6Appleby M C,Hughes B O.Welfare of laying hens incages and alternative systems:Environmental,physical and behavioral aspects[J].World's Poultry Science Journal,1991,47(2):109-128.
7Fleming R H,Whitehead C C,Alvey D,et al.Bone structure and breaking strength in laying hens housed indifferent husbandry systems[J].British Poultry Science,1994,35(5):651-662.
8Tauson R,Abrahamsson P.Foot and skeletal disorders in laying hens.Effects of perch design,hybrid,housingsystem and stocking density[J].Acta Agriculturae Scandinavica Section A:Animal Science,1994,44,2:110-119.
9Webster A B.Welfare implications of avian osteoporosis[J].Poultry Science,2004,83(2):184-192.
10Theo Peters,Hysex-Euribrid.Weight at five weeks deter-mines feture laying performance[J].World Poultry,1997,6(13):43-44.