Dossier

PigStun

The PigStun project runs from January 2022 – May 2025 with the aim to improve animal welfare during the stunning process of pigs in slaughterhouses. In this European project researchers and slaughterhouses in Germany, Denmark, Spain and the Netherlands worked together to test alternative stunning methods for pigs to replace conventional CO2 stunning.

In EU pig slaughterhouses two stunning methods are most commonly applied: electrical stunning of individual pigs and carbon dioxide gas stunning at high concentration of pigs in groups.

Carbon dioxide gas stunning of pigs in groups is widely used because of its efficiency and reduced pre-slaughter stress, as pigs are handled and stunned in small groups. However, exposure to high concentration of CO₂ during stunning raises concern because it’s aversive, causing hyperventilation and painful irritation of the mucous membranes

Electrical stunning is another commonly used method for stunning pigs at slaughter and results in immediate unconsciousness of the animal. But prior to stunning the animals need to be lined up in a row. To keep the animals moving whilst going from a group to a single line often involves stress and (painful) stimuli such as brushes and electric prods.

The general objective of the PigStun project was to encourage EU pig slaughterhouses using high CO2 concentration for stunning pigs to convert to systems that are less aversive. This is done by testing promising alternative systems and improvement strategies with respect to animal welfare. The PigStun consortium produced four main deliverables. D4 soon to be published.

Each of the deliverables describes a step in the process of the project, and the final one (D4) contains the Conclusions and Recommendations. The four main deliverables provide a scientific account of the project’s findings.

Deliverable D1 A report that describes the stunning practices for pigs in high throughput slaughterhouses and their socio-economic drivers.

Deliverable D2 A description of the planning phase and the selection of alternatives to be implemented, the scientific, technical and socio-economic data to be collected, and the bench mark ranges obtained from conventional commercial practice.

Deliverable D3 A report on the implementation of the selected alternatives under conditions similar to the commercial situation, and the collection of the pre-selected data.

Deliverable D4 SOON TO BE PUBLISHED The analyses and comparison of the results of the selected alternatives, and the recommendations addressed to slaughterhouses and other stakeholders.

To support the move away from current high CO2 stunning systems, PigStun tested novel approaches and stunning systems along two lines of thinking. The first one looked at the induction phase of different Controlled Atmosphere Stunning (CAS) systems and using inert gasses. The second one aims to reduce stress during pre-stun handling (see next section).

Induction phase in CAS systems: Three systems that can use inert gases as alternatives to conventional high CO2 were evaluated in the PigStun project. An Optimised CAS process is proposed that aims to achieve better control over CO₂ (and O₂) concentrations through the integration of additional sensors, ensuring that the desired levels are maintained. Although still based on high CO₂ levels, it is considered an improvement to more variable conventional systems.

A bigger step that was investigated is the move towards Inert gasses. These have previously been shown to cause very little or no stress during the induction phase.

The Argon Retrofit system is an alternative that can be used following conversion of an existing Dip-Lift or Paternoster high CO₂ stunning system. It provides stable atmospheres of inert gases such as argon or argon-nitrogen mixtures at very low oxygen levels (<1%).

The Helium system consists of a newly designed technical system where the gondola moves up and lifts the animals into the gas, instead of going down.

To support the move away from current high CO2 stunning systems, PigStun tested novel approaches and stunning systems along two lines of thinking. The previous section is about the induction phase of different Controlled Atmosphere Stunning (CAS) systems and use of inert gasses. This section describes the second line: reducing stress during pre-stun handling, allowing a calmer entry into the stunner.

Pre-stun handling: The improved pre-stunning handling in CAS systems aims to minimise stress levels of groups of pigs. The different alternative CAS systems had different approaches. Of course it has to be acknowledged that even very calm and low stress handling will not remove the distress caused by exposure to high CO₂ concentrations in the induction phase.

The Improved Electrical Stunning system focusses on pre-stunning handling, the design of raceways and the entrance of pigs into the stunner. It consist of reducing the maximum number of animals per stunner per hour by installing more stunners, guiding pigs in small groups from lairage to the raceway, ensuring a modified route up to the raceway, allowing pigs to freely choose into which raceway they are walking to enter the stunner.

The Results, Conclusions and Recommendations of the project were presented at a Stakeholder Meeting in Brussels on 4 April 2025. Around 50 delegates attended the meeting physically, and 150 joined the lively discussions on line.

The webstream includes all presentations and the discussions (the times indicate the starting point on the web stream). The first part of the meeting was chaired by dr Hans Spoolder (Wageningen Livestock Research – PigStun co-coordinator) and the conclusions and discussion by dr Andrea Gavinelli (Head of Unit at DG SANTE).

In April 2025, the PigStun project presented its outcomes by native speakers to an audience of 128 stakeholders (in total) in 6 main pig producing countries. The 6 countries were The Netherlands, Spain, Germany, France, Poland and Denmark.

The meetings consisted of several presentation explaining the alternative stunning systems that were tested, as well as the outcomes of the research. The meetings were concluded with a discussion on the main results and conclusions of the work. Please click on a links below to find the webinar presentations offered in five different languages.

The consortium of the PigStun project consisted of academic and industry partners.

Click here for the LinkedIn page of the PigStun project.

Wageningen Livestock Research (Coordinator - NL), Compaxo Vlees Zevenaar BV (NL), Marel Red Meat BV(NL), Aarhus University (DK), Danish Meat Research Institute - Danish Technological Institute (DK), Danish Crown (DK), Friedrich Loeffler Institut - Bundesforschungsinstitut fur Tiergesundheit(DE), Max Rubner Institut Bundesforschungsinstitut fur Ernaehrung und Lebensmittel (DE), Institut de Recerca i Tecnologia Agroalimentàries (ES) and Frigoríficos del Nordeste SA (ES).

Associated Partners are: Vion Perleberg GmbH (DE), Georg-August University of Göttingen, Department of Animal Sciences, Divisions Production of animal products and Functional Breeding (DE), Air Liquide Deutschland GmbH (DE) and Westfort Meat products (NL).