Turkeys raised for meat production (e.g. whole turkey or drumsticks) are bred to grow and gain weight very rapidly, with birds ready for processing at around 10 weeks old. Once they arrive at the abattoir, turkeys are removed from their transport crates and shackled by their legs in preparation for stunning. In Australia, stunning occurs by passing the bird’s head through an electrical waterbath which aims to ensure that the bird is unconscious prior to slaughter. Immediately after stunning, birds are bled out so that they are dead before further processing occurs.
Electrical waterbath stunning systems
Electrical waterbath stunning is the most common stunning method used for turkeys. It involves conscious birds being shackled upside down by their legs on a moving shackle line. The birds are stunned by passing their heads through an electrified waterbath, i.e. an electric current passes from the water through the head, body and legs and to the metal shackle.
The correct voltage, current, current type, frequency, and application time are critical to ensuring that birds are effectively stunned. Where appropriate electrical parameters are used, birds immediately lose consciousness and will remain unconscious until death from bleeding out occurs.
What are the animal welfare issues with electrical waterbath stunning systems?
There are significant welfare concerns with electrical waterbath stunning. Where inappropriate electrical parameters are used, birds may not be stunned effectively or even electro-immobilised meaning they are conscious during bleed out.
Shackling of live birds requires handling and inversion. Hanging upside down is a physiologically abnormal posture for poultry which causes fear and stress and the compression of the legs by shackles is painful. The experience of pain and stress during shackling is particularly an issue for turkeys due to their heavy body weight and large size.
Severe wing flapping can also occur during shackling which increases the risk of injuries to the wings, as well as the risk of pre-stun electric shocks. Painful pre-stun shocks can occur when birds flap their wings and make contact with the electrified waterbath before their heads are immersed, or when a bird’s head misses the electrified waterbath completely or partially, leading to birds being ineffectively stunned. Turkeys are particularly prone to pre-stun shocks because their wings hang lower than their heads when shackled upside down [1].
If birds are not stunned effectively, they may be fully conscious at bleed out, when the major blood vessels in the throat are cut resulting in death through blood loss before further processing occurs.
What are the alternatives?
Due to the inherent welfare issues associated with electrical waterbath stunning systems, RSPCA Australia strongly encourages they be phased out and replaced with alternative stunning systems where birds are rendered unconscious prior to being shackled.
Controlled atmosphere stunning (CAS) systems using carbon dioxide, are commonly used to stun meat chickens in Australia but unfortunately are not yet used for turkeys. In CAS systems, birds are either moved into the stunning module in their transport crates or tipped out and transferred onto a conveyer belt which then moves the birds into the stunner. Birds gradually lose consciousness as a result of exposure to increasing concentrations of carbon dioxide. However, carbon dioxide gas at high concentrations is aversive to poultry and can lead to hyperventilation, breathlessness, and suffocation. Therefore, where CAS systems are used, it is critical that birds are first exposed to low concentrations and only exposed to higher concentrations (≥40%) once they have lost consciousness.
An alternative to carbon dioxide CAS systems and a more humane option, is controlled atmosphere stunning using inert gases. Inert gas mixtures appear to be less aversive, with studies indicating stunning with mixtures of argon or nitrogen gas may be best for poultry [2].
Low Atmospheric Pressure Stunning (LAPS) is a newer method of stunning where birds are placed in a chamber and the atmospheric pressure is gradually reduced, causing birds to lose consciousness gradually due to hypoxia (lack of oxygen). Research suggests that, during LAPS, birds display similar behaviours to that observed during gas stunning, including non-aversive gas methods such as inert gas mixtures.
Both CAS and LAPS have the benefit of not needing to handle and shackle live birds, reduced stress, and greater uniformity of the stun between birds. However, currently, inert gas CAS systems and LAPS systems are not yet available in Australia for the commercial slaughter of poultry.
What is the RSPCA’s view?
Due to the inherent welfare issues associated with electrical waterbath stunning, RSPCA Australia strongly encourages they be phased out and replaced with alternative stunning systems where birds are humanely and effectively rendered unconscious prior to being shackled.
References
[1] Shields SJ, Raj ABM (2010) A critical review of electrical water-bath stun systems for poultry slaughter and recent developments in alternative technologies. Journal of Applied Animal Welfare Science 13(4):281-299.
[2] Berg C, Raj M (2015) A review of different stunning methods for poultry: animal welfare aspects (stunning methods for poultry). Animals 5:1207-1219.
