Grasslands, Forage and Soil Partnership


All GB dairy farms are reliant on the production and utilisation of home-grown grass and/or forage. As this element of feed input into a dairy system is almost always the cheapest in terms of cost per unit of energy or protein (relative to bought-in feeds), maximising the growth potential and use of home-grown resources is a key element of efficient and profitable milk production. In addition, the role of soil management in this strategic intent is often overlooked, even though good practice in soil care forms the basis on which efficient grass and forage production and utilisation can be achieved.

This partnership applied research in both arenas of grass and forage use, and soil management. 

Key findings:

  • Grass varieties. When selecting a grass variety, the focus should be on ME yield rather than just yield, to provide a balance between yield and quality. In addition, seasonal grass growth should always be matched with the individual farm demands.
  • Nutrient for grassland production. If slurry is separated, it is important to test the separated fraction to get an accurate measure of nutrient content and availability. There is no difference in grass growth or grass DMI at pasture when using liquid fraction of whole slurry: however, the N recovery and milk yield responses are likely to be somewhat lower than that of separated slurry.
  • Increased DMI of grass. Replacing TMR with grazed grass or cut-and-carry grass will decrease milk production, but it will increase the profitability of the feeding system. A regular assessment of fresh grass will help to minimise variability in DMI. Providing access to pasture for 6 hrs/day between morning and afternoon milking will not have a major impact on daily DM intake, milk yield, composition or live weight change, but can reduce feed costs by 20 to 35p/cow/day. However, access to pasture for 6 hrs/day and limiting TMR intake to 75% of ad libitum will reduce milk performance despite the higher grass intake.
  • Conserved forage production and evaluation. Clover-grass mixtures: there is a high variability in composition and nutritional value, especially with different red clover concentrations. On average predicted crude protein content was 1.24% lower in grass-clover silages using NIRS compared with wet chemistry: new equations have been developed for silages from grass-clover swards and are currently being integrated into the main analytical laboratory protocols. About maize silage, its inclusion in diets at any rate increases intake and milk yield. When it is the main forage in a ration it is important to balance it with high protein feeds as maize is low in protein.
  • Lucerne.  To successfully establish the crop, spring sowing is more reliable than late summer/autumn: moreover, late summer sowings take 12months to match productivity and quality of spring sowings. A high rate of inclusion of lucerne in a maize silage based ration will reduce intake and milk yield compared to a lower inclusion rate, but will increase feed conversion efficiency. At high levels of inclusion of lucerne, whole tract digestibility is reduced. Due to the high protein content, the inclusion of lucerne can result in significant savings. A longer chop length will increase pH and rumination time, while a shorter chop length will increase DM intake, milk yield and diet digestibility.
  • Forage Peas. Spring grown forage peas are a rapidly growing crop that can produce over 7t DM/ha in 12 weeks, with a crude protein content of 200 g/kg DM. Feeding spring sown forage peas can reduce feed costs by up to 0.5ppl due to savings in both purchased feed costs and the lower growing costs of forage peas. When compared to grass silage, feeding forage peas will result in marginally lower milk yield and milk protein yield, with no effect on fat yield, or live weight change. Tannin levels in forage have no effect on performance.
  • Outwintering. The largest financial benefit from out-wintering 1-2 year old heifers is the potential savings in capital costs. In total, rearing costs can be reduced by out-wintering by approximately 50%, or £150/heifer. With a proper planning and management, in-calf Holstein heifers can be out-wintered successfully in high output dairy farms without a negative impact on performance or fertility. If managed appropriately, out-wintering on strip grazed grass fields can be achieved without substantially damaging pasture or reducing the subsequent years grass production.
  • Soils. On heavy soils, compaction from animal trampling and tractor traffic increases soil bulk density (by as much as 20%), reducing air space in the soil and increasing water retention in the soil by 14%. The impact of compaction on soils structure also reduced DM yields, particularly on heavy soils. The greatest reductions were evident at first cut silage (up to 19% reduction for the tractor compaction and 12% for the trampling).
  • Functional fibre. Maize silage in the UK has a similar particle size to North America at 10.5 mm, but grass silage is considerably longer at 42.6 mm. The majority (58%) of UK dairy farms have moderately or poorly mixed diets (different composition along the feed face). There is significant diet selection on many (66%) of farms, which could affect individual cow performance and/or health. A high proportion of farms (34%) have no feed refusals in the morning and are therefore underfeeding some or all of their cows. A short chop length grass silage will increase intake of early lactating cows compared to an average length grass silage in grass or grass/maize silage based diets. A short chop length grass silage will also increase milk production. Chop length of grass silage has little effect on rumen pH. Intake, milk production, milk protein content and live weight gain will be higher when cows are fed a mixture of grass and maize silage than grass silage alone.

For further information reports are available. Please see the links to the individual research projects included in the grasslands, forage and soils partnership.

Project code:
01 June 2011 - 31 March 2019
AHDB sector cost:
Total project value:
Project leader:
SAC Commercial LTD, Harper Adams University


411099_Final report

About this project

AIms and Objectives: 
The overall objectives of the research related to the profitability and environmental sustainability of GB dairy farming.
To conduct robust science based research which will enable GB dairy farmers to improve resource use efficiency and profitability by:
  • Producing more milk from cheaper home-grown grass and forage, either grazed or conserved, taking into consideration potential effects of climate change
  • Developing a system for targeting the genetic improvement of grasses that is more relevant to GB dairy farmers 
  • Applying soil management and plant nutrient techniques that improve the growth and utilisation of grass and forage crops, whilst reducing losses from soils and using nutrients from animal slurries and AD digestate
  • Using in vivo derived information on the energy and protein content of crops that allows dairy farmers to more accurately formulate diets and thus improve feed conversion efficiency
  • Opening the possibility of replacing bought-in proteins with home-grown high quality protein crops
  • Developing systems of outwintering that are more cost effective than housing

To provide a science-based approach to improving the environmental sustainability of GB dairy farms by:

  • Increasing milk production from home-grown energy and protein at the expense of less sustainable bought-in feeds
  • Determining  the impact of soil compaction and management on GHG emissions
  • Developing precision farming techniques that reduce input per unit of grown and utilised dry matter
  • Improving nutritional efficiency through the use of accurate information on the energy and protein contents of forage crops

Related resources

close-up of a green grass

AHDB Grass