The beginning of the 21st century is an appropriate time to review a century of poultry genetics, because it is one hundred years since Mendel's pioneering work was rediscovered and became part of the mainstream of science. Although, in my opinion, Mendel enjoyed more than a fair share of luck in reaching his conclusions, he nevertheless laid a foundation on which students of poultry, and many other species, were able to build a vast body of literature. Mendel's choice of the height of pea plants, in retrospect, was not a wise one. Here is a trait that is basically quantitative, and yet he was able to describe it, and reach his conclusions, in qualitative terms!

The hen's egg plays a crucial role in the embryonic development of the bird. It serves first as a source of energy and nutrients of high digestibility and, second, protects the embryonic bird against external aggressions. The unique structure of an egg with yolk containing the embryo surrounded by albumen and shell as physical barriers, is the first element of this protection. The second one consists of the specific composition of yolk, albumen and shell with many molecules possessing elevated biological properties. Thus, these molecules represent a major source of active principles usable by medical, pharmaceutical, cosmetic, nutraceutical and biotechnological industries. In this review, we will focus particularly on nutritional, health, and biotechnological activities of egg molecules and on the approaches, which are proposed by European research groups, to exploit this bioactive potential.

Proteins in solution can form objects of various shapes. One fascinating possibility is the formation of fibres with a length up to micrometers, but with a thickness of a few nanometres, therefore referring to them as nano-fibres. Many proteins show this behaviour under the appropriate conditions. Gel properties of nano-fibre containing systems can be manipulated by adjusting the fibre properties. The systems exhibit particular behaviour under flow, which can be utilised in processing. Such nanofibres have innovation potential for foods in terms of for example extremely low weight fraction gels, and their presence may give rise to unexpected novel, including sensory related, material properties.

A first product of this European project was a tool for scoring chick quality. A link was established between chick quality and embryonic physiological parameters such as heat production. Eggs from broiler breeders that give rise to rapidly growing broilers have a different embryonic development that may need modified incubation conditions. Within genotypes, better chick quality induces better liveability and faster growth in broiler production. Extensive data on broiler breeder production were generated. Feed restriction was necessary to maintain welfare and reproduction at acceptable levels in standard broiler breeders. The dw-experimental genotype (E) was more tolerant to ad libitum feeding. If an alternative to feed restriction had to be found, the use of a dw genotype with less severe feed restriction could be adopted. Fibre per se, or partial feed restriction during the growing period, only compensated to a small extent for the negative effects of early fast growth on later reproduction. The results of the project on behaviour did not support welfare concerns on feed restriction. They confirmed the hypothesis that environmental pecking is a displacement activity rather than a sign of frustration. Factors other than central control by pituitary hormones seem to be involved in the modulation of the laying rate. The local (intra-ovarian) role of growth factors such as Insulin-like Growth Factors (IGFs), Bone Morphogenetic Proteins (BMPs) and leptin are known to modulate the effect of gonadotrophins on ovarian function. For both BMPs and IGFs, feed restriction enhanced the interaction between growth factors and gonadotrophins as well as the proliferation of granulosa cells in vitro. Future genetic selection of broiler breeder production might aim at uncoupling the control of growth factors in the ovary from the selection for rapid growth to maintain or increase the growth rate of chicks without further penalising the already poor reproductive performance of broiler breeders. Putative quantitative trait loci for ovulation rate were identified in the project and may eventually facilitate selection by breeding companies for birds that could be fed enough feed to optimise their welfare.

Selection for fast early growth rate and feeding and management procedures which support growth have lead to various welfare problems in modern broiler strains. Problems which are directly linked to growth rate are metabolic disorders causing mortality by the Sudden Death Syndrome and ascites. Fast growth rate is generally accompanied by decreased locomotor activity and extended time spent sitting or lying. The lack of exercise is considered a main cause of leg weakness, and extreme durations of sitting on poor quality litter produces skin lesions at the breast and the legs. Management factors which slow down early growth alleviate many welfare problems. Alternatively it may be considered to use slow growing strains which do not have the above mentioned welfare problems. Since growth is a main economical factor, there are problems of acceptability of these measures in the commercial broiler production. Stocking density is a central issue of broiler welfare. It is evident, that the influence of stocking density on growth rate and leg problems acts through its influence on litter and air quality. High moisture content of the litter enhances microbial activity, which in turn leads to increase of temperature and ammonia in broiler houses, and thus, high incidence of contact dermatitis. High stocking density impedes heat transfer from the litter surface to the ventilated room. This restricts the efficacy of conventional ventilation systems in alleviating heat stress. Lighting programmes with reduced photoperiods are considered essential for the stimulation of locomotor activity and the development of a circadian rhythm in the birds. Extended dark periods, however, reduce growth when applied in the first weeks of age. Compensation occurs when the time of the production cycle is substantially increased. Various methods to enrich the environment have shown only moderate effects on the behaviour and physical conditions of broilers.

A requirement under humane slaughter regulation is that stunning methods should induce immediate loss of consciousness and sensibility. If the onset of unconsciousness is not immediate, the induction of unconsciousness with a stunning method should not cause in animals avoidable anxiety, fear, pain, distress or suffering. The duration of unconsciousness induced by a stunning procedure must be longer than the sum of time that lapses between the end of stun and the time to onset of death. Since the effect of a stunning method is momentary, the onus of preventing resumption of consciousness thereafter relies on the efficiency of slaughter procedure; i.e. the prompt and accurate severance of blood vessels supplying oxygenated blood to the brain. Electrical water baths and gas or controlled atmospheres are commonly used for stunning poultry under commercial conditions. The electrical waveforms (sine wave alternating current or pulsed direct current) and frequencies (Hz) employed to stun poultry and the amount of current applied to individual birds in a water bath stunner widely varies. Rationalisation of electrical variables is urgently warranted. Varieties of gas mixtures have been proposed or used for stunning or killing poultry in crates or conveyors however the bird welfare implications have not been communicated effectively to facilitate progress. This review deals with the efficacy of electrical variables used in the water baths and of slaughter methods, and the relative merits of different gas mixtures used for stunning or killing broilers.

Enhancing meat production by genetic selection for growth has already produced 5-week-old broilers weighing more than 2 kg. As growth performance characteristics continue to improve and the time it takes to achieve market size decreases, the period of embryonic development becomes a greater proportion of the bird's life. Therefore, in parallel to genetic selection, other approaches, such as environmental manipulations in the embryo or in the early days posthatch, are becoming more relevant for increasing muscle growth and meat production.

Recently, we have shown that nutritional treatments, i.e., providing feed immediately posthatch, or environmental treatments, such as heat conditioning or monochromatic green-light illumination during the first days posthatch, increase muscle growth and breast muscle weight at marketing day. In all cases, the increase in muscle growth was due to changes at the cellular and molecular levels leading to increased satellite cell proliferation and differentiation.

The significant effects on muscle growth resulting from the treatments in the first days posthatch raised the hypothesis that muscle growth could be affected during the embryonic development. In experiments in which eggs were illuminated under monochromatic green light from embryonic day 5 (E5), there was a positive effect on embryo development and posthatch muscle growth. Further studies revealed that this enhanced muscle weight was due to increased satellite cell number and fiber synchronization during early days posthatch. Thermal manipulation at 38.5°C from E16 to E18 for 3 h/day had a delayed effect on satellite-cell proliferation and differentiation, resulting in enhanced hypertrophy of myofibers at market age.

The microflora of the digestive tract of poultry is still incompletely known. Microbial populations of varying size and complexity occur throughout the digestive tract and the highest and most complex floras are found in the crop and the caeca. The upper part of the digestive tract is predominantly settled by facultative anaerobes, whereas the caeca are mainly the site of obligate anaerobes. The types, numbers and metabolic activities of the organisms are affected by numerous factors such as individual, animal age, environment, and diet. Bacteria produce various metabolites that can be useful or detrimental to the host. Interactions between bacteria and the gastrointestinal epithelium lead to various structural and functional modifications of the digestive tract. Bacteria can impair lipid digestion and may modify carbohydrate and protein digestion. They cause an increase in energy and amino acid requirements. They have a negative effect on vitamin nutrition. Beneficial bacteria can protect birds against pathogens through a competitive exclusion process. Moreover, the flora is involved in the development of the intestinal immune system. Overall, bacteria have a negative effect on bird growth. They may also have an effect on meat and egg quality. Improved knowledge of the microflora of the digestive tract and its consequences may contribute to its control and beneficial use for birds as well as breeders, consumers and the environment.

Optimal utilisation of limited phosphate resources in animal feeding requires detailed knowledge of both the requirement for available phosphorus (P), and the availability of P from relevant feed ingredients. In growing ducks, the P concentration of gained body weight and the inevitable P losses voided determine the requirement for available P. The concentration of available P needed in the diet then depends on the feed conversion ratio. Plant and mineral feedstuffs contribute to the available P content of the diet depending on their respective availability. This review summarises the literature on P nutrition in ducks with regard to factors affecting P requirement and considerations of P availability, including the use of microbial phytase. Most of the published data refer to the Pekin duck. The P content in body weight gain is 5.0–5.5 g/kg in young ducks, and it probably decreases with age. The ratio of Ca to P in body weight gain is about 1.8:1. Inevitable P losses are not yet quantified and can only be estimated to account for 1 g/kg of feed intake. Availability of P from plant-based diets without P supplements and phytase ranged between 28 and 49%. Availability of P from different mineral sources ranged between 77 and 100%. Microbial phytases were efficient in improving the availability of P from plant-based diets. A simple model is presented, which allows flexible calculations to be made of the necessary P concentrations in the diets for ducks. The most efficient tool for reducing the use of P sources is the frequent adjustment of the dietary P content during the growth period. Data from growth studies indicate that the suggestions made herein are sufficiently safe for application in Pekin duck feeding.

This study attempts to identify the poultry meat farmers' objectives of production, analyse their socio-economic characteristics, determine the optimal farm size and prioritize the constraints to achieving the enterprise objectives. Taking Osun State of Nigeria poultry meat farmers as a case study, data on poultry meat business enterprise objective(s), socio-economic characteristics of farmers and farms, quantity and prices of inputs and output, and constraints to production were collected. Data were analysed using descriptive and inferential statistics, regression technique and importance indices.

From the profit function analysis, the profit maximizing output level was 1034 birds which was higher and more profitable than the mean output level (765 birds) that farmers operated. As many as 88 percent of the farmers sampled produced below the profit maximising level of output. Producing at the average profit maximizing level of output (223 birds) resulted in lower level of output and lower total profit than the mean and profit maximizing output levels. About 90 percent of the farmers produced higher than average profit maximizing output level. The constraints that limit farm size and which could affect sustainability of the enterprise were irregular demand of poultry meat, poor feed quality, high mortality rate and feed price instability in that order. These constraints, if addressed, would lead to increase in poultry meat supply to meet local demand and export.