1a. Objectives (from AD-416):
Develop DNA markers associated with causative pathogens of necrotic enteritis.
1b. Approach (from AD-416):
DNA markers will be identified first by analyzing genetic differences of disease resistance difference in NE between two genetic lines of poultry; second by analyzing transcriptional profiling based on gene microarray and RNA sequencing, SNP genotyping of NE-related markers using SNP array; and finally validating NE-associated biomarkers in commercial chickens.
3. Progress Report:
The increasing trends of legislative restrictions and voluntary removal of antibiotic growth promoters worldwide has already impacted, and will continue to affect, poultry production and animal health. Necrotic enteritis, an intestinal infection that can be caused by the bacterium, Clostridium perfringens and parasite, Eimeria maxima, is considered among the most important infectious diseases in the current poultry production system globally. The disease an estimated annual economic loss of more than $2 billion, largely due to medical treatment and impaired growth performance. Thus, there is an urgent need to develop rational, alternative, and integrated management strategies to not only control, but also to prevent necrotic enteritis. In order to accomplish these goals, a better understanding of the genetic factors involved in the development of or susceptibility to necrotic enteritis is necessary. During this reporting period, we compared three commercial broiler chicken lines using an experimental disease model of Necrotic enteritis in commercial broiler chickens. Chicks of three different broiler chicken lines, Cobb, Ross, and Hubbard, were orally infected with live Clostridium perfringens or Eimeria maxima and fed a high protein diet to promote the development of experimental disease. Body weight loss, intestinal lesions, and a unique serum protein were measured as parameters of disease susceptibility and to determine immune response by the chickens. Results suggest that Cobb chickens may be more susceptible to Necrotic enteritis in the field compared with the Ross and Hubbard lines. Understanding the genetic mechanisms and identifying DNA markers associated with disease resistance to Necrotic enteritis will lead to a logical DNA marker-based strategy for selection of Necrotic enteritis-resistant chickens.