Aviary systems enable higher stocking densities and ensure full movement of birds. The systems encourage
birds to carry out natural behaviors such as nesting and perching, and provides access to floor litter.
Photo: Vencomatic Group
Many food retailers across North America, Europe, and even Asia have pledged to source 100% of their eggs from cage-free facilities in the next 5 to 10 years. This has created uncertainty for the egg market and among egg producers about how to successfully manage laying hens in cage-free systems while maintaining profitability. Further complicating matters is the fact that the definition of “cage-free” is somewhat unclear and differs depending on the country and regulatory or verification agency. This has left producers uncertain on how to switch to cage-free housing, the system to switch to, and how to manage birds under these systems.
Three main types of cage-free systems
There are many different types of cage-free systems. The most commonly employed designs are:
- floor raised
- aviary
- enriched colony cages
Each of these systems has its own advantages and drawbacks to be considered when converting to cage-free production.
Aviary systems enable higher stocking densities and ensure full movement of birds. The systems encourage birds to carry out natural behaviours such as nesting and perching, and provides access to floor litter. This allows increased movement, exercise, and flight for the laying hens, bringing associated welfare advantages but this type of system also creates farm management challenges.
Enriched cages allow birds more movement plus amenities such as perches, scratch pads, and nesting areas thus facilitating greater feed and health care practices.
Floor housing systems provide birds full access to litter and movement including perches and nesting for comfort.
The aviary and floor housing systems have the distinct disadvantage in that the birds are exposed to litter and excreta, creating potential health and food safety concerns.
Cost differential
In a 2010 study by the USA Coalition for Sustainable Egg Supply (CSES), a Midwest layer farm was examined using 3 different housing systems over 3 years covering 2 laying cycles. The housing systems examined were aviary housing, an enriched colony system, and conventional cages.
The research examined various productivity parameters and factors relating to 5 sustainability areas, being:
- animal health and well-being
- food safety and quality
- environment
- worker health and safety
- food affordability
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As illustrated in Table 1, the study showed that total operating costs in the aviary system were 23% higher than conventional cages. The operating costs of the enriched colony were slightly higher (4%) than conventional cages. Overall, the aviary system was the most expensive to operate in all cost categories. The study examined production parameters across 3 housing systems on a single farm, at the same location and employed the same accounting definitions for consistent biological and financial measurement within each housing system.
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Higher mortality and associated issues
One interesting observation from the study revealed that hen mortality in the aviary systems was 2.5 times higher than conventionally caged hens with a mortality rate of 11.75% and 4.7%, respectively (Table 2, Figure 1). Higher mortality in the aviary system was mainly attributed to hypocalcaemia, vent picking/pick-outs, prolapses, bumble foot, and birds simply getting caught or injured in the cage structure. With higher rates of hypocalcaemia, aviary birds may have an additional calcium demand due to changes in laying behaviour and calcium metabolism. As such, hen behaviour and mineral nutrition should be further investigated to reduce this mortality rate.
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New way of thinking
In today’s market-driven environment, consumer demand needs to be considered and addressed across the entire food production system. With this, a new way of thinking is emerging on how we view the nutrition and health programmes of conventionally raised laying hens versus those in cage-free environments. Updated research and reviews on nutrition and health programmes must be undertaken to determine the revised nutrient requirements and potential health strategies to be employed under this enhanced welfare standard for laying hens. In closing, all production factors such as bird genetics, nutrition, health, and management need to be considered in order to raise welfare-friendly hens as desired by consumers.
This article orginally appeared in Poultry World
