Feather pecking in laying hens is an important issue in animal welfare. Four studies in laying hens were selected which investigated increased or reduced pecking behaviour using direct or indirect measures of feather pecking behaviour. Direct comparison of the selected experiments is difficult, as the selection criteria and even the selection procedures varied. Keeping these differences in mind, the results of the experiments showed that a) It is possible to change pecking behaviour in the desired direction using selection, b) Aggressive pecking is not related to feather pecking, c) There is no clear consensus as to the relation between selection on pecking behaviour and laying performance and egg quality, d) Plasma serotonin level in the blood was reduced in the lines selected against pecking behaviour in both the individual selected lines and the group selected lines and there were indications that dopamine also plays a role in the regulation of pecking behaviour, and finally e) There are differences between the selected lines and their control lines with regard to the immune parameters both in the individual selected lines as the group selected lines, indicating that direct as well as indirect selection for reduced pecking behaviour changes the immune response.

Growth performance and meat yield of commercial broilers and turkeys has improved linearly each year during the past four decades (Havenstein et al., 2003b; Havenstein et al., 2003a; Havenstein et al., 2007), and this trend is likely to continue in the future as new technologies in genetics, biotechnology and developmental biology are adopted by the poultry industry. As the time it takes meat birds to achieve market size decreases, the period of embryonic development becomes a greater proportion of a bird's productive life. Therefore, incubation and embryonic development towards hatch is of greater relative importance to the successful rearing of meat poultry than ever before (Hulet 2007; Foye et al., 2007b). Consequently, anything that supports or limits growth and development during the incubation period will have a marked effect on overall growth performance and health of modern strains of meat poultry. Many poultry researchers now realize that future gains in genetic and production potential of poultry will come from advancements made during the incubation period and embryogenesis (Elibol et al., 2002; Peebles et al., 2005; Christensen et al., 2007; Collin et al., 2007; Leksrisompong et al., 2007). The urgent need to explore and understand the biology of incubation has been emphasised by several symposia: two held at the annual conference of the U.S. Poultry Science Society (July 2006-Edmonton, Alberta, Canada “Managing the embryo for performance”, and July 2007-San Antonio, TX Informal Nutrition Meeting “The impact of imprinting on biological and economical performance in animals”), and one held by the European Federation of World Poultry Science Society (October 2007-Berlin, Germany “Fundamental physiology and perinatal development in poultry), which were specifically devoted to demonstrating the importance of the embryonic period on poultry performance. This review will summarise the metabolic events and pathways in four of the most active tissues of embryos during the period just prior to hatch, and the hormonal control that coordinates the marked changes as the embryo prepares for its post-hatch life.

The effect of the organic production (OP) system on the qualitative characteristics and consumer perception of poultry meat is reviewed in the following paper. Age at slaughtering, genetic strains (fast- and slow-growing), physical activity, and pasture intake are key factors in determining meat quality. In conventional farming, fast-growing chicks are generally used, but these are not suitable for OP, since they may develop health and welfare problems, the most recurrent of which are leg disorders and lameness. Conversely, use of slow-growing strains in OP has positive repercussions on both animal welfare and product qualitative characteristics (eating quality and appearance) perceived by consumers. From the published data it can be concluded that organic poultry can be a viable production method, especially if suitable changes in EU Regulation. 1804/99 are made. The market opportunity for both organic and free range poultry products does not yet seem to be fully developed. We suggest that structured integration between production and consumption stages could resolve this problem.

Influenza A viruses that infect poultry can be divided into two groups. Very virulent viruses cause highly pathogenic avian influenza (HPAI), with flock mortality as high as 100%. These viruses have been restricted to subtypes H5 and H7, although not all H5 and H7 viruses cause HPAI. All other viruses cause a milder, primarily respiratory, disease (LPAI), unless exacerbated. Until recently, HPAI viruses were rarely isolated from wild birds, but for LPAI viruses extremely high isolation rates have been recorded in surveillance studies. Influenza viruses may infect all types of domestic or captive birds in all areas of the world. The frequency with which primary infections occur in any type of bird usually depends on the degree of contact there is with feral birds. Secondary spread is typically associated with human involvement, either by birds or bird product movement or by transferring infective faeces from infected to susceptible birds, but potentially wild birds can be involved. In recent years the frequency of HPAI outbreaks appears to have increased and there have been particularly costly outbreaks of HPAI in densely populated poultry areas in Italy, The Netherlands and Canada. In each outbreak millions of birds were slaughtered to bring the outbreaks under control. Since the 1990s, AI infections due to two subtypes have been widespread in poultry across a large area of the World. LPAI H9N2 appears to have spread across the whole of Asia in that time and has become endemic in poultry in many of the affected countries. However, these outbreaks have been overshadowed by the H5N1 HPAI virus, initially isolated in China that has now spread in poultry and/or wild birds throughout Asia and into Europe and Africa, resulting in the death or culling of hundreds of millions of poultry and posing a significant zoonosis threat. To date control methods seem to have been unsuccessful on the larger scale and HPAI H5N1 outbreaks continue to be reported.

Between 1970 and 2006, regional patterns of egg production and egg trade changed considerably. Until 1980, European countries dominated global egg production. In the following decade, less developed countries surpassed the more developed countries in their production volume. This shift was caused by the rapid increase of egg production in Asia. In 2006, Asian countries contributed more than 60% to the global production volume. In particular, the dramatic growth in China has been responsible for the spatial shift of production centres. In several other countries, such as India, Indonesia, Malaysia, egg production increased also considerably. The expansion of egg production had impacts on the patterns of egg exports and imports. European countries still dominate the trade in shell eggs, but Asian countries could gain market shares, in particular since the 1990s when several newcomers entered the global egg market. Malaysia and India became important egg exporting countries and changed the traditional market patterns in the Near East and in Southeast Asia. In 2005, 25% of all shell eggs that were traded worldwide had an Asian country as their destination. Besides importing countries with a long tradition, such as Singapore, Saudi Arabia or the United Arab Emirates, new importing countries entered the market, such as Japan. Asia will also play an outstanding role in the projected additional egg demand of 12 million t until 2015 and will also strengthen its position as the leading continent in egg production. About 75% of the expected additional demand will occur in Asia, more than 50% in China alone. In 2015, Asia will contribute over 62% to global egg production in 2015. These future dynamics will open new markets in several Asian countries for breeding companies as well as developers and producers of equipment for laying hens. In these countries, the feed industry will expand, which again will impact on the trade patterns of raw materials for compound feed. The growth of egg trade and the new patterns of trade flows will increase the risk of the introduction and dissemination of highly infectious poultry diseases. This and the foreseeable increase of feed prices may result in slower growth rates and even massive disturbances of the present and projected pattern of egg production in Asia.

Phytic acid is an anti-nutritional constituent of plant derived feeds. As a reactive anion, it forms a wide variety of insoluble salts with minerals including phosphorus, calcium, zinc, magnesium and copper. Phytic acid is also known to form complexes with protein and proteolytic enzymes (pepsin and trypsin). Because of the lack of endogenous phytase enzymes that hydrolyze phytic acid; phosphorus, calcium, protein and other phytic acid bound nutrients are less available to poultry. Commercially-available microbial phytase has great nutritional significance and ecological importance. Poultry diets supplemented with microbial phytase result in improved growth performance and increased digestibility and availability of phytate bound phosphorous, calcium, zinc and copper. Microbial phytase supplementation has also been shown to increase ileal digestibility of crude protein and amino acids. The efficacy of supplemental microbial phytase depends on its rate of inclusion, dietary calcium and phosphorus ratio, vitamin D3, nature of diet, age and genotype of birds. Thus, microbial phytase can be used to exploit the inherent nutritional potential of feedstuffs for more economic and environmentally-friendly poultry production.

When egg storage periods are prolonged (>7 days), hatchability and chick quality declines. The reason for this decline has been investigated, but is still not completely understood. At oviposition the developmental stage of the chicken embryo varies and so do the total number of viable cells. During storage, changes can occur in the embryo. Embryo viability at the end of storage seems to be dependent on the number of viable cells and the developmental stage of the embryo at oviposition. When the hypoblast is completely formed (during the quiescent developmental stage), the embryo seems to be more able to endure prolonged storage periods than embryos that are less or more advanced. During storage, changes also occur in egg characteristics such as albumen viscosity, albumen pH and yolk pH. There appears to be an interaction between albumen pH and embryo viability during early incubation and perhaps also during storage. An albumen pH of 8.2 seems to be optimal for embryo development. Albumen pH may influence embryo viability, but embryo viability may in turn, affect albumen pH. It has been hypothesised that an embryo in which the hypoblast is completely formed is better able to provide an effective barrier between the internal embryo and the exterior (yolk and albumen) and/or is better able to produce sufficient amount of carbon dioxide, which will reduce the pH level in the micro environment of the embryo to the optimal pH of 8.2. It appears that, to maintain hatchability and chick quality after prolonged storage periods, embryonic development should be advanced to the stage in which the hypoblast is completely formed or the atmosphere during storage and early incubation should be altered in such a way that albumen pH is maintained at the optimal level of 8.2.

Hatchling length and weight are used as tools to measure hatchling quality. However, the relationship between these parameters and later performance are not well known. This review evaluates the relationship between hatchling length or weight and slaughter weight, breast meat yield and feed conversion ratio (FCR) in both male and female broilers.

Datasets from two trials were compared. In the first, hatchling length and weight of 100 male and 100 female broilers were measured and body weight and breast meat yield were determined at 38 days of age. In experiment 2, hatchling length of 187 female and 230 male broilers was measured and body weight was determined at 21 and 42 days of age. Feed intake was determined between 21 and 42 days of age.

In both experiments, male broilers showed a positive relationship between hatchling length and slaughter weight or breast meat yield, but no relationship was found with hatchling weight. The relationship between hatchling length and performance in female broilers differed between the two experiments. In female broilers, a negative relationship between hatchling weight and breast meat yield was found. No relationship between hatchling length and FCR in both male and female broilers was found. From this limited dataset, it can be concluded that hatchling length seems to be a better parameter to predict subsequent chick performance, excluding FCR, than hatchling weight, but gender needs to be taken into account.

The heart rate (HR) of chick embryos before hatching is a relevant physiological parameter for the evaluation of regulation mechanisms of the cardiovascular system under different environmental conditions, e.g. oxygen supply. Movements of the embryo can be interpreted as a behavioural response to such changes. Using the PowerLab hardware and Chart software (AD Instruments), the ECG of a 14 day old chick embryo was recorded almost non-invasively by three electrodes penetrating the otherwise intact egg shell. The Chart program can be used to calculate the HR and its variability from the precisely detectable R-waves of the ECG. Artefacts in the ECG trace are derived from movements of the embryo. Under hypoxic conditions, the program can show that HR and HRV increased, whereas the embryo movements decreased. Using this technology, it can be determined that the embryo compensates for lower oxygen supply with faster blood circulation and saves energy by reducing unnecessary movements.