1. Commercial - stepped and vertical up to 6 tiers high, gravity, scraper and belt clean with space allowances of approximately 450, 500 and 600cm²/bird. Some containing perches.
2. Experimental modified enriched cages - 7 types including those designed by the Universities of Edinburgh and Bristol and Gleadthorpe and Funbo Lovsta poultry research centres.
3. Multi-tier stocked at 15.5 and 18 birds/m².
4. Single tier stocked at 11.7 birds/m².
5. Tiered wire floor type (e.g. Marielund and Lovsta).
6. Perforated floor type plus perches (Vencomatic) stocked at 15 to
7. Some members of the group visited tiered wire floor aviaries in the Netherlands, and Natura and Boleg aviaries in Switzerland, stocked at 18 to
21 birds/m², in connection with the Report on the Welfare of Laying Hens in Colony Systems 1991.
Deep litter and modified deep litter
8. With and without an attached "winter garden", stocked at 7 to
9. Large fixed houses with set stocked or rotational pen pasture.
10. Large polythene tunnels houses moved approximately once a year.
11. Small houses moved frequently over the pasture.
12. All stocked at about 1000 birds/ha. of total land assigned to the flock.