Traditional battery cages for laying hens will soon be banned in the EU but the increased risk of feather pecking (FP) hampers the adoption of alternative housing systems. FP can cause injury and lead to cannibalism and the painful death of target birds. Current management practices (beak trimming, low light) have associated problems. In a joint European project we sought alternative solutions. In our study of associated traits, birds from a line showing low (LFP) rather than high feather pecking (HFP) exhibited greater sociality (motivation to be near companions) and a passive ‘coping’ style. High sociality and passivity were also negatively associated with FP in adults. These findings may guide future breeding programs. Trimming hens’ feathers to mimic the results of FP elicited pecking and some cannibalism, even by birds that had previously shown no FP. Social transmission of gentle but not severe FP occurred when LFP and HFP birds were housed together. Gentle pecking could conceivably lead to severe FP. We then examined chickens’ pecking preferences to guide environmental enrichment strategies. Bunches of string elicited substantially greater interest than other stimuli, including feathers, and white or yellow string was the most attractive. The birds’ manipulation of the string resembled preening. Incorporating silver beads or moving the devices reduced pecking. String sustained lengthy interest, reduced FP in HFP birds, and decreased feather damage in caged layers on a commercial farm. String offers effective, affordable and practicable environmental enrichment. The integrated application of appropriate environmental and genetic strategies is likely to attenuate the expression of FP and its harmful consequences.

Walking ability is related to motor co-ordination which, in rodents, can be assessed by an established test in pharmacological studies — the rotarod test. The purpose of this study was to evaluate a modified rotarod test for chickens and its relation to the often-used gait score system. At the end of their rearing period, we tested 138 male chickens (Gallus gallus domesticus) from three differing growth performance strains: Ross 308 (fast-growing; n = 46), Lohmann Dual (medium-growing; n = 46) and Lohmann Brown Plus (slow-growing; n = 46). First, the chickens’ gait scores were assessed and, immediately following this, they were placed gently onto a steady rod. The velocity of the rotating rod gradually increased, and the latency to leave the rod was recorded. By using a linear mixed model, we were able to show that the latency to leave the rotating rod was significantly predicted by the gait score. Fast-growing chickens had shorter durations on the rotating rod, and these durations were associated with gait score. We conclude that the rotarod test provides an objective alternative method for assessing walking ability in chickens without the need for intense observer training or the risk of observer biases and propose that this novel methodology has the potential to function as a precise, objective indicator of animal welfare.

The avian alimentary tract has evolved into different histologic structures to accommodate the physical and chemical features of several food types and flight requirements. We compared the esophagus, proventriculus, and gizzard of the domestic fowl, Gallus gallus domesticus (GGD) and kestrels, Falco tinnunculus (FT) using immunohistochemistry and scanning electron microscopy with various stains and lectins [Dolichos biflorus agglutinin (DBA) and Ricinus communis agglutinin I (RCA120)], and α-smooth muscle actin (α-SMA). The esophagus of GGD demonstrated thickened epithelium, muscularis mucosae, and inner circular longitudinal tunica muscularis layers; moderate outer longitudinal tunica muscularis layers; and a true crop. In contrast, the esophagus of FT showed a thin epithelium, no muscularis mucosae, moderate inner longitudinal and thick outer circular tunica muscularis layers, and no true crop. In the proventriculus, the nature of the secretion in GGD was neutral, but that of FT was acidic and neutral. In the gizzard, the muscle coat of GGD by α-SMA had no muscularis mucosae, unlike FT, which had muscularis mucosae. In summary, there are many histologic differences between GGD and FT to meet their different physiologic needs, such as feeding.

Junglefowl display adaptive characters like seasonal breeding, well-established social hierarchy, explorative behaviour, territoriality, aggression and short ranged flight, however, they are smaller, produce less and mature later than commercial breeds. Non-green junglefowl cocks display eclipse plumage – a reliable indicator of genetic purity and a trait that has been disappeared from chickens. Junglefowl show high sexual dimorphism, however, intra-sex level variation is considerably limited. There are conflicting reports on viability of hybrids from junglefowl, however, red junglefowl crossed with chickens invariably produce fertile offspring. Although junglefowl and chickens share common parasites and diseases, junglefowl exhibit high variability in natural immunity and are relatively resilient to infection. Junglefowl prefer secondary forests and village environs, demonstrating their propensity for human landscapes. Habitat preference and historical, ritual and leisure activities of ancient man might have resulted in junglefowl being recruited for domestication. Particularly, native chickens share a number of phenotypic characters with junglefowl, however, cosmopolitan chickens have experienced high phenotypic input from world-wide dispersal and adaptation to a wide range of management and breeding regimes. Based on morphological scores and behavioural ecology, red junglefowl resembles chickens and amongst the junglefowls, red and Ceylon junglefowl are closely related, whereas grey and green junglefowl have been found to be distant.

This study reports the development of a novel multiplex PCR assay based on SCAR (Sequence-Characterised Amplified Region) markers for the simultaneous diagnosis of the 7 Eimeria species that infect domestic fowl. Primer pairs specific for each species were designed in order to generate a ladder of amplification products ranging from 200 to 811 bp. Sensitivity tests for each species were carried out, showing a detection threshold of 1–5 pg, which corresponds approximately to 2–8 sporulated oocysts. Distinct isolates of the 7 Eimeria species from different geographical sources were tested and successfully detected by the assay. All the species were amplified homogeneously, whether or not one of them was present in a high quantity, indicating that there was no cross-interference. The assay was also tested with different sources of Taq DNA polymerase and thermocycler models, confirming the high reproducibility of the reaction. The economy of consumables and labour represented by a single-tube reaction greatly facilitates the molecular diagnosis of a large number of samples, making it appropriate for field epizootiological surveys. We propose the use of this multiplex PCR assay as a rapid and cost-effective diagnostic method for the detection and discrimination of the 7 Eimeria species that infect domestic fowl.

The pecten oculi is a highly vascularized and pigmented organ that overlies the optic disc and projects into the vitreous body in the avian eye. First reported over 300 years ago, its function(s) remains a puzzle to ornithologists, ophthalmologists and anatomists. Morphometric study of this unique organ was undertaken in birds exhibiting apparently different visual acuities, namely two species of diurnal birds (the ground-dwelling domestic fowl Gallus gallus var. domesticus and a highly active predator bird, the black kite (Milvus migrans) and a nocturnal bird (the spotted-eagle owl Bubo bubo africanus). The volume of the owl's eye was 4.8 and 2.2 times larger than that of the fowl and the kite, respectively. However, the pecten of the fowl consisted of more pleats (16–18) compared to the kite (12–13) and the owl (5–6). The volume of the pecten of the kite was 1.4 and 2.7 times larger than that of the fowl and the owl, respectively (P < 0.05). Similarly, the surface area of the pecten of the kite was 2.6 and 4 times larger than that of the fowl and owl, respectively (P < 0.05). The volume density of blood vessels (lumen and wall) in the pecten of the kite, fowl and owl comprised 67.7%, 66.9% and 62.6%, respectively, the pigmented tissue constituting the rest. Both the volume density and the volume of the blood in the pecten were higher in the diurnal birds (kite, fowl) than the owl (P < 0.05). The surface area of the capillary luminal surface was 1.7 and 5.3 times higher in the kite than in the fowl and the owl, respectively (P < 0.05). These results suggest that the functional morphology of the pecten correlates with the life-style of the bird and with functional need, and lends further support to the nutritive role of the pecten.

Modern fowl breeder production has resulted in a wide disparity between the environment, mating behaviour and morphology of modern breeds in comparison with progenitor species. The environment is strictly controlled in most respects and dim lighting is maintained with luminaires that were originally designed for humans and that differ substantially in terms of intensity and colour balance from natural daylight. The elaborate mating displays observed in feral poultry and red jungle fowl rarely, if ever, occur in breeder houses. In most avian species females choose the males, whereas cockerels in breeder houses often appear to mate forcibly and aggressively with hens in the absence of any assessment by the hen. Cockerel and hen breeder fowl also differ morphologically from their progenitor species through genetic selection (larger and heavier) or mutilations (dubbing, etc). Given the apparently large differences between the subtle, gradually evolved mating ‘ecology’ found naturally and the production environments found commercially, it is perhaps surprising that little consideration has been given to this disparity in modern breeder production environments. An understanding of the factors governing choice of mate in commercial breeder houses and the influence of the visual environment may highlight novel methods whereby efficiency of these enterprises can be improved and elements of the welfare of breeder fowl assessed.

Haemorrhagic enteritis (HE) of turkeys is an economically important viral disease of turkeys, not only because it causes high mortality and immunosuppression, but also due to increased slaughterhouse condemnations. The disease is characterized by haemorrhagic enteritis and necrosis of lymphoid cells and a proliferation of reticuloendothelial cells in the spleen. In marble spleen disease (MSD), in addition to splenic changes, pulmonary congestion and oedema are also seen. Whereas splenomegaly in chickens (SMC) is characterized by lesions in the spleen similar to those of HE and the pulmonary lesions of MSD. The causative agents of HE of turkeys, MSD of pheasants and SMC are serologically indistinguishable group II Aviadenoviruses. All the three viruses can be propagated in lymphoblastoid cell lines derived from Marek's disease virus induced lymphoma in turkeys viz. MDTC-RP-16 and MDTC-RP19. The infection can be diagnosed by isolation and characterization of aetiological agents, serological tests such as the agar gel precipitation test, enzyme linked immunosorbent assay and the use of immunoperoxidase to demonstrate intranuclear adenovirus-like particles in infected cells shown by electron microscopy. The control of HE is possible by vaccination using avirulent MSD virus of pheasants as well as avirulent or attenuated strains of turkey HE virus.

Avian infectious bronchitis (IB) is a major cause of economic loss to the poultry industry. The disease, which has been identified in many areas of the world, primarily affects the respiratory tract of – usually young – domestic fowl. However, in addition to their common affinity for the respiratory tract, IB virus strains differ in their tropism for such other target organs as the female reproductive system or the alimentary tract and kidneys. The names now normally given to the disease are ‘infectious bronchitis nephritis’, ‘IB nephritis’ and ‘NIB’. These reflect its inflammatory nature and the organ primarily affected. The pathogenicity of IB virus strains varies and the severity of a disease outbreak is also influenced by the age of the birds and by environmental/management factors. In young broilers, which appear to be the type of stock most affected, the main symptoms of nephritis IB are generally the sudden occurrence of mild respiratory signs which tend to decline within a week. This is followed by a rapid rise in mortality causing the loss of 5–25% of the birds over the ensuing 10 days or so. The birds tend to die abruptly. Gross lesions are mainly confined to the kidneys. The kidney parenchyma of affected chickens is pale, swollen and mottled; tubules and urethras are distended with uric acid crystals. In pullets IB nephritis occurs principally in modern hybrid laying stocks shortly after the onset of egg production when, for several weeks, mortality is typically around 0.4% per week. Post mortem lesions resemble those found in broilers but usually visceral urate deposits are also present. Diagnosis of nephritis IB needs to include detection of IB viral antigen using immunofluorescence on frozen kidney sections and/or viral isolation and identification of IBV following standard techniques. Vaccination with the commonly used IB vaccines such as the H120 strain affords only limited protection against nephritis IB. Attention is drawn to the need for further research.

A serological survey of brucellosis in traditionally managed local domestic fowl was carried out using the microtitre serum agglutination test with Brucella abortus antigen. Sixty two of 172 domestic fowl sampled (30%) were positive. Because most traditionally managed animals are not segregated, this indicates a potential source of infection to other livestock. Most of the birds identified as positive had titres of 1:40. The public health importance of the disease is highlighted and control measures suggested.

Vitamin A is an essential nutrient that has an influence on immune responses in birds. Both low and high vitamin A intakes result in impaired immune responses. Low dietary vitamin A has been shown to cause reduced antibody production, defective T-cell responses and reduced phagocytosis, and decreased resistance to infection by bacterial and viral pathogens and protozoan enteropathogens. Enhanced immune responses can be elicited by high, but not excessive, dosages of vitamin A. Optimum immune responses in growing chicks and turkeys were obtained with vitamin A intakes that were 3–10 fold higher than NRC recommended levels.

An ability to alter sex ratio could be enormously beneficial to the poultry industry. As a consequence, there has been increasing scientific interest in avian sex determiniation and sexual differentiation. Recent progress in avian cytogenetics and molecular biology has enhanced understanding of the mechanisms involved. Surgical and endocrinological techniques have been used to reverse sexual differentiation. Mixed sex chimeras, containing both male and female derived cells and produced by embryo engineering, can be used as a novel model for sexual differentiation. A combination of new knowledge and the refinement of techniques could open up new frontiers for the advancement of our understanding of sexual regulation in poultry.

Broodiness or, more precisely, incubation behaviour, results in the regression of the ovary and in lost egg production. It is a particular problem in turkeys and broiler breeders and may become more of a problem for other types of poultry if ‘welfare friendly’ husbandry systems become more widely used. Any system that allows the expression of full nesting behaviour will encourage the development of broodiness. The incidence of broodiness can be reduced in three ways: changing the genotype, manipulating the environment and by administering veterinary products to alter hormone function. The first two methods are generally employed, but are costly. While the third approach has not proved to be commercially viable, the situation may change. Recent advances in understanding the hormone control of broodiness have led to the identification of two novel potential veterinary products for immunization against broodiness. The first is based on the observation that an increase in the secretion of the pituitary hormone, prolactin, causes broodiness. The prolactin gene of the domestic fowl has been cloned and used to produce recombinantderived prolactin. This has been used successfully to immunize domestic fowl against broodiness, without compromising a high rate of egg laying. The second immunological approach is based on the identification of the avian prolactin releasing hormone as vasoactive intestinal polypeptide (VIP). This 28-amino acid neuropeptide was originally isolated from the gut. Immunization against VIP suppresses prolactin secretion and inhibits the development of broodiness while maintaining a high rate of egg laying. It is concluded that two novel immunogens – recombinant-derived prolactin and vasoctive intestinal polypeptide – are effective in suppressing broody behaviour and are available for further development as practical veterinary products.

This paper reviews the literature on the response of young domestic fowl to various food restriction patterns. Emphasis has been given to anatomical, endocrine and immunological factors and their interactions with the genetic background. Under restricted feeding (limitation of the amount or time of access to food) chickens learn quickly to ingest the allocated quantity of food within a short period of time. When exposed to a single sequence of food removal and restoration, body weight losses are reduced for non-adapted compared with adapted individuals, for light breeds compared with heavy breeds, and for older compared with younger chickens. Adaptation to food restriction includes increased capacity and slower evacuation of the gastrointestinal tract (mainly the storage organs) to increase the supply of nutrients during the periods of food deprivation; increased hepatic lipogenesis and glycogen synthesis during the feeding cycle; and decreased heat loss on days of food deprivation. Synthesis and secretion of digestive enzymes in response to intermittent feeding has been found to be population dependent and consistent with the hypothesis that the amount of intestinal chyme mediates the synthesis and excretion of digestive enzymes from the pancreas. Numerous hormones are directly or indirectly involved in the metabolic responses to food restriction. Hyperinsulinaemia, increased plasma levels of growth hormone, triiodothyronine, thyroxine and plasma prolactin have been observed after the reintroduction of full feeding. It is suggested that the altered hormonal environment induced by food restriction contributes to a metabolic situation that may enhance immunocompetence.

Throughout south-east Asia the keeping of indigenous domestic fowl by village communities has been practised for many generations. The custom is likely to continue and remain popular in rural areas. This paper reviews the performance of these fowl in respect of body weight and egg production under intensive and semi-intensive husbandry systems in Malaysia.

Since the recognition of mycotoxicosis about 30 years ago, various research projects have been undertaken to develop measures to prevent or reduce the serious financial losses it causes. Although inhibitors which prevent mould growth and the production of toxic substances have been developed, several factors still limit their effectiveness and practical use by the feed industry. Various kinds of sorbent materials have also been assessed for their ability to remove or diminish the adverse effects of mycotoxins in animal feeds. Even though it does not bind all the mycotoxin and allows partial absorption of toxin in the gastrointestinal tract, hydrated sodium calcium aluminosilicate (HSCAS) is considered to be an outstandingly effective additive. Several new possibilities have emerged involving the use of the sulphur-containing amino acids, antioxidants, vitamins, trace mineral and other nutrients in building detoxicants. Research into methods of preventing mycotoxicosis in poultry needs to be carried out against the background of the underlying levels of mycotoxins found under the normal storage conditions for feed used in the industry.

The paper addresses all feasible applications of long ahemeral light cycles in breeding flocks and reviews the limited published studies. Long cycles are likely to be most beneficial towards the end of the production cycle – when eggshell quality is often poor – and at the beginning of lay to increase the proportion of eggs exceeding the minimum weight for incubation. Published reports show an improvement in both fertility and hatchability of breeding flocks under long cycles.

Although still in the experimental phase, the technique of freezing domestic fowl semen may prove of interest and value to the industry. Various stages of the application of this method of preservation still need to be improved. One of the most critical aspects is the choice of cryoprotectant and its use during the process of freezing and thawing. While glycerol has a better cryopreservative action than other cryoprotectants in domestic fowl semen, it exerts a widely demonstrated contraceptive action, the mechanism of which has not yet been clarified. Thus the use of glycerol as a cryoprotectant must be accompanied by its complete removal before insemination.

The fertilizing capacity of semen preserved by freezing is notably less than that of fresh (non-preserved) material and has been evaluated as 1.6% and 19.7%. Genetic influences appear to affect spermatozoan response and tolerance to thermal treatments resulting in differences in subsequent fertility. Most studies using fowl semen report final freezing temperatures between –79°C and –196°C, a cooling rate of 1–10°C/minute and a thawing rate of 50–70°C/minute.

Straws have been found to be more satisfactory containers than glass vials or ampoules for preserving semen from domestic fowl.

Reports and observations relating to the skeleton and bone biology of the domestic fowl from the mid 16th century onwards have been assembled. Reference is made to early observations on osteology, pneumatic bones, bone growth, vital staining, bone cell microscopy, vitamin D in relation to rickets, genetics, archaeology and the folklore associated with the clavicle.

There has been a long and continuing interest among poultry breeders and scientists in relationships of domestic fowl with their jungle fowl ancestor. Recent commercial practices in poultry breeding have greatly changed and improved the meat and egg stocks available for the production of food. There is concern, however, that artificial selection for traits of economic importance has caused a narrowing of the genetic base and subsequent reduction in genetic variability. Because continued progress in the achievement of increased growth or egg production depends heavily on genetic variability, its present status is of interest. Current techniques in molecular biology allow estimations to be made of genetic distance among populations. This paper reviews DNA fingerprinting in poultry using results from this technique to survey genetic diversity among jungle fowl, domestic fowl representative of stocks from several decades ago and today's commercial broilers and layers. The genetic distance between wild jungle fowl and layers has been found to be similar to that between wild jungle fowl and broilers. Within the two types of modern commercial fowl there is less genetic diversity among broiler than layer stocks.