Estimation of Inbreeding Coefficients Using Pedigree and Microsatellite Markers and Its Effects on Economic Traits of Shirvan Kordi Sheep

In this study, pedigree data of 7170 lambs produced from 177 rams and 2182 ewes collected during 1989 to 2009 in the Shirvan Kordi sheep breeding station, were used for calculating inbreeding coefficients. The impact of inbreeding on the studied traits was investigated by including inbreeding coefficients for each animal as a covariate in the animal model. Average inbreeding coefficient of the flock in base year, 1989, was estimated as 0.668%. The low average inbreeding in the flock could be ascribed to the structured breeding regime of the station for preventing mating among relatives. Totally, 23.3% of the animals were inbred with average inbreeding coefficient of 2.87%. Out of these, 1668 animals were inbred including 823 males and 845 females with the mean inbreeding coefficients of 2.81% and 2.93%, respectively. Coefficients of inbreeding were also estimated in this population using 6 microsatellite markers (BM8125, BMS2361, BM6526, BM6526, BMS1004 and BM6444) and 100 blood samples. Within population, inbreeding F-statistic (F IS) ranged from -0.1859 (BM6526) to 0.3329 (BM6438). The F IS estimates were positive for BM6438 and BM6444 loci (0.3329 and 0.2287), respectively and estimates for the other loci were negative. Average inbreeding coefficients based on molecular markers was estimated as 0.2617%. Birth weight, weaning weight, body weight at 6 months, body weight at 9 months, body weight at 12 months, annual wool production and number of lambs per ewe lambing were changed by -0.0131, 0.0795, 0.0013, 0.0653, -0.0921, 0.0083 and -0.023 kg, respectively for every one percent increase in inbreeding.