This paper provides a review of research on ascorbic acid as a nutrient in poultry published subsequent to a major review in this journal in 1986. Further experiments have confirmed the effects of a nutritional supply of AA in limiting the metabolic signs of stress and alleviation of the physiological consequences of stress is manifest in the performance, immunological competence and behaviour of birds. Birds under stress can recognise the stress-relieving properties of a diet containing AA and increase their intake of it, though they require a colour association to make the correct diet selection. Practical studies have generally confirmed the experimental findings, though the responses have been more variable, perhaps because of the greater difficulty in establishing the degree of stress experienced by birds under practical conditions. Optimum responses in growth, feed efficiency and/or liveability in broilers under heat stress seem to occur with supplements of about 250 mg AA/kg. Laying hens under stress, particularly climatic stress, have also shown responses to supplemental AA. This has resulted in improvements in liveability, food intake, egg production and egg quality with dietary AA concentrations in the range 250–400 mg/kg. AA can be beneficial in countering the adverse effects on shell quality of drinking water containing a high concentration of salts. The AA concentrations that have been found to be effective lie in the range 1–2 g AA/kg feed or /I drinking water, though it is possible that breed differences or additional stress factors might affect the response. Studies on the role of AA in the growth of poultry bone and connective tissues have suggested possible benefits of dietary supplementation in some stress or disease situations. AA has also been shown to interact with a number of other vitamins and minerals.

Newcastle disease (ND) is a highly contagious disease. The present paper deals with classification of ND virus (NDV), clinical signs and pathology, virus strain classification and molecular backgrounds for the pathogenicity. Major emphasis is reviewing immunity and vaccination. Clinical forms of the disease vary depending on many factors, but mainly on the virulence of Newcastle disease virus (NDV) strains. Virulent strains are considered List A pathogens by the ‘Office International des Epizooties’ (OIE). The virulence has been traditionally determined using in vivo pathogenicity tests to distinguish between highly, moderately and low virulent isolates. More recently, molecular biological techniques like polymerase chain reaction and sequencing have been described to differentiate virulent from non- virulent strains.

The systemic and mucosal immune systems are considered to function more or less independently. Systemic antibodies are essential elements in protection against ND, whereas the local antibodies limit multiplication of NDV at the site of entry. Cytotoxic T lymphocytes specific against NDV have been detected in the spleen of vaccinated birds, however, their contribution to protection remains to be elucidated.An increase of the number of various leukocyte subsets was noticed in the respiratory tract and the Harderian gland (HG), which favours involvement of local cellular immunity in the defence against NDV infection. It is tempting to speculate that the local lymphoid infiltrates are involved in first defence and that cytolytic cells clear virus by directly lysing infected target cells at the site of NDV inoculation. Secondly, various cell types, mainly T-lymphocytes and macrophages, may be equipped to produce a range of cytokines with antiviral activity and cytokines that stimulate B-lymphocytes to proliferate and differentiate into antibody-forming cells responsible for the local antibody production against NDV.

Studies on genetically modified (GM) feedstuffs for poultry (and other livestock species) have not added any substance to public concerns in Europe about their safety for human or bird health. The compositions of maize lines engineered for insect resistance (Bt-maize) or herbicide tolerance (glyphosate) and herbicidetolerant soybean have all proved to be essentially indistinguishable from their conventional counterparts. Consequently, and not surprisingly, comparative feeding studies with broilers and layers in which conventional maize (50 to 78%) or soybeans (27%) were replaced in feeds by transgenic varieties, also have failed to show differences of any significance in production parameters. These data indicate that feeding studies with target livestock species contribute very little to the safety assessment of crops engineered for input traits that have little or no detectable effect on chemical composition. However, comparative growth studies made with broiler chicks, particularly sensitive to any change in nutrient supply or the presence of toxic elements in their feed, can be used to screen for any unintended adverse consequence of the recombinant event not detected by compositional analysis. This does, however, depend on whether the GM plant can be matched to a parental line or another suitable control and its suitability for inclusion in broiler diets. The discovery that DNA fragments from the digestive tract can be found in the tissues of animals evoked interest in the fate of ingested transgenes. Plant DNA derived from feed has been detected in the muscle, liver, spleen and kidneys of broilers and layers, although not in eggs. However, no fragments of transgenic DNA or its expressed protein have been found to date in poultry meat or eggs or in any other animal tissues examined.

To accommodate the rapid transition to external nutrients, the chick's gastrointestinal tract undergoes dramatic changes within the first few days of life. These include a rapid increase in mass, villi number and length, enterocyte number, crypt depth and proliferating cells. Concomitant with the development of digestive structures and functions a rapid development of the gut associated lymphoid tissue (GALT) occurs. This lymphoid system works within and in concert with digestive tract parenchyma, however, there is little information describing the normal development and immunological function of the avian GALT in the immediate post-hatch period. The purpose of this review is to summarize current knowledge on the structure and function of the avian GALT during the early post-hatch period. At hatch, the gut is poorly populated by both innate immune leukocytes and lymphocytes. The basal numbers of lymphocytes are the result of early waves migrating from the thymus and bursa of Fabricius. Further waves of lymphocyte migration occur after 4 days of life and continue intermittently with time. In concert with this pattern of lymphocyte population adaptive immunity develops. Hence, the gut of the hatchling is unprotected by adaptive immunity during the first few days of life. Protection during this critical period might be the result of maternal antibody activity or that of the innate immune system. This system appears to be functional at this time, though much work is needed to establish this possibility. Upon maturity of the immune system, most of the immunological activity within the chick GALT is concentrated in the hindgut, and specifically so in the caeca and bursa of Fabricius. Once immune responses have become established the relevant cells disseminate systemically and to other areas of the small intestines. Finally, observations on the beneficial effects of early feeding on development of gut and GALT are discussed with reference to management of hatchlings.

Despite the use of pigeons (Columba livia domestica) since 2500 BC by man for meat production, ornamentals, sports and experimental animals, limited information is available on their nutrient requirements and feeding. This could partly be attributed to the rearing of growing chicks (squabs) to mature body weight at 28 days by the parents. Squabs have an extraordinary high rate of maturing (0.1466 to 0.1945 g/d) in comparison to other domesticated avian species such as poultry (0.0450 g/d) and quail (0.077 to 0.097 g/d). This growth rate is achieved by regurgitation of a holocrine substance (crop milk) by both parents, formed in response to prolactin secretion and triggered by brooding. Crop milk consists primarily of protein (11.0 to 18.8% on as is basis) and fat (4.5 to 12.7% on as is basis), and lacks significant levels of carbohydrates. Furthermore, adult pigeons are mainly fed mixtures of whole grains. Special feeding characteristics inherent to the pigeon thus prevent extrapolation of nutrient requirements determined with other avian species. A dietary crude protein content of between 12 and 18%, and metabolizable energy (ME) content of around 12 MJ/kg, based on production of offspring, is recommended for feeding of adult pigeons. Apparent metabolizable energy, corrected for nitrogen retention (AMEn) for maize (14.76 MJ/kg), barley (12.36 MJ/kg), sorghum (13.87 MJ/kg) and peas (14.01 MJ/kg) did not differ substantially from values derived for poultry. Pigeons could utilize lipids better than carbohydrates as energy sources. Feed additives and suggestions for future research are discussed.

Current European Union legislation prohibits the washing of Class A eggs. This is in stark contrast to countries such as the United States of America and, more recently Japan, which have embraced egg-washing technology. The emergence in the UK of egg associated Salmonella enteritidis as a significant cause of food poisoning has, combined with the increase in non-cage egg production systems, increased interest in technologies that might improve the microbial quality of the egg. This paper reviews the history of egg washing in the European Union and more specifically its restricted use in the UK and contrasts this with its uptake in the United States among other countries. Similarly the technological advances in egg washing are reviewed, in the context of the underpinning science.

The first attempts in producing table-eggs for the Turkish market on commercial egg farms were initiated in Basmakci County in 1974. Since then farmers have started to produce table-eggs through their own efforts, and as a result of rapid development Basmakci is now the main egg-centre of Turkey. However, there have been several factors having negative impacts on egg production in the region. This study involved investigations into the nutritional and husbandry characteristics of egg production. The present work outlines the structure of egg production along with the present problems of management, nutrition and environment. Egg production for Basmakci's producers can be considered as a secondary commercial activity within the farm enterprise. The producers have set up the Association of Basmakci Egg Producers (ABEP) to deal with the problems of supplying the laying stock and marketing the eggs. However, some important problems were encountered in the form of egg production drops during the course of the present investigation. The older conventional cage systems (A-type and California type) are still preferred by the farmers. Leading international commercial breeds of laying hens have been imported for egg production, but field tests of these breeds have not yet been carried out by the commercial breeding companies under local conditions. Neither laying house environmental conditions nor least-cost feed formulation were found to be well controlled in interests of optimum egg production. The producers failed to keep continuous and meaningful production records, and this causes difficulties in implementing different feeding programmes and management solutions. Manure management and other health-related issues are still being ignored. However, in order to improve the production level we suggest that poultry extension works should be established here with the strong collaboration between the universities, Egg Association, breeding companies and the Agricultural Ministry