Momani Shaker M., Kridli R.T., Abdullah I,A.Y., Malinová M., Sonogo S., Šáda I., Lukešová D.,
Abstract
The objective of this study was to evaluate the effect of crossbreeding on body weight and growth efficiency of
lambs from birth to weaning. The study was conducted on the Awassi sheep fl ock and their crossbreds with Charollais
and Romanov breeds maintained at the Agriculture Centre for Research and Production at JUST Irbid. In 2004, 2005 and
2006 live weight was determined in 420 lambs (95 Awassi, 158 Charollais x Awassi F1 crossbred and 167 Romanov × Awassi
F1 crossbred) at birth and subsequently every fortnight until weaning. Average live weights of lambs at birth,15, 30,
45 and 60 days of age were 4.18 ± 1.13 kg, 8.85 ± 2.12 kg, 12.20 ± 2.80 kg, 15.70 ± 3.50 kg and 19.25 ± 4.60 kg,
respectively. ADG of lambs from birth until weaning was 255 ± 0.10 g. Genotype of lambs and litter size affected ADG,
live weight of lambs at birth, 15, 30, 45 and 60 days significantly (P ? 0.001). Investigations of the effect of
sex on live weight of lambs at birth and at 60 days showed that the differences between males and females were
statistically significant (P ? 0.001). Differences in ADG and live weight at 15, 30 and 45 days according to dam
age were also significant (P ? 0.001). Similarly, the effect of dam weight at mating and at lambing on ADG, live
weight of lambs at 15, 30, 45 and 60 days of age and until weaning were confirmed (P ? 0.01). Regressions of BW,
ADG and weight at 15, 30, 45 and 60 days age of lambs on dam weight after lambing were significant (P ? 0.001).
Likewise, live weight of lambs at birth, ADG until weaning and live weight at 15, 30 a 45 days of age were affected
by the year of lambing (P ? 0.001). Results indicate that the CA and RA crossbred sheep showed better growth
performance than purebred Awassi, which may presumably indicate the effect of hybrid vigour in first generation
crosses compared with pure Awassi.
Key words:
Awassi, Charollais, Romanov, growth ability, systematic effects, crossbreeding