This is a subscriber-only article
As September approaches, cattle farmers will be entering the final stages of the grazing season. Land type, ground conditions, grass growth and weather will determine how long you can extend the grazing season into the autumn.
Following these simple steps will allow you to plan ahead and ensure you have adequate grass supplies to graze cattle through the next two months.
1. Work out your grazing demand
Simply calculate how much grass your cattle require every day using the following example:
Number of stock X average liveweight X daily intake (2% of body weight) / grazing area
For instance, 20 steers averaging 500kg on a grazing area of 5ha will have a daily demand of 40kg DM/ha/day (20 steers X 500kg X 2% (0.02) =200 / 5ha = 40kg DM/ha/day).
2. Work out how many grazing days ahead you have
Once you know the grazing demand of your cattle, work out how many grazing days ahead you have. Grazing days ahead simply means that if there are 20 days ahead of stock, then cattle will be back in the field they are currently grazing in 20 days’ time.
If you are a novice at grass measuring, simply record the average height of grass in each field using your boot or a stick with some measurements marked on it to give you an idea of grass height.
A rough rule of thumb is that every 1cm is 250kg DM/ha grass. As cattle will graze down to 4cm, this is the height where sward covers become available for grazing (known as residual height).
For example, a sward with an average height of 10cm has 6cm of available grazing (10cm – 4cm residual cover). This means the field has a grass cover of 1,500kg DM/ha.
Taking the daily grazing demand for our group of 20 steers at 40kg/ha/day, at an average cover of 1,500kg DM/ha of grass, there are currently 37 days of grazing ahead of the group.
If you have insufficient grazing days ahead, then you should reduce the size of the group or increase the grazing area.
3. Monitor grass growth weekly
Grazing ground should be walked weekly to keep an eye on grass supplies and ground conditions. Grass growth will start to drop off significantly as autumn progresses, especially on older swards, so re-calculate grazing demand and days ahead weekly. This will enable you to act early to stretch out the grazing season.
4. Increase grazing rotation
As autumn progresses, it is important to extend your grazing rotation by increasing the number of days ahead. Bringing silage ground back into the grazing platform will help to stretch the rotation as grass growth drops off.
Rotation length should be 21 to 22 days at the start of September. As a rule of thumb, increase your grazing rotation every week from now by 1.5 days. Therefore, between now and the end of September, your rotation should have increased by six days.
5. Increase residual grass height
As grass growth slows down, you need to speed up re-growth. Increasing the residual height of grass when livestock are leaving a paddock to 5cm or 6cm will increase the rate of re-growth in autumn. In late season, the higher residual cover will be more responsive to any fertiliser applied. As grass is now past the heading out (reproductive) stage, sward quality will not be affected.
6. Fertiliser
Applying 25 to 30 units/acre of nitrogen will boost grass growth. Even at this stage of the year, there is still a good response to fertiliser applied. Apply chemical fertiliser before the closing date of 15 September. Avoid spreading a fertiliser with high levels of potash when grazing freshly calved autumn cows.
7. Slurry
Some farmers will be under pressure to empty any remaining slurry on farm, or where tanks have refilled with silage effluent or rainwater. Avoid spreading slurry on paddocks that will be grazed within two to three weeks as it will reduce intake and cattle will become more unsettled. Instead, apply after grazing as the rotation length increases upwards on 25 to 30 days ahead of cattle.
8. Use electric fencing
Using a couple of temporary electric fences will give better control over grazing. If paddocks have a heavy grass cover, cleanout will be better. Likewise, re-growth can be protected using a back fence helping to build covers for grazing later in autumn.
9. Keep to the target number of grazing days
In autumn, there is no risk of grass heading out. Therefore, if a paddock is not fully grazed out, grass quality will not be affected in the next rotation. If you normally move livestock into a new paddock every three days, continue to do so throughout September. This will prevent a situation whereby you are carrying too much grass into October, especially on heavier paddocks which may not be able to be grazed.
10. Wean cows earlier
Early spring born cows, especially those with low milk yields, can be weaned in September. These animals can be stocked at a higher rate if ground conditions permit. If ground conditions start to deteriorate, these animals can be housed to prevent sward damage, leaving younger, lighter cattle at grass. Early weaning will reduce the grazing demand of stock, therefore helping to build grazing covers.
SHARING OPTIONS: