Influence of birth mass on incidence of dystocia in the Northern Transvaal Bushveld.
Seven cow herds (Afrikaner, Hereford, Bonsmara, Simmentaler, Hereford x Afrikaner, Simmentaler x Afrikaner, Simmentaler x Hereford x Afrikaner), consisting of 40 animals each, were investigated from 1979 until 1983. The incidence of dystocia as observed during 1187 calvings, was classified into four groups: 0 = no assistance, 1 = unnecessary assistance, 2 = normal calving impossible and 3 = abnormal position of calf in the uterus. The average birth mass of calves, expressed as a percentage of cow mass, was 8,1% in dystocia cases as against 6,8% in the case of normal, unassisted calving.