Graduate Thesis Or Dissertation
 

Effects of early rearing environment on learning ability and behavior in laying hens

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  • The effects of enriching the rearing environment of laying hens on their learning ability and behavior were investigated. Day old ISA brown layer chicks were group housed in open floor pens that were either enriched or unenriched. The enriched rooms contained visual stimuli in the form of hanging decorations, auditory stimuli via classical music, and nutritional and tactile enrichment consisting of mealworms, plants, hay, and daily human contact. Human approach tests were conducted with a familiar handler at 2, 4, and 6 weeks of age and with novel handlers at 8, 10 and 11 weeks of age. Ability to locate food presented in novel food and water containers was also examined at week eight. At week 10, a barrier test was conducted and at week 13, a foraging test was done, both to investigate the effects of rearing environment on the birds' problem solving and spatial navigation abilities. Additionally, the productivity of the hens was observed. Egg numbers, egg weights,and locations of eggs laid were recorded for 13 weeks following the onset of lay at 17 weeks of age. The level of aggression birds displayed toward each other during the laying period was also recorded once a week for three weeks using 20-minute scan sampling. Bird weights were also recorded every two months. At the end of the study at the start of week 30, feather scores were recorded. Enriched birds were less fearful of familiar and novel humans (p=0.05), but there was no difference in ability to locate food and water in novel containers as a function of rearing environment (p>0.05). Also, there was no effect of enrichment on performance of the birds on the barrier test (p>0.05). However, the enriched birds located more food patches and demonstrated more vertical investigations than the unenriched birds in the foraging test (both p=0.05). No differences were found between enriched and unenriched birds in regards to egg numbers, egg weights, or the number of eggs laid on the floor. While enriched birds broke more eggs than unenriched birds (p=0.05) they also used the nest boxes more fully, laying more eggs in the top tier of the nest box (p=0.05) than unenriched birds. Additionally, enriched hens weighed more than the unenriched birds (p=0.005) and had better feather condition (p<0.0001). Overall, the results suggest that enrichment positively affects hen behavior in that it reduces fear of humans and novel environments, reduces feather pecking and inter-bird aggression, increases and improves the use of vertical space and ability to locate resources in the vertical plane, without impairing productivity.
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