Veterinary World (Jun 2013)
Immunocompetence index selection of broiler chicken lines for disease resistance and their impact on survival rate
Abstract
Aim: This study was aimed to develop the disease resistance broiler chicken lines over two generations (G0 , G1 and G2 ) of selection for immunocompetence (IC) index by targeting all the facets of immune response traits viz., humoral response (HR) to Sheep red blood cells (SRBC), cell mediated immune response (CMI) to phytohaeagglutination- Pmitogen (PHA-P), levels of serum serum immunoglobin- G (IgG) and serum lysozyme (LZM) level.Materials and Methods: The SDLSynthetic Dam Line (SDL) broiler line consisting of 303, 204 and 300 birds in G0 , G1 and G2 generations, respectively were screened for immunocompetence traits such as humoral response to SRBCs, cell mediated immune response to PHA-Pand levels of serum lysozyme by Lysoplate assay and IgG by SRID method, and ranked based on their IC index values. Results: The percent survival rate up to 6 weeks of age in SDL broiler chicken lines were selected for high immunocompetence index (HIC) and low immunocompetence index values (LIC) over two generations (G1 , G1 and G2 ) of selection and observed that significant differences (P< 0.05) in percent survival pattern in the base population (n= 303) with the highest survivability of 100.00% was observed in 5-6 weeks of age followed by 99.37% and 97.23% in 4-5 and 0-4 weeks of age respectively. In the G1 generation, significant differences ( P<0.01) was noticed in the selected high and low index lines up to 6 weeks of age with the overall survival rate lower in high index lines (93.10% ) as compared to the low index lines (97.62%). Whereas the reverse trend was observed in the G2 generation that the high index line had significantly (P<0.05) higher survival percent (98.62%) as compared to the low index lines (97.93%). Moreover, the overall survival rate was better substantially over the two generations of divergent immunocompetent index selection of SDL broiler chicken lines. The present investigation revealed that breeding for better immunocompetence status by selection index could lead to better health status in term of improved survival rate in broiler chicken over the generation of selection and further suggested that index selection for more number of generations coupled with economic traits would seem to be a viable option for development of disease resistant chicken lines.Conclusion: Breeding for overall genetic improvement of immunocompetence status by index selection with all the facets of immune system could lead to better survival rate and development of disease resistant chicken.
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