How can one be short of grass at the end of May, with conditions ideal for grass growth?

Well it can happen and at least half the farmers I spoke to this week were complaining of being tight for grass.

Even though growth rates have been relatively good, some farmers say they took out too much area for silage, were too slow cutting it or because they cut back on nitrogen a lot this year the steam ran out of swards earlier than they expected.

Some of these farmers were hovering around average farm covers of 130kg to 140kg per cow, when they should be at 160kg to 180kg per cow.


It would be OK to be low for a week or so, but one would prefer to see the cover to quickly bounce back up to the target.

Pre-grazing yields on these farms are low at around 1,100kg/ha and rotation length was at risk of speeding up into an unsustainable spiral.

The fear of running out of grass, when one shouldn’t really be short of grass, can make the farmer feel inadequate

The first comment to make is that it’s an awful feeling to be in – the fear of running out of grass, when one shouldn’t really be short of grass, can make the farmer feel inadequate.

The thing to remember is that there are many others in the same boat.

Underestimating demand

One possible reason why farmers can find themselves in this position is that they are underestimating the demand for grass of the herd and this then lulls them into a false sense of security when making decisions around dealing with surpluses.

In other words, the cows are actually eating more than the farmers think they are.

Most farmers presume that their cows eat 18kg of feed per day and that if they feed 2kg of meal then the grass demand is 16kg per cow per day.

While this may have worked well in the past, it doesn’t work as well in the present.

The reason for this is that the modern dairy cow is producing about 20% more milk solids per day than cows did 10 or 15 years ago.


It is now common to be on farms where herds are producing 2.2kg MS/cow per day for weeks on end, whereas before they may have peaked at 2kg MS/cow per day for a week or so, with 1.8kg MS/cow/day being more like the norm.

This additional output requires additional input. Cows don’t produce milk from fresh air – they need to convert feed to milk solids.

Cows produce more now because we have been breeding cows with higher intake potentials and higher output.

Has it ever happened that grass growth was greater than grass demand, but yet average farm cover dropped?

Technically, that shouldn’t be possible, but it can happen if the demand figure is being underestimated.


The issue is that if farmers think the demand is lower than it actually is, they may be lulled into taking out more area for silage than they should really take out.

I think this could explain why some farmers are tight for grass now. Solving that problem means putting in additional feed to slow down the rotation length or applying some more nitrogen.

On most farms, there is extra land to come in after silage is cut, so that will be a help in rectifying the problem.

In the meantime, do regular back calculations on covers to see if you are correctly estimating the herd’s demand for grass.