Genetic parameters and genomic regions associated with growth rate and response to Newcastle disease in local chicken ecotypes in Ghana and Tanzania Local chicken breeds play an important role in the livelihoods of people in both rural and urban areas of Africa. One of the main constraints to the poultry sector in many sub-Saharan countries is disease, with Newcastle disease (ND) being the most important. Because vaccination does not adequately control ND, selective breeding offers an effective complement, provided there is genetic variation in resistance, tolerance and/or response to ND. We investigated this topic by challenging 6 local ecotypes from Ghana and Tanzania with a lentogenic (vaccine) strain of Newcastle disease virus (NDV), then measuring growth, anti-NDV antibody levels, and viral load from hatch to 38 days of age. We estimated variance components and performed a genome-wide association study using 2800 birds genotyped with the 600K Affymetrix chicken genotyping array. Heritabilities were moderate to high (0.14 – 0.55) for all the traits studied, which indicates that selection to improve these breeds for resistance to ND can be feasible. GWAS also revealed several genomic regions that explained ≥0.5% of the genetic variance, including a candidate gene region for antibody response on GGA1. We conclude that all traits investigated in this study appear to be highly polygenic in nature. Future studies will characterize differences between the breeds/ecotypes, determine if large breed-specific quantitative trait loci can be identified, and evaluate the response of the same birds to endemic, velogenic NDV strains. Keywords: Newcastle disease, local chicken ecotypes, disease resistance, immune response.

Esinam Amuzu- Aweh, Boniface Kayang, Amandus Muhairwa, Princess Botchway, Augustine Naazie, George Anning, Rodrigo Gallardo, Terra Kelly, Huaijun Zhou, Susan Lamont, Jack Dekkers

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Biology - Disease Resistance 3, , 774, 2018
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