Adding White Clover to Grass-Based Grazing Systems Increases Milk Production

IRELAND - Irish dairy farmers are finding renewed interest in white clover, says Michael Egan, a Teagasc researcher, writes Melanie Epp.
calendar icon 24 May 2016
clock icon 3 minute read

Mr Egan, who works at the Animal and Grassland Research and Innovation Centre in Moorepark, attributes this renewed interest partially to the rising cost of nitrogen, but also to the fact that dairy farmers have found that white clover gives extra nitrogen from increased N fixation.

Unexpectedly, his research also revealed that dairy cows that graze on grass and white clover swards show increased milk production.

Quick facts about white clover

  • Clover growth begins at approximately 8°C (but 5–6°C for grass)
  • Clover tolerates moderate, but not severe drought
  • Does not like low soil pH (less than 5.8)
  • Avoid overgrazing and winter damage
  • Stolon survival is essential for continued growth

While the general perception has been that white clover is not suitable in intensive grass-based milk production systems, that perception is beginning to change, said Mr Egan in a recent interview. Clover has poor spring growth due to low soil temperatures, he continued. But this challenge can be overcome.

Once established, though, white clover offers great potential. For one, he said, it may allow producers to reduce their use of chemical N fertiliser.

“In our experiment we have reduced nitrogen by 100 kg to 150 kg per hectare,” he said. “However, it depends on your system and the amount of cows you are carrying.”

If a reduction in fertiliser needs isn’t enough to convince dairy producers to incorporate white clover into their systems, an increase in overall milk production just might. In his experiments Mr Egan found that white clover increased dairy cow milk production by as much as 15 per cent per cow.

“The results have been consistent for three years of the experiment,” he said. “We have seen the increase in milk production from mid-June onwards.”

The increase, he said, is caused by the high intake of higher quality swards. Clover sward quality tends to decrease at a slower rate than it does in grass.

In the months of May and June, perennial rye grass produces a stem in the vegetative stage. This causes a reduction in grass quality.

“By having clover in the sward, it helps maintain a higher quality sward as clover does not produce a stem like grass,” explained Mr Egan. “This allows the cows to eat more.”

White clover management tips

In a recent talk, Mr Egan provided tips for growers who might be thinking about working white clover into their grass-based systems. The best time to sow is usually late spring or early summer when the weather is good. Post-sowing management will help promote clover growth, but Mr Egan warns growers not to let grass get higher than the clover as it will prevent light from reaching the base of the sward.

Post-sowing, depending on the weather, it should be grassed approximately 6–8 weeks after. “A little test you can do is to walk into the field and pull some of the grass and clover by hand,” said Mr Egan. “If the roots remain in the ground then it’s ready to graze.”

When grazing, it is important not to let the grass get too high.

“Again, it will prevent light reaching the base of the sward, and light is essential for clover growth,” he reiterated. “By keeping the grass height low – approximately 18–21 days regrowth or a cover of 1400 kg DM/ha (2900 kg DM/ha in the UK) – by doing this it also allows you to graze the sward tight to the ground, to 4 cm residual.”

“But the main thing is to let light to the base of the sward,” he said. “Finally, you should also try and prevent damage to the sward at all times – in adverse weather conditions – as this will damage the clover and grass and reduce it in the sward.”

Learn more about Michael Egan and his work at Teagasc here.

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