PS11-26. Effects of a Pecan Shell-containing Diet on Inflammatory Responses of Endotoxin-challenged Beef Calves.

Weaning and shipping calves may induce inflammation, morbidity, and mortality, costing the beef industry ±$900 million annually. Pecan shells contain phenolics with anti-inflammatory properties. This study evaluated the effects of pecan shells on inflammatory and immune responses in steers exposed to lipopolysaccharide (LPS). Beef steers (n = 24) were blocked by initial BW (266 ± 4.8 kg) and randomly assigned to four treatments in a 2 × 2 factorial arrangement: no LPS (−LPS) or subcutaneous LPS injection (+LPS; 2 µg/kg BW) and corn grain-based diets (37% NDF, 13.4% CP, DM basis) containing 10% cottonseed hulls (CSH) or 10% ground pecan shells (PEC). Diets were fed at 1.9% BW (DM basis) daily in two equal meals. Steers were adapted to diets for 14 d before LPS injection on d 15. Rectal temperature (RT) increased in +LPS steers and was greater than −LPS steers at 1, 2, 4, 6, and 8 h (LPS × h; P < 0.01), and RT was lower in steers fed PEC than CSH at 2, 4, and 6 h (diet × h; P = 0.05). Cortisol increased in +LPS steers and was greater than −LPS steers at 1, 2, 4, and 8 h; cortisol also tended to be greater in +LPS steers fed PEC than CSH at 4 h (LPS × diet × h; P = 0.06). Macrophage inflammatory protein (MIP)-1β increased in +LPS steers and was greater than −LPS steers at 1, 2, 4, and 8 h, and tended to be lower in +LPS steers fed PEC than CSH at 2 h (LPS × diet × h; P = 0.09). Tumor necrosis factor alpha increased in +LPS steers and was greater than −LPS steers at 1, 2, and 4 h (LPS × h; P < 0.01). Total white blood cells (WBC), lymphocytes, and monocytes decreased in +LPS steers and were lower than −LPS steers at 1, 2, 4, and 8 h (LPS × h; P < 0.01). Blood glucose in +LPS steers increased and was greater than −LPS steers at 1 and 2 h, then decreased and was lower at 4, 8, and 12 h (LPS × h; P < 0.01). Increases in RT, cortisol, and pro-inflammatory cytokines in +LPS steers indicate stress and inflammation, while decreases in WBC likely reflect recruitment to inflamed tissues. Lower RT and MIP-1β in steers fed PEC suggest an attenuated inflammatory response, potentially mediated in part by anti-inflammatory effects of elevated cortisol in +LPS steers fed PEC.