Welfare indicators in laying hens

摘要: There is a growing concern regarding the welfare of laying hens worldwide and there are both ethical economic reasons for improving their welfare. Although several different indicators used today, ability to accurately reflect status sometimes questioned. This thesis sought increase knowledge number these by investigating whether what extent they were affected when layers exposed stressors. Three commercial hen genotypes birds challenged being excluded either from nests in furnished cages or litter area single-tier floor system. Excluding resulted an increased stress response that was detectable corticosterone metabolites droppings, concentration egg yolk, heterophil lymphocyte ratio shell irregularities. Excluding during first two weeks facility differences feather cover, approaches towards novel object, tonic immobility duration irregularities measured later period. Interestingly, according used, previously area, consequently deprived available had better than non-excluded birds. In addition, levels droppings influenced factors such as diet, genotype, bird age, cage tier, mass, time day kind assay used. The results showed several, but not all, able detect responses, suggesting more less appropriate use depending on situation prevailing. Many obtained few inconsistent correlations, displaying complex relationship between indicators. Overall, this indicates assessment should preferably be based careful interpretation required before stating firm conclusions