Study of population structure and inbreeding in Iran-Black sheep

The aim of the current project was study of population structure using pedigree analysis and also inbreeding depression of growth traits in Iran-Black sheep. Pedigree information related to 5481 animals and records of body weights at birth, weaning, six-month, nine-month and yearling, collected from 1982 to 2011 at Abbasabad Sheep Breeding Station in Mashhad, were used. Calculation of inbreeding coefficients was done by CFC, and Endog (v4.8) to compute other pedigree analyses, and WOMBAT software was used for estimating the inbreeding depression of growth traits. The total number of founders, the effective number of founders, the effective number of ancestors, the effective number of founder genomes, and the effective number of non-founder genomes, were 167, 22, 17, 11, 22 heads, respectively. The estimated average for coancestry, relationship and inbreeding coefficients was 4.71, 9.42 and 4.80 percent, respectively. The generation interval and the effective population size based on individual increase in inbreeding were 4.85 years and 26 heads, respectively. The average generation interval in the sire-progeny pathway was greater than the dam-progeny pathway. Also, half of the genetic diversity of the study population originated from 6 ancestors. The inbreeding depression for body weight traits at birth, weaning, six, nine and 12 months of age were 10.3, 130.6, 491.8, 525.5 and 414.7 g, respectively. The results showed a decrease in genetic diversity of the study population compared to the founder animals and observed inbreeding depression in the studied traits could also confirms it.