History

10. Early this century, egg production was based on small flocks of hens kept outdoors on mixed farms alongside other animal and crop enterprises. As farming became more specialised, the average flock size increased and the hens were kept mainly in houses with littered or part littered floors, often with access to an outdoor enclosure. Parasitic disease problems occurred commonly when many hens were kept on litter in limited areas. Various perforated (mainly timber slats or wire mesh) floored systems were developed in the 1930-1950 period to separate hens from their faeces and thus to minimise the risk of parasitic disease. However, these systems often resulted in problems of hysteria, feather pecking and cannibalism. The deep litter system, usually operating on two levels comprising part littered/part raised floored areas, gained popularity for large scale egg production.

11. During the 1930s the first commercial cages for laying hens were developed in the USA; these cages were designed to house single birds and consisted of a wooden framework with wire mesh floors. Feed and water provision, egg collection and removal of manure were all done by hand. Laying cages gradually evolved in the UK during the 1930s and 1940s and many were constructed entirely of metal. The detailed design of early cages was not ideal and often death and injury were caused by birds being trapped. However, hygiene was much improved, parasitic diseases virtually disappeared, and injurious feather pecking and cannibalism were reduced. After many years of subsequent development, mortality due to accidents and trapping in cages is now at a very low level.

12. During the 1940s, many laying flocks were moved from free range and semi-intensive systems to deep litter houses and wire floored houses. During the 1950s there was a rapid and sustained change towards laying cages. This took place, in particular, to make management easier but was also prompted by welfare and disease problems which were then prevalent in the veranda, straw yard, deep litter and wire floor group systems. Initially these cages were for single birds but in the early 1950s twin bird cages became popular and multi-bird cages soon followed. The trend continued during the 1960s (see Table 1). During this period the economic and welfare benefits of higher house temperature were discovered and the number of tiers of cages and stocking density in laying houses increased. Also at this time the realisation that there were production benefits from the use of controlled lighting patterns led to the common adoption of windowless, artificially lit housing. Improved house insulation was adopted to prevent condensation at higher stocking densities and fan controlled ventilation systems were introduced to cope with excess heat in summer. The result was the emergence of controlled environment housing which has continued in use until the present, now with increasing automation of control systems.

13. As cages, in various configurations, came into general use in the UK, feed and water provision, as well as egg and manure removal, were increasingly mechanised. Today about 86% of the UK's commercial egg production is derived from caged hens. Cages in various forms have evolved as the predominant system that reduces the management and disease problems found in other systems. However, there is an increasing awareness that hens are restricted in their freedom to move and ability to express fully a number of their behaviour patterns. Furthermore, there has been increasing public concern about the continued use of battery cages.

14. During the last ten years there has been a developing interest within the poultry industry in alternatives to battery cages; these "alternative systems" are described in Part III. This change was influenced by public attitudes to animal welfare and the willingness of a small proportion of consumers to pay a premium price for eggs from non-cage systems.

15. During the last 60 years, improvement in laying performance has been remarkable, as measured for example, by numbers of eggs laid per hen housed (total eggs laid by the flock divided by the number of hens originally placed in the house). The increase averages almost three eggs per hen per annum. Well managed flocks currently achieve about 310 eggs per hen per year (see

Table 2).

Table 1. Changes in egg production systems, % of eggs

Adapted from data of MAFF and in the Museum of the British Poultry Industry.

Table 2. Performance improvements in hen housed egg production