THE DESIGN OF PIG STUNNING TONG ELECTRODES - A REVIEW

The effectiveness of current electrical stunning systems for pigs is d iscussed and the need for improvements in the design and construction of stunning tongs and electrodes are explored A review of existing stu nning tong electrodes for use with free standing or restrained pig is discussed. The potential problems with existing systems are highlighte d as: (1) the profile of the pigs head precludes the application of ex isting electrodes in the correct position; (2) the small area of conta ct enhances carbon build-up which increases electrical impedance; (3) the electrodes ape easily tarnished with few cleaning tools provided. Good tong positions that span the brain are described as between the e ye and ear on each side of the head, below the ear an each sine of the head or, diagonal application between the top and bottom of the head. The notional contact impedance is the major component of resistance t o current flow within the stunning system. The proposed use of differe nt electrode designs and constructional material is investigated. The effect of the introduction of the fail-safe device would be to heighte n the interest in contact impedance within the plant and that could en sure that the investigation of different electrodes is explored at lea st at plant level. (C) 1997 Elsevier Science Ltd.