Author(s)

Janeen L. Salak-Johnson^1*, Sherrie R. Webb²

¹Department of Animal & Food Sciences, Oklahoma State University, Stillwater, OK, USA.
²Department of Animal Sciences, University of Illinois, Urbana, IL, USA.

The objectives of this study were to determine the effects of 4-day of cold and crowding stressors and social status on pig immune responsiveness to these stressors. Three unfamiliar white crossbred female pigs were mixed and assigned to ambient temperatures of either 8°C (COLD) or 22°C (control; TN) and floor-space of either 0.26 m²/pig (reduced, CROWD) or 0.45 m²/pig (adequate, CONT) over six blocks (n = 72). Pigs were identified as dominant (DOM), intermediate (INT), or submissive (SUB) based on aggressive encounters that occurred during the first 24-h post-mixing. There were no interactive effects of temperature × floor-space on immune indices. There was social status × stressor for body weight, natural killer (NK) cell cytotoxicity and phagocytosis (P < 0.05). DOM pigs that were COLD or CROWD gained the least amount of body weight compared to either INT or SUB pigs (P < 0.01). INT and SUB pigs subjected to CROWD stress gained more weight compared to their counterparts subjected to COLD temperature or CONT floor-space (P < 0.05). NK cytotoxicity was greater among CROWD-INT pigs and phagocytosis was greater among COLD- and CROWD-SUB pigs. Also, INT pigs had lower T and B cell proliferation regardless of the stressor. COLD stress significantly reduced NK cytotoxicity, total Immunoglobulin-G, and B-cell proliferation and enhanced total WBC counts and T-cell proliferation. These data imply that various immune indices were either enhanced or suppressed by COLD stress, but concurrent exposure to CROWD stressor did not exacerbate these effects. Moreover, social status played a role in determining a pig’s immune responsiveness as it modulated differential homeostatic stress response as the pig attempted to cope with stress.

Cold, Immune, Pigs, Social Status, Stress

Salak-Johnson, J. and Webb, S. (2018) Pig Social Status and Chronic Cold or Crowd Stressors Differentially Impacted Immune Response. Open Journal of Animal Sciences, 8, 280-293. doi: 10.4236/ojas.2018.83021.