Abstract
Data from 1219 Djallonke × Sahelian F1 crossbred lambs born between 1977 and 1979 at the Ghana Government/UNDP Sheep farm, Ejura, were analysed to study factors affecting birth weight, average daily gain (ADG), weaning weight and preweaning mortality. Average birth and weaning weights, ADG and mortality were 2.69, 11.7 kg, 74.3 g and 21.0%, respectively. Year, season and type of birth and sex affected (P < 0.01) birth and weaning weights and ADG. Season (P < 0.05) and type of birth (P < 0.01) affected mortality when the effect of birth weight was accounted for. Birth weight had a curvilinear relationship with mortality. Lambs born in the rainy season were generally heavier at birth and weaning, but had higher mortality than those born in the dry season. Lambs born as singles were heavier at birth and weaning and had lower mortality than twins. Males were also heavier at birth and weaning than females. Birth weight of lambs increased steadily from 1977 to 1979. Weaning weights on the other hand were highest in 1977 and lowest in 1978. Based on preweaning performance and preweaning survival of the lambs, it was tentatively concluded that it was advantageous to cross Djallonke and Sahelian sheep.
