Genetic gains from reciprocal recurrent selection for part period egg production in White Leghorn layers

The data on reciprocal recurrent selection for part period egg production up to 280 days of age over six generations were analyzed to evaluate direct and correlated responses in two pure lines (IWH and IWI) of single comb White Leghorn. The average realized genetic gains for part period egg production were found to be −0.14 and 1.73 eggs per generation in IWH and IWI lines, respectively. The genetic response in various correlated traits for corresponding lines were −0.66 and −0.77g for 40^th week egg weight, 1.29 and −0.05 days for age at sexual maturity, 7.28 and 15.30 g for 20 week body weight, and −6.47 and −2.19 g for 40 week body weight. Except for 20-week body weight in IWI line, the responses in all the traits for both the selected lines were non-significant. The realized genetic gain did not agree well with the expected one for all the traits in both the lines. The possible reasons for the discrepancies between the realized and expected response to selection have been discussed.