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Data representing 594 Barki and 582 Rahmani lambs raised at Alexandria University Experimental Station between 1991-2011 were utilized in this study to estimate variance components and heritability of birth weight (BW), weaning weight (WW) and average daily gain (ADG) from birth to weaning of lambs. Also, the effects of season and year of lambing, sex of lamb, type of lambing and parity on the previous traits were studied. The analysis indicated that fixed effects on all studied traits were generally significant (P<0.01or P<0.05) except for effects of season and year of lambing on BW of Barki lambs and effects of parity on ADG of both breeds. Variance components and heritability for the studied traits were estimated using the Wombat programme fitting four univariate animal models. Estimates of the direct heritability (ha) and maternal heritability (hm) were ranged from 0.161-0.353 and 0.145-0.147 , from 0.100-0.171 and 0.124-0.124 and from 0.014-0.172 and 0.119-0.121 for BW, WW and ADG of Barki lambs, respectively, the corresponding values for Rahmani lambs ranged from 0.204-0.519 and 0.094-0.215, from 0.139-0.168 and 0-0.021 and from 0.125-0.144 and0-0.001, respectively. Ignoring maternal effects from the model resulted in an over estimation of direct heritability of all traits of both breeds. Estimates of the total heritability (ht) were moderate to high for BW and low for WW and ADG of both breeds. Estimates of the total maternal effect (tm) were considerable for all studied traits of both breeds. The results in general showed that maternal effects were significant source of variation for early growth traits of Barki and Rahmani lambs. Therefore, these effects should be considered when carrying out genetic evaluations of early growth traits of Barki and Rahmani lambs in this flock.

ESTIMATES OF VARIANCE COMPONENTS AND HERITABILITIES OF PRE-WEANING GROWTH TRAITS OF BARKI AND RAHMANI LAMBS