Egg Industry Articles


Cage Free Housing Systems

Mar 24, 2017


In reviewing equipment offered by both U.S. and EU manufacturers at the 2017 IPPE and at the Midwest Poultry Federation Convention it is evident that our ‘cage-free’ market is now characterized by five distinctly different systems each with its own advantages and features relating to density, acceptability by flocks, and contribution to performance. 


The most important considerations weighed by potential purchasers relates to acceptability by customers. It is indeed unfortunate that decision makers among the major supermarkets, wholesale-club and QSR chains have little experience in production. They are frequently misguided by self-appointed welfare experts or they misinterpret published or posted data. 

This may have profound implications for a producer intending to supply a chain based on a short-term arrangement but with a financial commitment to a system of upwards of 15 years.

The various systems reviewed comprise:-

  • ENRICHED COLONY MODULES – With the move away from conventional cage housing, the HSUS and the UEP agreed in 2012 that enriched colony modules could be regarded as a practical and acceptable alternative. It was intended that the operating parameters associated with enriched colony modules would be incorporated in to a Federal standard.  Due to political opposition and scheduling restraints, the so called “Egg Bill” was never enacted.  Some producers anticipating passage of the Egg Bill purchased and installed enriched colony modules which proved to be highly successful.
  • As a hedge against uncertainty coincident with the need to expand, from 2012 through 2015, producers replaced conventional cages with “enrichable modules”.  The systems were designed to be retrofitted with partitions, nesting areas and other installations without major expense and disruption, although at an additional cost.  Given the failure of the “Egg Bill” and the subsequent trend to “cage-free” housing mandated by QSRs, food service companies and supermarket chains, these-modules are regarded as a confined system and are essentially unacceptable based on the paraphrase that “a cage is a cage is a cage”.  Accordingly there are virtually no new orders outstanding for enriched colony modules in the U.S.
  • SLATTED-FLOOR AND SLAT-AND-LITTER BARN SYSTEMS – Most of the new small units to house up to 20,000 hens erected by contractors are based on a barn equipped with slated floors, a litter area, mechanical colony nesting, power-ventilation, feeding and watering systems.  These installations can be configured to conform to a range of welfare standards with the addition of perches, and lighting systems with minimal disruption and cost. Most single-house contract farms allow for outside access of up to 2 ft2 per hen which is not possible for in-line units with 100,000 birds in a multi-level house with compartments.
  • OPEN AVIARIES – The system was initially introduced from the EU for either new installations or as a retrofit to existing high-rise houses with modifications for two-level production using both the pit area and the old cage compartment.  Open aviaries allow access from all tiers to the floor. Tiers are equipped with colony nests, feeding and water lines.  Open aviaries allow expression of natural behaviors including dust bathing and scratching. Movement of hens from the upper tiers to the litter and between adjacent rows may result in damage to the sternum of hens.  It is axiomatic that pullets to be housed in any aviary system must be reared in a compatible module to ensure that they develop the ability to move from the floor upwards into the tiers and acquire sufficient development of the pectoral muscles and balance for short flight.  Shortly after installation of the initial aviary systems it was noted that light-hybrid white-feathered hens favor the top tier resulting in uneven stocking density in the house.  In contradistinction brown-feathered pullets reared on the floor fail to use the second and third tiers creating over-population on the lowest tier and on litter resulting in smothering and an unacceptable level of floor-laid eggs in the restricted litter area.
  • SELECT ACCESS AVIARIES – Problems noted with the initial open aviaries were addressed with this system fitted with either moveable or more commonly fixed doors.  It is necessary for a hen to move from the floor upwards through the tiers to ascend to the top level and then to reverse the path back to the litter.  This obviates injury caused by attempts at free flight.  Doors also allow confinement of the flock during the four week “training period” after transfer when it is necessary to allow the flock to become accustomed to their environment and to find feed and water and to explore nests.  Unfortunately observers lacking in experience with management of flocks regarded the doors as a “cage” despite the fact that door opening can be monitored. At any time during the daylight period, hens are distributed fairly evenly among the tiers and on litter.  Nevertheless select access aviaries have been disallowed by some customers.
  • COMBI CONVERTIBLES – This system also referred to as a “Hybrid” closely resembles the enriched colony design but doors are deleted or if installed can be fixed in the open position after the initial four-week “training period”. Combi convertible modules offer the greatest flexibility in terms of configuration, but with variable customer acceptance and more demands on management. Experience has shown that performance in this system may be inferior to either open aviaries or select access aviaries especially with regard to feed conversion efficiency and livability as smothering does occur with the system.

To satisfy the demands of welfare certifying agencies, cameras mounted in houses can verify that the doors of Combi and Select Access aviaries are in fact open after the initial training period. Technology is offered to record the mechanical opening or closing of doors.  Under practical conditions a house containing over 50,000 hens would require extensive labor and time to open or shut doors and it would therefore be impractical to confine flocks after onset of lay.

Producers are naturally reluctant to commit upwards of $35 per hen to a specific installation until there is some assurance and certainty that their selected system will be acceptable to a range of potential customers.  A major problem relates to the definition and description of systems because each will require slightly different standards by which compliance can be judged.

It is strongly suggested that some coordinating body other than the USDA become involved in defining the systems, each with specific design features so that welfare agencies can develop broad standards to be applied by auditors.  Speaking to equipment suppliers and potential buyers at the 2017 Midwest Poultry Federation Convention it was evident that the selection of a system is somewhat analogous to group of penguins sitting on an ice shelf. 

They know they have to go into the water but they also know there are sharks and orcas offshore. Eventually one or two penguins dive in followed by the rest.  That is unfortunately where we are. We need to move on rapidly to meet the requirements of “substantial progress” in replacing conventional cages for more than 150 million hens supplying shell eggs within nine years.