Using Heat Detection Aids


8 min read

Using tail paint Heat mount detectors How to read heat detection aids Using electronic devices Electronic heat detection Using vasectomised bulls

Using heat detection aids efficiently will help ensure a successful mating period on your dairy farm. There are different heat detection aids for cows, including tail paint, heat mount detectors, electronic heat detection, and vasectomised bulls. There are benefits to using the varying aids, but using a combination will help you to read cows’ heat signs as effectively as possible. 

An effective use of heat detection aids will help ensure a successful mating period. There are several options and innovations available to aid heat detection and increase heat detection rates. Each cow must have a unique number to be readily and accurately identified. Determine which of the following options will suit your heat detection strategy. Remember, for the best results use a combination of aids and paddock observation.

Using tail paint as a heat detection aid

Correctly used, tail paint is an inexpensive and effective aid for people detecting heat. It is possible to achieve high heat detection rates using tail paint alone, provided the person using it is highly skilled and the paint is maintained appropriately.

A strip of tail paint is applied to the rear portion of the backbone of each cow. Cows on heat will stand when mounted by herdmates or a bull, and the tail paint will be gradually rubbed off as the other animal dismounts.

How to apply tail paint

  • Remove loose hair or dirt before applying tail paint and don’t apply the paint too thick.
  • When applying tail paint for the first time, apply the paint from the tail pushing towards the cow’s back - this will lift the hair and make it easier to detect heats when the cow is ridden. A cow that is ridden will either have the paint rubbed off or have their hair pushed down and dirtied by mounting.
  • The strip should be no more than 20cm long and 5 to 6cm wide. It should be thick enough to cover the skin, but hair fibres should still be visible.
  • Check the paint strip each milking. In 90 percent of cases, most of the paint will be rubbed off when a cow is on heat. A further five percent of cows will lose some paint, and with the remaining five percent confusion can occur, so experience in reading tail paint is needed for these cows. Paint is rarely removed by occasional mounting of cows not on heat in the yard or race.

Considerations for using tail paint

  • Tail paint should be touched up at least weekly.
  • Only commercial products labelled for use as tail paint should be used.
  • Always refer to manufacturer’s instructions for unique application requirements.

How to use tail paint efficiently

For cows on heat, re-check that the tail paint has been rubbed immediately before each cow is inseminated. This will help avoid inseminating cows that are not on heat (e.g. drafting errors).

Reapply tail paint to recently inseminated cows once the cow has gone off heat – generally at the next milking. Use a different coloured paint on cows after their first insemination. This will help identify cows that have not yet been inseminated, and this helps you decide whether to inseminate a cow that is showing only weak signs of heat.

Using heat mount detectors as detection aids

InCalf research has shown that using heat mount detectors can result in higher detection rates than tail paint alone, particularly in herds where less skilled or unmotivated staff are checking for cows on heat. Best results are achieved when heat mount detectors are combined with paddock checks for heat.

Heat mount detectors are applied to the rear portion of the backbone or rump region of each cow. Cows on heat will stand when mounted by herdmates or a bull and the detector will respond to the pressure or rubbing from the mounting animal, becoming brightly coloured and easily recognised.

There are several types of heat mount detectors – pressure-activated ‘tubes’, scratch-off ‘patches’ and electronic devices are now available.

Types of heat mount detectors

Pressure-activated heat mount detectors

These devices are pressure sensitive and are activated by standing heat behaviour with a built-in timing mechanism.

Some detectors are self-adhesive and some require gluing, always follow the manufacturer’s instructions. The device is mounted on the backbone with the top of the patch roughly between the hip bones. Adjust for the size of cow and aim for position that will receive maximum pressure from the brisket of the mounting animal. Examples include Kamar®, LIC Heat Patch, LIC Heat Patch Plus, Bulling Beacon, Heat Seeker Heat Detector.

Pressure activated heat mount detector

Scratch-off patch heat mount detectors

These devices have a silver surface that is gradually rubbed off with each mount, revealing the colour underneath.

Self-adhesive generally but some gluing may be required - always follow the manufacturer’s instructions. The patches are mounted across the backbone, roughly between the hip and tail head.

Examples include Estrotect™, Bulls-i, ScratchE Heat Detector.

A scratch-off heat mount detector

Electronic devices for heat mount detectors

These are touch sensitive and contain a microchip. They analyse mounting behaviour and look for specific patterns of riding activity such as frequency, number and length.

They require gluing to apply and sit adjacent to tail ridge. They have been designed to stay on across multiple heats within a single season.

Examples include Gallagher FlashMate®.

Considerations for using heat mount detectors

  • It is recommended to prepare the area two days prior to application. Remove loose hair and dirt (these disturb the oils in the coat and prevent glue from sticking). Some aids may require additional glue as some cows have too much oil in their coat. 
  • Electronic devices will need re-applying throughout season, particularly due to spring-moulting.
  • Apply heat mount detectors to every cow according to manufacturer’s instructions on the day before mating starts.
  • Check for other signs of heat if a heat mount detector is lost, as it may indicate a cow is on heat.
  • Remove activated heat mount detectors from cows on heat at the time of insemination.
  • Replace the heat mount detector following insemination when the cow is no longer being mounted. Continue this replacement policy until the end of the AB period.
  • Switch to tail paint after the first insemination if you are confident high levels of heat detection can be maintained. If you are not confident, use heat mount detectors after the first round of AB because the sexually active groups are smaller and less active making some cows harder to detect.
  • If you have any concerns during the AB period, consider applying a fresh aid to the entire herd to assist detection. This could provide a fresh perspective for you and the team.
  • Check heat mount detectors regularly and replace if they are damaged or are coming loose.
  • Avoid using heat mount detectors if cows have access to low tree branches that are likely to rub them off.
  • Check that the type of heat mount detectors you are planning to use will stay on yearling heifers.
  • Consider combining heat mount detectors with tail paint.

How to read heat detection aids

Increase the understanding and confidence of your team with these simple tips.

How to read heat detection aids

Video 1:47 min

How to use electronic heat detection

There are a variety of electronic heat detectors in cameras and activity meters.

The heat detection cameras ‘read’ heat from heat mount detectors. The camera systems work in conjunction with drafting systems, so both need to be installed to use the product.

Activity meters are electronic transponders that detect movement and can be attached to the cow’s leg, in an ear tag, or hung around their neck. They record cow movement as cows on heat typically walk more as they are restless, mounting and being mounted by other cows.

The amount of activity is compared to previous days to identify spikes in activity and 'identify' heat. Some brands compare cow activity to the rest of the mob on the same day, and rumination is included in some technology. This can be adjusted for days where there might be a long walk to a back paddock. Check the reliability and durability of this technology before you purchase it, and talk to other farmers with the system to discuss strengths and weaknesses.

How electronic heat detection works

Automated technologies are an aid to heat detection, but they do not directly diagnose cows in heat. When a cow is in heat, she becomes increasingly restless and this change in activity can be monitored by a motion sensor attached to the cow. Most automated heat detection systems work by monitoring changes in these patterns of cow movement.

The monitoring device is attached to the cow by a leg strap, in an ear tag, or a neck collar (which may be weighted to keep the device in position).

The simplest sensors have a ball or mercury switch inside a chamber that moves from side to side creating a total activity count. More advanced sensors measure both the direction and the intensity of movement in three different planes: side to side, up and down, and front to back.

Cow motion is monitored multiple times per second to help identify different activities such as lying, standing, mounting, walking, or grazing. The sensor sits inside waterproof housing that also includes a battery, a miniature processor for processing the data, a memory device for temporary data storage (usually up to 24 hrs), and a data transmitter.

Considerations for using electronic heat detectors

Automated heat detection systems deliver the most value when the herd manager is motivated to make the system succeed. Some investment in time is needed to actively manage the technology and correctly interpret the data. Cows that are flagged as being on heat only by their activity data require further investigation to determine if they are in fact in heat, so it is essential that your stockpeople are properly trained in the use of the system.

The time needed to install an activity meter system will depend on the size of the herd, the type of system being set up and the number of receivers required. In general, most herds can install a system in one full day. Set up will involve:

  1. Attaching neck collars, ear tags or leg bands to cows
  2. Installing receivers and connecting to mains power and a data transfer method
  3. Installing software on a PC located near the dairy and connecting the computer to the internet.

Some systems operate using a custom terminal, avoiding the need for a computer and software.

Consideration will need to be given to the available labour, health and safety risks and facilities required for handling cows to attach sensor devices. If power is not already available at the site of the receivers then this may need to be arranged prior to the day of installation. A suitable computer and office area may need to be set up near the dairy if one does not already exist.

A functional internet connection to the dairy computer may also be required.

Using vasectomised bulls

Vasectomised bulls may help identify cows on heat along with other heat detection aids. It is important to have enough bulls so that bulls are not overworked and injured or that they only ride cows with strong heats.

There is an expense to buying the bulls and feeding them and keeping vasectomised bulls on farm increases health and safety risks.

Last updated: Sep 2023
Tags related to “Using Heat Detection Aids”

Related content

Extending AB Period


3 min read

BCS Nutrition


4 min read

Bull Management


5 min read

Calving Pattern


4 min read

Fertility focus report


3 min read