Grass growth continues to push on, with growth rates pushing up to and over 90kg of dry matter (DM)/ha in parts of the country again this week.

Considering demand is still sitting around the 60kg DM/ha mark, many farms are growing more than they are consuming leaving them with a grass surplus.

At this time of the year, maintaining an average farm cover (AFC) of 650kg DM/ha or 190kg DM/LU ensures cows are entering paddocks with optimum pre-grazing yields, helping them to push on with solids.

PastureBase recording farms had a mean AFC of 721kg DM/ha last week, or 198kg DM/LU, which is as good as on target.

However, 37% of those farms were over-target, with AFCs of 763kg DM/ha.

That meant cows were entering paddocks with pre-grazing covers of 1,783kg DM/ha. This is too high and will only cost you in milk protein, which has already dropped marginally since mid to late May.

Adjusting the rotation

It can be a struggle to keep quality grass in front of cows throughout the month of June as grass is in its peak heading phase, especially with the long days and high moisture content.

A lot of farms have already taken paddocks out of the rotation for surplus bales, but considering there is no signs of any droughts hitting us any time soon, it may be worth adjusting the rotation length too.

If the rotation length is still up in the mid-20s, cows will only end up going in onto stemmy grass, which can limit their intake right back to 15kg of dry matter.

As well as that, 1kg of stemmy grass is only the equivalent of 0.9UFL, whereas 1kg of flush grass at the three-leaf stage in a cover of 1,400kg DM/ha will provide 1.0UFL.

If cows take in only 15kg of DM grass and eat only 2-3kg of meal, this will only support about 21L of milk, whereas if cows take in 18kg of DM grass with 2-3 kg of meal, it will support 28L of milk for your average Irish cow.

If the optimum targets are not being met, it will ultimately result in a leak in the milk cheque.

That is why it is critical to maintain a rotation length of 18-21 days, ensuring cows are going into 1,300-1,400kg DM/ha pre-grazing covers.

If the rotation length is corrected, it may be possible to reduce meal back to 1-2kg/cow/day, which will also help in boosting farm profitability.

However, even with the rotation length set correctly, grass walks will prove their worth at this time of the year as growth rates and farm covers can swing in a matter of days.

If growth rates start to slow rapidly and fall below demand, the rotation will need to be extended again to prevent a deficit.