Genetic correlations between body weight of cocks and production traits in laying hens, and their possible use in breeding schemes.

Genetic and phenotypic (co)variances between body weight of cocks (nm = 1,138), BWM, and production traits of hens (nf = 8,844), i.e., egg number (EN), egg weight (EW), feed intake (FI), and body weight (BWF) were estimated by the restricted maximum likelihood method for an animal model. Six multivariate analyses were carried out to get all desired components. Resulting heritabilities were .292, .754, .682, .732, and .790 for EN, EW, FI, BWF, and BWM, respectively. Estimated genetic correlations between BWM and EN, EW, FI, and BWF, were -.161, .338, .645, and .841, respectively. The corresponding estimates between BWF and EN, EW, and FI, were -.036, .294, and .787, respectively. The additional expected selection response in traits of hens from including BWM into the selection criterion of cocks is given for a particular structure with full- and half-sister information and different correlations between BWM and traits of hens.