The RedNEx programme is organised into 8 interlinked sub-projects (workpackages; WP)

 

Workpackage 1

WP 1 aims to improve methods to characterise the rate and extent of feed degradation and digestion in the gastro-intestinal tract. A faster and cheaper method to estimate 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 to both rumen micro-organisms and the host animal. A better balance will reduce N losses during rumen fermentation and intermediary metabolism.

Workpackage 2

Work Package 2 will develop new strategies to enhance the flow of proteins leaving the rumen by reducing or decelerating rumen degradation of proteins, and by optimizing ruminal microbial protein synthesis. Both in vitro and in vivo experiments will be carried out. Strategies to reduce degradation of proteins will be focussed mainly on inhibiting the activity of proteolytic bacteria by the use of essential oils, plant extracts, and antibodies. The effect of combining forages and various energy sources on microbial protein synthesis under low N input will be studied to develop strategies to optimise microbial protein syntheses. The modifications in microbial diversity and activity associated to changes in microbial synthesis will be determined. The role of protozoa will be emphasized.

Workpackage 3

WP3 will improve the understanding of amino acid absorption and utilization by splanchnic (gut and liver) and mammary tissues of dairy cows. Data from REDNEX partners describing amino acid absorption and metabolism by splanchnic tissues will be made available for development of models of amino acid absorption and metabolism within WP 5. This existing data base will be supplemented with novel data to quantify the impact of absorbable amino acid supply relative to requirements and dietary carbohydrate source on the utilization of amino acids and other nutrients for milk protein production and N excretion in urine and faeces. The ideal profile of absorbed AA for maximal metabolic efficiency for milk protein production will be determined for high yielding dairy cows. The data and knowledge obtained will then be available to refine and challenge mechanistic models of amino acid utilization and N excretion in lactating dairy cows.

Workpackage 4

WP4 will investigate a series of hypotheses crucial to modelling urea-N recycling (transfer of urea from blood into the gastrointestinal tract) in dairy cows. Analytical techniques will be developed linking in vivo urea recycling to the rumen with abundance of mRNA encoding urea transport proteins and cellular and sub-cellular location of transport proteins in rumen epithelium. Knowledge generated within this workpackage will be integrated in the mechanistic modelling work (WP 5) and will be used to formulate new feeding strategies accounting for the quantity of dietary N that can be replaced by the endogenous urea recycled to the rumen and thus make predictions on the potential reduction of N excretion under practical farming conditions.

Workpackage 5

WP5 will develop and apply improved mechanistic rumen models and models of gut wall, liver and mammary gland AA metabolism, in order to integrate data and concepts and ultimately replace current empirical protein evaluation systems. Data from REDNEX partners on N recycling to the rumen and amino acid absorption and metabolism will be used to develop or evaluate the mechanistic models. The models will indicate feeding strategies for other work packages, as well as help to identify key elements for applied farm level models in WP7. Extant rumen models will be further improved to represent microbial metabolism in the rumen in situations of low protein diets. New models of amino acid metabolism in gut wall, liver and mammary gland will help to quantify and evaluate strategies to optimize amino acid utilization and minimize excretion of N. Subsequent development of an interface will allow users to apply the post-rumen model for evaluation purposes. The post-rumen models developed may be integrated with any rumen model of choice to assist in the ultimate achievement of uniform European protein evaluation systems for cattle. Dissemination of models will take place within the framework setup in WP8.

Workpackage 6

WP6 aims to develop and refine non-invasive markers of nutrient supply and efficiency of utilisation that can be used to feed back into ration evaluation models to improve diet utilisation. These markers should ultimately be useable on-farm to provide information for input into a feed evaluation model to refine the formulation of dairy cow diets, thereby enabling a reduction of N excretion and improving the utilisation of dietary N for milk production. Two approaches will be applied in WP6: (i) refinement and increased understanding of factors influencing existing candidate biomarkers of rumen efficiency and microbial protein supply to the duodenum, and (ii) discovery and development of novel markers in biological fluids (blood, milk and urine).

Workpackage 7

WP6 aims to harmonise the methods of calculation of N excretion by dairy cows, to allow precise simulations of the effect of different feeding and husbandry practices on N excretion and to explore the room to manoeuvre for reducing N excretion by dairy herd. Two approaches will be applied: i) to test solutions proposed in WP2 (forages with reduced N degradability) and WP3 (ideal profile of absorbed AA) to reduce N content in the diet while maintaining milk yield, and ii) to build a model to facilitate accurate prediction of quantities of N excreted by dairy herds using standardized methodology in the EU countries. Such a model will simulate the effect of different diets and feeding practices on N excretion by dairy cows. Because the fate of excreted N is quite variable according to the biochemical form of N, the model will separately predict faecal N and urinary N excretion and urea N in urine. The model must be enlarged at the herd level, in order to take account of N excretion from non productive animals (the number of unproductive animals varies according to the age at first calving and replacement rate for a given milk quota). The utilisation of these models will enable comparison, from a common baseline, of the effect of different feeding and husbandry strategies on the amount of faecal and urinary N produced. This will help to evaluate the different feeding and management strategies with regard to the Nitrates Directive. In addition these models, when used as part of larger models (coupling with agronomical models), will predict the overall environmental impacts of the strategies (N leaching, N2O and ammonia emissions).

Workpackage 8

WP8 will disseminate project outputs by creating a participatory framework that will allow meaningful dialogue between the workpackage coordinators and the stakeholders/ end users to ensure that the project meets their needs and hence the implementation of the Nitrates Directive and the thematic strategy on air pollution. A stakeholder platform will be created to represent them and to discuss the progress of the project and future activity in terms of both research and dissemination. Annual workshops of project staff and key stakeholders will be organised to gain advice and to further develop the project. These workshops will be held at each annual meeting of EAAP and the conclusion reported to a wider audience at the main meeting of 800 – 1000 scientists. Project outputs will also be presented for discussion and feedback at the annual meetings of the European Federation of Dairy Farmers. It is also recognised that infrastructures for dissemination are under pressure in some countries and in this respect three regional workshops will be organised in central and Eastern Europe and the Mediterranean to wider disseminate the project outputs to ensure that they meet future needs in these regions and to train extension professionals in the use of project tools. Funds will be made available for early-career scientists from these countries to attend the workshops and the regional events.

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