Knowledge Based Bio-Economy


Reducing nitrogenous pollution by cattle

Project acronym: Rednex

Title of project: Innovative and practical management approaches to reduce nitrogen excretion by ruminants

Research area: Agriculture & Forestry (Reduction of nitrogen excretion in ruminants)

Contract No: 211606

EU contribution: €5550 000 EURO

Start date: July 2008

Duration: 60 months


Dairying is an important sector of EU agriculture’s intensive farm methods which have led to an increased use of high nitrogen levels in feed. This has had a negative environmental impact on groundwater (pollution with nitrates), surface water (eutrophication) and on the atmosphere (de-nitrification and ammonia volatilisation). There is a need to stimulate measures that improve management of nutrients, waste and water beyond those that are at present regarded as ‘usual good-farming practice’.

The objective of Rednex is to develop innovative and practical management approaches for dairy cows that reduce nitrogen excretion into the environment through the optimisation of rumen function, as well as developing an improved understanding and prediction of dietary nitrogen utilisation for milk production and excretion in urine and faeces.

Novel tools for monitoring these processes and predicting the consequences in terms of on-farm N losses will be developed. Research to understand amino acid absorption, intermediary utilisation and the processes involved in the transfer of urea N from blood to the gastrointestinal tract will further underpin model development and indicate strategies to reduce N losses. To predict on-farm N losses and the impact on profitability, a harmonised applied model will be derived from the mechanistic model and will be supported by tools to better describe feeds and biomarkers to indicate N status.

Expected impacts

This project should contribute to a reduction in problems associated with excess nitrogen release into the farm environment which, in turn, impacts on the quality of bodies of water such as rivers and lakes, which may result in abundant growth of waterweeds, freshwater algae, etc. Such eutrophication may affect biodiversity amongst fish and bird life as well as leading to acidification of the water with related deleterious effects. Hence, the results should contribute to the further reduction of nitrate loss to the environment, as controlled by the Nitrates Directive under which all Member States have to analyse the nitrate concentration levels and trophic state of their waters, as well as introducing and maintaining control measures. The work will also contribute to meeting the requirements of the Groundwater Directive and elements of the Common Agricultural Policy which lead to farmers setting up nutrient-management measures, such as wider buffer strips around water courses. However, since the farmer receives payments reflecting the benefits of this, if, ultimately, the project reduced this need then farmers’ income from this source could also fall.

Expected results

The main output of this project will be a detailed mathematical model of N utilisation by the cow. The project will generate improved methods to characterise the rate and extent of feed degradation and digestion in the gastrointestinal tract. This faster and cheaper method of estimating these characteristics will enable farmers and feed manufacturers to generate rations for dairy cows (and other ruminants) with a better balance between energy and N or protein supply. The project will also identify new strategies to enhance the flow of proteins leaving the rumen by reducing or decelerating rumen degradation of proteins, and by optimising ruminal microbial protein synthesis through both in vitro and in vivo experiments, including inhibiting proteolytic bacteria activity by using essential oils, plant extracts, and antibodies. It will also show the benefits of combining forages with various energy sources on microbial protein synthesis under low N diets. A development model will be produced describing amino acid absorption and metabolism. This will establish links between in vivo urea recycling to the rumen with an abundance of mRNA encoding urea transport proteins and cellular and sub-cellular location of transport proteins in rumen epithelium. Other models will be produced that reflect rumen mechanisms and the function of the gut wall, liver and mammary gland amino acid metabolism.

The models will indicate feeding strategies as well as help to identify key elements for applied farm-level activities combined with the use of non-invasive markers of nutrient supply and utilisation efficiency which can be used to feed back into ration evaluation models to improve diet use. Overall results will enable dairy cow diets to be modified, resulting in a reduction of N excretion and improving the use of dietary N for milk production. Overall, the project should result in information that harmonises methods for the calculation of N excretion by dairy cows and enables precise simulations of the effect of different feeding and husbandry practices on N excretion and exploration of the various strategies for reducing N excretion by dairy herds.

Website of project:


Coordinator: Ad van Vuuren,

Organisation: Wageningen UR Livestock Research, The Netherlands,


Aberystwyth University, UK,

European Association of Animal Production, Italy,

Friedrich-Löffler-Institute, Germany,

Institut National de la Recherche Agronomique, France,

Research Institute of Animal Production, Slovakia,

Universitat Autonoma de Barcelona, Spain,

Universiteit Gent, Belgium,

University of Aarhus, Denmark,

University of Reading, United Kingdom,

Wageningen Universiteit, The Netherlands,