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چکیده
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This study aimed to measure the contribution of autosomal and X chromosome to the phenotypic variation of growth traits including birth weight (BW), weaning weight (WW) 6-month weight (W6) and pre- and postweaning average daily gains (ADGa, ADGb), body measurements including body length (BL), height at wither (HW), height at back (HB), heart girth (HG) and scrotal circumference (SC) as well as efficiency related traits including pre- and post-weaning Kleiber ratio (KRa, KRb), pre- and post-weaning efficiency of growth (EFa, EFb) and pre- and post-weaning relative growth rate (RGRa, RGRb) in Makooei sheep. To this end, REML procedure fitting a series of 4 uni-variate animal models including various combinations of autosomal, X-linked and maternal effects were fitted to estimate variance components and corresponding genetic parameters. Bi-variate analyses were also applied to estimate (co)variances between traits. Estimates of autosomal heritability (ha 2) for growth traits ranged from 0.09 (ADGb) to 0.29 (BW). For body measurements, ha 2 was in the range between 0.01 (HW) and 0.42 (SC) and for efficiency related traits it was in the range between 0.08 (KRb and RGRb) to 0.13 (KRa). Except for body measurements, other traits studied were affected by maternal effects. The effects of Xlinked loci emerged after weaning in a way that for average daily gain and efficiency-related traits measured during post-weaning growth phase, the estimates of the X-linked heritability (hs 2) were comparable to autosomal heritability and ranged between 0.04 (KRb) to 0.07 (EFb). The highest hs 2 were observed for height of animals measured at back and wither as 0.12 and 0.13, much higher than corresponding ha 2 as 0.01 and 0.04, respectively. The autosomal genetic correlation ranged between 0.05 (EFb-HW) to 0.99 (HW-HB). The X-liked genetic correlation was in the range from 0.16 (RGRb-ADGb) to 0.99 (HW-HB) which showed that a part of genetic (co) variance between studied traits originated
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