Aversion of the domestic fowl to concurrent stressors Methodology

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Associations between behaviour and health outcomes in conventional and slow-growing breeds of broiler chicken

Broiler chickens are prone to a range of complex health and welfare issues. To support informed selection of welfare traits whilst minimising impact on production efficiency and to address a major gap in understanding, we systematically explored associations between health and behavioural indicators of broiler welfare. One conventional (CNV, n = 350) and two slow-growing broiler breeds (SGH and SGN, respectively n = 400) were reared from hatch in pens of 50 birds. Birds were assessed for health (gait, plumage cover and dirtiness, pododermatitis, hockburn, and leg deviations) at 2.2 kg liveweight according to the Royal Society for the Prevention of Cruelty to Animals Broiler Breed Welfare Assessment Protocol. Behaviour and resource-use of 10% of birds per pen, on days 29 (all breeds) and 43 (SGH and SGN), was (i) scan sampled every 60 min between three to six and between twelve to fifteen hours after photoperiod onset; and (ii) continuously sampled sequentially from focal birds for 3 min each in a random order, during 15 min observation periods at three and twelve hours after photoperiod onset. Binary logistic generalized linear models were used, to assess respective associations between pen prevalence of each health outcome and (i) pen mean percentage scans of behaviour, and (ii) pen mean frequency and duration per 3 min focal observation of behaviour. Better growth rate and feed conversion but poorer health outcomes (mortality, gait, pododermatitis, feather cover) were more prevalent in CNV. Strong associations between behaviour and several heath indicators revealed, (i) increases in side-lying inactive, sitting inactive, and use of the litter relative to other resources, as primary and general indicators of poorer health, and (ii) increases in standing inactive, perch use, walking, Comfort, High Energy and Exploratory behaviour as primary and general indicators of better health. Of these, changes in side-lying, standing inactive, walking, Comfort and High Energy behaviour were particularly sensitive to small differences in health outcomes important for breed acceptance in high-welfare schemes. Crucially these behavioural measures additionally represent motivational and affective aspects of welfare not captured by health measures and allow opportunity for earlier intervention. Thus, to provide a comprehensive assessment of broiler experience, behaviour should be incorporated into broiler welfare assessments

Controlled atmosphere stunning of broiler chickens. II. Effects on behaviour, physiology and meat quality in a commercial processing plant

International audienceABSTRACT 1. The effects of controlled atmosphere stunning on behavioural and physiological responses, and carcass and meat quality of broiler chickens were studied experimentally in a full scale processing plant. 2. The gas mixtures tested were a single phase hypercapnic anoxic mixture of 60% Ar and 30% CO2 in air with <2% O2, and a biphasic hypercapnic hyperoxygenation mixture, comprising an anaesthetic phase, 40% CO2, 30% O2, 30% N2, followed by an euthanasia phase: 80% CO2, 5% O2, 15% N2. 3. Birds stunned with Ar+CO2 were more often observed to flap their wings earlier, jump, paddle their legs, twitch, and lie dorsally (rather than ventrally) than those stunned with CO2+O2. These behaviours indicate a more agitated response with more severe convulsions during hypercapnic anoxia, thereby introducing greater potential for injury. 4. Heart rate during the first 100 s of gas stunning was similar for both gases, after which it remained constant at ≈ 230 beats min-1 for CO2+O2 birds whereas it declined gently for Ar+CO2 birds. 5. In terms of carcass and meat quality there appeared to be clear advantages to the processor in using CO2+O2 rather than Ar+CO2 to stun broiler chickens, e.g. a much smaller number of fractured wings (1.6 vs. 6.8 %) with fewer haemorrhages of the fillet. Meat quality was similar in both gas mixtures. 6. This study supports the conclusions of both laboratory and pilot scale experiments that controlled atmosphere stunning of broiler chickens based upon a biphasic hypercapnic hyperoxygenation approach has advantages in terms of welfare and carcass quality over a single phase hypercapnic anoxic approach employing 60% Ar and 30% CO2 in air with <2% O2