A new economic analysis by AHDB that has highlighted the significant extra costs and disruption that could result from a ban on the use of carbon dioxide in pork plants.
The report has prompted calls for any future transition to alternative methods to be evidence-led and underpinned by fully-funded, UK-based trials at a commercial scale sufficient lead-in time to allow the industry to prepare for the change.
Defra announced a commitment to ‘banning the use of CO2 gas stunning of pigs, subject to a consultation’, in the Animal Welfare Strategy published at the end of last year.
This was based partly on an opinion published in October from its Animal Welfare Committee, which recommended that stunning live pigs with direct exposure to high concentration CO2 gas mixtures should be phased out because it is ‘known to be aversive to pigs’. It called for a transition to alternative methods within five years.
While there is no firm timetable at this point, a consultation on formal proposals was expected in the early part of this year.
Plant-level costs
With this in mind, AHDB commissioned Europe Economics to estimate the plant-level costs and practical implications of converting from high-concentration CO₂ to alternative systems for stunning and killing pigs in a commercial UK pig processing facility.
Currently, 90% of pigs reared in England and Wales are stunned by being exposed to high concentration CO2 using paternoster CAS systems, according to a 2024 Food Standards Agency Survey. The remaining 10% are stunned using electrical stunning or for a very small number, percussive stunning with a penetrative captive bolt device.
The report analysed the three most likely alternatives and compared them to CO₂:
- Argon with added capacity, for example a second kill line
- Argon with extended operating hours
- Electrical stunning with appropriate pre-stun handling and restraint.
Under the central assumptions made, all the alternative systems are ‘materially more expensive than the baseline’ of CO₂. The analysis concludes that:
- Stunning and slaughter with CO₂ costs £0.42 per pig
- The cost of argon with added capacity is £1.49 per pig, an uplift of 257% compared with CO₂.
- Argon without added capacity is £1.36 per pig, a 226% uplift.
- Electrical stunning is £1.11 per pig, a 165% uplift.
The economic analysis is based on a ‘bottom-up cost model’ for a notional high-throughput UK site currently using a CO₂ system.
Wider impacts
The report highlights several wider impacts that are not quantified in the per-pig estimates because robust data are not available or because the effects depend on sector-wide dynamics rather than a single plant. These include:
- Technological and first-mover risks – No plant currently operates argon stunning at full commercial scale with stun-to-kill. Early adopters would face uncertainty over long-run performance, reliability, maintenance needs, gas consumption and welfare outcomes under UK conditions, as well as the risk that standards or preferred technologies change again after significant capital has been committed.
- Short-run disruptions and transition risks – Multi-week installation downtime, partial closure of lines and the diversion of pigs could impose substantial short-run costs and create winners and losers from sequencing effects.
- Demand side and competitiveness impacts – Higher processing costs are expected, in the long run, to raise wholesale and retail prices, reducing UK pork consumption or shifting demand towards cheaper proteins. There are also potential impacts for international competitiveness if UK plants adopt more expensive alternatives ahead of competitors that continue to use CO₂.
- Site-specific layout, footprint and downstream constraints – In some plants, accommodating argon or electrical systems would require significant building works or may be infeasible without relocation. In addition, chilling and downstream processing capacity may be the binding constraint.
- Gas supply and operational resilience – A large-scale transition to argon would introduce uncertainties around availability, pricing and logistics at sector scale.
- Welfare and meat quality considerations – Possible effects on blood spotting, PSE and other meat-quality parameters may have commercial consequences through trimming and downgrades. There are also conflicting views on the welfare impacts of different systems, which this report does not conclude on.
“Taken together, the evidence indicates that, within the ranges tested, all currently available alternatives to high-concentration CO₂ are expected to increase plant-level costs materially for a representative UK facility, with significant upside risk from transition logistics, site-specific constraints and other unquantified elements,” the report concludes.
The report stressed that the findings underline the importance of further commercial-scale validation, supply-chain assessment and coordinated transition planning before any large-scale shift away from CO2 could be considered.
Carefully managed
AHDB pork sector director Mark Haighton said a consistent theme emerged throughout the report.
“Any transition away from CO₂ would need to be carefully managed to avoid unintended consequences for both animal welfare and staff safety,” he said.
“Taken together, the sector’s view is not that change should be resisted, but that any future transition must be evidence-led, properly resourced and delivered over a realistic timeframe to ensure it results in genuine welfare gains rather than unintended setbacks.
“In practice, this would require fully-funded, UK-based trials at commercial scale, alongside sufficient lead-in time for evaluation, workforce preparation, and safe implementation across the processing base.”
Industry reaction
In the foreword to the report, Pig Health and Welfare Council (PHWC) chairman Duncan Berkshire said the report’s findings present a nuanced picture.
“While alternative systems may hold welfare potential, all options currently come with substantial financial, logistical and operational challenges.
He stressed that any transition away from CO₂ ‘will demand careful planning, cross-sector coordination and a clear understanding of the welfare, commercial and logistical implications’.
“Furthermore, it is important to recognise that any such transition will also need to be based upon further practical research, given the limited global availability of commercial scale experience with some of the potential alternatives,” he said.
He stressed that PHWC recognises the growing body of evidence highlighting significant welfare concerns associated with CO₂ exposure.
But he added: “To ensure this shift delivers genuine welfare, operational and economic benefits, it is essential that it is guided by robust science, proven commercial viability and clear regulatory frameworks.”
NPA chief policy adviser Katie Jarvis welcomed the ‘detailed and pragmatic’ report’s findings. “We absolutely understand and acknowledge the concerns and issues regarding CO2, and we are very much part of the conversation about developing viable alternatives,” she said.
“However, this report highlights that, currently, there is no feasible alternative – both argon and electrical stunning have their own challenges in terms of animal welfare implications and commercial application.
“We must avoid forcing change domestically, whilst our global competitors continue to use existing stunning and slaughter methods. This industry knows all-too well that pushing domestic animal welfare standards and costs higher whilst importing product produced to lower standards can have a disastrous impact, while doing nothing to improve welfare.
“We agree that any new policy must be evidence based and co-designed with industry to ensure objectives are actually achievable, with sensible transition periods – fully support calls for a largescale trial to help deliver the evidence we need.”
Charles Milne, spokesman for the Association of Independent Meat Suppliers (AIMS) and former Scotland chief veterinary officer, Scotland, welcomed the ‘high quality and useful’ report.
“The lack of existing commercial examples of running these systems supports the suggestion that a large-scale commercial trial is required to inform both government and industry of the practicalities of such an approach,” he said.
You can view the report HERE