Effects of pain mitigation and method of castration on behavior and feedlot performance in cull beef bulls.

ABSTRACT

The objectives of this study were to evaluate the effects of castration method (banding vs. surgical) and use of analgesia on behavior and feedlot performance in cull bulls. Angus, Hereford, and Angus-crossbred bulls (n = 20; initial BW = 384 ± 59.3 kg; 336 ± 20.1 d old) were housed in feedlot pens equipped with the ability to measure individual daily feed intake. A balanced randomized block design using a 2 × 2 factorial arrangement of treatments was used. A multimodal analgesia (MMA) protocol was used and consisted of sutcutaneous ketamine stun containing butorphanol (0.01 mg/kg BW), xylazine (0.02 mg/kg BW), ketamine (0.04 mg/kg BW), and a local 2% lidocaine hydrochloride anesthetic block of the spermatic cords (10 mL/cord) and scrotum (10 mL) on d 0. Flunixin meglumine (1.2 mg/kg) was administered intravenously on d 0, 1, 2, and 3 to MMA cattle. Cattle were stratified to treatments based on breed, BW, age, and a temperament score. Treatments included 1) band castration without analgesia (BND), 2) band castration with analgesia (BND-MMA), 3) surgical castration without analgesia (SURG), and 4) surgical castration with analgesia (SURG-MMA). All castrations were performed on d 0. Chute exit velocity (EV) and time in chute (TIC) were collected on d -9, 0, 1, 2, and 13. Willingness-to-enter-chute (WTE) score, rectal temperature (TEMP), heart rate (HR), and respiration (RESP) were collected on d 0, 1, 2, 3, and 13. Cattle were weighed on d -9 and 13 while feeding behaviors were collected continuously for 57 d precastration and 28 d postcastration. There was a tendency (P < 0.09) for ADG to be greater in cattle receiving analgesia. Both SURG treatments exhibited elevated TEMP on d 1 (P < 0.001) and 2 (P < 0.05) compared to BND treatments. Postcastration DMI was greater (P = 0.02) in MMA treatments compared with nonmedicated treatments throughout the trial. Meal duration was greater (P < 0.05) in BND than SURG castrates during the first week postcastration. Results suggest that pain mitigation reduces the impact of castration on ADG and DMI.