7Appleby M C,Smith S F,Hughes B O.Nesting,dust bathing and perching by hens in cages-effects of design on behaviour and welfare.J.British Poultry Science, 2003,34(5):835-947.
8Appleby M E,Walker A W,Nicol C J,et al.Development of furnished cages for laying hens.J.Poultry Science, 2002,43(4):489-500.
9Tina M McAdie,Linch J Keeling.Reduction in feather pecking and improvement of feather condition with the presentation of a string device to chickens.J.Apphed Animal Behaviour Science,2005,93: 67-80.
10Fleming RH, HA Mccormack, CC Whitehead.Bone struc- ture and strength at different ages in laying hens and effects of dietary particulate limestone, vitamin K and as- corbic acid[J].Brit Poult Sci, 1998(39) : 434-440.