Valinnan tuloksen ennustaminen eläimen kasvun emävaikutuksen osuudelle.

The juvenile growth in ruminants is grossly influenced by dam’s performance. The genetic variation in maternally affected traits could be expressed as a sum of individual’s own direct effect and dam’s (indirect) maternal effect. In a new beef cattle breed or uniparous species like reindeer, we have to make a plan for collecting suitable and sufficient amount of data for performing a genetic comparison of selection candidates. Assuming the same heritability of 0.3 for direct and maternal effect and genetic correlation of -0.4 between them, with proportion selected being 0.10 in males and 0.50 in females the response to phenotypic selection in phenotypic standard deviation units is 0.31 in direct and 0.04 in maternal effect. Information on relatives, e.g. dam’s 5 half-sib progeny would yield responses 0.27 and 0.09, respectively, but with a considerable delay in having the data. Adding contemporary sire’s female (30) half-sibs’ (or selection candidates’ cousins’) growth records provide qualitatively better responses 0.26 and 0.13, respectively. The selection outcome over several generations could satisfactorily be predicted using Wray-Hill approximation for BLUP. There is necessary to take into account Bulmer effect allowing the validation of the approach with simulation. The approximation gives room for assessing the outcome also for correlated traits or in principle, the use of (highly correlated) genomic information.