Effects of incomplete pedigree on genetic management of the Dutch Landrace goat

Genetic diversity in the Dutch Landrace goat was investigated based on information from the pedigree with about 6500 animals. Annual inbreeding rate after 1985 was below 0.5% and after 1987 close to 0%. However, pedigree information was incomplete, and 350 animals had unknown parents, while for the majority the real parents must have been in the pedigree. To determine the influence of unknown parents, 20 new pedigrees were created by random assignment of animals, alive at the time of birth, as parents to individuals with unknown parents. Only 12 founders remained for these pedigrees, and inbreeding levels varied considerably between these 20 pedigrees. However, inbreeding rates were remarkably constant. They increased to about 0.2%, indicating that the population is not endangered by inbreeding. The optimal contribution theory was used to evaluate possibilities of decreasing the average relationship in the population and thus to increase the genetic diversity of the breed. Optimal contribution decreased the average relationship in the population whether randomly assigned parents were used or not. However, individuals selected as parents for the resampled pedigrees differed from the original pedigree, and only a few animals were selected for all pedigrees. Candidates for inclusion in the genebank were also selected using optimal contribution. Adding animals to the genebank increased the conserved genetic diversity substantially, but as the lists differed between the analysed pedigrees it was not clear which animals were best added to the genebank.