A note of caution

Different slaughter methods may have different advantages and disadvantages for animal welfare and meat quality. The conventional electrical waterbath is not a preferred stunning method for poultry welfare because:

• there are inherent risks to animal welfare associated with inversion and shackling of conscious birds;
• it is difficult to control the effectiveness of the stun for every individual bird processed, eg to prevent pre-stun shocks, to ensure immediate immersion of the head in the electrified water and to prevent individual birds entirely avoiding the electrified water;
• commercial waterbath systems generally accommodate a number of birds simultaneously and are operated at a constant voltage, which makes it difficult to deliver the correct current amplitude to each bird;
• scientific research has reported that “...effective stunning [parameters] using the conventional waterbath almost exclusively produces blood splashing [in the meat]...” (Hindle et al, 2010). This may partly be due to the estimate that “only a small proportion of current applied in a water bath may flow through the brain and the majority may flow through the carcass”, which is likely to pose problems for welfare and meat quality (European Food Safety Authority, 2004).

The 2012 EFSA scientific opinion on electrical requirements for waterbath stunning recommended that “unless the problems...for all existing waterbath stunning methods can be resolved, other stunning methods should be used”. Therefore the world requires improved methods of stunning (electrical or otherwise), to guarantee better parameters for animal welfare and a higher quality carcass.

In the meantime, operating conventional electrical waterbath stunners to a high standard is critical for poultry welfare. In line with the HSA aim to provide information on good operational practices, which may reduce the risk of potential animal welfare problems, this online guide includes advice that prioritises animal welfare, based as much as possible on scientific evidence.

[At the time of publication of this document, the alternative large-scale slaughter methods for poultry were controlled atmosphere systems (CAS).  CAS may not be perfect for animal welfare but does offer significant advantages for poultry welfare (and staff health and safety) compared to electrical waterbaths, by avoiding the need for abattoir staff to directly handle, invert and shackle conscious birds and every bird is stunned by a well-run CAS system.  To read more about CAS systems, please view HSA publications at www.hsa.org.uk]

References: 

EFSA 2004 Scientific Opinion on the welfare aspects of stunning and killing methods. www.efsa.europa.eu/en/topics/topic/animalwelfare

EFSA 2012 Scientific Opinion on the electrical requirements for waterbath stunning equipment applicable for poultry. DOI: 10.2903/j.efsa.2012.2757

Hindle et al 2010 Poultry Science 89: 401–412

Next: Pre-slaughter handling & restraint