Submitted to: American Society of Animal Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/26/2003
Publication Date: 6/26/2003
Citation: LAY, JR., D.C., STABEL, T.J., TOSCANO, M.J. EFFECT OF MIXING AND TRANSPORTATION ON BEHAVIOR AND CORTISOL RESPONSE IN RELATION TO SALMONELLA INFECTION IN SWINE. PROCEEDINGS OF THE AMERICAN SOCIETY OF ANIMAL SCIENCE. 2003. ABSTRACT P. 323. Interpretive Summary:
Technical Abstract: When apparently healthy swine are transported, it is not uncommon for a small proportion of them to start to shed Salmonella. Our goal was to identify characteristics of those individuals that shed Salmonella and those that do not shed Salmonella. Thus, we experimentally created transportation stress in order to induce recrudescence of Salmonella in pigs. Two experiments were conducted using 30 pigs in each experiment. Experiment 1 (Exp. 1) differed from Experiment 2 in that Exp. 1 established catheters in the pigs while catheters were not established in Exp. 2. Salmonella-free pigs were inoculated intranasally with 1 x 10**6 Salmonella choleraesuis/pig 3 weeks prior to mixing and transport. Fecal samples were collected and cultured for S. choleraesuis at various time points post inoculation: 8 h, 24 h, 48 h, 7 d, 14 d, 21 d (pre-stress), 21 d (post mixing/transport), 21 d (post mixing/transport/mixing), 22 d (1 d post stress), and 23 d (2 d post stress). Ileocecal lymph node samples were collected 23 d post inoculation (2 d post stress), and cultured for S. choleraesuis. Pigs were mixed for 2 h, transported for 2 h, placed back in a pen together for 2 h, and then return to their individual pens. During the initial mixing, the number and individuals engaged in agonistic behavior was recorded. Blood samples were collected at 0, 3, 5, 7, 24, and 48 h for cortisol analysis. Upon necropsy the body condition was given a score to indicate degree of wounds due to fighting. Data were analyzed in relation to the expression of Salmonella infection. Pigs were classified as 'non-shedders' those that did not shed Salmonella in the feces; 'shedders' - those that did; and pigs that did not shed but had Salmonella residing in the ileocecal lymph nodes. In both Exp. 1 and 2 we found no differences in the number of fights, degree of wounds on body due to fighting, or plasma cortisol concentrations in relation to the Salmonella status of the pigs (P > .10). In each experiment, we had only one pig that was considered a consistent shedder. Interestingly, both of these had plasma cortisol concentrations that were below the mean and median for the group. It was thought that shedders would be more stressed, thus this observation is interesting and warrants further investigation.