Grass growth: Time running out to build grass

Average grass growth rates, across the country, have taken a slight dip – on account of the cooler nights and shorter days last week.

In terms of average grass growth rates, PastureBase Ireland figures are showing 52kg DM/ha in Ulster, 56kg DM/ha in Leinster, 49kg DM/ha in Connacht and 57kg DM/ha in Munster.

However, day time temperatures are set to improve as we move towards the weekend, so average growth rates should improve somewhat by then.

According to Met Éireann, rainfall last week was “below normal with the exception of the northern coastal areas with 24% above normal experienced here”.

Rainfall for this week will be near or above average in the west and north but below average elsewhere.

Where grazing conditions are difficult, particularly in the north and west of the country, some grazing techniques should be considered – to continue keeping grass in the cows’ diet for as long as possible.

Grazing techniques in poor weather:
  • Use on-off grazing;
  • Use spur roadways;
  • Use a back fence;
  • Graze in 12-hour blocks.

Empty cows could be the answer

Looking at autumn grazing targets, the majority of highly stocked farms are still below target for this time of year.

In five days’ time, we will be mid-way through the month of September; by then, your average farm cover should be around the 1,200kg of DM/ha mark.

So, if you are now at an average farm cover of 1,000kg of DM/ha, you will need to have a surplus of 40kg of DM/ha/day to be on target in five days’ time.

To do this, demand must be reduced to below grass growth rate. For instance, if demand was reduced to 20kg of DM/ha – at a stocking rate of 3.5 cow/ha and at a growth rate of 55kg of DM/ha – 35kg of DM/ha/day or 245kg of DM/ha/week would be available as surplus.

This may seem unrealistic for some, as it means introducing a lot of supplementation. However, there are other options, such as selling off empty or cull cows.

For a 150-cow herd, at a 10% empty rate, this is 15 cows. This would equate to a total surplus of 210kg of DM/day (14kg of DM plus 3kg of concentrates).

This is a much easier way of building grass than introducing a huge amount of supplementation; so, it should not be overlooked.

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