Heat Detection
Effective and accurate heat detection is essential for good reproductive performance. If a cow is not seen bulling, she cannot become pregnant. Today’s dairy cow is spending less and less time in standing heat with about 70% of all bulling behaviour occurring between 6 pm and 6 am. Half of all cows are in heat for between 6 and 12 hours, but a quarter are in standing heat for less than 6 hours!
As there are fewer and fewer staff about on dairy farms, heat detection rates have been reducing and the importance of using heat detection aids has never been greater.
Effect of heat detection on fertility
Let’s take two herds with 100 cows eligible for service and a conception rate of 40%. Herd A has a heat detection rate of 50% and so over a three week period, assuming all cows are eligible for service, 50 cows will be served and 20 will become pregnant.
Herd B uses heat detection aids and has a 75% heat detection rate and so in a three week period 75 cows will be served and 30 will become pregnant. Herd B gets 50% more cows in calf than Herd A, purely down to improved heat detection. This results in a shorter calving index, more cows pregnant when you want them and demonstrates that the importance of good heat detection cannot be overemphasised.
Effect of heat detection on a number of pregnant cows
How can we improve heat detection?
- It’s essential that all members of staff know how to identify a bulling cow. This should include tractor drivers or others who work around cows.
- Cows should be clearly identified with a freeze brand or a large management tag which is easy to read.
- Staff should have a notebook and pen; it’s easy to get confused between 123 and 132!
- Cows don’t all come bulling every 5 minutes. You really need a period of 20 minutes to get a good indication of what’s happening, three to four times a day. Late at night is a key time.
- Ensure good communication between staff to focus on animals likely to be bulling.
- Know which cows are likely to come bulling. Use the diary, Bray chart or computer. If a cow is bulling today, then put her details in the diary 18 days later so that you increase awareness that she will be returning to heat.
- Remember that cows will not show signs when there are other activities going on, such as milking and feeding.
The importance of heat detection aids
Anything which can increase the number of cows seen bulling will improve fertility. Even herds with good visual observation will see additional benefits.
Farmers and vets want heat detection aids that are both easy to apply and effective. Individuals have their own personal preferences. Scratch card technology, such as AI Ready, relies on the cow that mounts the bulling animal to rub off the silver coat of the AI Ready to reveal a Day-Glo colour that can be seen from afar. These are really popular.
AI Ready are self-adhesive and come in four different colours, which is very useful. One colour might be used for cows which have never been seen bulling, another for picking up three week return services and another for cows which are not pregnant at the vet check or problem cows.
AI Alert are also self adhesive and so really easy to apply. You just peel off the back of the device and stick to the cow, there is no messy glue. After cows have been mounted, paint is released and the AI Alert changes colour.
Everybody has their own personal preference. Both AI Ready and AI Alert are really easy to apply and that’s very important on a busy dairy farm where time is always an issue. They are ideal for application during vet fertility checks.
Some people use tail paint, however, this has to be applied regularly to ensure that it works well. This can be a very time consuming type of heat detection aid. Pedometers use proven technology and are very useful in detecting heats but have a high capital cost. There are other systems that involve high capital expenditure that can also be useful.
AI Alert and AI Ready have the advantage of being easy to apply, provide excellent value for money and most importantly, are effective without any large capital outlay. Every farm will benefit from using effective heat detection aids.
