Reducing the effect of parent averages from animal solutions in mixed model equations

Selection of animals based on their BLUP evaluations from an animal model r esults in animals that are closely related which leads to increased rates o f inbreeding. The tendency for higher inbreeding rates is greater at low he ritability values. Several attempts have been made to reduce the impact of parent average breeding values from animals evaluations in order to reduce inbreeding while not sacrificing genetic response. A method that modifies t he rules for forming the inverse of the additive genetic relationship matri x for use in best linear unbiased estimation of breeding values via an anim al model was developed. This method and several others were compared analyt ically and empirically, from the perspective of partitioning the animal sol utions into contributions from the data, from progeny, and from the parent average. The ratio of genetic progress to average level of inbreeding showe d dat the modified relationship matrix method was superior to the other met hods: Similar results could be obtained by using artificially high heritabi lity in a usual BLUP analysis.