In England and Wales in 1988, as in other European countries, eggs were identified as an important source of Salmonella enteritidis phage type 4 infection in humans. Unlike other non-host-adapted strains that can infect chickens, S. enteritidis PT4 is almost unique in that it can be isolated from the contents of intact, clean shell eggs. When present in the yolk of intact eggs it can survive certain forms of cooking, and analysis in England and Wales has shown that, in addition to outbreaks being associated with consumption of raw egg dishes and sauces, a number were also caused by cooked egg dishes. Although S. enteritidis PT4 is more heat-resistant than some other common poultry-associated strains, its ability to survive cooking is due more to the protective qualities of egg yolk.

In studies involving individually caged, naturally infected layers where the average prevalence was =1% of the output, the production of contaminated eggs was shown to be clustered but intermittent. This is in accord with observations made on other naturally infected flocks where the proportion of contaminated eggs has been observed to fluctuate. While salmonella-positive eggs were shown to be occurring during outbreak investigations involving human cases, some weeks later all eggs being produced by some flocks were found to be salmonella-negative even though the birds were shown to be carrying S. enteritidis PT4 at slaughter.

Although S. enteritidis PT4 has been shown to be highly virulent for young broiler chicks, it does not appear to behave in the same way in egg-laying hens. In three independent studies it was shown to be possible to infect mature hens with an inoculum as low as 100 cells. The organism was invasive and could be isolated from viscera and from egg contents. None of the birds, however, showed any signs of illness. Studies with naturally infected hens demonstrated that they have circulating antibodies against S. enteritidis PT4. There would also appear to be an association between antibody level and invasion by the organism. No such relationship exists with the production of contaminated eggs.

The ultimate control of this important human pathogen lies in the identification and eradication of infected flocks. Until that is achieved, however, significant improvements in egg quality and consumer safety can be made by storing eggs at 8°C or less. Fresh, naturally contaminated eggs contain small numbers of salmonella organisms and cool storage successfully prevents multiplication.

The method elaborated by Working Group 5 involves standard procedures for poultry meat sampling, sample preparation, inoculation of a selective isolation medium, counting of colonies and interpretation of results. These are described, together with full details of media preparation. Widespread adoption of the method in processing plants would help considerably in the establishment of more uniform quality control standards. In turn there could be significant benefits to international trade and to the image of the products of the poultry meat industry among consumers.

In Western Europe public awareness of ethical problems associated with farm animal production began to be seriously aroused in 1964 by the publication of Ruth Harrison's book Animal Machines. Although the restriction imposed by the battery cage system on laying hens was seen as a major cause for concern, it was not until the mid-1970s that applied research into improved or alternative production systems for laying hens began. Following initial smallscale trials in the UK on what became known as the ‘get-away cage’ the concept was developed, especially in Germany. Investigations were initiated into other alternatives, including aviaries, percheries and combinations of raised wire floors, and these continue in Denmark, the FRG, the Netherlands, the UK, Sweden and Switzerland. It has yet to be seen how far the benefits of such systems, chiefly the enhanced range of behaviours observed in the birds, can outweigh the disadvantages, especially the higher costs and some disbenefits, including feather pecking and cannibalism. Except where legislation forces the issue, as in Sweden and Switzerland particularly, the adoption of alternative egg production systems will depend on the willingness of consumers to pay a higher price for the product. Reference is also made to welfare problems associated with other classes of poultry.

The objective of the work described is the introduction of cage system modifications that enable the birds to express a wider range of behaviours, while preserving as far as possible the main advantages of the system. Preference testing and motivational studies have been undertaken in the process of assessing the value of increased space provision, perches and nest sites of various kinds.

Specific design features discussed are: the avoidance of traps which damage the plumage and cause injury, especially to feet, wings and head; the provision of abrasive strips on the cage baffle plate to keep claw length in check; the possible use of perches to improve foot condition and provide exercise; and the value of improved gate design, especially to reduce the risk of injury at end-of-lay bird removal. A new prototype multilevel system (Elson tiered terrace) is briefly described.

Preliminary results are given from studies of cage-housed birds provided with various combinations of nest sites (of various designs), perches (placed at the front or back of the cages) and dust bath boxes. Tibial bone strength in end-of-lay hens was found to be markedly greater where perches were provided – suggesting a clear benefit from this addition. Complex nesting facilities (external nest boxes) elicited more normal pre-laying behaviour than nest sites within the cage. There appeared to be a need for two nests for group sizes of four or five birds.

Although the concept of the get-away cage for laying hens originated in the UK in the early 1970s, most development has been undertaken in other countries, particularly in the FRG at Celle. After a series of seven experiments, each involving =4000 hens, it is concluded that forms of the system which include nest boxes and perches are capable of supporting performance levels that are similar to those obtained from birds in conventional cages. Whilst extra capital and labour costs might be expected to be up to 5% above those for normal cages, real welfare benefits are believed to result from opportunities the birds have to express an enlarged range of behaviours.

The incidence of bone breakage and other traumas in end-of-lay birds at the time of slaughter have important welfare and commercial implications. The problem is greatest among birds from the cage system where injury and stress appear to be particularly associated with the process of removing the birds from their cages and subsequent handling. The bone strength of cage-housed birds, together with some physiological and behavioural aspects, are briefly considered. Suggestions are made for reducing the incidence of injuries during bird removal.

The poultry industry of South-east Asia has two important types of production. These are: a commercial sector, characterized by its use of highly intensive units and the fact that it has developed very rapidly over the past two decades; and the traditional village-based system which has been little affected by the increasing numbers of commercial birds. The village poultry system relies on minimal resource input and, although secondary to other agricultural activities, has an important role in providing the local population with income and high quality protein. Almost every rural community keeps small flocks of indigenous chickens under a backyard type system. The sheds, when provided, are made from local materials. Whilst the birds are fed kitchen left-overs, sometimes supplemented with cheap, locally available grains, most of their time is spent scavenging. There is no breeding programme and close inbreeding occurs among the indigenous stocks. The high incidence of disease is the greatest constraint on rural poultry development.

Within the process of rural reform initiated in the early 1980s there has been a remarkable increase in the size of the Chinese poultry industry – some estimates indicate a tenfold growth between the start of the decade and 1987. The review covers aspects of the industry's structure and compares the relatively simple poultry health situation of former years with the more diverse and challenging problems of today. The organization of poultry health diagnostic and other services, together with poultry health research and training provision, are described. For the years ahead, attention is drawn to a number of necessary developments. These include the need for attitudes and practices to change, to bring about, in particular, greater integration between management and husbandry decisions and measures designed to promote good health. As part of the process major objectives are to improve education and training and to increase the number of those with specialized knowledge and skills in the field of poultry health. Greater international liaison and collaboration are likely to play a vital part in helping to bring the Chinese poultry industry up to the level of the most advanced countries. In the area of research there is an urgent need to establish an independent poultry health research institute that could take the lead in helping to co-ordinate the research being conducted in many different establishments throughout the country.