The present study was carried out at the Department of Poultry and Fish Production, Faculty of Agriculture at Menoufia University, Shebin El-Kom. The aim of the present study was to apply the immunoglobulin G (IgG) as early genetic maker to improve some egg production traits in Norfa chickens. The IgG and Ab titers were determined in blood serum of each individual at 20 weeks of age. Pullets were divided into three groups, control, high and low groups, based on the IgG concentrations in blood

more »

... rum. The results were discussed and summarized as follows: 1-The average concentrations of both IgG and Ab titers in the blood serum of Norfa chickens were 10.424 and 13.871 (mg/ml), respectively. The IgG makes up 75.1% of the total Ab titer concentrations. The IgG concentrations were 13.500, 7.576 and 10.195 (mg/ml) in high, low immune response and control groups, respectively. 2-Using high IgG concentrations (in high group) as early genetic marker improved, early age at sexual maturity with (10.0 days), light body weight at sexual maturity with (10.4%), light body weight at maturity with (9.0%) higher egg mass at 90days of laying with (25.4%) and higher egg mass at 42 weeks of age with (22.4%) as compared to control. 3-The IgG antibody classes can be used as good genetic marker to improve some egg production traits due to its positive correlations with most productive traits in chickens