Now is a good time to take action to improve grazing management and the best way to start is by measuring the sward. Compressed sward sticks are available from AHDB Beef & Lamb and are an important tool to provide the information needed to balance grass supply and livestock needs. To measure grass, follow the instructions on the sward stick and take up to 20 measurements per field to get the average pasture cover in kg of dry matter (DM) per hectare.
Use the numbers
Once you know how much grass is in the field, there are three simple steps to allocating grazing:
Step 1: Calculate the grass available for grazing (post-graze guidelines can be found in the Grazing strategies manual)
Grass available for grazing (kg DM/ha) is:
(pre-graze measurement – post-graze guideline) x field area (ha)
E.g: Pre-graze measurement = 2,500 kg DM/ha, postgraze guideline = 1,600 kg DM/ha with 2ha available
The calculation would be: (2,500 -1,600 kg DM/ha) x 2ha = 1,800 kg DM
Step 2: Livestock allocations
Livestock allocations per head are based on dry matter allocation as a % of body weight. Suckler cows in early lactation should be allocated 2.5% of bodyweight. Ewes with lambs at foot should be allocated over 3% of their bodyweight. Young animals are not to be included in grass budgeting until weaned.
- 60 cows with calves at foot, cow weight 650kg, allocation 2.5% of body weight
The calculation would be 60 x (650 x 0.025 (2.5%)) = 975kg DM per day for the mob.
Step 3: Working out how long the field will last
Divide the grass available for grazing (step1) by daily requirement of group (step2)
- 1,800 kg DM ÷ 975kg DM /day = ~two days
In this example, the stock should leave the paddock just shy of two days after entry and move on to another paddock in the rotation. Repeat steps 1 and 2 for all fields in the rotation.
For more information, see the BRP manual Planning Grazing Strategies for Better Returns.