GENETIC-VARIATION OF RESIDUAL FEED CONSUMPTION IN A SELECTED FINNISH EGG-LAYER POPULATION

The purpose of the study was to estimate the heritability of residual feed consumption (RFC) and the genetic correlations between RFC and ec onomically important traits. The genetic progress after four generatio ns of selection for RFC and the changes in economically important trai ts were also investigated. A selection experiment for RFC was carried out from 1983 to 1987. The total data consisted of 3,750 birds and 2,6 61 records. The (co)variance components were calculated using derivati ve-free bivariate animal model restricted maximum likelihood (REML). B reeding values were estimated for calculating genetic progress in RFC and correlated responses in the other traits. The heritability of RFC calculated from the whole recorded period (16 to 42 wk) and using all 2,661 records was .46 (+/-.04). The genetic correlations between RFC a nd egg mass, number of eggs, egg weight, and body weight were not sign ificant. The genetic correlation between RFC and feed consumption was .50 (+/-.04). The breeding value estimates indicated a moderate geneti c progress in RFC due to selection. Feed consumption was decreased and body weight gain showed reduction in the last two generations. No cha nge could be found in egg mass, number of eggs, egg weight, age at fir st egg, or body weight.