2008 Annual Report
1a.Objectives (from AD-416)
1) Identify environmental influences and management practices that contribute to the colonization of food-borne pathogens in pre-harvest poultry.
2) Identify environmental influences and factors that contribute to necrotic enteritis (NE) including: Clostridium spp. and parasites (Eimeria) that contribute to the onset of disease.
3) Identify prebiotics and symbiotics (lactose, cottonseed, etc.) that can be utilized as pre-harvest intervention strategies, and determine how chlorate and feed additives such as alfalfa control poultry enteropathogen colonization.
4) Identify environmental or management practices that contribute to antibiotic resistance acquisition and dissemination among and between the various pathogenic and commensal microorganisms found in commercial poultry.
5) Characterize the complex interactions between the innate immune and endocrine systems and develop a more fundamental understanding of the role of gastrointestinal endocrinology on the microbial ecology of the gut of food-producing animals.
1b.Approach (from AD-416)
1) Using a newly constructed (i.e., naive) commercial broiler production facility, we will follow bacterial, viral, protozoan, and fungal movement within the facility from prior to the first placement of birds through several successive production cycles. The movement of these organisms within the environment will be mapped using genetic identification and traditional culture methods.
2) Using a necrotic enteritis (NE) in vivo model developed in our laboratory and a primary cell culture model, we will investigate the interactions of Clostridium with other bacterial populations within the gastrointestinal tract of broilers and the development of NE. We will evaluate these bacterial populations using molecular-based techniques (DGGE, PFGE) in order to determine the dynamics between commensal gut bacterial populations and Clostridium. Additionally, we will examine the toxins produced by Clostridium using tissue culture techniques and Multiplex Polymerase Chain Reactions (PCR).
3) The efficacy of lactose, cottonseed and similar prebiotics and symbiotics will be evaluated under commercial conditions for their ability to reduce food-borne pathogens in poultry. Practical feeding trials will be performed to ascertain the ability of chlorate and alfalfa as alternatives to traditional antimicrobials, and the mode of action of these compounds will be determined. We will also study different quorum sensing autoinducers to determine the effects of biological and synthetic bacterial autoinducer inhibitors on poultry enteropathogens.
4) Utilizing an in vitro bacterial conjugation assay, we will identify flavophospholipol-like compounds (flavophospholipol has been shown to reduce horizontal gene transfer between Enterococci in vitro), that inhibit bacterial conjugation and resistance gene acquisition among gut bacteria.
5) We will characterize specific interactions between the immune and endocrine systems that influence enteropathogen colonization in the gastrointestinal tract of poultry. Microarrays will be utilized to assess fluctuations in key avian hormones that correspond to cytokine expression.
In FY 2008, sampling was initiated in new poultry facilities which, when analyzed, will result in a far better understanding of the overall poultry environment. Research continued to focus on investigations of a probiotic on laying hens and broilers and the benefits of these beneficial bacteria in preventing diseases caused by Clostridium spp. Investigations were largely completed on the efficacy of a pelletized chlorate feed additive in an experimental laboratory poultry facility. In collaboration with ARS scientists at Lubbock, Texas, significant progress was made in studies focused on establishing the impact of Salmonella on the endocrine system; several endocrine factors were identified for future analysis and assay development. (NP 108, Component 1.1, Problem Statement 1.1.4)
Biofilm and Planktonic Communities Inhibit Salmonella Colonization in Poultry:
Colonization of poultry by Salmonella and other food-poisoning microbes remains a serious food safety concern in poultry production, and new methods are needed to reduce the levels at which such colonization occurs. Scientists in the Food and Feed Safety Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, have shown that in laboratory studies, certain biofilm and planktonic communities that reside in the gut of young poultry are very successful in resisting colonization by Salmonella. This accomplishment is important because it establishes that beneficial microbial communities that occur naturally in birds might be manipulated in a manner so as to make them much more effective in pathogen resistance; such would be of particular value if achieved prior to pathogen exposure. This resistance, if maintainable throughout the life of the birds, would have a major impact in assuring that pathogen-free birds reach the processing plant and that pathogen-free poultry meat products are supplied to the consumer. (NP 108, Component 1.1, Problem Statement 1.1.3)
The Lesser Mealworm Beetle is a Mechanical Vector for Salmonella in Poultry:
The lesser mealworm is a common insect that infests commercial poultry houses. While the mealworm does not overtly affect the birds, it is not known what role it might play in the spread of pathogenic or food-poisoning microorganisms within the poultry environment, and particularly the possibility of infecting birds with these microbes. Scientists in the Food and Feed Safety Research Unit at the Southern Plains Agricultural Research Center, College Station, Texas, utilized a method previously developed by project scientists to externally disinfect the beetle, and then showed that relatively short exposures of the beetles to low levels of Salmonella result in the rapid acquisition of viable bacteria into the alimentary canal of the beetle. This accomplishment is important because it demonstrates that current poultry farm management practices can perpetuate beetle infestations and contribute to the dispersal of beetles, and of the pathogens they may harbor. This work will be extended by project scientists to develop biosecurity procedures against the beetle which should ultimately result in less pathogen colonization of the birds and, ultimately, in microbiologically safer poultry meat products reaching the consumer. (NP 108, Component 1.1, Problem Statement 1.1.3)
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Dunkley, C.S., Kim, W.K., James, W.D., Ellis, W.C., McReynolds, J.L., Kubena, L.F., Nisbet, D.J., Ricke, S.C. 2008. Passage rates in poultry digestion using stable isotope markers and INAA. Journal of Radioanalytical and Nuclear Chemistry. 276(1):35-39.
Landers, K.L., Moore, R.W., Dunkley, C.S., Herrera, P., Kim, W.K., Landers, D.A., Howard, Z.R., McReynolds, J.L., Byrd II, J.A., Kubena, L.F. 2007. Immunological cell and serum metabolite response of 60-week-old commercial laying hens to an alfalfa meal molt diet. Bioresource Technology. 99(3):604-608.
Landers, K.L., Moore, R.W., Herrera, P., Landers, D.A., Howard, Z.R., McReynolds, J.L., Byrd II, J.A., Kubena, L.F., Nisbet, D.J., Ricke, S.C. 2008. Organ weight and serum triglyceride responses of older (80 week) commercial laying hens fed an alfalfa meal molt diet. Bioresource Technology. 99(14):6692-6696.
Donalson, L.M., McReynolds, J.L., Kim, W.K., Chalova, V.I., Herrera, P., Gotcheva, V.G., Vidanovic, D., Woodward, C.L., Kubena, L.F., Nisbet, D.J. 2008. In vitro fermentation response of laying hen cecal bacteria to combinations of fructooligosaccharide (FOS) prebiotic with alfalfa and layer ration. Poultry Science. 87(7):1263-1275.
Donalson, L.M., McReynolds, J.L., Kim, W.K., Chalova, V.I., Woodward, C.L., Kubena, L.F., Nisbet, D.J., Ricke, S.C. 2008. The influence of a fructooligosaccharide (FOS) prebiotic combined with alfalfa molt diets on the gastrointestinal tract fermentation, Salmonella Enteritidis infection and intestinal shedding in laying hens. Poultry Science. 87(7):1253-1262.