title: Rearing piglets in a poor environment: developmental aspects of social stress in pigs.
abstract: Effects of rearing conditions on the development of social relationships were investigated in female pigs. For that purpose, one group of piglets was reared in a poor environment (i.e., a commercially used indoor 4.2-m2 standard farrowing crate) and the other in an enriched environment (i.e., 0.5-ha outdoor pasture with half-open farrowing crates). After weaning, all piglets were housed in pairs under standard conditions. Dominant and subordinate individuals were distinguished within pairs and social relationships between members of a pair were studied in adulthood. The results show that pairs reared in a poor environment behave more aggressively. The subordinates of these pairs also develop symptoms indicative of chronic social stress exposure: i.e., they show a delayed onset of puberty, a smaller daily weight gain, and elevated basal cortisol levels that are also higher 5 h after an acute restraint stressor (tethering stress). No such deviations were found in subordinates reared in an enriched environment. It is concluded that rearing piglets in a poor environment may facilitate the development of social stress in adult (subordinate) pigs. Two underlying mechanisms may be proposed: a) deteriorated social skills lead to increased social stress, or b) a failure to cope with stressors in general, and the stress of being subordinate in particular, occurs in animals reared under poor conditions.
authors.affiliation: Department of Animal Husbandry, Agricultural University, Wageningen, The Netherlands. Francien.deJonge@etho.vh.wau.nl
authors.forename: F H
authors.initials: FH
authors.lastname: De Jonge
authors.forename: E A
authors.initials: EA
authors.lastname: Bokkers
authors.forename: W G
authors.initials: WG
authors.lastname: Schouten
authors.forename: F A
authors.initials: FA
authors.lastname: Helmond
mesh_terms: D000374:Aggression / Q000502:physiology / Q000523:psychology; D000375:Aging / Q000523:psychology; D000818:Animals; D004971:Estrus / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006799:Housing, Animal; D006854:Hydrocortisone / Q000097:blood; D011606:Psychosexual Development / Q000502:physiology; D012149:Restraint, Physical; D012930:Social Dominance; D012931:Social Environment; D013315:Stress, Psychological / Q000503:physiopathology / Q000523:psychology*; D013552:Swine; D015430:Weight Gain / Q000502:physiology
chemical_list: D006854:Hydrocortisone