EFFECTS OF AN ENRICHED AND BARREN ENVIRONMENT ON BEHAVIORAL AND PHYSIOLOGICAL RESPONSES RELATED TO LAYING HEN WELFARE

This study was conducted to determine the effects of housing environment on behavioral and physiological responses related to laying hen welfare. General observations and two behavioral fear assessments (emergence test [EM] and tonic immobility test [TI]) were used as behavioral assessments. A heterophil/lymphocyte ratio was used as a physiological stress indicator. Nine hundred day-old Leghorn chicks were randomly assigned to either a floor pen environment or a commercial cage housing environment. The cage chicks were housed in 20 commercial battery brooder cages (25 per cage) up until four weeks of age and then moved to 39 battery grower cages (10 per cage). At 16 weeks of age, the pullets were moved into 39 commercial layer cages (8 per cage) for the remainder of the experiment. The floor pen birds were continuously housed in 14 individual floor pens (28 per pen) enriched with perches, dust baths, and nest boxes. General behavioral observations were recorded on birds from nine randomly selected floor pens and cages. Both TI and EM were conducted on ten randomly selected hens from the cage environment and ten randomly selected hens from the floor pen environment. Blood collection from twenty randomly selected hens from each environment was used for a heterophil/lymphocyte ratio. When the two environmental treatments were compared, there were significant differences (P\u3c0.05) between the floor pen birds and cage birds for percentage of birds standing and the log odds of sitting behaviors. Although there was a significant (P\u3c0.05) interaction present between treatment and time, there were significant differences in percentage of birds feeding and log odds of other behavior during certain weeks. There was also an interaction present between treatment and time for EM and TI, which again had significant differences between floor pen and cage birdsat certain weeks (P\u3c0.05). There was no significant difference across all weeks between the cage and floor pen treatments for average heterophil/lymphocyte ratio. Although interactions were present in some of the assessments, looking at trends within the data reveal that floor pen birds may be housed in an environment that is better suited to meet their welfare needs than birds housed in the commercial cage system