Although it is not recommended to breed a heifer until she is 24 months of age, pressure on the industry means that many are bred long before this, with some bred as young as 14 months of age, and others at 19 months of age, with those who mature larger bred later than those that mature smaller. The goal then being that a heifer will be around 2 years of age when she calves her first calf.
Delivery of a Calf
Calving time is often indicated by signs of discomfort and restlessness. A cow may go off her feed, she may kick or bite at her belly and move away from the herd, possibly even hiding. The calf is moving into position for delivery and contractions are taking place. This stage can take 2 to six hours, longer for a heifer than a cow (note cow generally refers to an animal that has had a calf already, heifer is a first time mother).
The hips of the cow may seem more pronounced as the calf is in position, and the cows vulva will be more relaxed, she may even have milk drip from her teats.
Usually a water sac appears, it may be dark purple in color, it may rupture when still in the cow, or when out, dark yellow fluid will spill out. Another sac which contains the calf will also be presented, this being white with thick, clear, fluid.
The cow will have active contractions and will be more restless. Often getting up and laying down to break the first sac. The calf's feet should appear, one slightly ahead of the other, with the head on top. At this point you want to start timing as the calf should be fully delivered within an hour, if it takes any longer you will want to check to make sure it is positioned okay (be sure you have 2 front legs and a head, or two back legs).
You want to supervise but not interfere, you need to make sure when she does lay down that there is room behind her for the calf to be delivered. She will push repeatedly, and eventually the head will come out, she may take a rest and then push out the shoulders, and finally the whole calf. The amniotic sac which contained the calf is usually broken by the mother and the calf will spit out some liquid, if the mother does not remove the sac you may break it.
If the time between the first sac being presented and the actual delivery of the calf is any more than 2 hours you may want to call the veterinarian, or check the position of the calf and correct if you know how. Bull calves are often bigger and may require assistance, if you need to pull do so only when the cow is pushing, and keep the legs one ahead of the other as this makes the shoulders narrower.
At this point the mother may still rest, this is fine, but she should soon lick her calf and then stand up and encourage it to stand as well. Try to leave them alone and resist the urge to help. The cow will have placenta that will shed usually in a few hours, do not pull it out. If it takes longer than 10 hours to shed you should call the vet.
Watch to be sure the calf is drinking, and getting milk. The umbilical cord will break on its own and can be dipped in iodine.
photo source - cow and new calf.
Note that cows can have twin calves, but triplets are quite rare.
If calving in the winter, or early spring, be sure your cattle are moved close to your home, or barn, to enable you to keep an eye on them, and be sure they have proper shelter. Ideally the cows that are due should be kept in the barn at night. A heat lamp may be needed.
If the cow does not care for its calf, and uses force to reject it, you may need to bottle feed the calf. It will need colostrum within the first 18 hours of birth, and proper cow's milk formula (not milk from the store) after that.