Information concerning 493 single calvings of the double-muscled beef cow herd of the institute was collected to investigate the relationship between the characteristics of dams and calves with regard to dystocia. Factors affecting dystocia are similar in double-muscled cattle to those in non-double-muscled cattle but the occurrence of dystocia is greatly increased in double-muscled cows. Incidence of caesarean section was significantly correlated with parity (–0·243), age of dam (–0·232), post-partum dam weight (–0·185), and calf birth weight (0·164). Caesarean deliveries were required for 89·5% of the parturitions. Calvings without caesarean section were characterized by higher means for post-partum dam live weight (634·7 kg), age (1675·5 days), parity (3·1) and the ratio of post-partum dam weight to calf birth weight (14·4), compared with 580·2 kg, 1251·1 days, 2·1, and 11·8, respectively for births with caesarean setion, while calf birth weight was lower in non-caesarean calvings (45·8 v. 49·9 kg). Caesarean births involved more male calves than females (55 v. 45%). Even when calf birth weight was 30 kg or lower, and also in multiparous cows, 40 and 86% of the deliveries, respectively, still occurred with a caesarean section.
Incidence of caesarean section could not be accurately predicted from pre-partum characteristics such as pre-partum dam weight, age and parity.