Workshop 28th March 2014, EUROSTAT, Luxembourg Excretion coefficients livestock Guidelines for a common methodology Reactions on task 5 report WUR (final draft Oenema et al., February 2014) Harald Menzi Workshop 28th March 2014, EUROSTAT, Luxembourg

Points of view – my different hats Switzerland Swiss agriculture and nutrient balance policy Responsible for Swiss excretion coefficients and NH3 emission inventory International Scientific Networks (with chair function) EAGER (European Agricultural Gaseous Emissions Inventories Researchers) RAMIRAN (Recycling Agricultural, Municipal and Industrieal Residues in Agriculture) Scientific work on nutrient flows and environmental impacts of livestock production

Excretions factors in Switzerland Excretions coefficients (ExC) are of crucial importance in Switzerland for implementation of nutrient balance policy Compulsory annual N/P balance for each Swiss farm Criterion for "Ecological Performance" policy and direct payment program that contributes an important share of farm income But, data not collected systematically Detailed emissions factors (approx. 20 major categories, total >50 categories) Critical control of reliability of ExC by stakeholders Experience on influencing factors and limits of ExC ExC are also used for national or regional emission inventory calculations and N/P balance calculations

Comparison Swiss situation vs. WUR report Good agreement Swiss ExC N and P default values in report Same general level of ExC  report and CH in good agreement Differences can (mostly) be explained by management Weakest comparability for pigs – we know that these values are the least up to date We use ExF based on mass balance calculations since 1994 Revisions 1994, 2001, 2009, (2016) "Correction factors" provided for dairy cows (milk yield) and monogastrics (CP and P content of diets) Pig and poultry farms can use import export approach for nutrient balance if they use low N/P content diets From NH3 emission work based on representative survey on farm management we have more differentiated ExC for dairy cows and monogastrics

Tier level in Switzerland National average excretion/ha slightly below proposed limits for tier 2; some regions are higher Swiss approach = tier 3, differentiated national approach, partly consideration of milk yield etc. tier 2 because of infrequent revisions Yearly calculations of ExC could face difficulties Roughage composition (ruminants) Importance of different diets (cattle) Amount and content of concentrate (cattle) Use of pure amino acids, phytase, phase feeding Variability of productivity level of farms

ExC in international scientific networks (personal perception) Seldom a topic Is this a research topic ? Comparison of national assumptions is an important exercise, but not easy (trust, flexibility etc.) Better comparability of ExC than emission factors (tier 3 level) ExC less robust for pigs than for cattle Skepticism towards (too strong) harmonisation Differences in production technique adequately considered ? Different national experience and priorities Definition livestock categories is often not clear enough

Personal reflections Excretions coefficients must be based on input/retention balance calculations "Bellow tail" approach is adequate basis to consider livestock production in all nutrient flow work (fertilization, intensity, balance, efficiency, emissions, environmental impacts and load) ExC can not be standardized across Europe  national/regional assessment is necessary A harmonized approach to determine ExC is necessary, if we want to compare countries ExC should be based on sound (national) data and experience on livestock production Livestock units (LU) are not adequate for nutrient balance work

Personal reflections (2) Standard approach Must allow to consider differences in Productivity level Diet types and production technique (grazing, housing systems, empty periods etc.) Roughage composition, CP and P content of diet etc. Comparability and comparison of national approaches is important Standardized data template for input data production Common definition of livestock categories Concerted comparison by livestock experts A tier 3 approach with yearly determination of ExC will be difficult in many countries, especially for ruminants

Personal reflections (3) Critical aspects Definition of categories Level of detail of categories; do they reflect production? Statistics in line with categories? Empty period Data and experience on farm management Feed contents General approach and aim Input for farm management or for environmental impact Reflect farm situation as well as possible or with safety margin Expert bias ? Documentation

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