Direct and correlated response of divergent selection for humoral response to sheep erythrocytes in immunological traits in WLH chicken
SANJEEV KUMAR AND M.C. KATARIA
Molecular Genetics Laboratory Central, Avian Research Institute
Izatnagar (UP) - 243122
Divergent selection based on humoral response to sheep erythrocytes (SRBC) was carried out in an elite White Leghorn line. Primary selection was done on the basis of layer traits using OSBORNE index. Nine hundred five chicks (548 in High and 357 in Low SRBC lines) belonging to second generation were obtained in five hatches and evaluated for important immunological traits viz., response to Sheep RBCs (measured through HA titre), serum lysozyme level (by ‘Lysoplate Assay’) and cell mediated immune response (measured by wing web index as response to PHA-P). The data were analyzed by least squares analysis of variance taking sire as random and sex and hatch as fixed effects. The LS means of these traits were 9.44 ±0.18, 2.96 ±0.07 mg/ml and 0.34 ±0.04mm in HSRBC and 8.61 ±0.21, 2.79 ±0.10 mg/ml and 0.41 ±0.03mm in LSRBC lines. The ANOVA revealed significant effect of hatch (P<0.01) only on HA titres in both lines. Other effects were non-significant on other traits in both the lines. The data pooled over lines were also analyzed taking line, sex and hatch as fixed effects and sire effect nested within line in the model. Significant differences between lines for all the three immunocompetence traits were observed. The high line had significantly higher HA titre (P<0.01) and serum lysozyme level (P<0.06) than the LSRBC line, which had significantly (P<0.05) more CMI response. Divergent selection has positive effect on serum lysozyme level also.