Could low atmospheric pressure stunning (LAPS) be suitable for pig slaughter? A review of available information

Low atmospheric pressure stunning (LAPS) is a slaughter technique which may be less stressful for pigs (Sus scrofa domestica) than current commercial stunning and slaughter methods. The main methods used currently for slaughtering pigs are electric and carbon dioxide stunning, both of which are widely recognised as stressful for pigs. There is currently no published research on the use of LAPS for stunning adult pigs, however there is a significant body of relevant experience from investigations into the effects of low pressure and hypoxia on humans, hypoxia for killing pigs and the use of LAPS for killing poultry, rats and piglets. In this paper, the basic physics and biology of LAPS is briefly reviewed and relevant experience from research with humans, poultry, rats and piglets is presented. On the basis of this information, some initial parameters for LAPS trials with pigs are proposed, potential welfare issues identified and an approach to achieving LAPS at a commercially viable speed is outlined. While the effects of LAPS on pigs is, at present, uncertain, the evidence from research with humans and other animals suggests that healthy, fasted pigs undergoing LAPS are unlikely to suffer from air hunger or from pain. Any pigs suffering from upper respiratory tract disease, tooth decay or excess gas in the alimentary canal may, however, experience pain. A total killing cycle is likely to require 9 to 14 min. To implement LAPS in a commercial, high throughput processing plant will require the use of multiple decompression cylinders. The evidence available suggests that LAPS could be commercially viable for pig slaughter and that for most pigs it will be less stressful than current commercial slaughter methods.

Humane harvesting and slaughter of farmed fish

The overwhelming majority of farmed fish produced throughout the world are killed with little or no consideration for their welfare. Fasting periods can be excessive, transport stressful and killing inhumane. At the time of writing, the salmon industry is the only sector in which consideration of the welfare of the fish at slaughter has resulted in significant improvements throughout most of the industry. There are signs of interest in the use of more humane slaughter methods for some other fish species. This is mostly initiated by the demand for higher standards from European fish retailers. For most species, the humane killing options are limited to percussive stunning and electrical stunning. However, even these methods can have a poor welfare outcome if insufficient consideration is given to the needs of the fish or if the equipment has not been properly designed. The use of food-grade anaesthetics to assist with the harvest has significant potential for improving welfare and their wider use should be investigated further.

Characteristics of electronic training collars for dogs

A wide range of electronic dog training collars (e-collars) is available in the UK, but information enabling purchasers to compare the important characteristics of these collars is not available. In this research, the electrical characteristics of 13 e-collar models were examined, and an approach to ranking the strength of the electrical stimuli was developed. To achieve this, the electrical impedance of dogs' necks were measured so that e-collars could be tested under realistic conditions. This impedance was found to be about 10 kΩ for wet dogs and 640 kΩ for dry dogs. Two replicates of eight e-collar models and single copies of a further five models were then examined. The stimuli generated by these collars comprised sequences of short high-voltage pulses. There were large differences between e-collar models in the energy, peak voltage, number of pulses and duration of the pulses, but little variation between the replicates. The peak voltage varied with the impedance, from 6000V at an impedance of 500 kΩ to 100V at 5 kΩ. The highest voltages were generated for a few millionths of a second. Stimulus energy levels at the maximum strength setting with a 50 kΩ load ranged from 3.3 mJ to 287 mJ. A stimulus strength ranking indicator was then developed to enable the strengths of e-collars with diverse electrical characteristics to be ranked. This ranking shows a wide range in the stimulus strengths of collars, and that the relationships between 'momentary' and 'continuous' stimuli for various models differ significantly.

Safeguarding the welfare of farmed fish at harvest

Fish welfare at harvest is easily compromised by poor choice of handling and slaughter methods, lack of attention to detail and by unnecessary adherence to fish farming traditions. The harvest process comprises fasting the fish to empty the gut, crowding the fish, gathering and moving the fish using brails, fish pumps, and sometimes also road or boat transport and finally stunning and killing the fish. The harvesting processes commonly used for bass, bream, carp, catfish, cod, eel, halibut, pangasius, salmon, tilapia, trout, tuna and turbot are outlined. These harvesting processes are discussed; the consequences for fish welfare identified and practical tests which can be made at the harvest site highlighted. Welfare at harvest for the majority of farmed fish species can be improved by adopting and adapting existing procedures already known to be beneficial for fish welfare through their use in other fish farming systems or with other species. It is seldom necessary to develop completely new concepts or methods.

Head-only electrical stunning of poultry using a waterbath: a feasibility study

1. The objective of this work was to investigate the feasibility of head only waterbath stunning as a means of generating immediate and long lasting unconsciousness while preventing wing flapping and avoiding carcass damage. 2. EEG measurements showed that immersion of the heads of the broilers for one second in a waterbath containing water of conductivity 2 x 5 mS/cm and a 50 Hz electric field of 10 V/cm resulted in immediate unconsciousness, and that increasing the electric field strength extended the duration of unconsciousness. 3. The passage of a 25-30 mA alternating current of frequency 2000 Hz through the broilers' bodies suppressed the wing flapping that followed a stun. 4. When the body current and electric field were applied simultaneously, wing flapping was prevented and EEG signals were suppressed for over 30 seconds indicating that the immediate unconsciousness lasted long enough to facilitate humane slaughter.

Active Suspension Control for an Off-Road Vehicle

After a review of recent developments in active suspension systems, a semi-active system fitted to an off-road vehicle is described. Theoretically predicted results are presented alongside data measured on the actual vehicle. The benefits of the semi-active system over a passive suspension are improved ride comfort and improved body attitude control.

Behaviour of domestic ducks exposed to mobile predator stimuli. 1. Flock responses

1. Small flocks of ducks (Anasplatyrhynchos domesticus) were exposed to two stimuli, a small mobile vehicle and a walking human, to investigate their flight responses. 2. Experiment 1. Flocks were herded around an annular arena by each stimulus at 0.5 ms(-1) and the flight distance between the stimulus and the centre of the flock, and individual positions within the flock were recorded every 10 s. Flocks maintained a significantly longer distance from the human (6.0 m) than the vehicle (5.1 m) and usually did not maintain visual contact with either stimulus. Significant consistency in individual positions within the flock was found within and between trials. 3. Experiment 2. Flocks were exposed to each stimulus which approached them as they were feeding in a circular arena. The latencies for cessation and resumption of feeding were recorded and the paths followed by the flocks described. Ducks showed a significantly shorter latency to cease feeding in response to the human (4.9 s) compared with the vehicle (6.9 s). 4. Domestic ducks apparently perceive an approaching human as a greater threat than a small vehicle. The findings are discussed in relation to the development of herding robots.

Behaviour of domestic ducks exposed to mobile predator stimuli. 2. The association of individual duckling attributes with relative position in a flock

1. We investigated whether an individual duckling's (Anas platyrhynchos domesticus) attributes were associated with its response to an approaching human when it was a member of one of three flocks of 12. 2. Each individual was scored according to its response to (i) an approaching human when alone and feeding, (ii) a taxidermist's model fox when alone and feeding, and (iii) an approaching human when alone in a 9 m annulus, and its nearest neighbour distance in the home pen, competitiveness for food in a series of paired encounters, running ability and physical characteristics. 3. Each flock was herded around a 7 m diameter annulus in separate trials by a human walking at 0.5ms(-1). The distance maintained by each duckling from the human, and hence its relative flock position, was calculated. 4. Individual flight distance maintained from an approaching human when alone in an annulus was the attribute that predicted distance maintained from an approaching human when part of a flock. 5. Some ducklings had reduced average distances from an approaching human when they were in a flock compared to when they were tested alone, and inter-individual variation in distance from the human was greatly reduced when birds were part of a flock.