Innovative and practical management approaches to REduce Nitrogen EXcretion by ruminants (Rednex): Final Report to the Welsh Government

The EU project Rednex (“Innovative and practical management approaches to REduce Nitrogen EXcretion by ruminants”) was a collaborative Seventh Framework Programme project co-ordinated by ASG Veehouderij B.V. in the Netherlands and involving 10 other partners. These are Aberystwyth University (UK), European Federation of Animal Science (Italy), Friedrich-Löffler-Institut Bundesforschungsinstitut für Tiergesundheit (Germany), Institut National de la Recherche Agronomique (France), Slovenske Centrum Polnohospodarskeho Vyskumu (Slovakia), Universitat Autonoma de Barcelona (Spain), Universiteit Gent (Belgium), University of Aarhus (Denmark), University of Reading (UK), and Wageningen Universiteit (Netherlands). The objective of Rednex was to develop innovative and practical management approaches for dairy cows that reduce N excretion into the environment through the optimization of rumen function, an improved understanding and prediction of dietary N utilization for milk production and excretion in urine and faeces. These aims were met through a series of workpackages that investigated novel methods of feed analysis, modelled rumen and ruminant metabolism, investigated the effects of low N diets on rumen function, amino acid absorption and urea recycling, herd-level modelling of N utilisation and excretion, and biomarker discovery to understand rumen and whole animal N use efficiency.
Work carried out at IBERS, Aberystwyth University, included:
• the development of rapid methods of feed protein characterisation using Fourier transform infrared (FTIR) spectroscopy,
• in vitro and in vivo experiments of rumen function to characterise the rumen microbial ecosystem and key bacterial and protozoal groups associated with rumen N metabolism,
• analysis of biological samples using metabolomic analysis of blood and milk samples generated by partner organisations to develop rapid methods of rumen and whole-body N use efficiency,
• testing of models of herd-level N use using data collected from Welsh dairy enterprises,
• workshops in Wales and in other European countries to disseminate the results of this and related projects to Welsh Government staff, and to farmers, nutritionists, advisors and policy-makers.
Key outcomes of the work carried out at IBERS include:
• ruminant feed protein and fibre concentrations can be accurately predicted by FTIR, but degradation characteristics are not so well estimated,
• rumen protozoa have a substantial effect on rumen fermentation patterns and methane emissions, increasing methane emissions by their presence,
• protozoal predation of rumen bacteria contributes to the inefficiencies in the use of rumen-available N,
• changes in the supply of rumen available protein and energy-yielding nutrients to dairy cows significantly affect the rumen microbial ecosystem,
• metabolic profiles of plasma and milk are relatively poorly correlated with rumen fermentation parameters, but significant correlations with rumen ammonia and duodenal N flows were found; correlations with plasma were better than those for milk,
• of the Welsh herds investigated, higher yielding cows were more efficient (per kg milk produced) than lower yielding cows.