Meeting grazing objectives

Published 11 October 13

How to meet grazing objectives

Key messages

  • Grass grows grass
  • Look for the ‘sweet point’
  • Graze at 2.5+ leaves
  • Go in at about 8-10cm (2,800kg DM/ha), graze to about 3.5 to 4cm (1,500kg DM/ha)
  • Feed budgeting identifies underachieving pasture – as well as improving quality and allowing the herd to be fed efficiently
  • Aim to develop your ‘eye’ for allocating grass – once you’ve had some practice!

 Farmers on the Dr John Roche DairyCo Utilising Grass Course last week put together a list of their grazing objectives:

  • Grow as much pasture as possible     
  • Early turnout in spring
  • Maintain pasture quality mid-season
  • Cows grazing until late autumn
  • Grazing season > 280 days

The group then looked at how to achieve these. Part of the course was spent on-farm, looking and learning – hands on – how to assess pasture.

John Roche looks at grass

Below are notes from this section of the course – more to follow in future editions of  Forage for Knowledge.

Look at the way the Ryegrass plant grows.

Grass grows grass – you get a higher DM yield with longer rotation to three leaves:

  • The plant stores carbohydrates above ground and uses them to grow first leaf
  • The plant then puts some back into stores as it grows second leaf, which is why it is slower in growing that second leaf
  • The third leaf is the biggest and largest with 45-55% of the plant yield
  • The plant grows three live leaves, so as the fourth emerges the first leaf dies
  • Quality only declines marginally with each leaf stage.

Dr Roche talked about looking for that ‘sweet spot’ when the grass plant is neither too young nor too old. Aim for grazing when as much grass as possible has been grown, without reducing quality – before leaves begin to die off:

  • When there is adequate pasture, graze at 2.5+ leaf stage
  • Graze to 3.5 to 4cm post-grazing height
  • Go back in at 2,800kg DM/ha
  • At this height you are looking at canopy closure and that means you will lose quality below; if you can't see the soil, the plant can't see light and will produce stem to reach up
  • If you don't graze down low enough, the plant will grow again from that point and there will be less time for canopy closure. This means more rubbish will be grown next time and quality will reduce
  • If you are having problems reaching this post-grazing height, pre-mow or put into bales but make that 3.5cm mark to ensure future quality
  • When it comes to locking up for autumn, it’s the plants with more residuals that produce less next spring.

What to do if you’re in pasture surplus or deficit

If in pasture surplus, lock up paddocks for silage – don’t jeopardise pasture quality by going in when the grass is too old. If in pasture deficit, increase rotation length in order to grow more pasture

  • Bring in supplementation to feed rotation
  • Don't  go into early and start chasing your tail
  • Be a grass farmer – bring supplementation in for the grass not the cows.

Tools to help with grazing planning

Grazing wedge is a visual representation of the grass on the farm. A line is drawn from the ideal pre-grazing yield to the desired post. It needs to be completed weekly during the main grazing season.

Feed budgeting allows herd to be fed efficiently, improves grass quality and allows underperforming paddocks to be identified – moving your worst performing paddocks up to the level of your middle ones can mean £18,000 to a 250 cow-herd.

Methods of assessing grass

Cutting a representative quadrant

  • Place a 0.5 x 0.5m quadrant on an area representative of the pasture (avoiding gateways, round water troughs etc
  • Knock off excess moisture
  • Cut grass within quadrant to 3.5-4cm, leaving 1,500kg DM/ha behind
  • Use the following equation to work out pasture mass: Weight of grass x DM% (link to table in Grass+ of estimating DM %) x 40,000 = pasture mass.

John Roche and quadrant

Plate metering

  • Take measurements across the paddock in a X or W shape – avoiding previous electric fence lines, areas around water troughs etc.
  • Divide the number by the number of readings (usually about 6)
  • It is more of an approximate than other methods
  • It will give you a good idea of farm cover to help you set out your wedge.

John Roche and plate meter

Other methods such as using a bike reader are also available.

Don’t underestimate the value of the human eye when it comes to assessing and allocating your pasture – you will soon become the best judge of what you have available.