title: Anhedonia in pigs? Effects of social stress and restraint stress on sucrose preference.
abstract: The fact that consumption of normally palatable foods is affected by stress in both humans and rats suggests a means to assess hedonic reaction in non-verbal animals. However, little is known about anhedonia and stress in productive animals such as pigs. Thus we examined the separate effects of social stress and restraint stress in 42-day old pigs on the preference for dilute sucrose solutions over water. Pigs in the social stress group (SS) were mixed with unfamiliar animals from separate pens for two 20 minute periods (Experiment 1). Pigs in the restraint stress group (RS) were immobilized three times a day, for 3-min periods, on 3 consecutive days (Experiment 2). Consumption of dilute sucrose solutions and water was examined after these stress manipulations and in the unstressed control groups (CG). Pigs were tested in pairs (12 control and 12 experimental) with a choice between water and sucrose solutions (at either 0.5% or 1%) during 30 min sessions. In both experiments CG pigs showed higher intakes of 0.5% and 1% sucrose solutions over water. Neither SS nor RS pigs consumed more 0.5% sucrose than water, but both groups did consume more 1% sucrose than water. Both social stress and restraint stress reduced sucrose preference at low concentrations but not at higher concentrations suggesting that stress may limit food consumption in pigs unless a palatable feed is present. In addition, the results suggest that stress reduces the hedonic impact of dilute sucrose. Therefore, sucrose preference may be a useful test for the presence of stress and anhedonia in pigs.
authors: Animal Nutrition, Management and Welfare Research Group, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain; Departamento de Fomento de la Producción Animal, Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago 8820000, Chile. Electronic address: jaime.figueroa@u.uchile.cl.
authors: Jaime
authors: J
authors: Figueroa
authors: Animal Nutrition, Management and Welfare Research Group, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
authors: David
authors: D
authors: Solà-Oriol
authors: Animal Nutrition, Management and Welfare Research Group, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
authors: Xavier
authors: X
authors: Manteca
authors: Animal Nutrition, Management and Welfare Research Group, Facultat de Veterinària, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
authors: José Francisco
authors: JF
authors: Pérez
authors: School of Psychology, Cardiff University, Cardiff, Wales CF10 3AT, UK; School of Psychology, University of New South Wales, NSW 2052, Australia.
authors: Dominic Michael
authors: DM
authors: Dwyer
mesh_terms: D059445:Anhedonia; D000818:Animals; D002755:Choice Behavior; D019422:Dietary Sucrose; D004327:Drinking Behavior / Q000502:physiology; D060766:Drinking Water; D005260:Female; D005518:Food Preferences; D008297:Male; D012149:Restraint, Physical; D012938:Social Perception; D013315:Stress, Psychological / Q000209:etiology; D034421:Sus scrofa / Q000523:psychology*
chemical_list: D019422:Dietary Sucrose; D060766:Drinking Water
keywords: Anhedonia; Pigs; Stress; Sucrose