The effect of selection for traits of low heritability conducted in noninbred populations on the basis of progeny or performance tests

The investigations were carried out to compare selection conducted on the basis of progeny with that on the basis of animals'own performance. Selection was conducted for the body weight at weaning (at the age of 21 days), which is a trait of low heritability (h²=0.1). It was run throughout 15 generations, whereas in generations 13 and 14 three experimental replicas were crossed to obtain population free of inbreeding. A cumulated response to selection was higher in the group selected on the basis of animals' own performance, but after crossing the replicas it decreased clearly in the both groups. The cumulated selection differential was higher in the group selected on the basis of animals' own performance. However, a statistical analysis of the obtained results showed no significant difference between the two selection methods.