EFFECTS OF SOCIAL-STATUS AFTER MIXING ON IMMUNE, METABOLIC, AND ENDOCRINE RESPONSES IN PIGS

The effects of social rank on immune, metabolic, and endocrine respons es were studied in 10 newly mixed groups of German Landrace pigs (9 in dividuals each) at an ape of 12 weeks. Immediately after mixing, the a gonistic interactions (AI) of all group members were continuously reco rded over 3 days (10 h daily). An individual dominance value (DV) was calculated by the number of wins minus defeats in relation to all deci sive fights (DV less than or equal to 0, subordinate; DV > 0, dominant ). Blood samples were taken 24 h before and 3 days after mixing. The d ata showed that the social status had a significant effect on lymphocy te proliferation in responses to different mitogens: socially dominant pigs had higher proliferative response than subordinate pigs. In addi tion, during the observation period the lymphocyte activation by mitog ens increased in the dominant animals and decreased in the subordinate animals with increasing number of agonistic interactions. The rise in total serum IgG concentration 3 days after mixing was higher in domin ant pigs compared with subordinates. The dominance status did not sign ificantly affect plasma metabolic levels nor cortisol concentrations. However, mixing appeared to increase glucose and total protein values and to decrease alkaline phosphatase and cortisol levels in both, domi nant and subordinate pigs. In conclusion, mitogen induced cell prolife ration seems to be a valuable marker for acute social stress in pigs. (C) 1998 Elsevier Science Inc.