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Summertime Cow Nutrition: A Lot Done, More to Do

26 April 2022
Type Media Article

John McCabe, Teagasc/Aurivo Joint Dairy Programme

We have come a long way in the last 20-25 years in terms of managing the feed we give to dairy cows during the summer. However, there is still a lot more to be done in terms of mid-season cow nutrition.

  • A cow will eat 10% less grass if she is put into a paddock with an 1800 cover (too strong) instead of a cover of 1400 (ideal).
  • A cow will typically eat less when the strip wire is used to offer fresh grass to cows and to get good clean outs at every grazing compared to 36 hour allocations.
  • An 1800 cover will usually have lower energy per kg of grass DM eaten than a 1400 cover.

Armed with these three powerful pieces of information on cow nutrition, I discuss how it goes wrong during the summer and some pitfalls to avoid.

Pasturebase data shows that in late April, May and June roughly 2/3rds of farmers graze their grass about 2-6 days after the grass was at the ideal cover. This means the cover is way too strong and there will probably be poor cleanouts. Do this across every paddock in the farm for a few rotations and by the middle of the summer you are a meal salesperson’s dream. I say this because in these scenarios when we reduce meal feeding, the bulk tank will suffer a lot. The finger is pointed at the drop in meal feeling and not at the poor quality covers that are being strip grazed.

I advise that twice a week when you open the gate for the next grazing - walk into the field and look at the grass with a critical eye. Is this cover 1400? Or is 1800? If it is too strong walk to the next paddock, and if that paddock is too strong keep going until you find the best grass.

Growth is usually at its strongest at this time of year so unless you have a farm of creeping bent grass, have no fertiliser out, are stocked up to 5+ cows/ha or there unfavourable growth conditions, you should whip out them strong paddocks straight away for baled silage.  You will have lovely after-grass coming back for milking cows. Don’t let these paddocks bulk up. Don’t fall into this very common trap. It’ll be white at the butt when you get around to cutting it and there could be another 2 paddocks to cut out at that stage. It will be growing for an extra week and take a week longer to grow back to 1400.

Cut them straight away even if it is showery. The grass can stay down for a good few days. A few light showers won’t do the cut grass any harm and the after-grass will be ready in 15-25 days rather than 25-35 days. The idea is to try keep milk protein % rising every month. The other aim is to keep milk solids per cow up after peak and avoid a big drop off.  Every paddock should get a run of a mower during the year. Baling is much preferred to topping.

My intention is not to open up a debate about topping. The purist grass enthusiasts wouldn’t have it said that a paddock should be topped but there is no shame in topping 3 or 4 paddocks later in the summer as long your number one go-to method all summer has been to mow out surplus. To be clear, topping every paddock for a rotation because you can’t get cleanouts is absolutely the wrong thing also.

If you want to avoid a lot of bales, do not understock the milking platform during the summer as you will have too much surplus grass and it is not advised to bale paddocks twice in the year due to costs. On the flipside, don’t overstock the farm for the summer as you will not be able to correct grass quality.  On a trial a number of years ago, Ballyhaise Research farm found that a stocking rate of 4.5 cows/ha ended up with very poor grass quality by the time they were turning their attention to building Autumn grass and this was mainly down to the fact that they couldn’t afford to mow many paddocks.

Around 4 cows/ha is the advice for the next 3 months however some herds would be better served at 3.8 cows/ha. (Either high production 550kgs of solids herds where cows are eating a lot of grass, or drought prone farms, or farms that have lower levels of grass growth on the milking platform)

Continuous 1400 grass covers + no strip wire + correct paddock sizes + aftergrass from mid-May =
Low meal requirement, milk protein rise and peak milk is sustained for longer. More profitable.
Continuous 1800 grass covers + strip wire + incorrect paddock sizes + little to no aftergrass until July =
High meal requirement to maintain yields, milk protein fairly static from April – August and buying meal to sustain peak. Less profitable.