Can simple visual discrimination learning be used on laying hens as on-farm assessment?

  • Dr Franziska Kuhne, Department of Veterinary Clinical Sciences, Division of Animal Welfare and Ethology, Justus-Liebig-University of Giessen, Germany
  • Silke Adler, Department of Veterinary Clinical Sciences, Division of Animal Welfare and Ethology, Justus-Liebig-University of Giessen, Germany
  • Anika Sauerbrey, Department of Veterinary Clinical Sciences, Division of Animal Welfare and Ethology, Justus-Liebig-University of Giessen, Germany
  • Feather pecking and cannibalism are the key welfare problems in commercial laying hen husbandry. Both abnormal behaviours have been suggested to originate from the thwarting of highly motivated behaviours in the context of exploration, grooming, foraging and/or perching. Moreover, cannibalism was found to be associated with impaired spatial cognition, while feather pecking has been proposed to reflect some form of behavioural disinhibition. The assessment of specific learning and cognitive skills is crucial to elucidate the neuropsychological underpinnings of these impairments. The aim of the present study was, therefore, to assess the performance of commercial laying hens in a visual discrimination task that can be modified to study a wide range of learning and cognitive skills. Eleven hens, aged 34 weeks, were conditioned and tested on acquisition, reversal, extinction, and relearning of a simple visual discrimination. The experimenters randomly assigned red and blue paperboard discs as discriminative stimuli. The learning criterion was 90% pecks on the correct discs in two consecutive sessions with 20 trials each. Effects of choice latency, number of pecks, and reward delay were analysed using the GLM procedure (SPSS 16®). The hens could be habituated to the test procedure within a reasonable time. Latency in choosing decreased significantly during the procedure, choices to peck at a disc were made more rapidly (p=0.000). The time delay, i.e. the time between pecking the right disc and reinforcement, affected in a negative way this latency in choosing (p=0.011). The number of pecks at the correct disc increased in each learning session (p=0.000). The study suggest that naïve commercially deployed laying hens can be trained in simple visual discrimination tasks within a reasonable time. The assessment of learning and cognitive skills of hens will enhance the understanding of the origin and development of feather pecking and cannibalism.