pedigree structure of some herds of iranian holstein cattle and their impacts on inbreeding

pedigree information of iranian holstein dairy cattle, collected via animal breeding centre of iran from 1971 to 2007, were utilized to describe the reasons for the increasing inbreed coefficient. inbreeding coefficient (f) and pedigree completeness (pci) of all the available cattle were found out using a pedigree structure of 883713 animals. the herds with pci of above 0.85 were picked out and divided into two groups, one group (g1) with high f ( and pci=0.97) and the other (g2) with low f ( and pci=0.95). for each group, a reference population (animals born within years 2002 to 2007) was defined and the pedigree traced back. the number of individuals picked out from the pedigree were 35638 and 41850, for g1 and g2 respectively. the probability of gene origin (effective number of founders, founder genome equivalent and non-founders) were estimated for both groups. the number of founders, effective number of founders, founder genome equivalent, non-founders, and the number of founders, contributing to 50% of the gene pool of reference population were recorded as 5226, 296.84, 9.31, 9.61, and 134 in g1 and while 7562, 331.46, 16.78, 17.67, and 153 in g2, respectively. the results finally indicated that the higher inbreeding coefficient in iranian holstein may be attributed to a small number of effective founders.