‘Farmers need to look at how many dairy-bred heifers they need on their farm’

“We think that once dairy farmers have bred the replacement heifers that they need, they can go on to use the Dairy Beef Index (DBI) and produce quality animals that can then be taken up by beef rearers and produce a good profit. That is the way of the future.”

This was a statement made by director of Teagasc, Prof. Gerry Boyle, at the recent launch of Phase II of the Teagasc Green Acres Calf to Beef Programme.

Dairy farmers all over the country are guilty of breeding too many replacement heifers for their dairy herds.

In a good milk price year this may not eat away at your profits too much, but in a poor milk price year rearing surplus stock can be very expensive.

The fact of the matter is that rearing heifers – unless they are going on to be milked in the herd – is not a money-making exercise. Rearing replacement stock is one of the single biggest costs on your farm.

To rear a replacement heifer from birth to calving (at 24 months old) costs between €1,300 and €1,500 and she is usually into her second lactation milking before she breaks even.

If that heifer fails to go back in-calf, becomes lame or leaves the herd for any other reason before she is halfway through her second lactation, she will have made you nothing.

So, if you are rearing heifers with the intention to sell off surplus, you would need to be rearing some exceptional stock if you want to cover all the costs she has incurred to you.

As it stands, on average, the national dairy herd is achieving 2.9 lactations per cow, which is way behind where we need to be if we want to reduce our greenhouse gas emissions by increasing the longevity of our dairy herds.

To increase our herd’s average lactation per cow, we need to be sticking to the target replacement rate of 20% and not let it slip above this figure – unless the herd is expanding.

A replacement rate greater than this can force you to put pressure on the farm’s feed availability, housing, feed space and labour; which can impact negatively on the other stock on the farm and yourself.

Also, having a replacement less than this can restrict the use of voluntary culling.

How many weeks of dairy AI do I need to do?

You should be tactically thinking about how many weeks of dairy AI you need to do – to get the amount of dairy bred heifers you require.

For a 20% replacement rate – for a 150-cow herd – you will need 32 replacement heifers. It is a good idea to keep a couple extra in case of any unforeseen circumstances.

If this herd already has 30 heifers entering the herd, all of these should be bred with dairy AI. For heifers, an in-calf rate – at the end of the breeding season – between 98% to 100% is desirable. So, the heifers should hopefully generate at least 14 of next year’s replacement heifers.

Source: Teagasc

For the cows, an average three-week submission rate of 70% and a conception rate of 50% will result in a 58% in-calf rate after six weeks of AI.

At least half of these should be heifers, so will result in the cows generating approximately 34 replacement heifers. More than enough for the herd.

This in-calf rate can be lower or higher depending on the fertility status of the herd and the amount of cows submitted in the first three weeks of the breeding season.

Reducing the number of weeks using dairy AI back to four or five weeks will reduce the number of surplus heifers generated by this herd.

Dairy farmers can then go on to use the DBI to select bulls for breeding thereafter. Another option to consider is to breed your lower-performing cows with beef breeds.