The big debate at the moment is what rotation length to go on. On most farms average farm cover is still relatively OK, at 100-200kg/cow, but is only around 300-400kg/ha because farmers have reduced stocking rate by grazing silage ground.

As a rule of thumb, doubling average farm cover per hectare will give you the pre-grazing yield. So a lot of farmers are grazing covers of 600-800kg/ha. Remember, dry matters are almost at 30%. This means there is about twice as much feed value in a fistful of grass now than there was a month ago.

If a 100-cow farm is stocked at three cows/ha, there are 33ha available for grazing. If the average farm cover is 300kg/ha then the pre-grazing yield will be around 600kg. Going on a 30-day round length will mean there are 1.1ha available per day, or 6.6kg of grass DM available per day. This would need to be supplemented with up to 6kg of meal and 5-6kg of silage. If farm cover is 150kg/ha and pre-grazing yield is only 300kg/ha, then the cows will only get 3.3kg/cow/day. More meal and/or more silage will have to be fed in this case to get the 18kg DM into them. Going on a 20-day round will increase the amount of grass available per day to 5kg, but you will run out of grass faster.

At the end of the day, it doesn’t really matter that much whether you are on a 20- or a 30-day round, as feed will either have to be fed now or in the future.

It’s important not to under- or over-graze now. The ideal post-grazing height is 3.5cm to 4cm. Grazing lower than this will kill tillers, while grazing higher than this is wasting valuable grass. Measure post-grazing height to make sure you are getting it right.

In brief

  • Average growth rate is 26kg/day.
  • Keep rotation length at between 20 and 30 days.
  • Make sure the cows are hitting residuals of 3.5cm to 4cm.
  • Keep measuring grass to assess average farm cover and growth.
  • Brendan Horan

    Teagasc Curtins, Co Cork

    Stocking rate (cows/ha) 2.76

    Growth rate (kg/day) 23

    Average farm cover (kg/cow) 107

    Yield (l/cow/day) 21.52

    Fat % 4.29

    Protein % 3.45

    Milk solids (kg/cow) 1.72

    Supplement fed (kg/cow/day) 6

    Growth has levelled off at 23kg/day and we are holding farm cover. Pre-grazing herbage is very stemmy and relatively poor quality, so we maintain a 25-day rotation. While milk yield has remained largely unaffected at 21.52l/cow/day, milk composition has been declining as bale silage now constitutes 30% of the total diet. Both fat and protein are 0.3% below normal figures for July, at 4.29% fat, 3.45% protein and 1.72kg MS/cow. We have suspended nitrogen applications until rainfall resumes.

    Brian Murphy

    Oldcastle, Co Meath

    Stocking rate (cows/ha) 3

    Growth rate (kg/day) 45

    Average farm cover (kg/cow) 217

    Yield (l/cow/day) 17.4

    Fat % 4.70

    Protein % 3.74

    Milk solids (kg/cow) 1.52

    Supplement fed (kg/cow/day) 6

    We are probably not representative of the rest of Meath, as we have been irrigating the wetter parts of the farm. These fields are growing over 100kg/day, while the drier parts are growing around 10kg/day. We got 20mm of rain about a month ago. The cows are on a 28-day round and pre-grazing yield is around 1,000kg. They’re getting 6kg of soya hulls in the parlour. We’re grazing out covers to 1,450kg total, which is tight, but we always do it and quality is excellent. This year, we will cull empty and poor cows earlier than normal.

    Barry Reilly

    Teagasc, Ballyhaise

    Stocking rate (cows/ha) 2.86

    Growth rate (kg/day) 48

    Average farm cover (kg/cow) 205

    Yield (l/cow/day) 22.3

    Fat % 4.04

    Protein % 3.56

    Milk solids (kg/cow) 1.75

    Supplement fed (kg/cow/day) 6

    Things are going well here. Most of the farm is very green and it’s growing well. Any paddocks that weren’t cut for silage are stemmy and ugly looking, but most of the farm has been cut – and got slurry after – and is growing very well, with covers of 1,200kg/ha. We fed silage for a few days last weekend, but took it out again when we did the cover on Monday. We will probably increase the meal fed to 7kg from tomorrow, as pre-grazing yield is beginning to drop. Cows are on a 22-day round length.

    Danny & Patrick Cremin

    Newcastlewest, Co Limerick

    Stocking rate (cows/ha) 2.63

    Growth rate (kg/day) 16

    Average farm cover (kg/cow) 201

    Yield (l/cow/day) 23

    Fat % 4.54

    Protein % 3.59

    Milk solids (kg/cow) 1.93

    Supplement fed (kg/cow/day) 10

    Growth rate has slowed down a huge amount, even though this farm is heavy enough. Pre-grazing yield is around 1,000kg and we are currently on a long rotation length of over 30 days, to get as much out of the high covers as possible. Cows are on 6kg of meal in the parlour and ad-lib access to palm kernel in the field. I don’t know exactly how much they’re eating of it, but we’re estimating 4kg/cow. We’re continuing to spread fertiliser because the farm is green and while growth is slowing down we think there is a return from spreading.

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