Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: March 5, 2003
Publication Date: March 5, 2003
Citation: Kahl, S., Elsasser, T.H. 2003. Dissociation of glucocorticoid and tumor necrosis factor-alpha (TNF-Alpha) responses to repeated endotoxin (LPS) challenges: Effects of individual versus group penning [abstract]. Journal of Animal Science. v 81(1):192. Technical Abstract: The development of effective intervention strategies to limit over-production of proinflammatory cytokines during immune challenge depends on an accurate assessment of how animal-to-animal variability influences the interpretation of data and subsequent conclusions. Our objective was to determine the effect of two LPS challenges (LPS1 and LPS2, 5 d apart; 0.2 ug/kg BW, i.v.) on plasma TNF-a and cortisol (C) responses in heifers kept in individual or group pens. Forty two heifers (309 kg) were fed a forage-concentrate diet and assigned to individual (IND, n=32) or group (GRP, n=10) pens. For LPS challenges and each blood collection, GRP heifers were moved from a group pen to the squeeze chute (total moving distance < 50 m). In IND heifers, LPS challenges and blood collection were performed in assigned individual pens, without animal transfer. For each challenge, jugular blood samples were obtained at 0, 1, and 2 h after LPS injection. The primary response to LPS challenge was measured as area under the time x concentration curve (AUC, ng/ml x h). Overall mean plasma TNF-a and C responses were lower after LPS2 than LPS1 (2.64 vs 4.57, P<0.01 and 48.2 vs 54.8, P<0.05, respectively). However, TNF-a responses were greater in IND than GRP heifers after LPS1 (5.20 vs 3.92, P<0.05) and LPS2 (3.93 vs 1.35, P<0.01). There were no differences in C responses between IND and GRP heifers in LPS1 and LPS2 (52.3 vs 50.8, P>0.05). Results indicate that handling and management of heifers prior to and during acute phase response (APR) to LPS affect the magnitude of proinflammatory cytokine (TNF-a) release. The data also suggest an animal management-related dissociation between glucocorticoid and TNF-a response during APR that compromises interpretation of the degree to which LPS tolerance develops.