4Th G C M Fiks-van Niekerk,H A Elson.Categories of housing systems for hying hens.Animal Sciences Group,Wageningen UR,2006.
5T Shimmura,T Suzuki,S Hirahara,et al.Pecking behaviour of laying hens in single-tiered aviaries with and without outdoor area.British Poultry Science,2008,49(4):396-401.
6Hegelund L,Sorensen J T,KJ?R J B &Kristensen I S.Use of the range area in organic egg production systems:effeet of climatic factors,flock size,age and artificial cover.British Poultry Science,2005,46:1-8.
7R TAUSON.Management and housing systems for layers-effects on welfare and production[J].World's Poultry Science Journal,2005,61:477-490.
8Vestergaard K S,Lisborg L.A model of feather pecking development which relates to dustbathing in the fowl.Behaviour,1993,126:291-308.
9Aerni K,Brinkhof B M W,Webchelser B,et al.Productivity and mortality of laying hens in aviaries:a systematic review[J].World's Poultry Science Journal,2005,61:130-142.
10Patrick H.Zimmerman,A.Cecilia Lindberg,Stuart J.Pope,Elizabeth Glen,J.Elizabeth Bolhuis,Christine J.Nicol.The effect of stocking density,flock size and modified management on laying hen behaviour and welfare in a non-cage system.Applied Animal Behaviour Science,2006,101:111-124.
