Although many factors affect the welfare of hens housed in cage and non-cage systems, welfare issues in cage systems often involve behavioural restrictions, whereas many welfare issues in non-cage systems involve biosecurity, health and hygiene. This review considers and compares the welfare of laying hens in cages, both conventional and furnished cages, with that of hens in non-cage systems, so as to highlight the welfare implications, both positive and negative, of cage housing.

Barn (and aviary) egg production systems provide hens an opportunity to practice a repertoire of behaviours when compared to cage systems, and provide better biosecurity, predator protection and environmental control than the free-range systems. However, fractures, foot-pad lesions, feather pecking, manure-borne diseases and parasites are reported to be high. While less popular than free-range systems in Australia at present, barn and aviary systems could be a welfare choice over cage systems in future.

The twenty-first century has seen a large shift in table-egg production systems due to changing consumer expectations, which has seen chickens move from cage production to floor-based and free-range production. This has represented challenges to the industry, and the breeding companies have responded through genetic selection for improved behaviour, dietary and welfare outcomes. Together, breeding companies and producers are now able to produce table eggs cost effectively in a variety of housing systems that enhance animal welfare.

Incubation and hatchery practices have become a focal point for producing optimum chick quality as this has been positively correlated with overall flock performance, especially egg production, shell quality, liveability and animal welfare. Recent advances in incubation have focussed on the benefits of single-stage machines, and modern incubators have been designed to maximise chick yield and chick robustness, which reduces chick 7-day mortality. Together, recent improvements in incubation and hatchery practice provide commercial layer chicks that are healthy and of high quality, which are then in an optimal condition to thrive and achieve their true genetic potential.

The early rearing environment of pullets has a major effect on the behaviour and welfare of laying hens throughout the laying period, in particular the development of feather pecking. The effect of housing system, lighting, air quality, environmental enrichment, social grouping, feeding and beak trimming during rearing are discussed.

Captivity may restrict behaviours that animals have instinctive, intrinsic propensities to perform whatever the environment or behaviours that are elicited by deficits in the animals’ environment. Behavioural restriction may also thwart general motivation to seek variety and/or avoid monotonous conditions. The present review examines the most contentious natural behaviours in terms of the welfare of laying hens. The review also examines the implications of a lack of opportunity for variety and/or to avoid monotony on abnormal behaviour in laying hens.

It is essential to understand responses to stress and the impact of stress on physiological and behavioural functioning of hens, so as to assess their welfare. The current understanding of stress in laying hens is comprehensively reviewed here. Understanding the regulation of stress responses and the impact of stress on normal functioning of hens will provide important advances in the assessment of welfare of laying hens.

The impact of management and husbandry decisions on the welfare of laying hens is a diverse topic, including physical aspects of the hen’s environment, routine husbandry, and interactions with the stockpeople. This review sheds new light on many of these topics under Australian conditions, and topics for future research have been identified.

Hot blade (HB) beak trimming results in short-term pain. Chronic pain will result with HB trimming when an excessive amount of beak is removed. Current levels of infrared beak treatment (IRBT), which coagulates blood vessels in the beak followed by sloughing of the beak tip, does not result in chronic pain. HB trimming can reduce feed intake, pecking efficiency and comfort behaviours, while IRBT results in minor changes to pecking efficiency.

Feather pecking is an abnormal behaviour performed by laying hens leading to the removal of feathers from other hens, often accompanied by wounds, poor feather cover and increased risk of cannibalism. This review discusses the multifactorial causes of feather pecking and describes good management practices to reduce the risk of pecking outbreaks occurring in commercial flocks. While the welfare of pecked hens is reduced, flock egg production also declines, indicating the need to control feather pecking on commercial farms.

Induced moulting is used to extend the period of lay for hens and reduce replacement costs. It involves restriction of nutrients, and occasionally reduced lighting, which results in loss of bodyweight and feathers, regression of the reproductive tract and cessation of egg lay. When moulting is completed, the reproductive tract regenerates and egg production resumes. Induced moulting can increase bird stress and increase aggression and injurious pecking.

Non-infectious diseases are a cause of considerable concern in modern egg layer flocks and particularly in cage-free management systems. The major issues seen include grass impaction, smothering, exposure to high-intensity light, predation, obesity and increasing age. Increased emphasis on managing these conditions will have major impacts on hen welfare.

Infectious diseases of layer chickens are a significant welfare concern as they cause a range of clinical signs and mortality. Basic skills in the early detection of the disease are important for making a provisional diagnosis and taking immediate action to eliminate or reduce the impact on bird’s welfare. To facilitate rapid diagnosis, here, in this review, diseases have been described on the basis of their presentations, which include sudden death, respiratory illness, ill thrift, diarrhoea, lameness or recumbency, and reduced egg production and quality.

Antimicrobial use in egg layers has increased with the growth of extensive free-range production systems. There are very few registered antimicrobials for use in hens producing eggs for human consumption and continued use can lead to loss of effectiveness, with welfare implications, as health can be adversely affected. Continued development of alternative disease control measures, such as vaccines and non-antimicrobial treatments, is vital for future bird health and welfare, and to strengthen antimicrobial stewardship.

Euthanasia of an animal requires a quick and humane death, administered in a timely manner to minimise pain and suffering. This review discusses the three main reasons for euthanasia in the laying hen industry: humane destruction of day-old male chicks, euthanasia of individual birds, and depopulation of flocks for disease control or because transport and slaughter is uneconomic. Impact on animal welfare of current practices as well as the development and adoption of newer techniques and technologies are addressed.