Anticipatory and foraging behaviors in response to palatable food rewardin chickens : Effects of dopamine D2 receptor blockade and domestication

• Behaviors associatedwith anticipation and search for palatable foodmay provide information about dopaminergicreward processes and positivemotivational affect in animals. The overall aimwas to investigate the involvement ofdopamine 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 aimswere to describeeffects of mealworms (palatable food for hens) and haloperidol (a dopamine D2 antagonist) onforaging behaviors and cue-induced anticipatory behaviors in Red Junglefowl (RJF; the wild ancestor of modernlaying hens) and awhite layer hybrid (LSL). RJF (n=26) and LSL (n=20)were initially trained on a conditioningschedule to anticipate mealworms (unconditioned stimulus; US) 25 s after exposure to a red light (conditionedstimulus; CS). For the experiment, hens received haloperidol or saline injections 30 min before exposure to oneCS + US combination. Behavior was registered 10 min before CS and 10 min after US (foraging behaviors), andduring 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 toRJF. Haloperidol suppressed CS-induced headmovements in both breeds, and the frequency of foraging behaviorsafter reward delivery. The results support a role of dopamine signaling in the regulation of reward processes inchickens, and suggest that domestication has changed the threshold for perceiving food incentives and/or forexpressing reward-related behaviors that may be indicative of positive motivational affect in hens.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

Animal welfare Positive emotions Positive motivational affect Bird Learning Reward

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