The milk production benefits of incorporating white clover in grass swards
Since 2013, researchers in Teagasc Moorepark and Clonakilty have been looking at the benefits incorporating white clover into grass swards can bring. Along with reducing the requirement for chemical nitrogen, milk production benefits have been witnessed.
The sustainability of Irish milk production systems is underpinned by the efficient conversion of grazed grass to milk. Irish pasture-based milk production systems are amongst the most efficient in the world, converting a low cost, home-grown feed source, grass, into milk.
Dairy cows convert a human in-edible protein source (pasture) into a human edible protein (milk). Sustainable grass-based systems require the introduction of white clover to reduce the use of chemical nitrogen fertiliser, achieved through the nitrogen fixing capacity of white clover.
Another benefit of white clover for the dairy farmer is increased milk production. A number of grazing systems experiments have been undertaken since 2013 at Moorepark and Clonakilty examining the role of white clover in pasture-based milk production systems. This article will summarise the research findings in terms of milk production.
Results
Milk production is influenced by the dry matter intake (DMI) of the dairy cow and the quality of the feed ingested (Table 1). Data from Moorepark shows that, on average, cows grazing grass-white clover swards with an average annual white clover content of 21% had 1.0 kg/cow greater total DMI compared to cows grazing grass-only swards.
At Clonakilty, cows grazing grass-white clover swards (average clover content of 16%) had 0.5 kg/cow greater total DMI compared to cows grazing grass-only swards. The increased DMI occurred in summer and autumn, when sward neutral detergent fibre (NDF) content (fibre) was lower in grass-white clover swards compared to grass-only swards (Table 2). Lower fibre content allows faster passage rate of feed through the cow’s rumen, promoting greater DMI.
Cows grazing grass-white clover swards at Moorepark and Clonakilty had higher milk yield (+1.2 kg/cow per day) and milk solids yield (+0.09 kg/cow per day) compared to those grazing grass-only swards (Table 1). The milk constituents were similar (fat and protein %), and so the increased milk solids yield was as a result of increased milk volume.
Table 1. Average dry matter intake and milk production from cows grazing grass-only and grass-white clover swards, and sward quality parameters, at Moorepark and Clonakilty
| Grass-only | Grass-white clover | |
|---|---|---|
| Moorepark research | ||
| Dry matter intake (kg per cow) | 16.3 | 17.3 |
| Milk yield (kg per cow) | 20.5 | 21.6 |
| Milk solids yield (kg per cow per day) | 1.74 | 1.81 |
| Fat (%) | 4.83 | 4.89 |
| Protein (%) | 3.71 | 3.69 |
| Clonakilty research | ||
| Total dry matter intake (kg per cow) | 16.7 | 17.2 |
| Milk yield (kg per cow per day) | 19.1 | 20.4 |
| Milk solids yield (kg per cow per day) | 1.61 | 1.72 |
| Fat (%) | 4.79 | 4.75 |
| Protein (%) | 3.84 | 3.84 |
Table 2. Sward quality parameters, at Moorepark and Clonakilty, in grass-only swards in spring (May), summer (July) and autumn (September)
| Spring | Summer | Autumn | ||||
|---|---|---|---|---|---|---|
| Grass-only | Grass-white clover | Grass-only | Grass-white clover | Grass-only | Grass-white clover | |
| Moorepark research | ||||||
| Sward clover content (%) | - | 18.9 | - | 31.3 | - | 37.7 |
| Crude protein content (%) | 21.2 | 20.8 | 20.7 | 21.7 | 24.1 | 24.5 |
| NDF content (%) | 34.9 | 34.4 | 39.6 | 36.4 | 39.8 | 36.2 |
| Organic matter digestibility (%) | 86.1 | 86.2 | 82.4 | 82.2 | 82.5 | 82.1 |
| Clonakilty research | ||||||
| Sward clover content (%) | - | 9.0 | - | 14.2 | - | 23.7 |
| Crude protein content (%) | 19.7 | 21.6 | 18.0 | 21.3 | 17.5 | 21.1 |
| NDF content (%) | 36.0 | 35.3 | 41.4 | 39.6 | 41.2 | 36.9 |
| Organic matter digestibility (%) | 78.9 | 78.8 | 78.6 | 78.8 | 77.5 | 78.0 |
Conclusions
Incorporating white clover in grassland swards results in increased dairy cow DMI and increased milk yield and milk solids yield compared to cows grazing grass-only swards.
This article by Deirdre Hennessy, Brian McCarthy, Áine Murray, Hannah Irish and Ellen Fitzpatrick was first published in the Moorepark 2023 open day book. The authors wished to acknowledge funding by the Dairy Levy Trust administered by Dairy Research Ireland and the Teagasc Walsh Scholarship Scheme.
For more information on the research activities at Moorepark, access the Moorepark 2023 open day book here.