Analysis of genetic diversity in Iranian Holstein dairy cattle by using genealogical information

The aim of the present study was to evaluate genetic diversity in Iranian Holstein dairy cattle by using collected pedigree information during 1981 to 2011. The percentage of animals with both known parents in the pedigree was 70.2%. Average number of discrete generation equivalents reached 7.5. Average of all ancestral paths traced back in the pedigree was 37.5. The pedigree completeness index (PCI) of the whole pedigree going back, 5 generations, was 51% and PCI for 15 generations back was 27%. The average inbreeding coefficient and coancestry estimated 3.38% and 2.9%, respectively. Total number of founders, effective number of founders, founder genome equivalent and effective number of nonfounders estimated in the reference population were 52625, 475.5, 14.5 and 14.9, respectively. The results revealed that beside the unequal founder contributions, jointly bottleneck and genetic drift were very important causes the loss of genetic diversity in Iranian Holstein cattle. Furthermore, the most important cause of genetic diversity loss was genetic drift accumulated over non-founder generations. The effective numbers of ancestors estimated 25.7. The numbers of ancestors that explain a given 24%, 50% and 75% of gene pool in the reference population were 2, 11 and 82, respectively. These results showed that in recent years the genetic diversity are slightly higher than the other country but trend in loss of genetic diversity was large. Therefore, mating strategies seem to be properly controlling the rate of the loss.