35. Light, both in terms of photo period and intensity, is a major factor in relation to the welfare of turkeys grown for meat and those reared for breeding purposes.
36. We have carefully considered the views from animal protection societies which called for bright, well-lit houses and from industry representatives who preferred low levels of light. Clearly, there is a difficult balance to strike: if light intensity is increased, turkeys become more active but the incidence of aggression and injurious pecking is also increased, as is the likelihood of body damage; alternatively, if light intensity is reduced, aggression is considerably lessened and beak-trimming can be reduced but birds are also less active and are unable to investigate their surroundings adequately. Turkeys are aggressive birds and producers of meat birds use low light levels to help to control aggression. Whilst we believe that very low light levels and routine beak-trimming are undesirable, until methods of avoiding these problems are devised it may sometimes be necessary to use a light level which is dim enough to prevent injurious behaviour in turkeys which have not been beak-trimmed (see paragraphs 54-64). Nonetheless, light levels should be adopted which are as bright as practicable and they should be reduced only in the event of aggression.
37. Lighting programmes are used by turkey breeders to regulate the birds' breeding behaviour and maximise the production of fertile eggs. In lightproof houses these programmes usually require the birds' environment to be lit for 8 to 15 hours at a minimum intensity of 25 lux. Turkeys kept in these conditions are usually beak-trimmed to avoid injurious pecking. Breeding birds may also be kept in naturally lit pole barn housing. Such birds are beak-trimmed to avoid injurious pecking.
38. Breeding companies have stressed their belief that beak-trimming is an essential management aid to control aggression when turkeys, particularly stags approaching sexual maturity, are reared in daylight or artificially lit houses. We comment on beak-trimming later but otherwise we do not consider there to be welfare problems caused by present lighting regimes in relation to breeding turkeys.
39. The lighting programmes used for meat birds in conventional (enclosed) houses are quite different from the regimes for breeding birds. Typical intensities at brooding are between 20 and 25 lux for the first few days to encourage activity and feeding, reducing gradually to about 10 lux or less after a week or so. The rearing sheds are lit to about 1-4 lux, although some companies use slightly higher intensities. Most of the larger producers adopt a period of darkness during each 24 hours and there is also evidence that intermittent lighting patterns encourage activity and help to improve leg health.
40. Our discussions, observations and the scientific evidence listed at Appendix C draw us to conclude that light intensity levels are not generally sufficiently high and should be increased to the advantage of the turkeys; and that continuous, or almost continuous, light is inadvisable and may cause eye damage and increase stress levels within flocks. We are aware that some commercial producers use carefully controlled, stepped lighting patterns because sudden change can create activity which can lead to wing damage etc.
41. The environment for brooding poults should be lit at a minimum of 25 lux for the first few days, although it may be necessary to reduce light levels in the event of aggression.
42. The housing and management systems should not require that the birds be kept at such a low light level that normal investigatory and other behaviour is seriously impaired.
43. The industry should be encouraged to investigate changes (e.g. enriching and modifying the environment) so that measures such as low levels of light are not needed to minimise injurious behaviour.
44. Lighting systems in houses containing turkeys reared for meat should be designed and maintained to provide a minimum light intensity of 5 lux measured on a horizontal plane at bird eye height, although it may be necessary to dim the lights for a few days if aggression occurs.
45. After the first few days of life, turkeys must not be kept in continuous light. Lighting should be reduced gradually to give a period of darkness of about 8 hours in each 24 hours.
46. It is essential that further research and development are undertaken as a matter of urgency to determine the optimum light intensity and pattern for turkeys reared indoors which will increase light levels and minimise welfare problems. This information will be required within a 5-year period to enable the Council to review its position. We expect to see levels increased to well above 5 lux within this period.