Preparations for the breeding season are more than likely underway on many dairy farms across the country.

Over the coming weeks, heat detection is going to play a crucial part in determining how successful the breeding season is.

Heat detection plays a crucial part in determining the amount of cows submitted and the number of cows correctly submitted for breeding.

The task of identifying what cows are in heat can be a difficult task, especially when the average heat only lasts nine hours. As well as that, most standing activity occurs at night, which makes the task all the more challenging.

According to Teagasc, 70% of heats displayed occur between 9:00pm and 7:00am.

Therefore, in order to make life easy, there are a number of heat detection aids that can be used which will eliminate some of the stress at breeding time. Some of these detection aids are listed (below).

These include: 

  • Tail painting;
  • Kamars;
  • Scratch cards;
  • Vasectomised bull;
  • FlashMate heat detector.

Tail Painting

Tail painting is a common sight on most dairy farms throughout the breeding season - especially as it's one of the cheapest methods of identifying cows in heat through the use of a thin strip of paint applied to the top of the cow’s tail.

If the cow is mounted, the thin strip of paint will be rubbed off - which would suggest that she is in heat. This will indicate to the farmer that it is time for the cow to be served.

For best results, tail paint should be topped up regularly (about twice a week) to ensure animals are correctly identified as in heat.


Kamars are another heat detection aid that are found more frequently on dairy farms. It is a pressure-sensitive device with a built-in timing mechanism that is activated by a standing heat behaviour.

The device, which is glued onto the tail of a cow, will change colour from white to red when the pressure from a mounting cow is applied to the device.

This mechanism helps distinguish between true standing heats and false mounting activity, as the detector requires approximately three seconds of mounting activity before it changes colour.


Scratch Cards

A number of companies sell scratch card type heat detectors on the Irish market. The products are relatively cheap to buy.

These cards can either come with a self-adhesive back or may require the use of glue to apply them to the base of the cow’s tail.

When mounting activity occurs, the scratch card is rubbed and changes colour to indicate that the cow may need to be served.

Vasectomised Bull With A Chin-Ball Harness

Another effective way of detecting cows that are in heat is through the use of a vasectomised or ‘teaser’ bull fitted with a chin-ball harness.

The bull has a chin ball harness attached which contains a coloured paint and this marks the cow when she is mounted.

The cost of performing the procedure on a bull is €90-120 and it should be completed at least 40-60 days before the ‘teaser’ bull is introduced to the herd.

The teaser bull can be more useful towards the end of the breeding season, when it comes becomes more difficult to identify what cows are in heat.

FlashMate Heat Detector

The FlashMate heat detector sits on the cow’s flank adjacent to the tail ridge and can be used alongside tail paint.

The product is designed to stay on across multiple heats and alert the farmer to each opportunity to inseminate – with a red flashing light.

Each device contains a microchip and is touch-sensitive. It analyses mounting behaviour among cows – often identifying extra submissions from ‘silent’ cows that the farmer may not otherwise submit, resulting in extra pregnancies.