News & Advice

Heat detection – thinking changing your system?

Aug 30, 2022 | Dairy, Dairy Farm Reproduction

Katrina Roberts, Herd Health Veterinarian, Anexa Vets

I have been asked loads of questions about the use of technology and heat detection in the last few years. It seems you all want to know, “Will I get better results because I spend the big bucks on some wearables?” And although this is a valid question, I then ask you: “Are you getting the repro results you want with the current system you have and is your current system repeatable?” This is quickly followed with, “Do you know if the heat detection on your farm is one of the main reasons for you not achieving the repro results you want?” Unfortunately, I cannot provide a specific answer until I have all the information about your farm. That said, the most important job on your farm during AB is picking the cows on heat, and the best way to achieve exceptional results is going to be slightly different for each farm. Still, there are some key principles below that apply to ALL farms.


What factors do you need to consider before you make changes to your current heat detection system?


1. Is your current heat detection system achieving the results that you want and is this system repeatable?

Evaluating your herd’s heat detection success is not only about the 6-week in-calf rate; also consider if you are getting enough keeper calves or if you are using more non-cycling treatments than you are comfortable with. Heat detection is innately intertwined with non-cyclers – if you can’t pick cows on heat pre-mating, then it’s likely you won’t be picking them once mating starts either. 


2. Who is doing heat detection on your farm?

InCalf research tells us that this job needs to be done by the most experienced people in your farm team and should not be shared between all staff. For some farm teams the most experienced person may still not be competent enough to be the sole heat detector, and likewise you may not have more than one person that can share this job i.e. what if someone gets sick? Therefore, having a backup plan is crucial – we don’t want this season’s results dragging into next season. Our Repro 101 farm staff training session is a great place to come for a refresher of all things mating!


3. Are you considering all AB?

If you have been pondering this, remember that staff get exhausted with continual maintenance of heat detection aids (e.g. touching up tail paint) and physically inspecting cows for bulling activity and then drafting them. After the first round of AB, there is still lots of work to do with the average farm having half the herd not-in-calf. As mating goes on less cows on heat means smaller sexually active groups and these cows are harder to find. Increased temperature and humidity can depress signs of heat as we head into summer. Your team must be prepared and committed for the long haul. Some cows are particularly hard to detect in heat and bulls are more likely to find them.


4. Do you have a lot of non-cycling cows?

Herds that achieve 78% 6-week in-calf rate are achieving submission rates of more than 90% of their herd submitted for AB by the end of week 3; the national average submission rate is only 80%. We know that missed heats is one of the primary reasons for herds not achieving target submission rates. If you have a lot of non-cycling cows you need to be prepared for unusual return intervals, big numbers of returns over a short-period (if they have been treated in a non-cycler programme) and that even the cycling cows in your herd may be harder to detect as their heats may be less strong.   


5. Is there anything about your farm that makes certain heat detection aids tricky to interpret?

If you have lots of low trees or hedges then some of the heat detection aids may be more difficult to interpret. Are any of your staff colour blind so may struggle to read certain heat detection aids (about 1 in 12 (8%) males and 1 in 200 females are colour blind so it may be more common than you think)? What is the light like in the cowshed? Can you actually see properly in your shed to be confident that the aids have gone off/or a cow has been rubbed?


6. How do you get up to cow height to read the aid?

How easy is it to read the aids and reapply the aids in your cowshed? What can you change or improve to make sure this is working better for this season?


7. Are your herd records up-to-date and is the cow ID system fit for purpose?

Cows that have no unique ID (ear tag or EID) due to imperfect herd records create issues with heat detection. Poor ID will lead to cows being mis-drafted leading to the wrong cow being mated, and the right cow being missed.


8. What is your current drafting system like?

Are you 100% confident that when a cow needs to be drafted she will be pulled out every time? Autodraft is not always perfect so ensure you do a dummy run during pre-mating to make sure all systems are in working order. If staff are manually drafting cows, is the system easy to use? If drafting is hard for the team and the cows, then cows will get missed. And the frustrating thing is that the cows being missed are the cows on heat that you have detected – what a waste!


9. Are there other factors at play in your herd influencing the intensity of heats that makes heat detection more difficult?

The duration that a cow is in standing heat varies considerably (range 2-28h but typically 12-18h), therefore those cows with shorter heats really need some dedicated observation to be identified and put up at the right time. The intensity or strength of a cow’s heat can be negatively affected by factors such as poorer body condition score, poor health, lameness, low energy intakes, adverse weather conditions and stress. The heat behaviours exhibited are due to the hormone oestrogen, and therefore the higher the levels of oestrogen, the stronger the signs of heat.


10. Are you considering doing herd synchrony for the cycling cows?

When lots of cows are on heat at once in a short space of time your heat detection needs to be even sharper. Dealing with large numbers of cows increases the chance of the wrong cows being detected, and the timing of AB being incorrect. Therefore your system needs to be spot on to maximise the benefit of the extra cows on heat.


Is everyone on your farm aware of their role in the heat detection system? 

Good heat detection does not end with a person or computer observing a cow showing signs of being on heat. There also needs to be good communication of that information, to the right people, to ensure the cow gets submitted for insemination at the right time. Well performing technology can achieve an accuracy similar to an experienced farm manager, but performance varies between and within systems. A backup, should be used in case of technology system failure. Automated systems can be costly and will require time spent learning the way they work. You have probably spent many years learning how best to maximise the heat detection aids you use so you need to expect to invest this time in the new technology to get the best results. All the tools we use to assist with heat detection (technology or traditional) are heat detection ‘aids’. No aid is perfect. Therefore, a combination of aids and increasing the time spent interpreting and reading the aids will lead to better results.

If you want every cow that is on heat to be successfully mated, now is the time to tweak your systems. Chat to your vet to set up a plan or fill in a request on our Farm Staff Training page and we will be in touch to organise some on-farming training for your farm team.


Some Anexa resources you might find helpful:

PODCAST – 3 tips for making the pre-mating period count

Bull Soundness.pdf

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