Estimation of inbreeding depression for economic traits in Isfahan improved native chicken population

Monitoring the inbreeding rate of native chickens in breeding stations is of significant importance because of planned matings and lack of gene flow inthe population. This study was undertaken to estimate the inbreeding coefficient, investigate the trend of inbreeding changes and evaluate the effects ofinbreeding depression on the economic traits in Isfahan improved native chicken population. The studied traits were body weight, age at sexualmaturity, weight at sexual maturity, egg number, mean egg weight and egg weight at first day. In the present study, data of 97272 birds recordedduring 21 generations were included. In order to estimate the inbreeding coefficient of each bird and the effect of inbreeding on the traits, CFC andWOMBAT software were used, respectively. Pedigree analysis indicated that 79.48 percent of population were inbred. The estimated averageindividual and maternal inbreeding coefficients were 4.3 and 3.5 percent, respectively. According to results, for every one percent increase ininbreeding, rate of inbreeding depression for the traits including the body weight in 1 day, 8 weeks and 12 weeks, age at sexual maturity, weight atsexual maturity, egg number, average weight of eggs and egg weight at first day was -0.008, -2.52, -3.51, 0.23, -3/97, -0.13, 0/02 and 0.06,respectively. Based on the results of the present study, although in closed populations under genetic selection, the absence of inbred bird is almostimpossible, but, the reduction of inbreeding can be achieved by controlling the matings, which prevents the adverse effects of inbreeding in thepopulation.