1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. Thank you for your attention
Agroscope
good food, healthy environment