Increasing global demand for cereals and soya, coupled with future climate changes, means identifying long-term alternative protein sources will play an important role in reducing forthcoming feed costs.
As Dr Debbie McConnell, DairyCo’s research and development manager, explains, lucerne could be one of these alternative protein sources and new DairyCo funded research has looked at developing optimum strategies for using lucerne in GB dairy systems.
Dr McConnell says lucerne, commonly known as alfalfa, is a high-protein nitrogen-fixing legume and the most widely grown forage crop in the world. “It is known for its drought-tolerant nature, due to its deep tap root and, as a result, the crop flourishes in lower rainfall areas with free draining, light soils.
“The main growing period in GB is from April to September and, under good management, yields can reach up to 10-15 tonnes per hectare per annum, with a typical crop being harvested four to five times each year,” says Dr McConnell.
In addition, due to its nitrogen-fixing capacity, lucerne does not require any inputs of N fertiliser, ensuring production costs can be comparable to those of grass silage.
Although there is an estimated potential of 600,000 hectares (1.5 million acres) of land in Britain which could support lucerne production, difficulties in establishing the crop mean little lucerne is used here, with only 20,000ha grown annually.
Once established, the crop typically persists for four to six years under correct management. However, if a poor establishment seen, it can be difficult to recover the crop as lucerne is auto-toxic and will not support overseeding.
Dr McConnell says: “As part of the DairyCo grassland, forage and soils research partnership, a number of DairyCo-funded trials are being started at Harper Adams University, SRUC and the University of Reading, to address issues with establishment and provide information on different strategies to ensure successful establishment.
“As part of a three-year programme of work, the researchers are investigating whether spring or autumn establishment is preferential for lucerne production.”
“In addition, one of the biggest challenges at establishment is weed infestation, so a cleanseed bed is key to successful establishment. Researchers are currently investigating how the presence of a cover-crop [such as spring barley] can reduce the weed burden.
Lucerne can act as an excellent complement to maize silage and Dr McConnell says the crop, if harvested at the leafy stage, can contain more than 20 per cent protein. As a result, it can be an excellent protein source in dairy cow diets, although ME content of lucerne is typically lower than what is found in grass silage (9-11 ME). Normally, lucerne has a high level of rapidly digestible fibre and, similar to most legumes, a high buffering capacity in the rumen due to its mineral composition.
Dr McConnell says: “Studies in the United States have shown use of lucerne silage, compared with red clover, can result in an increase in dry matter intake, plus milk yield, fat and protein levels. However, there has been little research on the feeding value of lucerne.
“Researchers at SRUC and HAU have been investigating the optimum rate of inclusion in the diet of high yielding cows when combined with grass and maize silages and this winter they will also be conducting trials on the impact of lucerne silage chop length on animal performance and rumen health.”