DIALLEL ANALYSIS IN LAYING HENS

A complete diallel cross with 9 White Leghorn lines was twice replicated in two consecutive years. Traits monitored were: average egg production per hen day laid from the 151st to the 425th day of age, average egg weight per cage in the 46th week of age and live weight at the 105th day of age. First the least squares means of all 81 combinations and their standard errors were calculated from a linear model taking into account all nongenetic effects. Then the genetic parameters of the model of Eisen et al. (1983) were estimated by weighted least squares. The direct genetic effects were the most importance effects in all traits. As the maternal effects also were important in all traits, the lines tested should be selectively used in sire or dam position. Heterosis was important mainly in egg production (average heterosis 11 eggs - 6.2%). Line heterosis, specific heterosis and residual reciprocal effects were of minor importance. Most estimates of effects were relatively unstable over years.