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Development of a Disease Model for Gangrenous Dermatitis in Broilers and an Evaluation of Cobb Chickens to the Disease


<OL> <LI> To To establish a working model of Gangrenous dermatitis (GD) in 4- to 8-wk-old broilers; <LI> To To determine the effects of GD in vivo; we will challenge parental lines 12 and 58;<LI> To To challenge experimental chickens from line 59 (high vs. low) and monitor for the development of GD.

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Approach: Our laboratory will collect field isolates from commercial chickens with active GD from 2-3 different geographical locations around the country. Samples will be processed for bacterial isolation under anaerobic conditions. Samples will be tested for purity, and bacterial isolates will be further characterized utilizing the API strip-32A. After we have identified several bacterial candidates (Clostridium septicum, Clostridium perfringens type A, and Staphylococcus aureus), we will combine these bacteria in a chemostat utilizing continuous flow culture methodologies. We will also take birds exhibiting clinical signs of GD and place their intestinal contents into a separate chemostat. Utilizing this in vitro methodology will potentially allow us to re-create the mixed microflora populations of gastrointestinal system of GD birds. There are many influential factors that contribute to GD. As we begin the developmental stages of the model, we will carefully introduce new parameters so that we can re-create a compatible field model. We will utilize the information that we have learned from our previous experience in developing our Necrotic enteritis model and apply these same methodologies to GD. We will carefully evaluate parameters which will include: environment, antibiotic growth promoters, bacterial populations, viruses, protozoa, feed composition, and vaccination programs. Throughout the process of model development, we will continually evaluate data collected to proceed as accurately as possible. After a disease model has been created, we will evaluate several parental lines of Cobb-Vantress, Inc.

McReynolds, Jackson
USDA - Agricultural Research Service
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