2011 Annual Report
1a.Objectives (from AD-416)
The objectives of this work include: 1)Determine the impact of stress on the immune response and on colonization of foodborne pathogens in turkeys; 2)Optimize strategies for decreasing the impact of stress on colonization
of turkeys with pathogens of food safety importance.
1b.Approach (from AD-416)
We hypothesize that the response to common stressors of commercial turkey production, including Escherichia coli respiratory disease (airsacculitis), moving and transport, and temperature extremes, can increase pre-harvest contamination of turkeys with pathogens of food safety importance, and that basic understanding of how turkey immunity is affected by stress will lead to the development and application of practical strategies to improve product safety. Because stress has been shown to both increase disease resistance at low levels and decrease disease resistance at high or sustained levels, its effects on food safety have been difficult to quantify. We have developed transport stress and cold stress models which result in repeatable levels of stress-induced infection of turkeys with E. coli. We will use these models to study the colonization of turkeys with other bacteria of food safety importance. Cell culture studies of the interaction between bacterial pathogens and primary turkey synovial cells, macrophages, and heterophils, from normal and stressed animals will provide basic data and systems for testing the efficacy of therapeutic and prophylactic products to modulate the stress response, improve disease resistance, and decrease carcass contamination with pathogens. Novel non-antibiotic interventions will include antimicrobial peptides and acute phase proteins that will be developed using exploratory analysis of physiological reactions in our stress models as described in the previous section. These products will be incorporated into stress models; however variations in both dosage and timing relative to stressor will be emphasized in multiple experiments to maximize production gains while minimizing pathogen contamination.
The data generated from this research project has consistently indicated that production stressors can both increase and decrease the colonization of turkeys with foodborne pathogens. The severity of stress is the tipping point that determines whether the stress will be beneficial or detrimental. Severe stress or multiple concurrent stressors will increase colonization in many individuals, while low levels of stress appear to decrease pathogen colonization. We have determined that this tipping point is also affected by the growth rate of the individual, with fast-growing turkey lines more sensitive to environmental changes and more likely to harbor pathogens as compared to slow-growing lines. Strategies for decreasing the impact of stress have been developed. These include inclusion of yeast extract feed additives prior to anticipated stress events and avoiding the movement and/or transportation of turkeys during production. Alternative management systems that allow poults to remain in the same facility throughout production may improve turkey health and the safety of turkey products. There is a lack of diagnostic reagents that are specific for determining the health and immune status of turkeys. This project has generated proteomic and mass spectrometric approaches to purify and identify the mature forms of antimicrobial peptides beta defensin (gallinecin-2) in both chicken and turkey heterophils and thymosin-beta in macrophages. Methods were also developed to determine the amount of these peptides following stimulation of blood cells with different immunomodulating agents, resulting in technology that will aid future research in determining the efficacy of strategies for decreasing the impact of stress on pathogen colonization. This work has been greatly impacted by the increasing cost of turkey feed, and further work will necessarily rely on using more efficient model systems to decrease the cost of research. Over the course of this project extensive studies have evaluated natural plant extracts' ability to reduce enteric foodborne pathogens in poultry. Data from our laboratory demonstrates that natural compounds have the potential to reduce pathogens in poultry, both prophylactically and therapeutically. In addition to extensive work with traditional poultry production, we have also targeted the organic poultry market, which restricts antibiotics use.
Antibacterial effect of natural plant extracts on food safety pathogens in chickens. Salmonella and Campylobacter are major foodborne pathogens transmitted through poultry products colonizing the chicken intestinal tract, leading to contamination of carcasses during slaughter. In collaboration with the University of Connecticut and the University of Arkansas, we investigated the antimicrobial efficacy of plant extracts from cinnamon bark, oregano, and clove oil against Salmonella and Campylobacter in chicken intestinal contents. Results demonstrated that all of the plant-derived extracts were highly bactericidal. These finding may provide a safe strategy for reducing foodborne pathogens in poultry products.
Japanese quail selected for different stress responses differ in pathogen colonization. Contamination of poultry with Salmonella may increase as a result of production stressors. Salmonella was isolated from significantly fewer individuals of a quail line selected for a low hormone response to restraint stress as compared to both unselected quail and a quail line selected for a high response. This research, done in collaboration with USDA/ARS/NADC, supports previous studies suggesting that these quail lines will be useful as a model for determining the impact of production stressors on foodborne pathogen colonization in commercial poultry, and will enable efficient and cost-effective testing of strategies for decreasing the impact of stress.
Rasaputra, K., Liyanage, R., Lay, Jr, J., McCarthy, F., Rath, N.C. 2010. Tibial dyschondroplasia associated proteomic changes in chicken growth plate cartilage. Avian Diseases. 54(4):1166-1171.
Donoghue, A.M., Donoghue, D.J. 2010. Probiotics as Natural Solutions to Enteric Pathogens with Organic Production Implications in Poultry. E.M. Binder, editors.World Nutrition Forum: the future of animal nutrition. Nottingham, England: Nottingham Press. p. 211-215.
Zhou, Z.L., Rath, N.C., Huff, G.R., Huff, W.E., Rasaputra, K.S., Salas, C., Coon, C.N. 2011. Bone characteristics of 16 wk-old turkeys subjected to different dietary regimens and simulated stress. International Journal of Poultry Science. 10(5):332-337.
Kannan, L., Rath, N.C., Liyanage, R., Lay, Jr., J.O. 2010. Effect of toll-like receptor activation on thymosin beta 4 production by chicken macrophages. Molecular and Cellular Biochemistry. 344(1-2):55-63.
Metcalf, J.M., Donoghue, A.M., Ventinarayanan, K.H., Reyes-Herrrera, I.H., Aguair, V.F., Blore, P.J., Donoghue, D.J. 2011. Water administration of medium-chain fatty acid caprylic acid produced variable efficacy against cecal Campylobacter jejuni concentrations in broilers. Poultry Science. 90:494-497.
Kollannor, J.A., Darre, M.J., Donoghue, A.M., Donoghue, D.J., Venkitanarayanan, K. 2010. Antibacterial effect of trans-cinnamaldehyde, eugenol, carvacrol, and thymol on Salmonella Enteritidis and Campylobacter jejuni in chicken cecal contents in vitro. Journal of Applied Poultry Research. 19:237-244.
Donoghue, A.M., Blanco, J. 2010. Sperm viability - Determination of sperm viability using fluorescence microscopy. In: Bakst, M.R., Long, J. A. editors. Techniques for Semen Evaluation, Semen Storage and Fertility. 2nd edition. St. Paul, MN: Midwest Poultry Federation. p. 39-41.