This organic standard commentary from
DEFRA
8.4 Poultry
8.4.1  Poultry must be reared in 
open-range conditions and cannot be kept in cages. 
8.4.2  Water  fowl  must  have  access  to  a  stream,  pond  or  lake  whenever  the  weather 
conditions permit in order to respect animal welfare requirements or hygienic conditions.
8.4.3  Buildings for all poultry must meet the following minimum conditions:  
 
  -  poultry  houses  must  be  structures  with  their  own  dedicated  grazing,  air  space, 
ventilation, feed and water; 
 
  -  at  least  one  third  of  the  floor  area  shall  be  solid, that is, not of slatted or of  grid 
construction, and covered with a litter material such as straw, wood shavings, sand 
or turf;   
 
  -  in poultry houses for laying hens, a sufficiently large part of the floor area available 
to the hens must be available for the collection of bird droppings;  
 
  -  they must have perches of a size and number commensurate with the size of the 
group and of the birds as laid down in Annex VIII;.  
-  
they must have exit/entry pop-holes of a size adequate for the birds, and these pop-
holes must have a combined length of at least 4 m per 100 m2 area of the house 
available to the birds; 
-  each poultry house must not contain more than: 
     
    
4800  chickens; 
3000    laying hens; 
5200     guinea fowl; 
    4000  female Muscovy or Peking ducks or 3200 male Muscovy or Peking ducks 
or other ducks; 
    2500  geese or turkeys;   
  -  the total usable area of poultry houses for meat production on any single production 
unit, must not exceed 1,600 m2. 
8.4.4  In  the  case  of  laying  hens  natural  light may be supplemented by artificial means to 
provide  a  maximum  of  16  hours  light  per  day  with  a  continuous  nocturnal  rest  period 
without artificial light of at least eight hours. 
8.4.5  Poultry, must have access to an open-air run whenever the weather conditions permit  
and, whenever possible, must have such access for at least one third of their life. These 
open-air  runs  must  be  mainly  covered  with  vegetation,  be provided with protective 
facilities, and permit animals to have easy access to adequate numbers of  drinking and 
feeding troughs.