BEHAVIORAL, ENDOCRINE, IMMUNE, AND PERFORMANCE-MEASURES FOR PIGS EXPOSED TO ACUTE STRESS

Weanling pigs (n = 132) were used to investigate the effects of three common stressors (and a control) and differing social status on behavi or, immunity, plasma cortisol, blood chemical, and performance measure s. Eleven blocks of 12 pigs each were evaluated. Each pen contained th ree pigs of dominant (DOM), intermediate (INT), or submissive (SUB) so cial status. Two weeks later, random pens of pigs experienced either a control treatment (CON) or they were stressed for 4 h by shipping (SH IP), heat-stressed (HEAT) with overhead heat lamps in their home pens, or cold-stressed (COLD) by direct application of water and an air cur rent. Treatments did not influence body weights; however, percentage w eight loss during SHIP was greater than for other treatments. Body wei ghts were heavier for DOM pigs than for INT and SUB pigs. Social statu s had large effects on plasma cortisol, globulin, acute-phase proteins , body weight, and weight changes. Only acute shipping stress resulted in weight loss. Many immune and blood measures were not changed among acutely stressed pigs; however, the relationship between social statu s and mitogen-induced lymphocyte proliferation and natural killer cell cytotoxicity was disrupted during acute stress. Pig behavior was sign ificantly changed by each stress treatment in a unique manner. During acute stress, behavioral changes seem to be the most consistent and re liable indicators.