White-feathered broilers dominate world poultry meat production owing to their rapid growth and high feed efficiency. However, consumers' preference for colourfeathered and slow-growing meat-type quality chickens is growing in certain regions of the world. Among them, the ‘Three Yellow’ of China and ‘Label Rouge’ in France are two famous examples. The appearance (plumage, skin, combs and so on), meat flavour, and meat texture are the main attributes that attract customers to purchase them. For practical breeding, quality chickens were initially produced by direct use of native chicken breeds, which are generally slowly-growing with poor feed conversion. Currently, the breeding for quality chickens in China is characterized with crossbreeding between native breeds and highly-selected lines with rapid growth rate or relatively high egg production. The breeding objectives focus on improving growth rate and reproductive efficiency while maintaining original appearance characters of native chicken such as plumage colour, body shape, comb shape, skin and shank colour and so on. The performances of native chickens have been greatly improved by crossbreeding. Two-way or three-way crossing is commonly used in producing commercial quality chickens in China. In some cases, the dw gene has been introduced into maternal line for better reproduction efficiency and lower feed cost. For future development, breeders and producers will place more and more breeding significance on meat quality traits, which include meat flavour, tenderness, fat deposition, muscle fibre composition, visual characters and so on. As evaluation of these traits is expensive and time-consuming, new molecular markers will play more important roles. Once reliable markers are identified, early marker assisted selection can be performed with great selection accuracy and without slaughtering. Attempts to identify candidate genes related to meat flavour, muscle fibre, lipid metabolism and other physical characters have brought great potentials for future breeding of quality chickens.

Genetic selection is an important breeding tool that can be used for improving animal's coping capability to modern production environments or for increasing economic benefits. However, over the past five decades, commercial breeding programmes have primarily concentrated on traits directly related to productivity. As a result those breeding programmes ignore traits that may impact animal welfare. To address this issue, a selection programme termed “group selection” developed. This method takes into account competitive interactions by emphasizing performance of the group, rather than the individual. Results from the current studies have showed that chickens'productivity and well-being can be improved the same time. We further demonstrated an association between the selected survivability and productivity and its respective physiological characteristics. These findings indicate that group selection altered the chickens' physiological homeostasis which is reflected in the line's unique coping ability with intensified domestic environments. These changes in physiological homeostasis provide an opportunity gain new insights for the development of interventions aimed at ameliorating the adverse impacts of the intensified poultry industry.

Maximum daily temperatures in excess of 30°C are common in many table egg-producing regions of the world. Such temperatures require the application of specialized management and nutrition if laying hens are to produce eggs near their genetic potential. Environmentally-modified buildings have been shown to be especially advantageous for commercial layers that are housed in high density cage facilities. Directing air movement onto floor-housed birds has also been found to maximize heat loss and was beneficial as long as the air temperature did not exceed body temperature. This latter procedure was especially useful where sporadic incidences of heat stress were common.

Nutritional manipulation of the diet also offers advantages, especially in overcoming problems of reduced appetite. This principle has been shown to apply to both growing pullets and adult layers. Recent research has confirmed that optimum production during lay depends on the adult hen having an adequate gut capacity and sufficient nutrition during rearing. Egg production during moderate heat stress can be improved by increasing the intake of protein relative to energy but energy requirements will likely increase in severe heat stress. Dietary supplementation with ascorbic acid and vitamin E and a supply of cool drinking water have also been reported to improve production during lay but the response to the latter treatment varied with genotype.

The present review focuses on three avian DNA viruses and two retroviruses; the DNA viruses are Marek's disease, chicken anaemia and fowlpox virus. The two avian retroviruses, reticuloendotheliosis and avian leucosis virus subgroup J were detected in theirproviral DNA form in the feathertip extracts, thus resembling DNA viruses. Whereas most previous reports focused on experimentally-infected chickens, in the present study we analysed naturally-infected commercial flocks.

We review now the presence of various viruses in the chicken feathers, showing the efficacy of feathers for research and diagnosis alongside with other organs. Data on the relative ability to detect viruses on feathers over prolonged periods of time is also provided. We also analysed the efficacy of feather testing for the assessment of environmental infection in poultry houses. The data obtained by the differential diagnosis of various viruses in conjunction with the analysis of organs from the same chickens, showed that the feathers were very effective for diagnosis and deserve more attention.

Recent decades have seen significant progress in the genetic selection of fast-growing meat-type broiler chickens. However, fast growth has coincided with inferior development of the visceral systems, especially the cardiovascular organs, contributing to difficulties in coping with heat stress. Global mean surface temperatures are expected to rise during the coming years and climate control systems are expensive. This situation, where growth rate and heat production increases on a yearly basis and the future foresees increasing temperatures, demands an efficient means to economically improve the acquisition of thermotolerance by broiler chickens in hot climates. In homeotherms, three direct responses participate in thermotolerance acquisition: rapid thermal shock response, acclimation and epigenetic adaptation. Together with physiological understanding, it is important to understand the physical aspects of broilerexcess heat dissipation. This paperfocuses on airvelocity as a principal parameterwhich dramatically affects sensible heat loss and its contribution to the ability of acclimated or epigenetic adapted broilers to efficiently maintain a favourable energy balance underhot conditions. Heat transfer equations and models for different body parts are presented which were used to determine energy balance components at different air speeds based on thermal imaging. The studies reviewed demonstrate that: (a). air velocity plays a major role in energy balance at high ambient temperatures; (b). the optimal air velocity for achieving maximal growth performance differs at different ambient temperature and has a point of inflection at ambient temperature below 30°C, where chilling affects the broiler;(c). high air velocity at high ambient temperatures affects the ability of broilers to maintain total body water, most probably as a result of cutaneous waterloss; (d). thermal conditioning at an early age increases the capacity of broilers to efficiently lose heat by radiation and convection; (e). genetic selection for growth performance has been to some extent at the expense of the broiler's ability to maintain favourable energy and water balances.

Well known as the cause of necrotic enteritis, C. perfringens (CP) is now recognized as causing a spectrum of effects including subclinical infection, mild disease with focal intestinal necrosis, diarrhoeal illness and liver disease, as well as the classic form of acute fulminant necrotizing enteritis. The mild and subclinical forms of infection appear to be widespread, and, possibly increasing in incidence. Furthermore, bacterial enteritis is increasingly being recognized less as an invasion by pathogenic organisms per se and more as an expression of the normal process by which the intestinal bacterial population changes overtime in response to changes in the intestinal environment. Such shifts in enteric bacterial populations have been referred to as dysbacteriosis. Management of the microbial ecology of the intestinal tract is therefore an important element of preventing disease, enhancing performance, and preventing foodborne illness. Diagnosis of emerging forms of bacterial enteritis including CP infection can be challenging and involves a comprehensive analysis of flock history and condemnation records, clinical signs, gross and histopathology, bacterial culture and empirical response to treatment, augmented by molecular techniques where available. Control measures are at present based on extensions of validated approaches to the control of the classical form of the disease: managing known risk factors for necrotic enteritis (coccidiosis, diet and litter quality) and the use of approved antimicrobial agents with proven efficacy against CP.

Egg production in the EU (15) increased by 12.2% over the last decade. In 2003 it reached a volume of 96.4 billion pieces. The leading countries in shell egg production are Spain with a share of 20.1%, France and Italy with a share of 17% respectively 14%. The self-sufficiency rate for eggs shows a great variety in the EU. In 2003, The Netherlands had the highest surplus with a rate of 175%, whereas Germany showed the highest deficit with a self-sufficiency rate of only 71%. Shell eggs are traded mostly within the common market of the EU. The Netherlands is the leading exporting country; Germany is the leading importing country.

Organic egg production has also increased continuously over the last decade, without, however, reaching higher market shares. The contribution of organic egg production differs considerably among EU member states. Denmark has the highest share, followed by Austria and the United Kingdom; on the other hand, in southern European countries, organic egg production only plays a minor role. In spite of the increasing production volume, trade with organic eggs is still relatively unimportant in the EU.

The new EU directive for laying hen husbandry and the new German directive will have far reaching impacts on egg production and egg trade in the EU. Due to the banning of conventional cages from 2007 on in Germany the amount of alternative egg production will increase dramatically in this country, but it is a still open question if the consumers will buy these more expensive eggs. The self-sufficiency rate for eggs will decrease from 71% to about 35% and force Germany to import about 10 billion shell eggs per year or about two thirds of all eggs that are being traded on the world market.

Commercial broilers are increasingly being subjected to environmental temperatures that are above their comfort zone. This is mainly because birds are growing faster than before and are therefore larger at any given age, but also because broiler production is being introduced as a farming system in environments that are unsuitable for such production. It is not economic for most producers to modify the environment within the broiler house to account for these problems and so it would be useful to know of nutritional strategies that could be used to reduce the effects of heat on broilers in the finishing stage.

Nutritional strategies discussed in this paper include the use of feeds with a high ratio of net energy to metabolisable energy, feeds whose amino acid composition is closer to that required by the birds, feeds with additional salts or vitamins and the use of pelleted feed and timed feeding. However, dietary modification will increase the cost of feed and the producer will usually not reap a net benefit. Some advantage may be gained by adding vitamins C or E to the feed, because of their action in reducing lipid peroxidation resulting from the increased body temperature of the bird: but it is impractical to reduce the heat increment of a broiler feed unless poor quality ingredients are currently being used. Heat production by the broiler may be lowered by reducing activity, by feeding pellets instead of mash, or by withholding access to feed before the temperature increases to stressful levels. Some improvement in performance can be obtained by increasing water intake. This can be achieved by cooling the drinking water and by adding salts, though these are only effective if the water is kept cool.

Most nutritional strategies that have been proposed as a means of reducing the heat of digestion in the broiler result in a maximum theoretical saving in metabolic heat production equal to the effect of lowering dry bulb temperature in the broiler house by about 1°C. None of these strategies is as effective in terms of growth rate, feed conversion, liveability or carcass quality as reducing the radiant heat load on the birds by making appropriate modifications to the structure of the broiler house and to the husbandry practices employed.

Except for conventional cages, the most common housing systems for laying hens comprise deep litter, aviaries and more recently furnished cages. Layers in floor systems may also include out-door keeping. Furnished cages will be the only legal form of cages in the EU from 2012 (1999 EU-directive) but have as yet only been installed in significant numbers in Sweden and partly in Norway, Germany and Great Britain. Climate, feed, bird genotype, group size as well as the legal possibility to beak trim or to use certain medical treatments (mainly against endo- and ectoparasites) or not, are all conditions affecting results with different housing systems in different countries. Offering benefits to the bird as regards increase in behavioural repertoire as well as providing more space, all alternatives to conventional cages, require new orspecial knowledge of management. This is due to the fact that these systems often include higher potential risks in production and health of layers. This especially applies to non-cage systems (Petermann, 2003). The main issues to control in largergroup floorhousing are parasitic disorders, outbreak and spreading of cannibalistic pecking, increased feed intake, misplaced eggs, catching of spent hens and airquality (dust and ammonia levels). Many management practices to reduce some of these risks have been presented including rearing method, medication, vaccination, light intensity, genotype, feed composition, beak trimming and – for improved air quality – the use of spraying/fogging with water or oil as well as more frequent manure removal at closerintervals have been practised. Coming in a wide range of models and group sizes, the furnished cages attempt to combine the benefits and reduce the disadvantages of floorkeeping and conventional cages. The most developed models of furnished cages provide similar production results to conventional cages. However, differences still exists e.g. in egg quality traits between models. Design and location of nests, perches and litter are all important factors.

In conclusion, future trends in investments forhousing system in egg production will have to take into account several factors apart from the degree of success from technical development of each system. These will probably involve national directives regarding beak trimming, stocking densities, directives of withdrawal times of medication and occupational safety on one side and national markets and trades fordifferent categories of eggs on the other.