Research undertaken by the University of Bristol studied the incidence and effect of pre-stun shocks in a commercial broiler processing plant using an electrical waterbath stunning system, the most commonly used system in the UK.
The study identified a significant level of pre-stun shocks, particularly in lighter, more active birds, correlated with a significant level of adverse effect on carcase and meat quality. Pre-stun shocks were also seen to be a contributor to the incidence of mis-stuns (by causing birds to ‘fly’ the waterbath).
The results of the study indicate not only a serious welfare problem but also a significant financial burden for producers of broiler chickens stunned using the electrical waterbath.
A report, published in Animal Welfare, the journal of the Universities Federation for Animal Welfare (UFAW), states “EC Regulation (1099/2009) stipulates…that for electrical waterbath stunning a key consideration is the prevention of electrical shocks before stunning. The results reported here add very strong commercial and economic arguments to this legislative welfare requirement, entirely justifying any financial output that would be required to improve controlled entry of birds into a waterbath stunner…(pre-stun shocks) can be prevented by careful waterbath entry design and modification. It should be entirely possible to avoid (pre-stun shocks) in commercial processing plants and there is a strong economic reason to do so.”