Effect of preemptive flunixin meglumine and lidocaine on behavioral and physiological indicators of pain post-band and knife castration in 6-mo-old beef calves

One hundred and seventy-four Angus bull calves (248 ± 27.1 kg of body weight (BW), 6-mo-old) were used in a 71 d study to assess the efficacy of the combination of flunixin meglumine and lidocaine in mitigating pain associated with band and knife castration. The experiment consisted of a 3 × 2 factorial design that included castration method -sham (C), band (B) or knife (K); and medication – lidocaine (scrotal ring block 30 mL, 2% HCl lidocaine) and flunixin meglumine (single s.c. dose of 2.2 mg/kg BW) (M), or saline solution (NM). Animals were weighed on d 0 and weekly until d 71 (final BW) post-castration to obtain ADG. Physiological indicators included salivary cortisol collected on d 0 (30, 60, 120 and 240 min), d 2, 8, and weekly until d 48 post-castration; scrotal and eye temperature assessed on d 1, 2, 6, 8, and weekly until d 36 post-castration; fecal samples for E. coli collected on d 0, 2, 6, 8, and 22 post-castration. Behavioral measures included stride length on d 0, 8, and weekly until d 36, visual analog scale (VAS) evaluated during castration, and feeding behavior collected daily from d 0 to d 71 post-castration. Final BW and ADG were greater (P < 0.05) in C than B and K castrated calves. Salivary cortisol concentrations were greater (P < 0.05) in B and K calves than C calves up to 4-h post-castration, and remained greater in K calves up to 48-h post-castration, while concentrations were lower (P = 0.01) in M than NM calves. Fecal E. coli varied daily (P = 0.01) however, there was no obvious pattern over time. Scrotal temperature was greatest (P < 0.05) in K, intermediate in C and lowest in B calves, except at 30 min, and 22 and 36 d post-castration where they did not differ from C calves. Eye temperature was greater (P < 0.05) in B and K than C calves on d 2 and 8 post-castration. No differences (P > 0.10) were observed for stride length. The VAS scores were greater (P = 0.01) in K than C and B calves, while NM had greater scores (P < 0.01) than M calves. Dry matter intake and meal size were greater (P = 0.05) in M than NM calves. Meal duration was greater (P = 0.01) in B and C than K calves on d 0, while K calves had greater (P < 0.01) meal duration than C calves 1 and 2-wk post-castration. Overall, the combination of flunixin meglumine and lidocaine reduced physiological and behavioral indicators of pain, suggesting that their combined use was effective at mitigating pain associated with band and knife castration.