4Duncan I J H. The pros and cons of cages [J]. World's Poultry Science Journal,2001,57 : 385.
5Webster A B. WeKare implications of avian osteoporosis[J]. poultry Science, 2004,83 : 184-192.
6Parkinson G. Osteoporosis and bone fractures in the laying hen [C]. Progress Report of Work at the Victorian Institute of Animal Science, Attwood, 1993
7North M,Bell D. Commercial Chicken Production Manual (4^th Edition) [M]. New York:Van Nostrand Reinhold, 1990,336.
8Clubb S. Stop the practice of starving birds for egg production [C].Association of Avian Veterinarians Newsletter, 2001.
9Arshad M. An ecological study of Red Jungle fowl (Gallus gallus spadiceus)in agriculture areas[M]. University Putri Malaga, 1999.
10Van Liere,Bokrna S. Shorter maintenance as a function of dust-bathing in laying hens [J].Applied Animal Behaviour Science,1987,18:197-201.
