Expected response and rate of inbreeding in a closed flock of White Leghorn under long term selection

Apopulation of White Leghorns, selected for aperiod of 9 consecutive generations to improve hundred days egg production (EP 100) was evaluated for response to selection. Regression analysis showed that there was an increase in the trait though not significant (0.83±0.76). The magnitude of selection differential, phenotypic standard deviation and intensity of selection varied from 6 to 14.08 eggs, 9.43 to 11.51 eggs and 0.567 to 1.33 respectively over generations. The average effective number of parents (Ne) overgenerations were 72.45 and increasein the rate of inbreeding (ΔF) per generation was 0.7%. The cumulative inbreeding over 9 generations of selection was 6.30%. The inbreeding coefficients would not probably have any effect on response to selection. However, a downward trend of the heritability estimate of the trait (EP 100) have shown that expected response were higher in earlier generations in this population.