Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/23/1999
Publication Date: N/A
Technical Abstract: Fescue toxicosis in cattle is a result of consumption of ergot alkaloids found in endophyte-infected (E+, Neotyphodium coenophialum) tall fescue (Festuca arundinacea). The condition is characterized by pyrexia, decreased weight gains, rough hair coats, and decreased calving rates. The objective of this experiment was to investigate whether steers grazing E+ fescue have altered host response to lipopolysacharride (endotoxin, LPS) challenge compared to steers grazing endophyte-free (E-) fescue. Angus steers (n=8) had continuously grazed either E+ (n=4) or E- (n=4) tall fescue for eight months prior to the experiment. The E+ steers had lower body weight, depressed average daily gain (ADG), and decreased basal serum prolactin (PRL) compared to the E- steers prior to LPS administration. Each steer received a single i. v. injection of LPS (0.2 ug/kg BW; Escherichia coli: 026:B6) dissolved in sterile saline and blood was serially collected every 30 min for 4 h and at 24 h post LPS administration. Lipopolysaccharide increased serum tumor necrosis factor alpha (TNF-alpha), cortisol, and haptoglobin (Hp) but decreased plasma glucose and insulin-like growth factor-1 (IGF-1). Importantly, however, TNF-alpha, cortisol, and IGF-1 responses to LPS were greater in E+ compared to E-. These results indicate that animals grazing E+ fescue had altered integrated metabolic host response compared to animals grazing E- fescue. Potentially, combined exposure to E+ fescue and LPS, could have greater deleterious effects to the animal compared with exposure to only one of the two and would likely lead to increased catabolism.