Sward height has been shown to be a good practical indicator for use in grazing management which will enable good grass utilisation and livestock performance. Sward height can be converted into the weight of grass in kilograms of dry matter per ha (kgDM/ ha)also known as cover or mass, this enables grass budgets to be calculated.
Knowing how much grass you have and how it is changing will help you to make management decisions to:
Measure all the fields in the grazing platform grazed by one class of stock on the same day.
Walk across a field in a W pattern you should aim to take at least 30 readings in each field. Record them on the app screen as you go and it will work out the average. Avoid gateways, hedgelines and any areas that are not representative of the field in general. If the field has a definite split between wet and dry areas it is a good idea to measure them separately. Measure to the top of the grass leaf with a sward stick or ruler - do not measure stems and flower heads and don't measure weeds. Follow manufacturer's instructions with a rising plate meter- these are less accurate at low sward heights and on steeply sloping ground.
During the peak of growing season sward height/cover can change fairly rapidly so consider measuring twice a week. The calendar can be used to remind you when to measure again.
Any tool that can measure height in cm can be used, including a sward stick, a rising plate meter, a ruler, walking stick, alkathene pipe or even your boots with a scale drawn up the side. For consistent results the same person should take measurements every time. With plenty of practice you will be able to make rough judgements by eye, but there is no real substitute for walking fields, looking at the sward and measuring sward height/cover.
By recording sward height/cover you will be able to improve the use of grass on your farm and optimise animal intakes and reduce grass waste. Grazing at the recommended height/cover will prevent swards becoming stemmy and maintain sward tiller density and quality through the grazing season and produce high levels of livestock performance.
Aftermath swards will respond differently to grazing pressure than normal grazing fields. They must be conditioned by grazing to encourage tillering before sward height/cover guidelines can be applied
Livestock Type |
Graze Period |
Rotational |
Continuous |
Notes |
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|
|
Pre-graze kgDM/ha |
Post-graze kgDM/ha |
* Interval days |
kgDM/ha
|
|
Lactating Cows/ Bulling Heifers |
Turn-out-May |
2400 |
1500 |
16-20 |
2000 |
Top to 5 cm if sward height is exceeded. Check your stock condition score and growth rate targets |
|
June-July |
2800-3000 |
1500 |
20-24 |
2200-2300 |
Swards above target in May should be topped by early June |
|
Aug-Sept |
3000-3200 |
1500 |
24-28 |
2300-2500 |
|
|
Oct-House |
3000-3200 |
1500 |
Variable |
2300-2500 |
All early/mid lactation cows will need supplements at this time |
Dry cows |
|
1500-1800 |
1500 |
|
1500-1800 |
Note cow condition score: for thin cows increase pasture mass |
Rotation interval given as a guide only, it may need to be varied. Post graze sward height is the primary decision driver. Pre-graze sward height and rotation interval give information to assess 'paddock skipping' and 'buffer grazing' in forward planning of grazing area.
BEEF CATTLE GRAZING COVER GUIDELINES (kgDM/ha)
Livestock Type |
Graze Period |
Grazing after rest on un-adapted sward |
Continuous |
Notes |
|
|
|
Pre-graze kgDM/ha |
Post-graze kgDM/ha |
kgDM/ha |
|
Lactating Suckler Cows/Bulling Heifers |
T'out-May |
2400 |
1500 |
2000 |
|
|
June-July |
2600-3000 |
1500 |
2300-2500 |
|
|
Aug-Nov |
2700-3000 |
1500 |
2300-2500 |
Graze to 1500 kgDM/ha with dry stock Nov/Dec |
Dry Suckler Cows
|
|
1800 |
1500 |
1900
|
Note condition. Increase cover for thin cows; restrict grazing for fat cows |
Growing/ Finishing Cattle |
T'out-May |
2400 |
1500 |
2000 |
Increase cover for finishing cattle through season |
|
June-July |
2600-3000 |
1500 |
2300-2500 |
Sward cover should be gradually increasing |
|
Aug- Sept |
2700-3000 |
1500 |
2300-2500 |
|
Weaned Stores |
|
2200-2700 |
1500 |
1900 |
Increase cover to increase stock growth rates |
Livestock Type |
Graze Period |
Grazing after rest on un-adapted sward |
Continuous |
Notes |
|
|
|
Pre-graze kgDM/ha |
Post-graze kgDM/ha |
kgDM/ha |
|
Ewes and lambs |
T'out-April |
2000 |
1500 |
1750 |
Provide supplementary feed until sward cover reaches 1750 kgDM/ha ( remember stock mineral requirements) Aim for gradual increase if possible |
|
May-wean |
2200-2400 |
1500 |
1800 |
|
Dry Ewes |
July Aug |
1700-1900 |
1500 |
1800 |
Reduce sward cover for Condition Score >3 |
Pre-tupping |
Sept-Nov |
1700-2100 |
1500 |
1900 |
Note condition: restrict grazing for fat ewes |
Weaned lamb for finish |
July-Sept |
2100 |
1700 |
2400 |
Allow gradual increase. Check stock growth rates targets |
Store lambs |
July-Start of finishing period |
1900 |
1500 |
1500 |
Increase sward height to increase lamb growth rate. |
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IBERS, Grassland Development Centre: 01970 823026 E-mail: GDCstaff@aber.ac.uk, Web page: www.grassdevcentre.co.uk GDC, Plas Gogerddan, Aberystwyth, Ceredigion, SY23 3EB
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