title: Anticipatory and foraging behaviors in response to palatable food reward in chickens: effects of dopamine D2 receptor blockade and domestication.
abstract: Behaviors associated with anticipation and search for palatable food may provide information about dopaminergic reward processes and positive motivational affect in animals. The overall aim was to investigate the involvement of dopamine signaling in the regulation of cue-induced anticipation and search for palatable food reward in chicken, and whether domestication has affected expression of reward-related behaviors. The specific aims were to describe effects of mealworms (palatable food for hens) and haloperidol (a dopamine D2 antagonist) on foraging behaviors and cue-induced anticipatory behaviors in Red Junglefowl (RJF; the wild ancestor of modern laying hens) and a white layer hybrid (LSL). RJF (n=26) and LSL (n=20) were initially trained on a conditioning schedule to anticipate mealworms (unconditioned stimulus; US) 25s after exposure to a red light (conditioned stimulus; CS). For the experiment, hens received haloperidol or saline injections 30 min before exposure to one CS+US combination. Behavior was registered 10 min before CS and 10 min after US (foraging behaviors), and during the CS-US interval (anticipatory behaviors). Higher frequencies of CS-induced anticipatory head movements, faster approach to rewards, and higher frequency of foraging behaviors were found in LSL compared to RJF. Haloperidol suppressed CS-induced head movements in both breeds, and the frequency of foraging behaviors after reward delivery. The results support a role of dopamine signaling in the regulation of reward processes in chickens, and suggest that domestication has changed the threshold for perceiving food incentives and/or for expressing reward-related behaviors that may be indicative of positive motivational affect in hens.
authors.affiliation: Animal Welfare Research Group, NMBU, School of Veterinary Science, P.O. Box 8146 dep., N-0033 Oslo, Norway; Department of Production Animal Clinical Sciences, Norway. Electronic address: randi.moe@nmbu.no.
authors.forename: Randi Oppermann
authors.initials: RO
authors.lastname: Moe
authors.affiliation: Animal Welfare Research Group, NMBU, School of Veterinary Science, P.O. Box 8146 dep., N-0033 Oslo, Norway; Department of Food Safety and Infection Biology, Norway.
authors.forename: Janicke
authors.initials: J
authors.lastname: Nordgreen
authors.affiliation: Animal Welfare Research Group, NMBU, School of Veterinary Science, P.O. Box 8146 dep., N-0033 Oslo, Norway; Department of Production Animal Clinical Sciences, Norway.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Janczak
authors.affiliation: NMBU, Department of Animal and Aquacultural Sciences, P.O. Box 5003, 1432 Aas, Norway.
authors.forename: Morten
authors.initials: M
authors.lastname: Bakken
authors.affiliation: University of Utrecht, Department of Biology, P.O. Box 80125, 3508 TC Utrecht, The Netherlands.
authors.forename: Berry M
authors.initials: BM
authors.lastname: Spruijt
authors.affiliation: Linköping University, IFM Biology, AVIAN Behavioural Genomics and Physiology Group, S-581 83 Linköping, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Jensen
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001947:Breeding; D002645:Chickens; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology; D018492:Dopamine Antagonists / Q000494:pharmacology*; D005247:Feeding Behavior / Q000187:drug effects; D005518:Food Preferences / Q000187:drug effects* / Q000502:physiology; D006220:Haloperidol / Q000494:pharmacology*; D009042:Motivation / Q000187:drug effects*; D012201:Reward
chemical_list: D018492:Dopamine Antagonists; D006220:Haloperidol
keywords: Animal welfare; Bird; Learning; Positive emotions; Positive motivational affect; Reward