Measures of insensibility used to determine effective stunning and killing of poultry

Abstract

Primary Audience: Producers, Researchers SUMMARYThe ability to assess the level of unconsciousness (insensibility) in poultry is important on farms and in abattoirs, where the effectiveness of stunning and slaughter needs to be ascertained. Moreover, knowledge of the most reliable indicators of insensibility is essential to producers and researchers responsible for maintaining acceptable levels of poultry welfare. A problem with assessing insensibility in poultry is that no single method is appropriate under all circumstances, and some methods are not practical in field situations. Several measures have been recommended and used to evaluate insensibility in poultry, including brain stem reflexes, such as the corneal reflex, and spinal reflexes, such as the pain withdrawal reflex. This review examines specific advantages and disadvantages of measures that have been used to assess insensibility in studies of killing methods, and provides an overview of recommended signs of effective stunning and slaughter. The measures that are used to monitor the state of insensibility in birds during anesthesia are also examined to provide additional practical means for assessing loss of consciousness in the field. In general, the absence of brain stem and spinal reflexes provides reliable evidence of insensibility after stunning and euthanasia procedures. Although the onset of neuromuscular spasms (convulsions) does not necessarily indicate insensibility, the complete cessation of neuromuscular spasms appears to be associated with brain death. Further research is necessary to validate these measures and other indicators, such as the absence of neck muscle tension and jaw tone, as reliable indicators of complete insensibility.

Current and novel methods for killing poultry individually on-farm

“…cessation of cardiac, respiratory, and brain function), and even where loss of consciousness is reversible, we cannot 'ask' animals about their experiences, thus it is not possible to accurately define the state of consciousness or sensibility of any living animal (Raj et al, 2006, Erasmus et al, 2010c. Many authors try to define the welfare costs or benefits of killing techniques based on how quickly animals lose consciousness (i.e.…”

“…The bird should be held inverted by the legs with the head and neck resting on the ground. As with manual cervical dislocation, there should be a gap in the vertebrae of the neck, the bird should not be breathing, and there should be no blinking or nictitating membrane response when the surface of the eye is touched, as indicators of death (Erasmus et al, 2010c). The bird's body is pulled upwards with a rapid movement at the same time as applying firm pressure to the stick, thereby dislocating the neck.…”

A review of bird welfare during controlled atmosphere and electrical water-bath stunning

“…2,28 Head-shaking has also been observed in birds stunned with hypercapnic hyperoxygenation systems, 1 and 1 study 11 found it occurred to a greater degree than with anoxic, hypercapnic anoxic, and hypercapnic hypoxic systems. [1][2][3]5,11 Studies have also found that the total amount of time that wing flapping occurred was less when birds were stunned with hypercapnic hyperoxygenation systems, compared with total time when birds were stunned with anoxic, 2,3,11 hypercapnic anoxic, 2,3,5,11,28 or hypercapnic hypoxic 11 systems. Respiratory disruption was greater in birds stunned with hypercapnic hyperoxygenation systems, compared with frequency in birds stunned with hypercapnic anoxic or anoxic systems.…”

“…1 The present review covers behavioral and physiologic reactions to poultry stunning methods and highlights areas in need of further research. Each method causes a variety of behavioral and physiologic reactions that must be carefully considered when assessing the humaneness of the method because there is no single reaction that can be used to accurately assess consciousness in poultry.…”

Validation of indicators used to assess unconsciousness in veal calves at slaughter

“…There is substantial debate about which indicators most adequately assess unconsciousness at slaughter and which merit further investigation (European Food and Safety Authority (EFSA), 2013). The use of recorded brain activity (as presented in an electroencephalogram (EEG)) is considered to be the most objective method available for assessing unconsciousness and is generally accepted as the current 'gold standard' (Erasmus et al, 2010;EFSA, 2013;Verhoeven et al, 2015a). Due to the complexity of collecting EEG data at slaughter, absence of behavioural indicators (i.e.…”