Why good management decisions are key in grazing white clover
Managing and maintaining the optimum level of clover in the sward (22pc yearly average), can often be challenging.
If not managed correctly it can lead to a decline in clover content or clover dominance.
Poor grazing management, high pre-grazing covers (>1600kg DM/ha) and high residuals (> 4.5cm), can result in a decline in clover content, as a result of reduced light intensity hitting the base of the sward which is essential for clover growth.
An 18-21 day rotation in mid-season with a pre-grazing cover of 1300-1500kg DM/ha and grazing swards to 4cm can maintain clover in an intensive grazing system.
To prevent clover dominance in paddocks, heavy cuts of silage should be avoided. This can result in an increase in the level of white clover in the swards.
Clover dominance can often lead to reduced spring herbage availability, as a result of lower over winter growth.
This can be minimised by the application of early spring nitrogen fertiliser (70 units by April 1 - 2 splits; 23 units January/early February and 46 units March) and early grazing to encourage tillering of the perennial ryegrass plant.
Bloat is a concern expressed by some dairy farmers in relation to white clover in grazing swards.
There are five main areas that can induce the onset of bloat in grazing animals;
- High clover content - > 45pc
- Low DM grass - after a heavy mist or rain
- Lush grass
- Hungry animals moving to a high clover sward
- Animals moving from grass only to grass/clover swards.
Bloat can be and should be prevented, there are two main areas of prevention that Teagasc Moorepark have identified; bloat oil in the water and grazing management.
Bloat oil can be placed in the water of the animals to prevent bloat.
When adding it to the water it should be added to the water 12 to 24 hours prior to the animals being turned into the paddock, to ensure that the bloat oil in the animals' systems prior to grazing the clover.
Grazing management is a simple low-cost effective way of reducing the onset of bloat; avoid turning excessively hungry animals into high clover content paddocks.
If turning animals into a clover paddock, a small strip wire can be placed at the top of the paddock for two to three hours.
The strip wire removes the animals gorging on the white clover and ensures that the stock graze some of the higher fibre perennial ryegrass component of the sward.
When the herbage is grazed in the strip, the fence is removed and cows have access to the remainder of the paddock.
This is only required when one of the five causes above is evident, and when the cow are first turned into a 24 to 48 hour grazing block.
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