5Vits A,Weitznbrger D,Hamann H,etal.Production egg quality bone strength,claw length,and keel bone defornities of laying hens housed in furnished cages with different group sizes.Poultry Science,2005,84:1511-1519.
6Guesdon V,Ahmed A M H,Mallet S,e-tal.Effects of beak trimming and cage design on laying hen performance and egg quality.British Poulty Science,2006,47:1-12.
7Leyendecker M,Hamann H,Hartung J,et al.Keeping laying hens in furnished cages and an aviary housing system enhances their bone stability.British Poultry Science,2005,46(5):536-546.
9Estevez I.Density allowance for broil-ers:where to set the limits.Poultry Science,2007,86(6):1265-1272.
10Dozier W A,Thaxton J P,Purswell J L,et al.Stocking density effects on male broil-ers grown to 1.8 kilograms of body weight.Poultry Science,2006,85(2):344-351.
