Phantom cows

She was observed to be on heat, she was put up for insemination and she was not observed in heat again. When pregnancy tested, she was empty.

Detecting these cows earlier will provide a much better outcome but how to make these cows visible? Often, we will point to the need to improve heat detection, but this is not always where the “blame” lies.

Phantom cows are a reality They come into visible oestrus, are mated and they not observed in oestrus again or they may or may not appear again more than 42 days after the original mating.

Finding these cows early is important if you are minimising calving spread and attempting to reach the industry goal of 78% 6-week in-calf rate. Early pregnancy testing at less than 6 weeks pregnant using an ultra-sound probe is very reliant on the operator’s skill. Some will use this early scanning technique.

Earlier diagnoses can be obtained using milk tests – one measures a pregnancy protein and is reliable from 28 days after insemination. This test can also be performed on blood. It is highly reliable at this stage of pregnancy but be cautious if you are using this pregnancy protein test later. Early embryonic deaths occur in 3% to 5% of pregnancies and this protein will still be present for around 60 days after the pregnancy has terminated.

The second milk test, measures progesterone and can be used 18 to 22 days after mating. At Totally Vets we have been working with this new test for just a season. While it is early days the reliability of this test at detecting open or non-pregnant cows was 100% but the numbers tested were small. The test measures the significant drop in milk progesterone that occurs at 18 to 22 days.

Back to Farm Animals

Dairy Articles

All website design, artwork, photos and other content © 2022, Totally Vets, New Zealand. | Log in