PSVIII-38 Oral hydration therapy and bovine respiratory disease affects rumination behavior, rumen pH, and rumen temperature in high risk, newly received beef bulls.

Abstract

The study objectives were to determine the effect of oral hydration therapy and bovine respiratory disease (BRD) on rumination behavior, rumen pH, and rumen temperature. A random subset of high risk, auction-sourced bulls from 3 truckload blocks (initial BW=188.9 ± 19.1 kg) were fitted with a collar containing a 3-axis accelerometer to quantify rumination time and activity index (n=58), and administered a rumen pH and temperature data logging bolus (n=33). At arrival, subset calves (n = 2/pen) were balanced across treatment pens (n=15/treatment; n=10 animals/pen) and randomized to receive 0.57 L water/45.4 kg BW from a modified oral drenching apparatus (H2O) or no water administration (CON). Standard arrival processing procedures were implemented and bulls were surgically castrated. Modified-live virus respiratory vaccination was delayed until day 28. Daily rumen temperature was altered (P=0.04) such that peak rumen temperature occurred earlier for H2O; whereas, CON had increased (P≤0.01) rumen temperature following delayed vaccination on day 28. Technicians assigned a clinical illness score (CIS) daily; calves with CIS ≥2 and rectal temperature ≥40°C were considered a bovine respiratory disease case (BRD) and treated with an antimicrobial. The fixed effect of BRD cases vs. non-treated cohorts (RCON) was determined retrospectively using data from the accelerometer collar (n= 19 vs. 29) and rumen bolus (n= 12 vs. 21). Calves diagnosed with BRD had decreased (P<0.01) rumination time between 2000 and 0400 hours, greater (P<0.01) rumen temperature until delayed vaccination on day 28, greater (P<0.01) hourly rumen temperature between 0900 and 0300, transiently decreased (P=0.04) activity index between day 9 and 32, decreased (P<0.01) activity index between 0800 and 2000, and altered (P<0.01) rumen pH. Earlier peak rumen temperature observed in H2O may indicate physiological modification enabling a more pronounced inflammatory response. Differences in rumination behavior and activity index are potential tools for early BRD detection.