It's early June and that means two things; the Leaving Certificate has started and grass has gone stemmy.

The former is a worry for school leavers, but the latter is a worry for farmers.

Stemmy grass affects milk production and daily liveweight gain. What can farmers do to correct it?

At this stage, grazing tight isn’t going to solve the problem. The grass is stemmy for a few reasons, but usually because it wasn’t grazed tight enough at previous grazings.

However, we can’t ignore the fact that time of the year is also a factor, in that grass wants to seed now and in order to support a seed head, it needs a strong stem.

So in many ways no matter how good the field was grazed previously, the grass will still want to go stemmy now anyway.


Another possible reason for stem is that grass is stressed either from a lack of moisture, in some cases, or a lack of nitrogen in other cases, or indeed both.

The stress factor sends a signal to the grass plant that ‘hey, I need to produce a seed before I die’, so it attempts to produce a seed head even at low covers.

Mechanical control of grass quality involves some form of mowing, whether that’s topping, pre-mowing or taking for silage.


The thing to remember with pre-mowing is that it reduces the cow’s ability to select the nice grass, effectively forcing her to eat the stemmy stuff.

For those who are lowly stocked, allowing residuals to creep up and letting cows to select the nice grass and leave the stemmy grass will probably be a better policy.

Although the swards will look dirty, the actual quality of the grass that the cows will be eating will be much higher than forcing them to eat pre-mowed grass.

For those who are higher stocked, pre-mowing can be a useful tool, but if the paddock is too strong to graze, pre-mowing is not the answer – put it into a bale.

Last resort

Topping should really be the last resort, as you are effectively leaving grass behind to rot, whereas it could have been converted to feed either in the bale or down the cow’s neck.

One thing to keep in mind is that cutting, pre-mowing or topping will reduce the growth rate on that paddock. So, if a lot of the farm is being cut, be prepared for a reduction in average growth rate over the subsequent weeks.