Effect of Lighting Pattern during Lay on Bone Strength and the Prevalence of Broken Bones in End of Lay Hens

Gregory, 1989, Broken bones in domestic fowl: Handling and processing damage in end-of-lay battery hens, Brit. Poultry Sci., 30, 555, 10.1080/00071668908417179 Gregory, 1990, Broken bones in domestic fowls: Effect of husbandry system and stunning method in end-of-lay hens, Brit Poultry Sci., 31, 59, 10.1080/00071669008417231 Anonymous, 1985. Development trials on lighting regimes for layers. North of Scotland College of Agriculture Technical Note 87 PH pp. 1–3. Aberdeen, Scotland. Belyavin, C.G. 1986. Changing the light pattern can increase margins. Poultry Misset 1986 (Feb): 20–23. Lewis, P.D., 1987. Responses of laying hens to interrupted lighting regimes. Ph.D. Thesis, University of Bristol, 262 pp. Nys, 1981, The effects of 6 and 8 hour light-dark cycles on egg production and pattern of oviposition, Brit Poultry Sci., 22, 391, 10.1080/00071688108447899 The prevalence of broken bones was assessed by physical dissection of the carcass as described in previous studies [1, 2]. Statistical analysis was performed by the Student's t test. Bone breaking strength was determined with a Stevens CR compression analyser (Loughton, Essex, UK) using a 3 point compression system. The moving force was applied to the midpoint of the bone, and it was equidistant between the two supports which were 36mm apart for the humerus and 52mm apart for the tibia. Previous studies had shown that the coefficients of variation between the left and right sides were 8% and 5%, respectively, for the humerus and tibia We thank the Ministry of Agriculture Fisheries and Food for their financial support with this project.