Genotypic preselection of full sibs prior to progeny-testing

Development of genotyping technology is leading to detect more major genes affecting quantitave traits. A dairy cattle population of 10000 commercial dams and 200 active sires, involving an open nucleus 4-pathways breeding scheme was simulated for twenty years of selection. Four major genes and remaining polygenic effect were simulated to meke phenotypes of milk yield trait. Population average, heritability and phenotypic standard devation of milk yield were assumed as 6500, 0.27 and 1100 respectively. Phenotypes affected by parity, season and herd fixed effects. BLUP animal model was used for proofing young bulls via progeny testing. No major gene effect involved in evaluation procedure for the conventional but for the second starategy genotypes of major genes were used to preselect within full sib families prior to progeny test. The present study showed that such preselection can improve genetic gain significantly (P<0.05).