MIVQUE ESTIMATION OF GENETIC-PARAMETERS FOR TRAITS OF DAM AND YOUNG TRAITS IN A PROLIFIC SPECIES

A two-trait model is proposed to analyse jointly a dam trait and a you ng trait in prolific species such as pigs or rabbits. The model is a t rue repeatability animal model for the dam trait and a sire-dam model with maternal effects for the young trait. A feasible MIVQUE is worked out to estimate the variance-covariance components involved in the mo del. In order to reduce demands on computer memory and time an equival ent model is proposed and some algebraic work has been done. Thus, the time required to compute the expectations of the MIVQUE quadratics is only 70 % of the one necessary to invert the coefficient matrix. Thus REML could be solved through an I-MIVQUE algorithm as an alternative to the EM algorithm. The suggested procedure presumes that the levels of the fixed effects are low. This is frequently the case when selecti ng pigs or rabbits in a nucleus. Finally, an example is presented for the analysis of litter size at weaning and weight at 77 days in a line of rabbits.