111 Changes in proinflammatory cytokines and chemokines in beef steers chronically exposed to endophyte-infected tall fescue seed

Abstract

Abstract Endophyte-infected tall fescue consumption adversely effects health and immune response. The aim of this study was to evaluate the impact of protein supplementation on cytokine response in steers consuming ergovaline, found in endophyte-infected tall fescue. Thirty-two beef steers were fed a total mixed ration (TMR) and randomly assigned to receive one of four treatments for 56 days: endophyte-free seed (0 ug/kg ergovaline) with either 18% (EF-18; n = 8) or 14% dietary protein (EF-14; n = 8) and endophyte-infected seed (500 ug/ kg ergovaline) with 18% (EI-18; n = 8) or 14% dietary protein (EI-14; n = 8). Blood samples were collected for cytokine analysis on d 28 and d 42 of the feeding period representing when steers vaccinated and boostered for bovine viral diarrhea (BVD) types 1 and 2 and infectious bovine rhinotracheitis (IBR). Cytokine concentrations were evaluated using Quantibody Bovine Cytokine Arrays. Data were analyzed using PROC MIXED of SAS with repeated measures. Statistical significance was determined at P0.05). Interestingly, concentrations of cytokines, IL13 (912±148 vs. 410.9±135 pg/mL) and IL21 (1636.0±295 vs. 629±305 pg/mL), which are involved in chronic inflammatory process were greater (P < 0.05) in EI steer compared to EF steers on d 28 and d 42. Concentrations of chemokine CCL4 and proinflammatory cytokines IFNG and IL-1alpha tended to be greater in EI steers compared to EF steers (P < 0.10). Overall, these data demonstrate that consumption of ergovaline increased proinflammatory cytokines and induced a chronic immune response. Developing a better understanding of overall immunity in cattle exposed to endophyte-infected tall fescue is fundamental to improve cattle health within the beef industry.