Abstract
Total allelic relationship (TA) as a possible alternative to the
pedigree-derived additive genetic relationship (RA) is defined.
The TA measures the actual allelic identity between individuals for
loci segregating for the trait concerned. Its value was studied by
simulation in populations of different family structure, different numbers
of loci, different numbers of alleles per locus, and different heritability
levels. The alternative types of relationship matrices were used in mixed
model equations to derive best linear unbiased prediction estimates (EBV) of
breeding values (BV). Accuracies of evaluations were calculated as
correlations of EBV with true breeding values. In populations with random
selection and mating, EBVTA derived using TA had higher accuracies than
EBVRA derived using RA. In populations with selection, EBVTA was more
accurate and resulted in higher responses than selection on EBVRA. We
conclude that not accounting for variation in average measures of
relationship and identity in state can be important sources of variance
of prediction error, and taking account of them increases the accuracy of
selection.