title: Effects of fighting after grouping on plasma cortisol concentration and lymphocyte blastogenesis of peripheral blood mononuclear cells induced by mitogens in piglets.
abstract: One litter (Group A) of three unacquainted groups of littermates (4 piglets/litter), 64.0 +/- 0.8 days old, was moved to the pen of another litter (Group B) and they were housed together for 19 days after grouping (phase 1). The pigs in Group B violently attacked all the pigs in Group A for 9 hr after grouping. The remaining group was not grouped and used as controls. The plasma cortisol concentrations 1 hr after grouping were significantly higher than those 1 hr before and 24 hr after grouping, and the suppression of lymphocyte blastogenesis of peripheral blood mononuclear cells (PBMC) induced by mitogens was observed on 3, 8 and 19 days after grouping. After phase 1 ended, the pigs in Group A were returned to their own pen for 7 days, and then they were regrouped with the pigs in Group B and reared together for a further 14 days. Neither agonistic behavior nor change of plasma cortisol after regrouping was seen. Though the lymphocyte blastogenesis of PBMC induced by the mitogens on day 0 after regrouping was significantly lower in the pigs of Groups A and B compared to those in control pigs, a significant difference in lymphocyte blastogenesis among three groups was not seen on 7 and 14 days after regrouping. These findings indicate that fighting after grouping unacquainted litters increases plasma cortisol, and suppresses lymphocyte blastogenesis for 26 days after grouping.
authors.affiliation: Department of Veterinary Internal Medicine, Faculty of Agriculture, Kagoshima University, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Deguchi
authors.forename: M
authors.initials: M
authors.lastname: Akuzawa
mesh_terms: D000378:Agonistic Behavior / Q000502:physiology*; D000818:Animals; D006854:Hydrocortisone / Q000097:blood*; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000276:immunology*; D012919:Social Behavior; D013552:Swine / Q000502:physiology* / Q000523:psychology*; D013997:Time Factors
chemical_list: D006854:Hydrocortisone