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  • Mohammed Shamsuddin
    Livestock Reproductionist / Breeder
    Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture
    International Atomic Energy Agency
    Vienna International Centre
    PO Box 100
    1400 Vienna, Austria
  • [email protected]
  • Mario Garcia Podesta
    Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture
    International Atomic Energy Agency
    Vienna International Centre
    PO Box 100
    1400 Vienna, Austria
  • [email protected]


Joint FAO-IAEA research looks for a stable-isotope based method to quantify feed intake

In an expert consultation organized by the Joint FAO/IAEA Division based in Vienna, Austria, the challenges and needs of developing countries in the context of feeds and feeding of animals for optimum productivity were presented and discussed, and the roles of stable isotopes in addressing those challenges and most promising applications were identified. After intensive discussions, the experts concluded that an accurate methodology to quantify or predict dry matter intake of cattle under grasslands is not available to date. This limits the application of appropriate and efficient feed supplementation strategies to realise the full potential of cattle in grasslands. Grasslands are among the largest ecosystems in the world, estimated to cover 40.5 percent of the terrestrial area excluding Greenland and Antarctica Grasslands. These are important as a feed source for livestock. In both developed and developing countries, many millions of livestock farmers, ranchers and pastoralists depend on grasslands for their livelihoods.

Against this backdrop, the experts developed a Coordinate Research Project (CRP) to evaluate a method combining
different n-alkanes profiles with natural 13C concentration data to quantify feed intake of plant species by cattle in rangelands containing multi-plant species. The method exploits the intrinsic alkane composition because individual plant species have their own alkane composition. Because the stable isotope measurement in alkanes is expensive, calibration using Near Infrared Reflectance Spectroscopy (NIRS) will also be developed to predict the dry matter intake data. The NIRS method is non-invasive, relatively low cost, easy to operate, and takes very little time (1-2 min per sample).  It is anticipated that in practice NIRS will be used to provide advice to farmers.

The project is entitled “Quantification of Intake and Diet Selection of Ruminants Grazing Heterogeneous Pasture using Compound Specific Stable Isotopes”, and aims to:

  • Quantify intake and diet selection of cattle grazing/browsing heterogeneous pasture using compound specific stable isotopes of long chain n-alkanes.
  • Create practical NIRS based prediction equations of total pasture dry matter intake, as well as its proportion of individual pasture species, based upon analysis of individual animal faecal composite samples.
  • Evaluate impacts on animal performance and efficiency of potential feed supplementation strategies using existing animal metabolic models based upon predicted pasture dry matter intake.
  • Strengthen research capacity among animal scientists in developing countries.
  • Networking among animal scientists from developed and developing countries.


The expected outputs from the project are:

  • A uniform dataset of n-alkanes concentrations and their stable carbon isotope composition of common pasture grass, legume and browse species, measured in many world ecosystems, which are consumed by cattle.
  • An improved prediction of intake and diet selection/composition of cattle consuming mixtures of plant species in pastures/rangelands.
  • A practical NIRS based prediction equation of intake and diet composition of cattle consuming multi-species pasture grasses, legumes and browses.
  • Recommendations for future research and development using stable isotope compositions of pasture/rangeland grasses, legumes and browses.
  • Publications and dissemination of results.
  • Regional and international collaborative linkages.

The expert meeting was attended by five experts, one each from Australia (Shimin Liu), Netherlands (Jan Dijkstra), South Africa (Ignatius V Nsahlai), Switzerland (Jorge Spangenberg) and the United States of America (Peter Robinson). Staff members from AGE (Mohammed Shamsuddin,  Mario Garcia Podesta and Gerrit J. Viljoen), AGA (Harinder Makkar ) and NAHU - Nutritional and Health-Related Environmental Studies Section of IAEA (Christine  Salter) also contributed to the discussions. The meeting was coordinated by Mohammed Shamsuddin.

This CRP, operated by IAEA in partnership with FAO, is expected to start in 2016 with 12-14 research contract holders and will conclude in 2020.