Well-grown heifer calves are capable of becoming pregnant from about 6 months of age.

Heifer calving at 13 months old after being mated as a 4 months old calf Bull calves can be fertile from about the same age. But pregnancies in yearling heifers are bad news, and the younger the heifer the more serious the consequences.

It’s far better to prevent heifer pregnancies than to deal with the consequences. So don’t allow any bull over about 4 months of age to run with heifers over 6 months old.

But accidents do happen! What if a bull jumps the gate and your lovely little heifer is mated?

  • If you decide to let nature take its course, what will happen?
  • The heifer is relatively small and the calf will become relatively large.
  • It will be a very difficult birth and the calf may die or be born dead.
  • If the heifer survives the birth she may have internal damage that results in paralysis, or infection or infertility.
  • If the calf gets stuck in the birth canal, the calf will die then the heifer.
  • If you call a vet before the heifer dies, the dead calf will have to be removed piece by piece by the vet.
  • The heifer’s growth will be permanently stunted, because the foetus will have grown normally and rapidly at the expense of her growth and body condition.

So what should you do if you suspect your heifer has been mated?

  • You must consult a vet as soon as possible, preferably within a few days.
  • If pregnancy is suspected and it’s very early, the foetus can be aborted relatively easily.
  • Later in pregnancy, your vet might advise drug-induced early calving before the calf gets too big. If it’s very late in pregnancy you might then have to decide whether or not to raise the premature calf or euthanase it.
  • Your vet might advise a Caesarean operation to minimise damage to the cow, and again depending on the maturity of the calf you might have to decide whether to try to raise it or kill it humanely.
  • If the heifer is well grown and the calf does not grow too large, you and your vet may decide to risk a normal calving. You will need good facilities like yards and a head bail, and your vet will need to be ‘on call’.
    For all these options you will need your veterinarian’s involvement, so resign yourself to the bills. They are usually a small price to pay to safeguard the welfare of your cow.
  • The only other option is to have your heifer killed humanely. You will get some return on the carcass if you send it to the works or use a home-kill butcher.
The bottom line

The bottom line is that if your lovely heifer gets pregnant, there isn’t usually a happy ending!

Better by far to make sure your fences are in good order (electric fences and electric outriggers are good) ... and make sure that bull is a long way downwind!

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