Estimates of genetic parameters of growth traits in Menz and Awassi x Menz crossbred sheep in Ethiopia

A study on genetic evaluation of 3 678 Menz (M) lambs born to 85 sires and 3 021 Awassi x Menz (A x M) crossbred lambs of 28 sires, was conducted. Data collected during 1993-2000 at Amed Guya and Sheno centers in the central highlands of Ethiopia, were used for the study. Traits studied included birth weight (BWT), weaning weight (WWT), 6 month weight (6WT), yearling weight (12WT); average daily weight gains from birth to weaning (ADG1), birth to 6 months (ADG2), weaning to 6 months (ADG3) and 6 month to yearling age (ADG4). Heritability estimates ranged from 0.09 +/- 0.11 for ADG4 to 0.33 +/- 0.11 for 12WT in M sheep, and 0.31 +/- 0.08 for ADGI to 0.78 +/- 0.23 for ADG2 in A x M crosses. The genetic correlations between growth traits ranged from 0.07 +/- 0.26 (between BWT and 6WT) to 0.96 +/- 0.18 (between 6WT and 12WT) for M sheep and from 0.35 +/- 0.24 (between WWT and 6WT) to 0.88 +/- 0..26 (between 6WT and. 12WT) for A x M crosses. Repeatabilities of BWT, WWT and ADGI were of moderate magnitude. The results suggested that appreciable genetic improvement in marketing/slaughter weights could be achieved through selection on 6WT or ADG2. A higher response is expected in A x M crosses and this would help in stabilizing the crossbreds through selective breeding.