Using Lucerne in the GB dairy industry

Published 27 March 14

Developing optimum strategies for using lucerne in the GB dairy industry

With soya prices this past winter remaining high (March 2014 prices £370 – 390/t; DairyCo Market Information), it is likely that alternative protein crops could play an important role in reducing feed costs in the future.  DairyCo’s Research and Development Manager, Dr Debbie McConnell, discusses how new DairyCo funded research will help develop optimum strategies for using alternative protein crops such as lucerne in GB dairy systems.

One of the first forage crops, lucerne (commonly known as alfalfa) is a high protein nitrogen-fixing legume. Lucerne silage, if harvested at the leafy stage, can have protein contents in excess of 20% and as a result is an excellent source of protein.  Typically, lucerne has a high, rapidly digestible fibre content and similar to most legumes, a high buffering capacity in the rumen, due to its mineral composition. Although ME content of lucerne is typically lower than other crops (9 – 11 ME), lucerne is an excellent complement to maize silage and previous research at the University of Reading has shown significant intake and cow performance responses to the inclusion of lucerne in dairy cow diets. There is some potential for grazing lucerne, however, due to the high N content, care needs to be taken to achieve a balanced diet and avoid N toxicity.

Lucerne

Photo 1 Lucerne plant – lucerne provides an excellent source of protein, however, it can be difficult to grow in colder, wetter climates.

Further questions still exist however, as to how we maximise the value of lucerne in dairy cow diets in GB. As a result, researchers at Harper Adams University (HAU), University of Reading and Scotland’s Rural College (SRUC) are undertaking a four year programme of work funded by DairyCo to identify optimum feeding strategies for lucerne. Over the next few years, researchers will investigate:

  1. The optimum rate of inclusion of lucerne in dairy cow diets when combined with maize and/or grass silage
  2. The effect of plant maturity at harvest of lucerne silage on forage quality and cow performance
  3. The effect of chop length of lucerne on ensilability, forage digestibility and cow performance.

Lucerne growing in GB

Approximately 30 million hectares of lucerne are grown globally each year; unsurprisingly North America is the largest grower, accounting for over one-third of this production. However,  while there is an estimated potential 600 000ha of land in the UK which could support the production of lucerne, difficulties in establishing the crop have meant that little lucerne is used in GB (an estimated 20 000ha are grown annually).

There are a number of distinct advantages to growing lucerne. Most notably due to the N-fixing nature of the crop it does not require any inputs of N fertiliser, reducing costs. In areas where lucerne can be grown successfully, crop yields can reach up to 10 – 15 t/ha/annum under good management, with a typical crop being harvested 4 -5 times per annum. However, although lucerne can be tolerant of colder temperatures, similar to other legumes production of the crop is significantly affected at temperatures below 10oC and the crop will not withstand wet, poorly drained or waterlogged soil. As a result the main growth occurs between April and September in GB and is only possible on free-draining, light soils.

The main barrier to use of lucerne in GB is the establishment phase; once established, the crop will typically persist for 4 – 6 years under the correct management. However, if a poor establishment has been achieved it can be difficult to recover the crop as lucerne is autotoxic and will not withstand overseeding of additional plants.

A number of DairyCo-funded establishment trials are being undertaken at HAU, SRUC and University of Reading to provide information on different strategies to maximise establishment. One of the biggest challenges at establishment is weed infestation and so a clean seed bed is key to successful establishment. Researchers are currently investigating whether the presence of a cover crop (spring barley) reduces the weed burden (see photo 2). Researchers are also investigating whether spring or autumn establishment is preferential for lucerne production.

Lucerne plot trials

Photo 2 Lucerne plot trials – DairyCo research is investigating the use of cover crops to reduce weed burden when establishing lucerne.

For more information on growing lucerne and to keep up to date with the latest DairyCo research, check out our new online guide available at www.dairyco.og.uk