The statistical methods for the estimation of genotype–environment interactions based on the concept of genetic correlation are reviewed and the implications of genotype–environment interactions in selection and in performance testing of genetic stocks discussed. From comparative testing of commercial poultry stocks there is overwhelming evidence for the occurrence of stock–testing station interactions. However, the relative importance of the effects may vary considerably between performance traits and between testing situations. In general, the consequences of genotype–environment interactions appear to be more serious in egg production stocks than in broiler stocks. For laying rate and viability particularly large effects have to be expected.

The literature concerning the influence of ahemeral light cycles on the quality of eggs is reviewed. Results pooled from published reports were used to arrive at a quantitative relationship between the length of light cycle (ranging from 23 h to 30 h) and the parameters of egg quality. Eggshell quality (whether measured as mg shell per unit surface area, as shell thickness or as shell weight per se) was found to depend on a curvilinear function of cycle length. Albumen height was negatively correlated with cycle length, whereas yolk and albumen weights were found to have a curvilinear relationship with cycle length.

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.

Egg yolk is an obvious source of fat in our daily diet. The trend towards a reduction in fat consumption and concern over the quality of any fat that is consumed have caused a significant erosion of the previously accepted dietary image of the egg. In spite of the extensive and continuing controversy over the quality of dietary fat and the incidence of coronary heart disease, it is now widely recommended that the consumption of animal fats does not predispose to health. Parameters describing what is a healthy dietary fat have been established. Egg fat is examined with regard to these parameters and the justification for its present poor image is scrutinized. So firmly entrenched are the present views on animal fat consumption, that to rehabilitate the egg with the consumer will require a change of approach, away from the complacency of the past to a more positive approach based on attempts to change lipid parameters to align with present consumer perceptions and requirements.

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.

Natural infections of turkeys with avian paramyxovirus type 3 (PMV-3) result in drops in egg production, respiratory problems, poor egg quality, virus excretion via the respiratory tract and the development of strong antibody responses. The viruses have been discovered in Canada, the USA, UK, France and Ireland. Field viruses were isolated using chicken embryos and identified using haemagglutination-inhibition tests, complement fixation tests, virus-neutralization tests and fluorescent antibody tests. The exact origin and mode of transmission of the virus remain to be elucidated. The epizootiological factors include geographical distribution, time space, age of turkeys at infection and route of natural exposure. The high mortality of young chicks following experimental infections with an English strain of the virus implies that turkey PMV-3 infections could also be a threat to the chicken industry.

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 technological advances in the processing and preservation of quail eggs and meat, evaluation of their nutritive values and development of further processed products therefrom are reviewed. The review of egg and egg products covers the physical and chemical composition of eggs, the influence of age and season on egg quality, storage stability of shell eggs and further processed products including pickled and brined eggs. Aspects concerning optimal slaughter age of quails and their processing, yields of carcass and meat, abdominal fat, nutrient composition, preservation and further processed meat products like pickled, tandoori (roasted), fried and smoked quail are also highlighted in this paper.

Salmonella enteritidis phage type 4 was recovered from the yolk sacs of broiler chickens in East Anglia, UK, during 1987. When the same phage type 4 was identified in two of the supply flocks, transovarian infection was suspected. These findings were of particular interest to the Public Health Laboratory Service because they provided a possible explanation for the unprecedented increase in food poisoning during 1988 linked to the consumption of shell eggs. Some of the problems of diagnosis are discussed in breeder hens and in the progeny. Effective control of S. enteritidis phage 4 in poultry is dependent on the accurate detection of infected breeder/layer hens in which vertical transmission is the essential distinguishing feature from most other non-invasive, enteric salmonellas found in poultry. The mandatory testing of poultry flocks by the UK Ministry of Agriculture introduced in March 1989 has led to the compulsory slaughter of a large number of birds as prescribed by the Zoonosis (1989) Order. The benefits of this policy should soon become apparent to poultry producers and to the consumer.

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.

The control of important poultry diseases in Asia is described, with the emphasis on vaccines, vaccination programmes and procedures. In most Asian countries there is routine vaccination for Newcastle disease, Marek's disease, infectious bronchitis, infectious avian encephalomyelitis, fowl pox and fowl cholera. However, depending on local conditions, programmes and procedures may differ from one country to another, or even from one farm to another within the same country. While some of the vaccines used are manufactured within the countries of the region, a large number are imported. India is the only Asian country that is self-sufficient in vaccine production.

Genetic improvement in production of commercial layers was examined by comparing production profiles of three strains representing commercial stocks of the two decades between 1950 and 1970, and by considering North American random sample tests for several production traits performed during the period 1970–80 with stocks that are used commercially in temperate climates around the world. Changes in the production profiles indicate commencement of production at an earlier age and increased persistency of egg production after reaching the peak level. Results from the North American random sample tests of multiple trait selected stocks show improvements not only in egg production, but also in egg size, while egg quality and viability have been maintained.

When multiple linear regression of feed consumption on metabolic body weight (MBW), body weight gain (BWG) and egg mass production (EM) is calculated between or within strains of laying hens, a standard deviation of 47–180 kJ metabolizable energy (ME) per day remains unexplained by these effects. This unexplained fraction, called residual feed consumption (RFC), has a heritability of 0-80%. A survey of the literature was performed to quantify this unexplained variation between strains and among individuals within strains of laying hens with respect to some energy metabolism parameters independent of MBW, BWG and EM. Genetic differences in ability to metabolize gross feed energy are found to be of limited magnitude; the coefficient of variation is 1–3%. From calorimetric experiments, the range of heat production (HP) between strains is found to be 44–118 kJ kg−0.75 d−1; variation among individuals within strains is of the same magnitude (standard deviation: 16–125 kJ kg−0.75 d−1). The range of maintenance requirements (MEm) is reported to be 41–113 kJ kg−0.75 d−1; standard deviation among individuals is 23–80 kJ kg−0.75 d−1. Variation of heat increment of production (constituting the difference between HP and MEm) seems to be small. The main component of HP variation and of RFC variation seems to be the variation of MEm: differences in physical activity, feathering density, basal metabolic rate, area of nude skin (comb, wattles, legs), body temperature and body composition. Net energy per g EM does not play an important role in variation of RFC.

The authors review the main studies of the last 30 years concerning the chemical and nutritional features of sorghum grain. They describe the problems related to the tannins which lower to various extents its metabolizable energy value, palatability and protein utilization for chickens. They also emphasize that the new sorghum cultivars with low tannin content and nutritive value similar to maize really are suitable for use as the only cereal component of commercial poultry diets.

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.

A chronological account of observations on the nature of the shell membrane protein system is presented. The review indicates that although the major protein in the shell membrane is not elastin, it does contain desmosine and isodesmosine – the cross-linking amino acids. The membranes also contain small amounts of collagen. The formation of these proteins can be impaired by the inclusion of lathyrogens in the diet of laying hens. This impairment is caused by a failure to synthesize cross-links of membrane protein and this is very similar to the effect obtained when hens are fed copper-deficient diets. The disruption of the protein system has a considerable effect on the development of eggs, which are abnormal in size, shape and shell texture. The lathyrogens also have a depressing effect on egg production. The problems and prospects of utilizing seeds of certain Lathyrus plants containing lathyrogens are indicated.