10.5713/ajas.2011.11259. Interpretive Summary: Gut bacteria provides beneficial effects towards poultry health by influencing various aspects of their immune cells. There is increasing scientific evidence to show how the management style and the farm environment where commercial chickens are raised affect the gut bacteria population. Furthermore, drugs that have been commonly used to control parasitic infections have also been shown to influence gut bacterial population. In this study, ARS scientists collaborated with farm veterinarians to investigate the effect of the combination of different drugs on the developing poultry immune system. The results showed that the type of drugs that are being used in disease control can have different effects on the developing gut immune system and poultry immune response to pathogens. This finding will help field veterinarians develop effective management strategies to reduce economic loss in the poultry industry due to disease.
Technical Abstract: The present experiment was conducted to evaluate the effect of dietary antimicrobials (anticoccidials plus antibiotic growth promoters) on the development of post-hatch immune systems in commercial broiler chickens. One hundred and five day-old broiler chicks were raised on the used litter and provided non-medicated (NONE) diet or medicated diets with either diclazuril (DECX) or monensin (COBN), in combination with bacitracin methylene disalicylate and roxarsone. Immune parameters examined included concanavalin A (ConA)-stimulated splenocyte proliferation, intestine intraepithelial lymphocytes (IELs) and splenic lymphocyte subpopulations, and cytokine mRNA transcripts in intestine mucosa and spleen. It was found that ConA-stimulated proliferation was low in DECX group at day 14, but high in COBN group at days 25 and 43, compared with the NONE group. Of note, dietary antimicrobials altered the percentages of various immune cells subpopulations expressing macrophages, B cells, and T cell subsets in IELs and spleen, and the levels of cytokine mRNA transcripts in intestine and spleen, compared with the non-medicated control group. It is clear from this study that coccidiosis control programs in combination with antibiotic growth promoters can modulate the development of post-hatch immune systems of commercial broiler chickens raised on the used litter.