Endogenous analgesia in the chicken

Endogenous analgesia has been identified in mammals, but little is known about suppression of tonic pain following trauma or disease. Birds suffer from gouty arthritis which can be induced experimentally by intra-articular injection of sodium urate (SU) crystals. SU injection into the ankle joint of the chicken tested in cages resulted in pain-coping behaviour (one-legged standing, sitting) together with severe lameness. Birds kept and tested in large pens showed significantly less pain-coping behaviour, while birds tested in novel pens showed either complete analgesia or marked hypoalgesia, together with a significant reduction in lameness. Complete analgesia was observed during pre-laying behaviour. These results demonstrate a remarkable ability of birds to suppress such severe tonic pain as SU arthritis

Gait analysis of poultry

Lameness is a major problem in the UK poultry industry, however, relatively few objective studies have been undertaken into the biomechanics of normal walking in these birds. In this study, the use of a pedobarograph as a novel method of gait analysis in poultry was investigated. Unlike most systems, the pedobarograph has a recording surface with a high degree of spatial resolution, allowing pressure patterns to be established for various regions of the foot. The highest pressures were found to act on the medial toe (149·4–218 kN m−2) and back toe (146·1–195-· kN m−2). The metatarsal pad, a region often associated with lesions, was subject to lower pressures (16·3–131·2 kN m−2). Maximum net forces of 116–145 per cent of bodyweight were found during normal walking, an order of the same magnitude as human bipeds. Routine spatial parameters were also measured, allowing further characterisation of the gait patterns

Effects of light on responses to Low Atmospheric Pressure Stunning in Broilers

1. Low atmospheric pressure stunning (LAPS) is a novel approach to poultry stunning invol-ving the application of gradual decompression lasting 280 s according to a prescribed pressure curve.2. The aim of this study was to determine how behavioural, electroencephalogram (EEG) and electro-cardiogram (ECG) responses to LAPS are influenced by illumination of the decompression chamber. Asecondary aim was to examine responses to the decompression chamber without LAPS being applied, assuch a“sham”control has been absent in previous studies.3. A two by two factorial design was employed, with LAPS/light, LAPS/dark, sham/light and sham/darktreatments (N= 20 per treatment). Broilers were exposed to each treatment in pairs, in each of which onebird was instrumented for recording EEG and ECG. Illumination was applied at 500 lx, and in shamtreatments, birds were identically handled but remained undisturbed in the LAPS chamber withoutdecompression for 280 s.4. Birds which underwent the sham treatment exhibited behaviours which were also observed in LAPS(e.g. sitting) while those exposed to LAPS exhibited hypoxia-related behaviours (e.g. ataxia, loss ofposture). Behavioural latencies and durations were increased in the sham treatments, since the wholecycle time was available (in LAPS; birds were motionless by 186 s).5. Within the sham treatments, illumination increased active behaviour and darkness induced sleep, butslow-wave EEG was seen in both. The pattern of EEG response to LAPS (steep reduction in medianfrequency in thefirst 60 s and increased total power) was similar, irrespective of illumination, thoughbirds in darkness had shorter latencies to loss of consciousness and isoelectric EEG. Cardiac responses toLAPS (pronounced bradycardia) closely matched those reported previously and were not affected byillumination.6. The effects of LAPS/sham treatment primarily reflected the presence/absence of hypoxia, whileillumination affected activity/sleep levels in sham-treated birds and slowed time to unconsciousness inbirds undergoing LAPS. Therefore, it is recommended that LAPS be conducted in darkness for poultry