Investigating inbreeding trend and its impact on growth traits of Lori-Bakhtiari Sheep

The aim of this study was to estimate the amount of inbreeding coefficient in Lori-Bakhtiari sheep and its impact on growth performance. In this study pedigree information and body weight at different ages (birth weight, one month weight, weaning weight, 6 month weight, 9 month weight and 12 month weight) of 7697 lambs from 291 rams and 2097 ewes were used. The data were collected at Shahrekord sheep breeding station during 1989-2012. Estimation of inbreeding coefficient was done by CFC program and quantifying the individual inbreeding regression on the traits was applied by Wombat software. Number of inbred animals in the pedigree was 3056 lambs, equal to 39.5% of the total population. The average inbreeding coefficient of the population and inbred population were 0.94 and 2.4%, respectively. The regression coefficients of inbreeding for birth weight, one month weight, weaning weight, 6 month weight, 9 month weight and 12 months weight were estimated as +0.5, -34.4, -109.8, -283.6, -193.1 and -234 g, respectively. The highest inbreeding coefficient was 31.25 % and most inbred animals had inbreeding coefficients lower than 5 %. These results confirmed the low level of inbreeding in the population. Annual trend of the population average of inbreeding coefficient was 0.098 which was statistically significant (P<0.05). Applying a designed mating system like crossbreeding could be a suitable method to avoid inbreeding depression via keeping the level of inbreeding under control.