Crossbreeding in tropical sheep: incidence of dystocia and parturition losses.

Studies were carried out on the incidence of dystocia and parturition losses during a crossbreeding experiment involving 96 West African Dwarf (WAD) ewes mated with rams of 4 breeds--WAD, Ouda, Permer and Yankassa. Results obtained indicated 8 (5.7%) cases of dystocia and 20 (10.64%) cases of stillbirths or death of lambs at birth. The WAD sires were not associated with dystocia or stillbirths but other sire groups were involved in both. All the difficult parturitions occurred during the rainy season while all stillbirths not associated with dystocia occurred during the dry season. The sires used and the level of feeding the ewes during pregnancy may be associated with the dystocia cases and parturition losses recorded. Eighty per cent of the dystocias involved ram lambs. The mean gestation period of the ewes that lambed during the dry season was significantly (P < 0.01) longer than that of the rainy season group. Application of traction and Caesarean operation were used in the treatment of dystocia cases.