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United States Department of Agriculture

Agricultural Research Service

2009 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.

3.Progress Report
Progress has been made toward the development of immune assays for measuring heterophil responses to stress and infection. We have documented the deleterious effects of transporting fast-growing turkeys to larger facilities on physiology, immunity, and production values. We have determined that ascorbic acid has differential effects on slow-growing and fast-growing turkeys.

1. Feeding natural fatty acids reduces food-borne pathogens in poultry: Campylobacter and Salmonella cause human food-borne illness, and epidemiological evidence indicates poultry and poultry products as a significant source of human infection. Reducing these pathogens in poultry would reduce contamination of food products. Collaborative studies by scientists in the Poultry Production and Product Safety Research Unit with University of Arkansas and University of Connecticut demonstrated prophylactic and therapeutic efficacy of feed-supplemented fatty acid, caprylic acid, against Campylobacter and Salmonella in poultry. Antoibiotic alternatives to reducing these pathogens are an important strategy to improving food safety of poultry production in the US.

2. Fast growing turkeys more susceptible to transport stress: Scientist in the Poultry Production and Product Safety Research Unit determined that transport stress and Escherichia coli challenge were more deleterious in a line of turkeys genetically selected for increased 16-week body weight when compared to its slow-growing parent line. This suggests that modern commercial turkey lines may become increasingly susceptible to stress-induced immunosupression and resulting opportunistic bacterial infections as selection continues for fast growth. The transport stress model mimicked the commercial practice of moving poults from the brooder house to a larger grow-out house at 5 weeks of age. The fast-growing turkeys that were transported and challenged were unable to eliminate E. coli from both the air sac and liver at 3 days post-challenge. Alternative management systems that allow poults to remain in the same facility throughout production may improve turkey health and the safety of turkey products.

3. Ascorbic acid may increase bacterial colonization in fast-growing turkeys: Ascorbic acid (Vitamin C) has previously shown both good and bad effects in stress and disease models. Scientists in the Poultry Production and Product Safety Research Unit determined that a 24-hour ascorbic acid treatment prior to transport stress was able to modulate the levels of stress hormone (corticosterone) in a slow-growing parent line of turkeys, but not in turkeys selected for fast growth. Ascorbic acid decreased the heterophil/lymphocyte ratio, which is a way to measure stress in birds, in the fast-growing line but not in the parent line, and this decrease was associated with a failure to clear E. coli from the air sac 3 days post-challenge. This research provides evidence of the need for caution when supplementing fast-growing poultry with ascorbic acid.

4. Yeast extract modulates bacteria-killing cells in transport stressed turkeys: Yeast extracts contain biological response modifiers that may be useful as alternatives to antibiotics for controlling pathogens in poultry production and preventing the negative effects of production stressors. Scientists in the Poultry Production and Product Safety Research Unit discovered that a yeast extract feed supplement (Alphamune) was able to increase the percentages of bacteria-killing cells and the ability of these cells to kill bacteria, and these changes were correlated with a decrease in the isolation of E. coli from both airsac and liver of birds fed the supplemented diet. In addition, yeast extract modulated the dramatic increase in activity of bacteria-killing cells due to transport stress. While activation is an important component of the innate immune response, the bacteria-killing cells are also responsible for inflammatory tissue damage. This study suggests that yeast extract supplementation may help to modulate the stress response in turkeys challenged with E. coli and subjected to transport stress.

5. Environmental exposure to E. coli can increase colonization of turkeys with the food pathogen Listeria monocytogenes: Scientists in the Poultry Production and Product Safety Research Unit have found that concurrent environmental exposure to an Escherichia coli challenge increased L. monocytogenes colonization of joint tissues in birds that were immunosuppressed with dexamethasone. Transport stress of challenged birds decreased L. monocytogenes colonization of joint tissues in the same study. This emphasizes the bi-phasic nature of the stress response, in that severe stress can be immunosuppressive while moderate stress can be beneficial. These results suggest that environmentally acquired L. monocytogenes can transiently colonize the joint tissues of severely stressed turkeys and may be a sporadic source of contamination of processing plants with a persistent type of L. monocytogenes.

6. Dexamethasone immunosupression results in high incidence of dermatitis: Scientist in the Poultry Production and Product Safety Research Unit documented that a dexamethasone (Dex) model for stress-induced immunosupression results in cellulitis lesions characteristic of the emerging disease clostridial dermatitis of turkeys. This disease results in high levels of mortality of production age birds. The high incidence of dermatitis in Dex-treated birds (33-72%) and the prevalence of this production problem in male turkeys nearing market age, suggests that production stress is involved in the etiology and that a stress challenge model may be useful for development of preventative treatment.

7. Quantitative method for measuring avian defensins: Defensins are known to be antimicrobial peptides, but all of their physiological actions are not known. Thus, they have great potential for use in food safety protecting against microbial agents. To realize this potential they need to be understood better. Scientists at the Poultry Production and Products Safety Research Unit in Fayetteville, Arkansas, characterized bacterial-killing peptides that were isolates from chicken and turkey blood cells. Using these peptides, called avian beta defensins-2 (AvBD2), similar peptides were identified in pheasant and quail, purified from bone marrow of the respective species, and sequenced using mass spectrometry. Using chemical modification and mass spectrometry, a method was developed to determine the amount of these peptides following stimulation of blood cells with different immunomodulating agents. Besides defensins being produced by heterophils, the cells that fight infection, they can be useful as biomarkers of stress and disease.

Review Publications
Dutta, V., Huff, G.R., Huff, W.E., Johnson, M.G., Nannapaneni, R., Sayler, R.J. 2008. The effects of stress on respiratory disease and transient colonization of turkeys with Listeria monocytogenes Scott A. Avian Diseases. 52(4):581-589.

Solis De Los, S.F., Donoghue, A.M., Venkitanarayanan, K., Metcalf, J.H., Reyes-Herrera, I., Dirain, M.L., Aguiar, V.F., Blore, P.J., Donoghue, D.J. 2009. The natural feed additive caprylic acid reduces Campylobacter jejuni colonization in market aged broiler chickens. Poultry Science. 88:61-64.

Kannan, L., Rath, N.C., Liyanage, R., Lay, J.O. 2009. Direct screening identifies mature beta-defensin 2 in avian heterophils. Poultry Science. 88(2):372-379.

Lorenzoni, A.G., Erf, G.F., Rath, N.C. 2009. Cellular component of lavage fluid from broilers with normal versus aerosol-primed airways. Poultry Science. 88(2):303-308.

Anup, K.J., Sageetha, A.B., Anu, C.S., Amalaradjou, M.R., Darre, M.J., Khan, M.A., Hoagland, T.A., Schreiber, D.T., Donoghue, A.M., Donoghue, D.J., Venkitanarayanan, K. 2009. Prophylactic supplementation of caprylic acid in feed reduces Salmonella enteritidis colonization in commercial broiler chicks. Journal of Food Protection. 72(4):722-727.

Durairaj, V., Okimoto, R., Rasaputra, K.S., Clark, F.D., Rath, N.C. 2009. Histopathology and serum clinical chemistry evaluation of broilers with femoral head separation disorder. Avian Diseases. 53(1):21-25.

Rath, N.C., Xie, H., Huff, W.E., Huff, G.R. 2008. Activation of macrophage and heterophil function by ovotransferrin, an avian acute phase protein. In: Muller, G.V., editor. New Immunology. New York, NY: Nova Science Publishers. p. 95-108.

Huff, G.R. 2009. Keynote symposium - avian influenza: Vectors, vaccines, public health, and product marketability introduction and welcome. Poultry Science. 88(4):835-836.

Shaniko, S., Agim, S., Huff, G.R., Kaiser, P. 2009. Effects of chronic and repeated coritcosterone administration in rearing chickens on physiology, the onset of lay and egg production in hens. Physiology and Behavior. 98(1-2):73-77.

Solis De Los Santos, F., Donoghue, A.M., Venkitanarayanan, K., Metcalf, J.H., Dirain, M.L., Aguiar, V.F., Reyes-Herrera, I., Blore, P.J., Donoghue, D.J. 2008. Therapeutic supplementation of caprylic acid in feed reduces Campylobacter jejuni in broiler chicks. Applied and Environmental Microbiology. 74(14):4564-4869.

Anup, K.J., Darre, M.J., Hoagland, T.A., Schreiber, D., Donoghue, A.M., Donoghue, D.J., Venkitanarayanan, K. 2008. Antibacterial effect of Trans-cinnamaldehyde on Salmonella Enteritidis and Campylobacter jejuni in chickens drinking water. Journal of Applied Poultry Research. 17(4):490-497.

Last Modified: 12/1/2015
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