Grass growth: Might be time to call a halt to the grazing season

Over the last while, in particular the last seven-to-10 days, a lot of stock across the country has been housed – as the 2020 grazing season comes to a close.

Many dairy farmers, over the past week, have decided to ‘pull the plug’ and house their cows for the winter.

Those lucky enough to have drier land are still grazing, even if it is only for a few hours or for 12-hour blocks during the day. For those that are still grazing, it is important though that the average farm cover (AFC) doesn’t drop below 500kg DM/ha.

Looking at average grass growth rates, PastureBase Ireland figures are showing 11kg DM/ha in Ulster, 19kg DM/ha in Leinster, 14kg DM/ha in Connacht and 18kg DM/ha in Munster.

Research by Teagasc has consistently shown that spring grass is twice as valuable as autumn grass. Therefore, it is hugely important to close at the correct closing cover, for your farm, to ensure that an adequate amount of grass is available next spring.

To ensure this, farmers must get out now and assess where they are in terms of their average farm cover (AFC).

According to Teagasc, farms stocked at between 2.5-2.9 LU/ha should be targeting an AFC of 700-750kg DM/ha on December 1.

By now, 60% of the farm should be closed on farms stocked at 2.5-3.0 cows/ha, while farms stocked at 3.5 cows/ha should have 70% of the farm closed since the start of November.

For those that have housed milking cows, it’s important to offer them good-quality silage for the last few weeks of their lactation period.

For those still out grazing, it is important to implement good grazing techniques to make the best of the remaining grass on the farm.

Examples of good grazing techniques include:

  • Use of spur roadways to minimise damage in paddocks;
  • 12-hour allocations and using a back fence;
  • On-off grazing: Three-hour blocks to avoid damage.

Selecting cows for drying off

With the 2020 milking season soon coming to a close, attentions should be turning to drying off and earmarking what cows should be allowed to go on holiday first.

The calving season won’t be long coming around, so it is important that cows are afforded an adequate dry period so that they can begin to build up body condition ahead of calving time.

Therefore, if not already done so, farmers should begin selecting cows which will benefit from a longer dry period (greater than eight weeks).

For example, thin cows with a body condition score (BCS) of less than 2.75 and first lactation cows should be earmarked for a longer dry period.

Ideally, farmers should be looking at giving first lactation cows a 12-week dry period, while the rest of the herd can make do with an eight-week dry period, as long as they are in good condition and aren’t suffering from lameness or any other health problems.

Some farmers may feel the need to milk thin cows to generate cash-flow. Cows that are dried off thin, can end up calving down thin, which will lead to calving difficulties, metabolic disorders such as milk fever – with this having a knock-on effect on the cow’s fertility – as well as poorer milk production in the subsequent lactation.