Diagnosing pregnancy in cows is one of the building blocks of fertility management in any dairy or beef herd. The sooner a cow’s non-pregnant status can be confirmed, the sooner corrective action can be taken.

There are various methods available to determine whether a cow is in calf or not. Of these, the visual assessment of the cow’s pregnancy status is probably the least reliable. The best-known method is manual direct transrectal palpation although nowadays ultrasound scanning (sonar) is also commonly used. In addition, many of the indirect methods employed allow for the detection of endocrine hormones such as progesterone and even pregnancy-specific proteins.

The most cost-effective method is visual observation of cows returning to oestrus after having been mated or inseminated. These cows can then be rebred or -inseminated; however, this carries a risk as they can be in calf already and only appear to have re-entered oestrus. This is often due to the secretion of oestrogens by the placenta or the developing amniotic membranes in early pregnant animals.

This method is also not very reliable, as many cows that re-enter oestrus may be overlooked.