Effect of a single dose of meloxicam prior to band or knife castration in 1-wk-old beef calves: I. Acute pain

摘要

In Western Canada, approximately half of the calves produced are castrated before 1 wk of age. Therefore, it is important to identify effective analgesic drugs to mitigate pain associated with castration and consequently improve animal welfare. The aim of this study was to assess the efficacy of a single s.c. dose of meloxicam at mitigating pain associated with knife and band castration in 1-wk-old calves. Seventy-two Angus crossbred bull calves (47.3 +/- 6.70 kg of body weight (BW), 1 wk old) were used in a 3 x 2 factorial design where main factors included castration method-sham (CT), band (BA) or knife (KN) castration- and medication-lactate ringer (NM) or 0.5 mg/kg BW of meloxicam (M). Measurements included different physiological and behavioral parameters. Samples were collected on day -1, immediately before castration (TO); and 60, 90, and 120 min and 1, 2, 3, and 7 d after castration except for visual analog scale (VAS) which was collected at the time of castration. The salivary cortisol concentrations were greater (P = 0.04) in KN and BA calves than CT calves 60 min after castration, while 90 min after castration BA had greater concentrations than CT calves. Substance P concentrations were greater (P = 0.04) in NM calves than M calves on d 3 and 7 after castration. The serum amyloid-A (SAA) concentrations were greater (P = 0.05) in KN calves than BA and CT calves on days 0, 2, and 3, while BA calves had greater SAA concentrations on day 7 than KN and CT calves. The visual analog scores were greater (P 0.01) in KN calves than BA, and in BA compared to CT calves. The KN calves tail flicked more (P 0.01) than BA and CT calves, and NM calves tail flicked more (P = 0.03) than M calves. No castration or medication effect (P 0.10) was observed for stride length, walking, standing, lying ventral, eating, foot stamping, head turning, lying and standing percentage, performance, platelets, or body temperature. Overall, knife castrated calves exhibited a greater acute pain response than band castrated calves. Meloxicam was able to reduce substance P concentrations, white blood cell counts and number of tail flicks after castration, suggesting that the drug was able to mitigate acute pain to some extent. However, meloxicam did not have an effect on the other physiological and behavioral parameters assessed.