Immunocompetence status of coloured plumage naked neck versus normally feathered broilers in tropical climate

The study was undertaken to evaluate the effect of naked neck gene on mortality, cell mediated and humoral immune response in coloured plumage broiler population. The homozygous naked neck (Na/Na) broiler population exhibited lower mortality as compared to heterozygous naked neck (Na/na) and normally feathered broiler population. The humoral immune response was measured against (1% v/v) sheep red blood cells (SRBC) for total haemagglutinin antibody (HA), 2 mercaptoethanol resistance antibody (MER or IgG) and 2 mercaptoethanol sensitive antibody titre (MES or IgM) titre on 7 days post-immunization. The titre was expressed as log2 of the highest dilution which shows complete haemagglutination. The Na/na broilers showed comparatively higher mean HA value than Na/Na and na/na broilers. The Na/Na and Na/na broilers had significantly higher MES antibody titre as compared to na/na broilers. The na/na genetic group had significantly higher MER titre than Na/na and comparatively higher than Na/Na broilers. In vivo cell response to PHA-P, measured as Foot Index (FI) in mm expressed comparatively higher response in Na/na and Na/Na broilers as compared to na/na broilers. The result of present study suggested that coloured plumage naked neck broilers had better immune response as compared to normally feathered broiler.