Test early for pregnancies

Vet Robert Bonanno says early pregnancy testing is a solid foundation to build a herd health program around. Photo by Jamie Salter

I am often asked what is the one thing that I would recommend on any dairy farm to lift productivity, profitability and improve herd health.

Well, while dairy farming is never so simple that just one thing alone will guarantee all those things, when pushed, I always advise that early pregnancy testing is a solid foundation to build a herd health program around.

It is well known that how a cow is managed during the transition period from three weeks before calving to three weeks after calving is the critical time in a cow’s life cycle where you will set her up for either success or failure.

But how can you manage with any precision this key time in a cow’s life if you don’t accurately know when she is due to calve?

In November, spring calving cows are being mated and often pregnancy testing is not top of mind, but the earlier a cow can be confirmed pregnant (or not), the better the management options that are available to us.

If you can confirm that a cow is pregnant to her AI date, then we can estimate her due date with far greater precision than if pregnancy tested later, when it can become very difficult to accurately determine her date of conception or future calving.

Accurately knowing her future calving date will allow us to ensure that she is proactively managed for optimal lactation length, dry period length and ensure that she will be starting transition feeding for her next lactation at the ideal time.

Early pregnancy testing (from around 28 to 35 days) is possible using ultrasound, milk, or blood testing.

Ultrasound has the advantage that the viability of the pregnancy can be assessed and cows carrying twins can often be identified.

The milk or blood pregnancy test when performed early is an extremely useful test to determine which cows are not pregnant as a negative result is very accurate. Negative cows are then able to be quickly resubmitted for another mating.

With blood and milk testing, determining a viable pregnancy is not possible — the test result may remain positive for days or weeks even after the fetus has been lost. Follow up testing is recommended.

Early pregnancy testing should be performed in herds before the oldest pregnancies reach 14 to 16 weeks of gestation. The ability to estimate the due date and match that up with her joining date is most accurate when done before this stage.

In many herds, I recommend two or more early pregnancy tests to really hone in on the accuracy.

Non return based on collars or tags or using heat detection aids, while a useful indicator of possible pregnancy, should not be relied upon because ‘phantom’ cows, cystic cows and other things can result in significant inaccuracy.

In normal conditions, early embryonic loss can occur in between five and 15 per cent of cows, so when practising early pregnancy testing, it is important to reconfirm pregnancy later so that any cows who have ‘slipped’ can be detected and either resubmitted or carried over and not dried off when empty.

Early pregnancy testing really pays multiple dividends and because of this, it will return a far greater financial return than the cost of an early or extra pregnancy test.

For advice or to book your herd in for early pregnancy testing, call your local dairy vet.

Dr Robert (Rob) Bonanno is the regional veterinary lead for ProDairy in Gippsland and northern Victoria.