For effective management decisions, it is essential to know which cows are pregnant and when they conceived, as this determines when they will calve. This allows you to:
- accurately measure the 6-week in-calf rate to assess overall herd reproductive performance;
- confidently cull cows as empty, at the right time;
- confidently dry-off cows at your preferred time before their due-tocalve date;
- differentiate AB from natural mating pregnancies;
- identify cows due to calve late;
- more accurately select cows that are close to calving;
- provide due-to-calve dates if selling cows;
- plan feed and labour management right through the dry-period, to next calving and mating; and
- refine your dry cow treatment (DCT) decisions with the vet.
Early-aged pregnancy testing helps ensure individual cows are dried off at the right time, based on age, body condition score and accurate due to-calve dates. This enables dried off cows to be better allocated to dry cow mobs for wintering. This results in accurate feed allocation, especially on crop, and easier management and observation of springing cows through the calving transition.
Pregnancy testing methods
The main methods used for determining the pregnancy status of cows are rectal examination using a hand or ultrasound probe. Other methods exist such as milk or blood pregnancy testing.
Pregnancy status can be recorded aged in days or weeks for manual or ultrasound testing, while all methods can be used to record non aged results.
Early-aged rectal pregnancy testing by a skilled operator is the most accurate method to identify cows that are 5 weeks pregnant or more. If tested between 5 and 14 weeks of pregnancy it gives a good estimate of when cows conceived.
Early-aged pregnancy testing helps ensure individual cows are dried off at the right time, based on age, body condition score and accurate due-to-calve dates, and dried-off cows can be better allocated to dry cow mobs for wintering. In turn, this allows accurate feed allocation, especially on crop, and easier management and observation of springing cows through the calving transition.
Alternatively, pregnancy status may be estimated using continuous heat detection.
Some cows confirmed pregnant by pregnancy testing may fail to calve. This is most likely to be due to pregnancy loss (abortion) occurring after the pregnancy testing has been done. When the loss rate is higher than normal, a specific reason for abortion (e.g. neospora or BVD) should be investigated to prevent a recurrence.
For further information check out Chapter 18 of the InCalf book.