EFFECT OF CAGE AREA, CAGE HEIGHT AND PERCHES ON FEATHER CONDITION, BONE BREAKAGE AND MORTALITY OF LAYING HENS

1. The health of 2 flocks of 896 ISA Brown laying hens were studied su ccessively over the years 1995 and 1996 under different caging conditi ons. Hens were kept in groups of 4 in a total of 224 cages. The treatm ents (7 different types of cages) differed in area per hen (450, 600 o r 800 cm(2)) and height (40 or 60 cm). In the large (800 cm(2)/hen) an d high (60 cm cage) treatment, half of the cages were equipped with pe rches (20 cm/hen). Each study lasted 48 weeks. 2. Feather condition wa s found to be independent of cage type. 3. No differences were apparen t between the 7 treatments in tibia breaking strength (using the 3-poi nt breakage technique). A significant increase in humerus breaking str ength was observed in the high cages. The frequency of broken wings re corded after slaughter tvas lower in high cages (23%) than in low ones (36%). 4. Mortality was different between treatments. This was explai ned by a higher proportion of birds killed by 'body cannibalism' in th e 60 cm high cages, and by a higher proportion of birds killed by 'ven t cannibalism' in the cages with perches.