Welfare Evaluation by Image Analysis of Laying Hens in Different Breeding Systems and Environmental Conditions

摘要

This work aimed to evaluate aspects related to behavior and welfare of hens, comparing a conventional housing system (battery cages) with another system using litter, lair and roost. In addition, the effects of environmental conditions (stress or comfort) on final egg quality and behavior responses (analyzed by precision techniques) were evaluated using two laying hen lines. Two groups of 20 birds (10 Hy-line W36 and 10 Hy-line Brown) at the beginning of the production phase were .submitted to two environmental conditions (26°C with 60% RH or 35°C with 70% RH) and two housing systems (battery cages or litter) during two consecutive weeks. During the evaluation period, bird behaviors were recorded by video cameras. Eggs produced during the whole experimental period were analyzed according to these quality parameters: egg weight, shell thickness, spec fie gravidity and Haugh unit. A significant (P<0.05) redaction in quality parameters was observed in eggs from laying hem raised under heat stress, mainly in those from the cage system. In relation to behavior, the housing system in litters proportioned the expression of all natural behaviors and those related to bird comfort, which permitted to improve welfare conditions. In the conventional system(laying cages), birds tried to manifest their natural behaviors in spite of lacking conditions for it. This impossibility for executing natural behaviors certainly promoted an increase of stress originated by this kind of housing system.