برآورد روند ژنتيكي و محيطي صفات اقتصادي در بزهاي مرخز

An Estimation of Genetic and Environmental Trend in Economic Traits in Markhoz Goats

Collected data, related to 2371 kids born during the years 1992-2002 in Sanandaj Markhoz Goat Research Station were used to estimate the genetic trend. Traits taken into account and analyzed were birth weight (BW), weaning weight (WW), 6-month weight (6MW); 9month weight (9MW), yearling weight (YW) and yearling fleece weight (FW). Heritability estimates were obtained for each trait while employing REML procedures under univariate Animal Model. Through ignoring or including either maternal genetic or environmental effects, 6 different models of analysis were fitted to each trait. Log likelihood ratio test indicated that the model including direct and maternal genetic effects as welt as permanent environmental effects to be most suitable for 13W, WW, 6MW while the models including only direct genetic effect were most suitable for 9MW, YW and FW. Mixed model methodology based on a uni-trait animal model, for prediction of breeding value, was employed. Genetic trends were estimated by regressing estimated mean in breeding value during year of birth. The additive genetic trends for BW, WW, 6MW, 9MW and YW were 0.003 ± 0.001, 0.040 ± 0.015, 0.045 ± 0.015, 0.114 ± 0.030 and 0.170 ± 0.038 kg per year respectively and for YFW it was 2.397 ± 0.299 gr per year. The maternal genetic trends for BW, WW and 6MW were 0.0002±0.001, 0.0002 ± 0.000 and 0.003 ± 0.002 kg per year respectively.