VERA TEST PROTOCOL “HOUSING SYSTEMS”

ADAMSEN, AP.¹, BJERG, B.¹, GALLMANN, E.¹, GRIMM, E.¹, HARTUNG, E.¹, KAI, P.¹, MOSQUERA, J.¹, OGINK, N.¹, HEMPEL, S.², ROBIN, P.², BECKERT, I.³

1 International VERA expert group “Housing systems”

2 Guests of the international VERA expert group

3 International VERA Secretariat, Germany

ABSTRACT: To meet the challenge of performing comparable and valid emission measurements in naturally ventilated animal houses, the VERA test protocol for

“Housing and Management Systems” (2011) has been revised based on the latest studies and an exchange of experts. The revised protocol offers guidance ranging from the selection of a suitable test location to correct measurements with artificial or metabolically produced tracer gases allowing an evaluation of the environmental performance and operational stability of emission-reducing procedures in livestock husbandry. To validate the revised method and assess the measurement uncertainties, a plan for an inter-laboratory test has been initiated.

Keywords: House, Inventory, Measuring method, Environmental evaluation, Verification.

INTRODUCTION: Making the environmental efficiency and operational stability of emission-reducing procedures transnationally comparable by using uniform and scientific test procedures was the objective of the Verification of Environmental Technologies for Agricultural Production (VERA) initiated by Germany, Denmark and the Netherlands in 2008.

The challenge involves performing comparable and valid emission measurements in naturally ventilated animal houses, as they are common practice in cattle farming, and standardising them has not been achieved in a satisfactory manner in recent years due to the insufficiently described and validated measurement methods. Furthermore, inter-laboratory studies to develop a reliable assessment of the measurement uncertainties for emission measurements in livestock husbandry systems are necessitating new initiatives.

1. MATERIAL AND METHODS: The development of the revised test and verification standard is based on the connection of expert knowledge and several scientific studies in Denmark, the Netherlands, Germany, Belgium, France and Switzerland. In this process, not only were literature studies consulted, but also a direct exchange involving experts with technical knowledge of the relevant issues was initiated and supported, as this is common practice during the creation of international standards.

Measurement methods

The coordination of the new standard was mainly supported by the relevant agricultural or environmental ministries of the interested countries. This setup was also applied for the planning of an inter-laboratory investigation in order to improve the assessment of measurement uncertainties when measuring ammonia in the agricultural environment of an animal house.

2. RESULTS AND DISCUSSION:

2.1. Revised test standard: A revised test standard for naturally ventilated animal houses has been created on the basis of completed studies and with the participation of scientists from various European countries. The results have been summarised in terms of a revision in the new version of the VERA test protocol for “Housing and Management Systems”. The focus is on testing ammonia, odour and dust emissions from livestock houses, measuring and respecting parameters which are related to the emissions (e.g.

ventilation rate, CO2, temperature) or to other factors such as the level of production (e.g. animal weight and density, manure parameters, feed) and the operational stability of the system in the test (e.g. uptime of system, consumption of electricity, water, chemicals). The latest findings from other European research projects evaluating the application possibilities and limits of various measurement methods for ammonia, dust and odour were considered for the revision.

To allow flexibility in the selection of the measurement methods and simultaneously assure high measurement quality, it was agreed to abandon the earlier approach based on a list of allowed measurement principles. This has been replaced by an approach with defined unique ‘reference methods’ for each of the primary measurement parameters.

The selected measurement methods must have been validated against reference methods in a standard procedure based on laboratory and field comparisons.

Reference methods are now defined for:

Ammonia: Impinger system

Odour: dynamic olfactometry according to EN 13725;

(Total) Dust: gravimetric measurement according to the relevant EN standards;

Air volume: fan-wheel anemometer or emission values derived from tracer gas.

2.1.1. Measurements for naturally ventilated buildings: Primarily, the revision discusses

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Case-Control design: As this test design is known to minimise non-system factors and allow a direct comparison, this remains the preferred option in the revised test protocol.

The maximum deviation for a case-control approach in terms of variation in e.g. animal weight or other aspects is defined. Use of a ‘fixed case-control’ or an ‘on-off’ approach may be alternative test designs if specific requirements are respected and other test conditions can be kept similar during the measurement periods. This can help to prevent the need for a multi-side approach, which is a more expensive option, as measurements at a minimum of four (instead of two) different test sites become necessary.

Emission patterns: Emissions can vary significantly depending on the animal weight and growth. Therefore, this effect must be considered in the planning of the test. Three types of ‘growth’ are defined as: stable (e.g. in dairy cows), linear increase (e.g. in fattening pigs) or exponential increase (e.g. in broilers). The sampling has to be performed in several periods of equal length depending on the growth type.

Sampling points: To gain valid results with the CO2 balance method, selecting the right sampling points is crucial. The distance between the sampling point and the side wall or an outlet opening, the minimum number of sampling points, and the height of the sampling line in order to minimise the effect of animals, cubicles and other obstacles are described.

Other sources and ingoing air: At least one sampling point outside the house at all open side walls at a distance of at least five metres is necessary to measure the gas distributed over one year is still the demand for a VERA test. The distribution depends on the emission pattern. The exact number of measuring days must be determined based on an analysis of the power of the test design.

Calibration, validation, on-site verification: Quality management in terms of testing by

‘good laboratory practice’ is emphasised more clearly. Any calibration and verification procedures must fulfil the requirements of ISO 17025 (2005) and be documented and reported.

Calculation of the emission value: To derive the best estimate of the emission value from the test data, the completeness of the data set has to be evaluated and the mean emissions calculated, taking the emission pattern into account. When the CO2 tracer ratio method is used, the calculation has to follow the rules of the International Commission of Agricultural and Biosystems Engineering (CIGR). An open Excel calculation tool is planned to assure equally correct use of the equations needed.

Measurement methods

2.1.2. Agronomic requirements – common baseline: In addition to the measurability of a test site, the representativeness of a test site is of utmost importance to allow the best possible transferability of the test results to other countries and to other farms. The Annex of this revised test protocol provides a comprehensive summary of agronomic requirements for an emission test in the three countries and includes a ‘common baseline’ of the standard animal housing conditions. For dairy cows, the loose housing with cubicles was found to be the highest common denominator for a ‘standard housing system.

To give an example of relevant criteria for the definition of agronomic requirements, Table 1 shows the demands for a suitable test location for dairy cows.

Table 1. Agronomic requirements for a test location (VERA, 2017).

Criterion (Excerpt) Example: Dairy cows Animal occupation rate 90–100%

Herd composition >70% of house must be occupied by cows Housing system in use before test >2 months

Production level ≥ 25 kg energy corrected milk per cow and day Feed composition ≥ 50% roughage, 160–180 g CP per kg dry matter

Naturally, only test farms with a production that complies with all national regulations on animal welfare, total environment, occupational health and safety and, if relevant, food safety for e.g. feed additives are acceptable. To allow the classification of the test results attained, the national emission factors of the VERA member countries were summarised for different animal categories and housing and management conditions.

2.2. Plan for an inter-laboratory test: To validate the measurement methods and to improve the assessment of measurement uncertainties, an inter-laboratory test with research and commercial laboratories will be planned. The first step will focus on the comparison of the measurement devices for NH3, CO2 and accompanying parameters upon use in a standardised gas measuring chamber with a mixture of different gases representing typical farm conditions. Furthermore, one measurement point in an animal house will be used to compare different measurement methods and instruments. In standard instrument calibration regimes, interference of other gases is usually not considered. The conditions of an animal house, however, require the measurement instruments to be in control of such incidences. Thus, the new setting is crucial to

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(2011). Retrieved January 10, 2017, from http://www.vera-verification.eu/fileadmin/download/Test_programs/Housing.pdf

ISO 17025, 2005. General requirements for the competence of testing and calibration laboratories

European Commission, 2015. BAT Reference document for the Intensive Rearing of

Poultry or Pigs. Final draft, August 2015.

Measurement methods

QUANTIFICATION OF SMALL SCALE NITROUS OXIDE EMISSIONS AND COMPARISON