Improving nutrient and water efficiencies from ‘root to rumen’

Published 21 June 13

Research update: Grass breeding key to sustainable farms

With rising costs of feed and fertiliser and an ever changing climate, improving the efficiency of how we use our resources of nitrogen (N), phosphorus (P), and even water will be key to maintaining sustainable farm systems.

Recently researchers at Aberystwyth University in partnership with DEFRA and the industry, including DairyCo, have been investigating nutrient and water use efficiencies from 'root to rumen', to help farmers adapt to meet the challenges of more efficient food production.*

At a recent open day at the University, scientists explained how their research is helping farmers meet these challenges. Dr Debbie McConnell, DairyCo R&D manager, reports back on some of the day's major points.

Improving nutrient efficiencies

For grassland farms in GB, N use efficiencies from soil to plant are generally low (between 10-40% for dairy systems) in comparison with arable systems (40 - 80%). To address this scientists have been focusing on breeding forage crops capable of using fertiliser more efficiently, reducing input costs and decreasing losses of N to the environment.

One method of improving protein utilisation in the rumen is to reduce the amount of crude protein content of the diet. Livestock are poor converters of grass protein into meat and milk, with approximately 80% of N consumed excreted by the animal. While clover provides a high quality feed and is effective at fixing N in the field, research at Aberystwyth has shown that cows fed grass-clover diets (at 30% clover) can excrete 2.5 times more N per day than cows fed ryegrass only diets. As a result researchers have focused on breeding varieties of white clover which have a lower N content in the plant but remain effective at fixing N in the field.

Scientists have also investigated improving phosphorus (P) use efficiency in both grass and clover varieties. P is a key nutrient for both plant and animal growth, but it is a finite resource which has risen in price significantly in the last few years. Researchers are currently testing varieties that both contain lower levels of P in their leaves, and that can perform well in low P soils. This summer these varieties will be fed to livestock to assess the impact of low P forages on animal P use.

Drought tolerance

Research is also being undertaken into developing new grass and clover varieties which are more capable of coping with drought conditions.

Dry conditions can significantly impact on grass yield; for every 50mm increase in soil water deficit, perennial ryegrass production is reduced by 1 tonne/hectare. Using conventional breeding methods, breeders from Aberystwyth University have crossed fescue plants taken from around the globe with Italian and perennial ryegrass varieties. The resulting hybrid varieties that have been produced have rapid root growth and a more extensive rooting system. This has benefits both in terms of water use efficiency and soil health and structure.

In fact, scientists are also looking further afield to natural varieties present in other areas of the world to help introduce some more functional traits back into our grass and clover varieties.

"Historically we have focused on yield as the main driver behind our breeding goals," explains clover expert Dr David Lloyd from Aberystwyth University. "This has unfortunately been to the detriment of some of the other traits such as persistency and stress tolerance which we value in our clover varieties.' To try and address this David is now collecting varieties from as far afield as Asia and the southern hemisphere, which have naturally developed certain characteristics eg winter hardiness. These varieties are being crossed with high yielding varieties bred in the UK.

Phenomics Centre

At the open day visitors also had the opportunity to see the new National Plant Phenomics Centre.

Recent improvements in genetics have allowed scientists to collect DNA  sequences from individual plants, from which they hope to identify specific 'markers' for individual traits such as disease resistance or persistency. This will provide vital information for plant breeders and allow them to make informed decisions early on in the breeding process.

However, to begin identify these genetic markers a large amount of physical and biological data must first be collected from the existing plants to match to these genetic sequences. While plant genetics can now be mapped relatively quickly thanks to advancements in technology, physically taking the required plant measurements can be extremely time consuming and is very labour intensive.

The new Phenomics Centre has automated a large proportion of these measurements. The centre consists of two state-of-the-art glasshouses each with accommodation for 440 individual plant pots. Every day each of these 880 plants pass through an imaging and testing centre which monitors the growth habit and chemical composition of the plant. Using cameras a 3D image of the plant can be constructed from all sides.

The facility can also be used to examine how individual plants react to different conditions. For example, when plants are under drought stress they will close their stomata to restrict the loss of moisture to the air, causing the temperature of the plant to rise. Thermal imaging software in the centre helps identify how individual plants cope with drought stress and monitors how water is re-circulated around the plant to cope with this stress. In the greenhouses, water, nutrients and lights are also administered automatically by computer programmes.

Recommended Grass and Clover Lists

Aberystwyth University is also one of the trial sites for the Recommended Grass and Clover List (RGCL) trials which are funded by levy boards (HCC, AHDB-DairyCo and EBLEX divisions) and BSPB.

Dr Alan Lovatt, Senior Grass Breeder at Aberystwyth highlighted the importance of using the RGCL system to select grass varieties on farm at
the recent event.

"The RGCL is an extremely important part of the plant breeding process," comments Alan. "It provides an excellent source of independent information for farmers."

Alan also warned against using varieties not on the list: "From time to time we test varieties which are being used extensively in other grassland areas of the world, however, differences in climate and seasonal growth patterns mean that often these varieties struggle to perform here in the UK.' In fact, approximately only 5% of grass and clover varieties which are tested here in the UK succeed in making it onto the RGCL, meaning that selectin varieties from the RGCL is the best way to guarantee performance of a new ley.

For more information on grass research and the RGCL visit the grassland management section of the DairyCo website www.dairyco.org.uk.

 *These projects are sponsored by Defra through the Sustainable Livestock Production (SLP) LINK Programme in association with IBERS
Aberystwyth University, Germinal Holdings Ltd, British Grassland Society (BGS), AHDB-DairyCo, AHDB-EBLEX, Hybu Cig Cymru (HCC), Livestock and Meat Commission of Northern Ireland (LMCNI), and Quality Meat Scotland (QMS). Please refer to the project website at http://www.greener-grasslands.ibers.aber.ac.uk/index.html    for more information.