Stage 1

  • Lasts ~6 hours
  • Relaxing of pelvic ligaments.
  • Mammary secretions change from transparent,honey-like to opaque, cellular colostrum.
  • Body temperature subnormal by ~0.6◦C.
  • Parturition will begin 12 hours after complete relaxation of the posterior borders of the sacrosciatic ligaments.
  • Heifers may show signs of abdominal pain for up to 24 hours before the cervix is fully dilated.
  • Occasional straining may occur.
  • Picks at feed, irregular rumination
  • 'Lowing'
  • Kicking of the abdomen
  • Restless, may stand with her back arched and tail raised.
    • May go down and rise again frequently
  • Pulse rate often increased to 80-90.

Stage 2

  • Lasts 30 minutes - 4 hours
    • Longer in heifers than in cows
    • Male calves take longer to be born
  • Onset marked by the appearance of the amnoin ('water bag') at the vulva.
  • Less frequent straining
  • Remains standing at first
  • During passage of the head through the vulva, the cow normally goes down and remains recumbent until the calf is born.
  • May lie on her side or in sternal recumbency.
  • Placental separation occurs more slowly than in the mare.
  • Umbillical cord of the calf is shorter than in the foal and generally ruptures as the calf falls from the vulva.

Stage 3

  • Expulsion of the foetal membranes usually occurs ~6 hours after the birth of the calf.
    • After 24 hours consider a pathological cause for retained placenta.
  • Cow will eat the foetal membranes. Hence the cow will show a marked reduction in milk production for at least a month due to indigestion of the foetal membranes.