Effects of Cold and Weaning Stressors on the Antibody-Mediated Immune Response of Pigs

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Abstract
Two experiments were conducted with 48 pigs to evaluate the effects of cold and weaning stressors on antibody-mediated immunity. In the first trial, littermate pigs were weaned at 21 or 35 days of age and exposed at 35 days of age to either a cold (0 C) or a thermoneutral (25 C) air temperature for 96 hours. In the second experiment, 8-week -old pigs weaned at 28 days of age were subjected to the same thermoneutral or cold ambient conditions for 120 hr at 56 days of age. Pigs in both experiments were immunized with sheep red blood cells (SRBC) 24 hr before the initiation of thermal treatment. Exposure to cold resulted in an increase (P<.05) in serum gamma globulin 10 days after the end of the 4 day treatment and also enhanced (P<.05) total and 2-mercaptoethanol (ME)-sensitive (IgM) hemagglutination antibody titers at 7 and 14 days after antigen injection. In the second experiment, gamma globulin concentration in 8-week-old pigs exposed to cold was not altered, but total SRBC antibody titers tended to be higher (P<.10) 10 days after injection of the antigen. Pigs that were weaned 1 day after immunization had lower (P<.05) total and ME-sensitive antibody titers than littermate pigs that were weaned 2 weeks before immunization. Gamma globulin concentration also was lower (P<.05) at 5 weeks in pigs that nursed continuously than in pigs that were weaned at 3 weeks of age. Weaning reduced antibody titers regardless of thermal exposure, and cold stress increased antibody titers regardless of weaning (P>.10). However, cold stress elevated antibody titers more than weaning depressed titers. These data suggest that environmental stressors alter physiological control systems that regulate immunological events. These changes could alter host resistance to infectious disease. More specifically, pigs weaned at 5 weeks of age synthesize slightly fewer antibodies of the IgM class than littermate pigs weaned at 3 weeks when the antigen is injected at 34 days. Nursing also appears to depress gamma globulin concentration in the serum. Cold exposure enhances antibody synthesis and elevates serum gamma globulin. The simultaneous exposure of pigs to the multiple stressors of cold and weaning does not produce an interactive effect. Copyright © 1981. American Society of Animal Science. Copyright 1981 by American Society of Animal Science.

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