The role of clover in dairy farms
David Alexander, Dairy Development Adviser, CAFRE
In the current climate all forage based livestock producers should at least take time to consider the relevance of clover to their system of production. This brief article will highlight some of the benefits of incorporating clover swards on your farm and address some of the concerns farmers may have on using clover.
Modern varieties of white and red clover offer higher yields, greater persistency and are more reliable throughout the growing season. They should not be considered as only relevant and economically attractive to low input / low output systems and organic production but have a role to play on many Northern Ireland dairy farms.
Potentially clover swards can be cost effective providers of high quality home-grown protein and reduce the reliance on fertiliser nitrogen, through their ability to make use of atmospheric nitrogen (nitrogen fixation).
White clover is potentially a long-lived perennial legume with multi-branched creeping stems (stolons). The nodules, which house the nitrogen fixing bacteria, are present as small growths on the roots. The stolon is a key organ in the plants persistence as it provides the means of surviving over the winter and regenerating the following spring.
Benefits of White Clover
- Nitrogen fixation – the conversion of nitrogen from the air into a farm that the plant can utilize. It is estimated that the amount of utilizable nitrogen produced is equivalent to 150-200 KG N per hectare.
- Intake – ruminant livestock may consume 20-30 percent more white clover than grass.
- Feed Value – a higher digestibility, protein content and mineral content than grass only swards as identified in Table 1.
Table 1
Typical quality characteristics of white clover and perennial ryegrass
| White clover | Perennial ryegrass | |
| Digestibility (Dvalue %) | 75-82 | 65-75 |
| Crude protein (%) | 27 | 17 |
| Calcium content (%) | 1.6 | 0.6 |
| Magnesium content (%) | 0.18 | 0.16 |
| Phosphorus (%) | 0.6 | 0.3 |
| Copper (ppm) | 10.0 | 6.5 |
| Selenium (parts per 100 million) | 0.6 | 0.2 |
| Source: IGER (2001) |
- White clover digestibility declines much slower throughout the growing season thus giving a wider cutting / grazing window of opportunity for fuller utilization.
- Modern white clover varieties can compete well with companion grasses even at quite high N fertiliser applications.
The role of red clover
Red Clover is a short-lived perennial that typically persists for two to four years and so is compatible with Italian and hybrid ryegrasses.
Unlike white clover it has an upright growth habit and a strong deep taproot. The upright stems arise from the crown of the plant. Therefore, unlike white clover, it is unable to spread through the sward and colonise vacant sites. This restricts red clover to systems where it can be cut or rotationally grazed.
As the crown of the plant is above ground, damage must be avoided to ensure plant survival and:
- cutting height should be 7-8 cm
- optimum grazing heights of aftermaths is 4-6 cm.
Benefits of Red Clover
- Nitrogen fixation – red clover can fix up to 200 KG N per hectare.
- High yields – red clover swards are capable of producing up to 15 tonnes of dry matter per hectare.
- Feed value – protein content is particularly high in red clover.
- Red clover can improve soil structure due to its deep rooting taproot.
- Improved animal performance. (Table 2).
Table 2
The production potential of clover silage
| Grass | Grass-Red Clover | Grass-White Clover | |
|---|---|---|---|
| Silage DM intake (KG/d) | 11.4 | 12.9 | 13.2 |
| Total DM intake (KG/d) | 18.2 | 19.8 | 20.1 |
| Milk yield (KG/d) | 24.9 | 28.6 | 27.9 |
| Milk fat (%) | 4.45 | 4.60 | 4.66 |
| Milk protein (%) | 3.26 | 3.21 | 3.22 |
| Source: IGER (2003) |
Management of clover swards for optimum performance
Bloat
This is a cause of concern for dairy farmers. To minimise or eliminate the risk of bloat:
- Introduce cattle to clover gradually. The time spent grazing clover rich swards should be limited initially to two to four hours per day.
- Avoid putting hungry stock into clover rich swards.
- Take care on cold, wet, chilly mornings.
- Dairy cows could be buffer fed with silage at milking times.
Ensiling clover-rich swards
Although clovers have low sugar content and high buffering capacity good fermentation can be achieved. It is important to wilt to at least 25 percent DM. Excessive wilting will lead to leaf shatter and lower feed quality. Inoculant additives will also improve fermentation.
Persistence
In white clover swards stolon survival is essential for the maintenance of clover in the sward. It is important to avoid overgrazing and winter damage.
Likewise in red clover swards it is important not to overgraze or cut silage swards too low to avoid crown damage and ensure plant survival.
Similar to all grazing or cutting swards good grass land management is essential to gain the rewards of clover.
Breeding Ewe fertility
The high level of plant oestrogens in red clover can lead to a reduction in ewe fertility if they are grazed on swards with a high red clover content around tupping time. Avoid grazing red clover swards 6 weeks either side of mating. Red clover has no effect on cow fertility.
Both white and red clovers do require careful management to maintain them in the sward but modern varieties are very competitive, persistent and reliable. They offer many potential benefits both economically and environmentally. Perhaps now is an opportune time to consider the role of clover on dairy farms in Northern Ireland.
Clover sward
Cattle grazing on clover