Genetic analysis of immunocompetence and growth performance in a selected strain of Rhode Island Red chicken

This investigation was aimed to assess genetics of immunocompetence (IC) and growth performances in a selected strain of Rhode Island Red (RIR) chicken maintained at Central Avian Research Institute, Izatnagar. Five weeks aged pedigreed RIR chicks (265) were immunized against 1% (v/v) sheep red blood cells (SRBCs) suspension and 5th day post immunization (dpi) haemagglutination (HA) titre, serum lysozyme and immunoglobulin G (IgG) concentrations were estimated. Data on these IC traits and body weights of different age groups were analyzed by least squares ANOVA taking sire as random, sex and IC levels as fixed effect in the linear model. Analysis revealed that sire had significant effect on serum IgG concentration, and both the sire and sex had also significant effect on body weights. The heritability estimates were 0.302 +/- 0.188, 0.516 +/- 0.22, 0.468 +/- 0.219, 0.302 +/- 0.188 and 0.344 +/- 0.21 for serum IgG, body weights at 16th, 20th, 40th and 64th week of age, respectively. The serum IgG concentration had moderate to high genetic correlations with the body weights of different age groups in positive trend. HA titre showed negative low phenotypic correlations with serum lysozyme and IgG concentrations. Birds with low serum IgG level had significantly the highest body weights at 40th and 64th week of age than those having medium or high levels. The results indicated that RIR birds' IC is sire-influenced and may also impact on birds' body weights.