Dielectric Induction of Temporary Insensibility in cattle - animal trials

Summary

Background
Religious communities (Jewish and Muslim) require that animals processed for human consumption are healthy, uninjured and normal at the moment of carrying out the exsanguination cut.  As a result, many methods of stunning used on modern commercial slaughter are not acceptable.  Head-only electrical stunning is used in sheep, but is not suitable for use in cattle because of concerns over the duration of insensibility being insufficient to allow death through exsanguination to occur prior to recovery from the stun, and also because of problems with ecchymoses (blood splash) in the meat.  It has been proposed that microwave energy technology may be suitable for application to induce recoverable insensibility in animals. If successful, this could result in an effective reversible stunning method that is suitable for religious slaughter.
Research
This project is part of a longer-term strategy to develop microwave stunning technology to a point at which it could be made commercially available to processors.  This will involve work with sedated/anaesthetised animals in order to understand the application parameters and limits required to ensure a consistent delivery of insensibility, and lead on to future work with conscious animals in order to develop animal welfare performance indicators, guidelines for assessing stun effectiveness and guidelines for use in a commercial situation.
Microwave energy is focused into the animal's brain to produce a rapid rise in temperature. This effect can be thought of as analogous to the induction of unconsciousness during a high fever. It is expected that controlling the brain temperature will result in insensibility, and allow the animal to regain consciousness without any adverse effects when the temperature of the brain has returned to normal.  This will give a recoverable insensibility that should be acceptable for religious slaughter.
In recent years, microwave technology has developed to the point that high power equipment is available that can focus the energy into the animal's brain to produce a rapid rise in temperature. It is expected that controlling the brain temperature will result in insensibility, and allow the animal to regain consciousness without any adverse effects when the temperature of the brain has returned to normal. This will give a recoverable insensibility that should be acceptable for religious slaughter.
In recent projects, carried out by CSIRO Food and Nutritional Sciences (formerly Food Science Australia), a suitable delivery apparatus was designed and built for sheep, and four anaesthetised sheep were subjected to microwave energy application. The trials on anaesthetised sheep were highly successful.  Higher power would be recommended for commercial use to allow the required temperature rise to be effected in less than one second. However, the applicator used in this previous project would not be suitable for higher power application, due to excessive surface heating and arcing. For commercial use, an applicator designed to minimise surface heating and arcing will need to be developed.
Further work was needed to fully understand the underlying neurophysiology and set critical limits for energy application. Furthermore, to allow this technology to be used in a commercial situation, guidelines for assessing efficacy and animal welfare status needed to be developed, as it would appear from the anaesthetised animal trials that rhythmic breathing remains present throughout. Further work was also required to calibrate and refine of a commercial prototype, to increase efficiency of energy transfer and reduce surface heating. Furthermore there was still a need to demonstrate that application of microwave energy at the power levels calculated does indeed render an animal insensible.
These projects aimed to demonstrate that microwave energy can indeed be used to raise the temperature of a bovine brain to a level at which insensibility would be expected to occur.  The projects generated raw data suitable to support an application to allow further development of the technology, including commercial trials.
Work was conducted to design a suitable restraint, microwave guiding system and applicator for the delivery of microwaves to cattle. The system was applied to heads of various sizes and shapes removed from cattle during conventional operations in an abattoir and the ability of the system to deliver the required rate of temperature increase was confirmed .The data generated in all of these trials provided the researchers with sufficient confidence to prepare an application to an animal ethics committee to allow the stunning technique to be trialled on anesthetized cattle immediately prior to slaughter.
Facilitated adoption and commercialisation
The technology is protected under patent in 14 countries, with costs being shared between MLA and the research provider under project P.PIP.0364.