Abstract:
This study was carried out to investigate the effects of breed (rams and ewes), sex and birth type on
growth performances of cross bred lambs of sheep under semi-intensive production system. Dorper
and Horro rams were used for comparisons crossing with three local breeds of ewes (Horro, Black
Head Ogaden (BHO) and Harreghe Highland (HH). Growth performance was determined using
General Linear Model procedures. The results of this study showed that Dorper cross breed lambs
were significantly (p<0.05) heavier than Horro ram for birth weight with average value of 2.88±0.26
and 2.67±0.26 weighed for Dorper and Horro crosses respectively. The breed of ewes had also a
highly significance (P<0.01) difference on average birth weight with the value of 3.17±0.26, 2.51±0.26
and 2.64±0.26kg for Horro, BHO and HH breed of ewes respectively. Sex of lambs had significante
(p<0.01) effect on birth weight with the value of 2.95±0.26 and 2.60±0.26 for male and female
respectively, but type of birth had not significance difference on average birth weight. Weaning weight
were affected by breed, sex as well as type of birth. Weaning weight of lambs were 12.89±0.46 and
12.46±0.46kgs for Dorper and Horro crosses. The average weaning weight of cross breed lambs from
Horro, BHO and HH ewes were highly significantly (p<0.001) different with the value of 13.74±0.46,
11.31±0.46 and 12.82±0.46kg respectively. Male and female lambs had also significant variation on
average weaning weight of 12.93±0.46 and 12.34±0.46 respectively while their average daily gain was
111.33±5.4 g/day and106.63±5.4 g/day, for male and female respectively. Male lambs exhibited higher
weights than females across all traits (p <0.01). Single births excessed twins in birth weight (p <0.05),
in weaning weight and average daily gain (p>0.05). From this study it is possible to conclude that the
cross breed lambs from improved Dorper breed of ram was comparable with Horro Ram crossed
lambs in growth traits but, Horro ram crossed lambs were best performed than Dorper in prolificacy
and pre-weaning mortality rate. Besides, cross breed lambs from Horro ewes were higher than the
other contemporaries in the three growth traits, mortality rate and prolificacy. Hence, this study
recommend that further study should be undertaken on comparison of rams and ewes from cross breed
lambs using large data and Horro rams
