During the past four decades, research efforts directed toward reducing shell egg cholesterol content have centred on genetic selection or alteration of the laying hens' diet with various nutrients, natural products, non-nutritive factors, or pharmacological agents. However, the vast majority of these experimental approaches elicited only minimal changes (<10%) at best or, as in the case of dietary azasterols and triparanol, resulted in the unacceptable replacement of yolk cholesterol by desmosterol. In contrast, when 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (‘statins’), garlic paste, or pharmacological amounts of copper were orally administered to chickens, yolk cholesterol levels were reduced by up to 46%, 32%, or 34%, respectively. The previous paper in this two-part series provided a justification for low-cholesterol egg production and reviewed cholesterol metabolism in the laying hen, avian embryonic cholesterol needs, and genetic and nutritional approaches to chicken egg cholesterol reduction. The present paper provides a comprehensive overview of the use of non-nutritive dietary factors and select pharmacological compounds as egg cholesterol-lowering agents, and discusses emerging strategies for lowering the cholesterol content of shell eggs. With the recent advances in avian genomics and transgenesis, it is anticipated that the greatest advances in the area of yolk cholesterol reduction will be attained through manipulation of key genes whose protein products mediate intestinal sterol absorption, hepatic cholesterol and lipoprotein synthesis, and/or lipoprotein uptake by growing oocytes. However, the future commercial availability of low-cholesterol eggs produced by transgenic hens ultimately will be influenced by the nature of the regulatory environment for bioengineered foods, public acceptance, and economics.

Three main aspects of chicken biodiversity are dealt within this report: (a) cluster analysis based on autosomal microsatellites, (b) microsatellites on the sex chromosomes, and (c) SNP-based biodiversity.

(a) Cluster analysis of autosomal microsatellites: We used 29 microsatellites to genotype 2000 chickens randomly selected from 65 different populations representing various chicken types and various geographical regions. The computer program Structure placed the 65 populations into clusters that are in agreement with their geographic origin and breed history. Only at two predefined clusters, there is little admixture between non-commercial populations originating from Asia and those from Europe. In contrast, commercial broilers and brown egg layers appeared as admixed populations of these two main gene pools. Increasing the number of clusters resulted in generation of specific clusters of commercial lines, having very low admixture with other clusters. In addition, we identified seven mixed populations, each of which shared portions of their genome with several other genetic clusters.

(b) Microsatellites on the sex chromosomes: We predicted 173 potential microsatellites on chromosome W by in-silico analysis of the chicken genome assembly (version WASHUC1). Twenty five microsatellites of the highest sequence quality were tested in the lab for gender specificity. Unexpectedly, PCR products were generated in both sexes. Moreover, 14 selected microsatellites were mapped (using the East Lansing reference panel) and in all cases, the “W specific” microsatellites were mapped to chromosome Z and except for one locus, to the same ∼6 cM region. We conclude that the draft assembly for chromosome W is quite inaccurate.

(c) SNP-based biodiversity: Ten distinct chicken breeds were genotyped at 145 single nucleotide polymorphisms (SNPs) located at 14 random DNA fragments and twenty five, each from different and unlinked genes. Microsatellite genotypes of the same ten breeds were used for comparison. Applying bootstrap values as the criterion for tree's reliability, we found that: (1) increasing the number of SNPs had a higher impact on the reliability of the analysis than increasing the number of individuals per population, and (2) the bootstrap values of phylogenetic un-rooted trees based on microsatellites were relatively low.

The purpose of the research was to identify measurable indicators, which can firstly provide objective measures of bird welfare and secondly act as ”lead” rather than “lag” indicators. Broiler welfare has historically been measured using lag indicators such as final mortality, stocking density, levels of contact dermatitis, reject levels and leg health. Although there are benefits to their use as indicators, the main disadvantage of these measures is that whilst they provide data for interorganisational and inter-growing cycle analysis the welfare issues have already occurred for the birds concerned and the information can only effect change in future production cycles. Alternatively, lead indicators are intra-cycle indicators which will provide information on bird welfare so that preventive/corrective action can be taken within the growing cycle. These indicators include feed and water consumption, air and litter quality and daily weight gain. It has been established that water is a vital nutrient that should be routinely analysed to ensure that it complies with accepted quality standards so that bird health and welfare is optimised. Furthermore water consumption, (both daily and per cycle) is a key indicator of bird welfare and worthy of further quantitative study to determine if it can be used as a headline “lead” indicator to determine health and welfare issues early in the growing cycle so that appropriate management action can be taken.

The aim of the study was to analyse water consumption data of commercially grown broiler chicken in order to ascertain whether:

1. i) the results obtained correlated with those reported in other studies;

2. ii) water consumption can be objectively used as a measure of bird health and welfare; and

3. iii) there is a correlation between total water consumed, reject levels and the incidence of contact dermatitis.

High ambient temperature could result in numerous physiological and metabolic changes in broilers, that adversely impact broiler performance and immune response. In addition to environmental control techniques that have been frequently used to reduce the negative impact of heat stress on birds' performance, other measures have been studied. Lately, proper nutritional management has shown to be effect as a preventive measure against heat stress because the function of the thermoregulating system of broilers (heat production, evaporative and nonevaporative routes for heat dissipation) can be influenced by diet. This applies particularly to the establishment of proper electrolyte balances due to their physiological importance in the heat stress mechanism. Thus, nutritional mechanisms should be reassessed as a tool to control this metabolic dysfunction in birds.

The avian egg is a nutritious food and also a major source of biologically active compounds that are beneficial for human health. These biologically active molecules are widely used by pharmaceutical, cosmetic and food industries. Egg proteins were previously studied using classical biochemical techniques such as chromatographic and electrophoretic separation and Edman sequence analysis. The development of molecular biology in the late 80's and the recent publication of the chicken genome sequence are major scientific advances leading to identification and characterization of a number of minor egg components that were not previously identified. Using recent data on the characterization of egg white and eggshell matrix proteins, we illustrate in this review recent developments in the biochemistry of the egg (proteomics) and in the molecular biology of the egg (cDNA and ESTs libraries, bioinformatic analysis of the chicken genome, transcriptomics). These methods have allowed the identification of hundreds of minor egg protein components with potential applications for industry. Functional studies to identify the biological activities of these novel egg protein components and to exploit their potential will form the next frontier of egg science.

Many avian species are considered sexually monomorphic. In monomorphic bird species, especially in young birds, sex is difficult to identify based on an analysis of their external morphology. For nestlings, sex identification is usually impossible by morphological examination. Sex identification in avian species is one of the key points of avian breeding and evolutionary studies. Through the knowledge of sex identification genes, poultry breeding programmes can be applied more successfully. Vent sexing, laparoscopy, steroid sexing and karyotyping are methods for sex identification used in monomorphic birds. However these methods are unreliable, time-consuming, and expensive while some of them could be painful and even lifethreatening for birds. The sex of an individual is established from the genes located on sex chromosomes. Female birds carry one copy of both Z and W, and male birds carry two copies of Z avian sex chromosomes. However, there are many DNA techniques, the most reliable one is amplifying sex specific CHD1 gene by P2 – P8 primer pairs.

The conditions under which laying hens are kept remain a major animal welfare concern. It is one of the most intensive forms of animal production and the number of animals involved is very high. Widespread public debate has stimulated the call for more animal friendly, alternative systems to barren conventional cages. Directive 1999/74/EC has encouraged technical changes in current systems. Not only have traditional cages been modified (so-called ‘enriched cages’), but also new alternative systems (e.g. aviaries) have been developed. There is an ongoing need to evaluate the actual welfare status of hens in these novel systems including those on commercial farms.

The LayWel project, was funded via the European Commission's Sixth Framework Programme and national funding from several EU countries. Its general objective was to produce an evaluation of the welfare of laying hens in various systems, with special focus on enriched cages, and to disseminate the information in all member states of the EU and associated countries. The project took into account pathological, zootechnical, physiological and ethological aspects.

A major achievement of the LayWel project was the compilation of a database collecting data from different housing systems and thus enabling data comparison. The project partners recommend that support is given to maintaining the database in the future so that data can be more reliably modelled.

As the type of data collected did not often allow a formal statistical analysis the evaluation of welfare was a presentation of risk factors and advantages and disadvantages of various housing systems. Conclusions are that, with the exception of conventional cages, all systems have the potential to provide satisfactory welfare for laying hens. However this potential is not always realised in practice. Among the numerous explanations are management, climate, design, different responses by different genotypes and interacting effects.

A second major achievement of the project was the development of feather scoring and integument (skin, head and feet) scoring systems together with comprehensive sets of photographs.

It is recommended that the integument scoring systems are widely adopted and used in on-going research. Farms should also routinely and frequently carry out integument scoring to assist in the detection of damaging pecking, which is currently a widespread welfare problem.

Within LayWel an on-farm auditing procedure was developed in the form of a manual for self-assessment. The manual first explains what is meant by welfare and outlines the relevance of welfare assessment. It also summarises risks to welfare in the main categories of housing system. The second part contains recording forms, with guidance for assessing hen welfare. These enable regular checks of a range of indicators of laying hen welfare to be carried out systematically. The indicators were chosen to be relevant to hen welfare as well as feasible and reliable to apply in practice.

A series of conclusions and recommendations were made on various aspects of housing systems, behaviour, health and mortality and other matters in relation to bird welfare. Full details of these and all other aspects of the LayWel project can be found on www.LayWel.eu. The information is also available on CDROM of which copies are freely available on request.

In chickens and in animals in general, growth is influenced by genotype as well as by environmental factors including nutrition. Hormonal changes form, in part, the causal link between these interacting factors and the physiological processes leading to growth. It is well established that growth-related hormones (GH, SS) play different roles in different tissues. Several studies have investigated the nutritional and/or genetic effects on growth in chickens, leading to the general conclusion that the improvement of growth in modern broiler chickens is largely influenced by the genotype. In addition, it has been shown that the nutrition-determined regulation of tissues is also genotype-specific.

Besides growth, genotype-nutrition interactions also influence reproductive parameters (sexual maturation, egg production) and their endocrine control (hormone levels), apparently having long lasting (or epigenetic) effects for the entire lifespan. Especially for broiler breeders, these interactions are of importance in terms of a long-term solution for the broiler breeder paradox. Indeed, broiler breeders need the genetics for rapid growth and yet have to show a high rate of egg production, in spite of the long recognized negative relation between growth and reproductive fitness. Currently, restricted feeding is the only practical tool available to obtain an optimal equilibrium between growth and reproduction. This has the potential for the impairment of welfare (hunger, behaviour, health, viability). Recent studies suggest that modifying the timing of restriction programmes, the quantity/quality of the diet or the use of genotypes that tolerate ad libitum feeding may achieve a good balance between growth and reproductive performance on the one hand and breeder welfare on the other.

Most rural households have poultry cared for by women, children and vulnerable people – the aged and physically challenged. Family poultry generate 19–50% of rural family income, make up about 77% of the national flock and contribute about 98% of poultry products consumed in the villages of developing countries. Households that accept innovation for semi-scavenging poultry production usually increase weekly consumption of eggs and meat. The importance of family poultry in assisting the landless poor and the destitute is reflected in many national poverty reduction strategy programmes which identify family poultry as one of the keys to accomplishing the millennium development goal of reducing the number of poor by half before 2015. There are few other alternatives in the livestock sector that can be used to reach so many poor people in rural areas. Wherever HPAI occurs in family poultry, it will wipe out the contribution of family poultry to family food security and to family income. While compensation and restocking are important, the greatest need of smallholder poultry producers faced with the challenge of HPAI is for information, knowledge and training for HPAI-safe family poultry production.

The current Highly Pathogenic Avian Influenza (HPAI) crisis, involving the H5N1 subtype, has developed quickly and has overwhelmed the human resource capacity of both international agencies and national governments in many affected countries. It has been recognized that the best way of preventing the emergence of a pandemic influenza virus of avian origin is to control the virus at source. The H5N1 subtype is now endemic in a number of countries and it has become clear that its control and eventual eradication will require a medium to long-term strategy involving multiple stakeholders. A common understanding of the problem and effective education and communication components are important elements of the control strategy. This paper reviews the challenges involved with the development of effective communication materials and methodologies for the wide range of partners involved in the prevention and control of HPAI, the communication lessons learnt to date and makes recommendations for improving the effectiveness and efficiency of communication activities in the future.