In EU pig slaughterhouse two stunning methods are commonly applied: electrical stunning and carbon dioxide stunning at high concentrations. In 2004 and 2020, the European Food Safety Authority (EFSA) concluded for the gas stunning of pigs that at concentrations above 30% CO2, the gas is aversive and causes hyperventilation and irritation of the mucous membranes. This is likely to be painful, and elicits hyperventilation and gasping before loss of consciousness. For this reason, high concentration CO2 stunning has been criticized.

The general objective of this project is to encourage EU pig slaughterhouses using high carbon dioxide concentration for stunning pigs to convert to more animal welfare friendly systems, by developing technical specifications for four promising alternatives. Three of these alternatives involve gas stunning, one of them aims at improving electrical stunning process. They are:

1. Multi-phase Box System: a system that facilitates pre-grouped animals in small groups to be transported into a multi-phase-stunning system. As a starting point this system uses CO2, but the unit can be equipped to facilitated other gas mixtures.
2. Helium: an alternative stunning system that uses helium in one or two-phases, in combination with nitrogen.
3. Inert Gas Retrofit System: an alternative that can be retrofit to existing Dip-Lift and paternoster stunning devices to allow for stable gas mixtures of alternative gases at very low oxygen levels.
4. Improved Electrical Stunning: this alternative will look at ways to improve the process of electrical stunning with special emphasis to pre-stunning handling, design of raceways and entrance of pigs into the stunner.