A monitored study of major physical activities in the perinatal calf.

Using doppler ultrasound and manual palpation per rectum, 10 heifers in late gestation were examined twice daily to determine fetal activity, posture and position. Three heifers calved early but seven were monitored over their final week. After birth the calves were watched to estimate their vitality. Much variation in activity occurred but there was a significant (P = 0.012) reduction 11 to 23 hours before birth. After bouts of activity an 'alerted' posture was struck with the head raised and forelimbs normally extended; pronation and engagement then occurred. These fetal movements were not necessarily progressive or irreversible and the final birth posture was not stable, in some cases, until the last 12 hours of gestation. Failure of 'alertness' and pronation resulted in dystocia in one heifer whose calf, together with one other which failed to show this alert phenomenon, had a low level of neonatal vigour. All 10 calves survived the neonatal stage.