259 Impacts of vaccination or lipopolysaccharide challenge on ruminal and physiological responses in beef cattle

Abstract This experiment compared feed intake, ruminal forage degradability, and physiological responses in beef cattle receiving a lipopolysaccharide (LPS) challenge or a modified-live vaccine for respiratory disease. Ruminally cannulated Angus-influenced steers [n = 15; initial body weight (BW) = 589 kg ± 45] were housed in individuals pens with free access to hay, water, and a commercial vitamin + mineral mix during the experiment (d -7 to 7). On d 0, steers were ranked by initial BW and allocated to 1 of 3 treatments: 1) i.v. bolus dose (5 mL) of bacterial LPS (0.5 μg/kg of BW; Escherichia coli 0111:B4) + s.c. injection (2 mL) of 0.9% physiological saline (LPS), 2) i.v. dose (5 mL) of 0.9% physiological saline + 2 mL s.c. injection of Bovi-Shield Gold One Shot (VAC), or 3) i.v. bolus dose (5 mL) and s.c. injection (2 mL) of 0.9% physiological saline (CON). Hay intake was evaluated daily from d -5 to 7. Immediately prior to treatment administration on d 0, polyester bags containing 4 g of ground dietary hay [dry matter (DM) basis] were immersed into the rumen of each steer and incubated for 0, 2, 4, 6, 8, 12, 18, 24, 36, 48, and 72 h for DM and neutral detergent fiber (NDF) degradability evaluation. Blood samples were collected at -2, 0, 2, 4, 6, 8, 12, 18, 24, 36, 48, 60, 72, 96, 120, and 144 h relative to treatment administration. Values obtained before treatment administration were used as a covariate within each respective analysis. Steers receiving LPS had less DMI (P < 0.01) on d 0 and 1 compared with CON and VACC steers. Steers receiving LPS had reduced (P ≤ 0.02) ruminal disappearance rate (%/h) and effective degradability (%) of DM and NDF compared with CON and VACC steers. Steers receiving LPS and VACC had greater (P ≤ 0.05) plasma concentrations of haptoglobin (P < 0.01) from 18 to 144 h relative to treatment administration when compared with CON, whereas LPS steers had greater plasma haptoglobin (P ≤ 0.05) concentrations compared with VACC at 48 and 60 h. Overall, administration of LPS and VACC elicited an inflammatory response in cattle with increased levels and plasma haptoglobin. However, only LPS administration reduced DMI and ruminal in situ disappearance parameters including ruminal disappearance rate and effective degradability of DM and NDF.