Mortality in dairy cattle herds is not only related to economic losses but also it would affect animal health and welfare. This study was carried out to estimate the effect of inbreeding on calves and Holstein heifers’ survival in Isfahan, using of data recorded by Vahdat Union in cooperation with Iran animal breeding centers during 1998 to 2013.The pedigree information which is used in this study contains 134537 animals on base year 1978. After editing basic information, pedigree of 54104 animals from 34 cattle herds were used for analyzing during 1998 to 2013. Inbreeding coefficient average of the cattle on base year 1978 was estimated as 2.15. The inbred animals in whole population of study was 57.63% (f 0) and related inbreeding coefficient, was estimated about 3.37. Seven period of lifetime was considered to study on: Days 1 to 30, 31 to 90, 91 to 180, 181 to 360, 361 to 760, 1 to 360 and 1 to 720. The mortality rate in these periods is calculated and comes follow in order: 2.17%, 3.42%, 1.98%, 2.55%, 4.17%, 8.20% and 12.20%. Regarding to mortality rate in the entire period which was 12.20%, an increase of 49% mortality with every 1% increase in inbreeding indicated almost high effect of inbreeding on Holstein heifers’ calves. Inbreeding loss for each period was calculated as following: 12.8%, 6.5%, 5.4%, 8.5%, 13.8%, 15.2% and 18.8%. Inbreeding loss in different parity showed different effects on the survival of calves born which has most of the Inbreeding loss can be observed in heifers. Key words : coefficient of inbreeding, calf mortality, survival, Holstein cow
