Genetic Parameters and Genome-Wide Association Study of Newcastle Disease Response Traits in Tanzania and Ghana Local Chicken Ecotypes

Local chicken production is of great importance to African households but faces major threats due to devastating Newcastle disease (ND) outbreaks that can cause significant economic losses. Newcastle disease also remains a threat in the US, as illustrated by recent outbreaks in domestic poultry in California. This study was conducted in two countries, Ghana and Tanzania, where three ecotypes in each country were challenged with a lentogenic (vaccine) strain of the ND virus and various response traits, including growth, anti-ND virus antibody levels, and viral load were recorded. We estimated variance components and performed a genomewide association study (GWAS) using 2839 birds. Moderate heritability estimates (0.15-0.55) for the above traits indicated that selection to improve these breeds/ecotypes for resistance to NDV could be feasible. GWAS results revealed several genomic regions that explained ≥0.5% of the genetic variance in response to ND virus. Ongoing research is establishing relationships of ND vaccine response with response to velogenic ND virus challenge.