Pregnancy a testing time

There are different strategies involved in mating our domestic farm animals to ensure that their progeny will be born at the best time of the year.

After mating takes place, it is a great advantage if we pregnancy test the animals to separate out those which have failed to become pregnant.

Ewes can now be easily pregnancy tested using real time ultrasound.

The scanning head is placed against the bare skin in the flank of the ewe and a picture is seen on the screen of the abdominal contents.

The best time to do this is between 50 and 100 days.

At this stage the number of lambs can easily be seen and empty ewes can be separated from ewes carrying singles as well as from those carrying multiples. Empty ewes can be remated if testing is done early enough or they can be run as dry ewes with reduced need of nutrition.

Empty ewes can also be sold off without the worry of selling potentially valuable future lambs.

Ewes carrying twins or triplets have always been a problem in the sheep industry. The extra lambs are of course a great bonus, but they need to be fed at a higher rate.

If single carrying ewes are fed at the twin rate the lamb becomes too big but if they can be separated at pregnancy testing time each group can be fed the correct amount.

In the best managed farms bulls are left in with the cows for nine weeks (three cycles) and then pregnancy testing can take place six weeks later.

A competent veterinary surgeon can very accurately palpate the cow's uterus and separate the empty cows.

The Australian Cattle Veterinarians has an accreditation scheme where vets with a proven record of success in pregnancy diagnosis can be recognised.

There seems little advantage in using real time ultrasound scanning to pregnancy test cows. It is true that the cows can be tested slightly closer to when the bull comes out of the herd but in a nine month gestation this is of little consequence.

The advantage in pregnancy testing cattle is mainly in the feed saved in the autumn. It is frustrating and expensive feeding cows which fail to produce calves.

Such animals should be sold the previous spring when there is plenty of feed. If you know the number of empty cows you can select more mated heifers to make up the numbers.

There is no place on a cattle farm for empty cows. Sheep can be kept for wool production even when not carrying a lamb but an empty cow is just a drag on your finances.

With mares we are back to pregnancy testing using a real time ultrasound scanner.

Only 15 days after mating needs to pass before the pregnancy can be seen.

By 28 days the heart beat of the embryo is visible and at around 60 days the sex of the foal can be seen.

One of the most important reasons for early pregnancy testing in mares is the detection of twins. Mares rarely produce viable twins.

Usually twin pregnancies end in abortion at about nine months.

At 15-20 days one of the twin vesicles can be squeezed and the problem is solved.

To have your mare pregnancy tested at your farm you need to have an adequate crush facility away from direct light.

Luckily, most mares can easily be transported so if you don't have a crush you can take the mare to where there is one.

   Printable Version