Observations of bovine parturition.

Summary A herd of 38 multiparous Hereford cows was kept under close observation during normal parturition in a 2 ha paddock. No consistent behavioural sign that parturition was imminent was observed, and 82% of the cows calved between midday and midnight. No relationship was found between time for calf to stand and birth duration, or time for calf to stand and birth weight. There was a significant positive regression of duration of birth on calf weight, and there was a significant effect of sex of calf on placental retention time. Cows giving birth to male calves retained the placenta longer than cows having female calves.