Creating and Housing the Modern Laying Hen

post-imageDr. Victoria Sandilands, Behavioural Scientist

​The poultry industry has evolved over the last several decades and it is important to understand how and why those changes have taken place. In this article we will explore the modern laying hen and why we can be proud of these birds.

The modern laying hen evolved from the insectivorous jungle fowl, which lived in dense forests and spent 60-80% of the day foraging. Historically speaking, poultry were the responsibility of the “farmer’s wife”. It was her job to feed and house the birds as well as to collect the eggs. These systems were largely outdoors with many birds running around freely during the day to peck and scratch for feed. The birds themselves were typically dual purpose and kept on mixed farms. Housing was in mixed sex groups, in naturally lit barns or outdoors. Shelter was sometimes provided in the form of a coop that birds would use to roost in at night. Birds were fed home-grown cereals and kitchen scraps. They received little to no vaccination or health care and were largely exposed to predators. For these reasons, birds did not grow to their full potential.

​As we began to better understand the needs of the laying hen, it became apparent that these animals needed to be cared for more intensively. Divergence began wherein birds were selected either for egg laying or meat production, but not both. Vaccines were developed, compound feed with added vitamins and minerals was created, and different housing systems were developed. Conventional housing systems (also called “battery” cages) came into style in the 1950s. In these systems, farmers could make better use of space (due to tiered cages), could easily identify and cull poor producers, and ensure proper hygiene of the birds because they were separated from their droppings, resulting in reduce disease and mortality.

Proportion (%) of laying hens housed, or egg produced,

in different housing systems in the UK (Hewson 1986, Defra 2016)

​Many of these changes have been positive for the welfare of the birds but have also introduced unique animal welfare concerns. As such, systems have again shifted to either free-run or enriched/furnished cage systems, both of which better provide for the behavioural needs of the birds in comparison to conventional systems.

Pullets

Pullets are provided with ad lib access to compound feed, fresh water, shelter, heated housed, and vaccinations. They may be raised in either cages or free-run in a barn. The birds are routinely beak trimmed at one day old using infrared laser treatments. Beak trimming is done to reduce damage caused by feather pecking and cannibalism later in life. Although bans on beak trimming have been attempted, the evidence has shown that the risk to birds is so much higher without trimming. Important considerations, however, are that:

– You are removing sensitive tissue (the beak tip)

– If a hot blade is used instead of infrared laser, it can cause neuroma formation in adult birds

– Infrared treatment has short-term effects on beak related behaviours (such as foraging or exploratory pecking)

– We are not treating the problem – why do birds peck each other?

We now know that there are a few management changes that can be made to help prevent feather pecking in a flock. These include:

– The use of dark brooders

– Making the rearing environment as similar to the laying environment as possible so that the transition is not as traumatic

– Getting chicks used to variety so that novelty is not upsetting

– Walk the flock at different times in different clothing

– Use various noises – a bucket falling, door banging, radio playing

Laying Hens

Pullets are transferred to the laying barn at approximately 16 weeks of age and are placed in either enriched/furnished cages or a single tier or multi-tier aviary barn. Free-range birds are also provided with an outdoor area.

“While enriched cages are a wonderful improvement over conventional systems, they are not without issue”

​Enriched or furnished cages are enhanced with scratching areas, nestboxes, and perches. While enriched cages are a wonderful improvement over conventional systems, they are not without issue. Some of these include the following:

– Hens cannot express all natural behaviours (such as dust bathing)

– Limited foraging – litter area is a scratch mat with feed dispensed onto it (some producers do not use this feature due to management issues)

– A nest box is provided but there is no nesting material so birds cannot nest build

– Birds are still kept on wire floors, which can lead to bumblefoot

– There is less weight-bearing exercise than in non-cage systems

– There is competition for resources, particularly feeder space

​Despite these concerns, enriched systems are a great alternative for egg farmers as they allow for smaller groups that are easier to inspect. This makes is easier to identify unhealthy birds. These systems also provide secluded nesting areas and perches and generally show very low mortality.

In non-cage systems (free-run, aviary, free-range), there can be a number of issues as well. Some of these include:

– These are generally large flocks, thus birds are unable to recognize flock mates

– Frequent interactions with strange birds leading to aggression

– Inspection of individual birds is difficult

– Litter is unrewarding with respect to pecking behaviour (usually made up of wood shavings and droppings)

– Freedom of movement and structures within the system (e.g. perches) may cause keel bone damage through flapping/flying behaviours

– If given access to the outdoors:

– A static house cannot move around to fresh pasture; ground gets worn

– Birds need shelter (trees, man-made) to encourage ranging

– There is competition for resources (favoured nest boxes or other areas can cause piling and smothering)

However, these systems can be very positive for the birds because they allow for freedom of behaviour, including the ability to perch, fly, wing flap, forage, dust bathe, and nest.

Depopulation

Depopulation of an average laying barn occurs after one year of egg production. This is due to reduced egg quality and declining egg numbers as the birds age. Some farms choose to humanely euthanize the birds and compost them on-farm. Others choose to transport the birds for slaughter. This can be a major welfare concern for birds at end-of-lay. Laying hens tend to have a weakened skeleton and the chance of injury during transport can be high. Bone fractures have been found to be higher in birds removed from conventional cages, typically in the wings. However, half the birds in free-run systems had bone fractures at some point during their lives as well, most commonly in the keel bone. These birds are fragile. Researchers continue to work on bone density and strength to find a better strain of bird or better management or feeding systems.

Conclusions

Housing methods can change rapidly based on scientific evidence and, unfortunately, fads to please consumer demand. It is important to remember that every system has its drawbacks. We need to endeavor to do better for the birds’ sake while still maintaining production. The bottom line is that any system can perform for a farmer but must be managed well.