Genetic evaluation of White Leghorn control population for immune response traits

Heritabilities and correlations among the immune response traits and correlations of these traits with growth and production traits were estimated. The heritability of age at first egg was 0.104 while the heritability estimates of body weights, egg production and egg weights at various ages ranged from 0.059 to 0.559, 0.072 to 0.169 and 0.058 to 0.721, respectively. The heritability estimates for antibody response to SRBC injection, antibody response against New Castle disease virus (NDV) vaccine and cell mediated immune response to PHA-P injection were 0.227, 0.982 and 0.084, respectively. The genetic correlations of anti SRBC titer with age at first egg and body weights at early ages up to 20 weeks were negative and moderate in magnitude. The genetic correlation with 40 weeks egg production was negative but with egg production up to 64 and 72 weeks of age, it was positive (0.105±0.106 and 0.164±0.149, respectively). The genetic and phenotypic correlation of antibody response to SRBC injection with antibody response against NDV vaccine was negative. The genetic and phenotypic correlations of antibody titer against NDV vaccine with age at first egg and egg production were positive. The immune response to PHA-P had a negative genetic correlation with body weights at 4, 6, 40, 52 and 64 weeks of age and a positive correlation with egg weight at 40 and 64 weeks of age. The study revealed that the humoral immunity can be improved through selection in White Leghorn control population. The positive genetic correlation of humoral immune response traits with annual egg production suggested the possibility of simultaneous improvement of both production and immunity.