Heat Detection in Cattle
Whether natural heats or those programmed with one of the various synchronisation techniques, the heats will all look the same, and the accurate detection of the first signs of standing heat is critical to maximise pregnancy rates from your AI. The only time this is not critical is when ‘timed AI’ is used after synchronisation (i.e. all animals are AI’ed at a set time irrespective of when they came on heat, and in some instances, whether that have even cycled).
KAMAR heat detector patches – These have a blister ball of red dye in them, and when the animal is mounted 4-6 times (by the bull, or another cow or steer), this blister ball is ruptured and the white patch turns red. Things to note about these patches:
– The glue for these comes in a separate tube & is very sticky – these rarely fall off and are very reliable in this way (although they can sometimes slide down off the tail head ridge of bone in skinny animals (& result in false negatives when mounted).
– The glue can be a bit messy if you get it on yourself.
– They are very difficult to get off, even 3 weeks later when you might want to put the next one on (& often pull all they hair out leaving a little bald patch)
– They can be scratched under a tree & opened up & the blister ball lost or ruptured to give a false positive.
Estrotect heat detector patches – this type is like a “scratchie” where the surface gray layer is rubbed off when the animal is mounted 4-6 times (revealing the underlying fluorescent pink, yellow or orange). We have started using these in 2021 because they seemed more flexible & cheaper and despite worrying that the glue might not be good enough for hairy animals, we are still using them today, although there are a couple of things to remember:
– They need to be warmed up for at least 30+ seconds (by rubbing them vigorously on your pants/thigh for example) to make the glue on the back sticky enough.
– They can be scratched on low hanging tree branches, but the gray layer never appears to be rubbed off in this situation
– They occasionally fall off (on a very hairy animal, or where the glue was not warmed up enough).
– They are easily removed in the paddock with quiet animals, or the crush.
– They can be cut in half length ways (as seen in these photos) and used on 2 animals.
Signs to Watch For When on Heat
Some animals show more overt signs here than others, with some heifers having shorter & somewhat ‘silent’ heats.
Signs of impending heat (12-24 hours prior)
♠ they will be often the ones wanting to mount those that are already standing
♠ this may annoy others and cause brawling and head butting
♠ they may be restlessness, may seek out other cattle and not graze as much
♠ clear stringy mucus may be seen hanging from the vulva or smeared on the pin bones
Signs of standing heat
Remember that the critical moment is when they are first noticed to be standing still while another animal mounts them. If you do not get to see them actually standing, there are other signs of standing:
♠ ruffled hair on the tail head
♠ scuff marks or dirt/mud half way up their back or down the sides from the mounting cow’s front hooves
♠ heat detector device changed colour
Cows will stand to be mounted for 12-24 hours (less than this for heifers), and during this time they may be jumped 50-80 times by various other cows (often by the ones who are about to stand later that day, or by a more dominant female).
The Secrets of Successful Heat Detection
Successful heat detection stems around being aware of the above signs, and taking the time to check for these. You need to check at least twice a day (ideally up to 4 times), at dawn & at dusk, remembering that most will stand for the first time in the dim or dark hours.
| Time | Percent of Cattle Cycling |
| 6am – Midday | 22% |
| Midday – 6pm | 10% |
| 6pm – Midnight | 25% |
| Midnight – 6am | 43% |
Take your time when you go out & check (take a glass of wine or a cup of tea with you). Take at least 15-20 minutes to observe their natural behaviour, and make sure there are no distractions (not at feed time, leave the dogs back in the house, don’t brush them) – try to be a fly on the wall! A torch helps at night of course.
Have the cattle as close to the house as practical so that you can also have a glance out the window at any time of day. This is especially important if you are using spontaneous heats.
Make use of heat detection devices as they will greatly improve your heat detection accuracy, but don’t rely on them totally (see ‘False Alarms’ below). Some animals will never be seen to stand but their heat detector has well and truly gone off. Heifers are a good example here and may only cycle for 6-8 hours and can easily be missed.
Heat Detection Aids
There are 3 commonly used aids:
1) Kamar® Heatmount Detectors – many believe these to be the most reliable, especially on the long hair of Highlands. Take care with their placement as per the directions, and second Kamars can be placed over the top of ones that have gone off. They do not go fully off until the cow has been mounted at least 3-4 times.
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2) Estrotect® Heat Detectors – also useful but maybe not be quite as sticky. We have switched over to these in 2021 because of the ease of application and removal. They are just as simple to tell who has been jumped, and just as accurate with false positives (if not easier to pick – see below). You need to pay attention to application technique to be sure the glue gets sticky enough (rubbing vigorously on your thigh for 30+ seconds to warm it up – especially important on colder days. Some will cut these in half length wise & get two uses from a single patch, thus halving the cost.
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3) Tail Paint – some have used this in Highlands and ta
il paint is generally useful but there are more potential for ‘false alarms’ with this method, so not recommended by us. Certainly the cheapest heat detection aid.
Heat Detection Animals (‘teasers’):
1) An older steer / bullock that was castrated later in life will certainly show you who is cycling, in much the same was as a bull might.
2) A side-winder bull will do the same job (this is an entire bull that has had his sheath operated on by a vet to make it point out to the side so that he can never effectively serve a cow).
3) Any other female, especially the more dominant one in the mob, that mounts the animal that is on heat, pretty much every time. This is all we rely on at Bairnsley.
False Alarms
Low hanging branches are a nightmare. Do not put animals with heat detector patches into any paddock with such branches. Far too confusing. Get the chainsaw out if you have no other paddocks.
Some KAMAR heat detector patches may fail to go off when mounted. This is rare but can happen & we have seen one such case. Not sure of the reasoning for this but may be due to a faulty patch or a cow that prefers the missionary position perhaps. Remember that with spontaneous heats or even the best synchronisation programs, 10% of females will not detectably cycle.
What about then they go ‘half off’. This happens a bit with either rubbing on branches or if they have been not quite standing still to be mounted in the 12-24 hours prior to actual standing heat. A cow may also have a weak heat & just keep moving around, never actually standing still long enough to be properly mounted. These are not proper heats and generally should not be bred with AI or used as recipients.
A small number of cows (up to 5%) may cycle & indeed stand while pregnant. We have had one cow who has stood several times during both of her pregnancies with us.
Some breeders are still confused by the bloody vulval discharge that is seen will only happen 2-3 days after they cycle, whether pregnant or not. This is NOT evidence of them losing the calf, just a normal part of the heat cycle of a bovine.