Poultry have four types of cone in the retina of the eye, and this means that they probably see colour differently from trichromatic humans. Notwith- standing the fact that humans and birds have maximum sensitivity in a similar part of the spectrum (545–575nm), poultry are likely to perceive light from various types of lamp at a different intensity from humans because they are more sensitive to the blue and red parts of the spectrum. Although colour has been confounded with illuminance in many trials, wavelength has an unquestionable effect on poultry production and behaviour. Growth and behaviour responses depend principally on retinal photoreception, whereas photosexual responses are mainly influenced by hypothalamic light reception. In turkeys and chickens growth under red illumination is inferior to that under blue or green light, and this may be a result of birds exposed to red light being more active and showing more aggression than birds exposed to shorter wavelength radiation. In contrast, the easier penetration of longer wavelength radiation to the hypothalamus makes red light more sexually stimulatory than blue or green, although the hypothalamic photo- receptors are more sensitive to blue/green light when illuminated directly. Egg production traits, however, appear to be minimally affected by wavelength.

As a consequence of selection and improvement in rearing and nutrition management, the characteristics of poultry production have changed dramatically over the last decades. Decreasing the age of birds at slaughter has altered the intrinsic sensory attributes of meat. Selection has also provided birds with increased muscle yield, altered muscle structure and metabolism. In broilers there are examples to suggest that such selection has had no detrimental effect per se on meat quality. Results in turkeys are more equivocal and suggest that increased performance may alter meat quality. Pre- and post-slaughter processes affect the ante-mortem physiology of the birds and the post-mortem metabolism of muscle, and can cause irreversible defects in subsequent meat quality. Production of optimal quality poultry meat depends on controlling both farming and slaughter-related parameters and understanding the complex interactions between them.

The aim of this experiment was to develop an alternative, acceptable and humane method for killing broiler chickens. Our main premise was that euthanasia should preferably take place in two steps. Firstly, the bird should be anaesthetised quickly and completely using appropriate procedures and, secondly, the anaesthetised bird should be killed as quickly as possible. Two gas mixtures were considered for anaesthesia: 40% carbon dioxide with 30% oxygen and 30% nitrogen or 40% carbon dioxide with 15% oxygen and 45% nitrogen. It was found that the birds' behaviour in the high oxygen environment was less disturbed, with less agitation and distress being demonstrated. For this reason, the high oxygen condition is to be preferred and this anaesthetic was used in the second part of the experiment. The bird was exposed for one minute to 40% carbon dioxide, 30% oxygen and 30% nitrogen (anaesthesia) and then to 80% carbon dioxide, 5% oxygen and 15% nitrogen (euthanasia). This condition was compared with the frequently used eutha- nasia condition involving argon. The use of argon is based on the idea that it produces fast suffocation of the birds. The argon condition consisted of 30% carbon dioxide and 60% argon in air with less than 2% oxygen and 8% nitrogen. The chickens died significantly later in the oxygen/carbon dioxide condition than in the argon condition. Judgements of death were based on both the pattern of electrical brain activity and on heart rate. The time taken for the chickens to become unconscious, as judged from the isolectric electroencepha- logram, was also significantly longer in the oxygen/carbon dioxide condition than in the argon condition. However, in the argon condition the birds immediately showed strong signs of agitation and distress, particularly intense and heavy muscle contractions, whereas these signs were less pronounced in the oxygen/carbon dioxide condition. It is concluded that, although the chickens lost consciousness sooner and also died sooner in the argon condition, there are good reasons to prefer the oxygedcarbon dioxide condition because it results in less disturbed behaviour and the birds exhibited milder signs of distress during the period when consciousness cannot be fully excluded. Hence, a milder death, taking somewhat longer, is preferred to a quicker but more distressing death. Finally, the oxygen/carbon dioxide condition was repeated with turkeys when, in general, the results were the same.

Atmospheric ammonia is a major aerial pollutant of poultry buildings. The current exposure limits for ammonia of 25ppm are set on the basis of human safety rather than animal welfare. This paper reviews the evidence for ammonia exposure affecting various aspects of poultry welfare. The reviewed evidence suggests that ammonia exposure (1) causes irritation to the mucous membranes in the eyes and the respiratory system; (2) can increase the susceptibility to respiratory diseases; and (3) may affect food intake, food conversion efficiency and growth rate. The behavioural effects of ammonia on poultry have recently been investigated and suggest that there may be a threshold for ammonia detection or aversion at or below the current exposure limit. The available evidence for the effects of ammonia on poultry welfare should be considered when setting future guidelines for ammonia exposure in poultry houses.

Ostrich production is highly management intensive. The ability to sustain long term profitability is dependent upon the use of strict management techniques by the producer and his workforce. Important factors include those favouring maximisation of production, elimination of disease, reduction in transport and abattoir damage, and minimising feed costs. Given the rise in the global competitiveness of the ostrich industry, the implementation of best practices on the farm is vital if the producer is to remain viable.