Abstract

Examples of the current standards, across the Member States, for nitrogen (N) and phosphorus (P) excretion by the major livestock categories have been considered within this review. The computation of these data are based largely on the well-known approach of nutrient balance, comparing total animal intakes with outputs in terms of animal products, including milk, eggs and wool and, also, liveweight gain. The sometimes substantial variability between standards reflects the variability in dietary composition, feed conversion efficiency and livestock husbandry; also differences in age and animal liveweight and length of production cycle. However, in some cases, it is clear that differences in terminology, or basis for calculation of excretal output (e.g. according to per ’animal’ produced, annual or per ‘animal place’) can account for problems in meaningful comparison. Therefore when “standards” are considered, it is important that the basis of the standards should be indicated and understood, and comparisons made only between what can be considered equivalent data. Alternative methods for quantifying nutrient excretion are considered, including direct measurements with livestock or with manure and the development of metabolic models and such estimates provide important opportunities for validation. A simple procedure for estimating P excretion based on the nutrient balance approach is proposed. This requires knowledge of the intake (dietary P) and output in animal product (milk, eggs, meat etc.). The difference between the two is assumed to be P excreted in urine and faeces

Published in

Publisher: ADAS consulting UK

SLU Editors

• Agostini, Francesco

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use


Permanent link to this page (URI)

https://res.slu.se/id/publ/22568