Breeding starts in the south of the country around 20 April for a late January start to calving the following year.

It means this week some farmers have already started heat detection to try to identify cows not cycling that will be scanned in late April during the first week of breeding. Research suggests that once breeding starts, each missed heat costs €250, so every effort must be made to correctly identify cows in heat.

I’ve categorised heat detection aids into four sections – 1. Paint; 2. Stick-on devices; 3. Teaser bulls and 4. New technology.

Tail paint, either from a gallon or a bottle, is by far the most popular and cheapest method available to help heat detection on spring-calving dairy farms.

You need to keep it topped up so when you or a member of staff sees a cow without paint the number is scribbled down and checked against the breeding chart in the office or in your pocket notebook.

Farmer experience suggests stick-on devices work better on maiden heifers than tail paint. There are a range of devices available like scratch card devices to more elaborate bubble-type devices that change colour once pressure is applied.

The key to success here is applying the devices on a dry day using a glue that is going to hold the device in place. Teaser or vasectomised bulls are a great help in picking up cows in heat but it is important to spare them until at least week four or five of the breeding season or they could be too tired when you really need them when heat action quietens down.

Finally, new technologies are available but cost is very substantial so you need a plan on what more it can deliver and how you can use the information.

1. Scratch card or kamar device – Stick-on devices work particularly well on maiden heifers. Scratch card devices turn red when another heifer mounts on the animal in heat. It is important to apply these onto a dry animal with the proper glue. Scotch Weld 77 glue in a spray can works well and is easier to apply than some other glues.

2. Tail head clipping – Clean off excess hair on the tail head with a clippers and wipe away the loose hair. A roll of 100 estrus alert scratch cards and a spray can of glue retails at around €90.

3. Tail-painted cows – Some farmers will change paint colour depending on the week or stage of activity of the cow in question but priority must be to keep paint on the animal – strong colours like red, blue and green work well.

4. Cow with neck collar dongle – there are a range of new devices that operate using either a collar or an ear tag that measure body temperature or movement. They are more expensive but some devices can pick up more than just cows in heat and may improve other aspects of herd health such as finding sick cows.