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

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 × 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 (T0); 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.

Effect of band and knife castration of beef calves on welfare indicators of pain at three relevant industry ages: II. Chronic pain.

Three experiments were conducted to evaluate the effects of band and knife castration on behavioral and physiological indicators of chronic pain in beef calves at 3 different ages (36 calves/age group): 1 wk of age (Exp. 1, 4 ± 1.1 d of age, 43 ± 1.1 kg BW), 2 mo of age (Exp. 2, 63 ± 2.3 d of age, 92 ± 1.7 kg BW), and 4 mo of age (Exp. 3, 125 ± 4.6 d of age, 160 ± 3.4 kg BW). In each experiment calves were randomly assigned to either sham (CT), band (BA) or knife (KN) castration. Experiments 1, 2, and 3 ended when the testicles of banded calves had sloughed off (68, 49, and 42 d, respectively). Animal BW and rectal temperature were recorded weekly over the experimental period. Salivary cortisol, substance P, haptoglobin, scrotal area temperature using infrared thermography, visual evaluation of swelling (5-point scale), and gait stride length were collected on d -1 and immediately before castration and weekly thereafter until the end of the study. Hair samples were collected 1 d prior to and 28 d after castration and at the end of the study for cortisol concentration. Standing and lying behaviors were recorded over a 28-d period immediately after castration. No differences ( > 0.10) were observed in salivary cortisol, substance P, haptoglobin, or hair cortisol among castration methods for any of the 3 ages. No changes in behavior were observed in calves castrated at 1 wk or 2 mo of age. In 4 mo-old-calves, BA spent less time lying ( < 0.01) than CT and KN calves. Also, the average duration of lying time for BA calves was greater ( < 0.05) than for CT calves. Both, 1-wk- and 2-mo-old calves had inflammation in the scrotal area lasting 7 d after KN castration, whereas inflammation was observed for up to 14 d in 4-mo-old calves. Swelling in BA calves lasted for 21 to 28 d in the 2 younger groups of calves, whereas in 4-mo-old calves swelling was observed until d 35 postcastration. Knife- and band-castrated calves did not exhibit indicators of chronic pain or distress when the procedures were performed in calves younger than 2 mo of age. Therefore, pain mitigation should be used when castrating to improve animal welfare, especially when castrations are performed in calves older than 2 mo of age independent of the method of castration.

Effect of band and knife castration of beef calves on welfare indicators of pain at three relevant industry ages: I. Acute pain.

Three experiments evaluated the effect of band and knife castration on acute pain for the first 7 d after the procedure on 1-wk-, 2-mo-, and 4-mo-old calves. All calves were blocked by age and weight and randomly assigned to 1 of 3 treatments: sham castration (control, CT), band castration (BA), and knife castration (KN). Experiment 1 evaluated 1-wk-old Angus bull calves ( = 34; 43.0 ± 6.61 kg BW), Exp. 2 evaluated 2-mo-old Angus bull calves ( = 34; 91.5 ± 11.93 kg BW), and Exp. 3 evaluated 4-mo-old Angus bull calves ( = 35; 157.6 ± 22.52 kg BW). For all experiments, physiological and behavioral parameters were collected before (d -1 and immediately before castration [T0]) and after (60 and 120 min and on d 7) castration to assess acute pain. Physiological measures included complete blood cell count, cortisol, substance P, and scrotal temperature. Behavioral measures consisted of a visual analog scale, stride length, and time and frequency budgets for walking, standing, lying, tail flicking, foot stamping, and head turning. Performance parameters included initial and final BW and ADG. In Exp. 1, tail flicking was greater ( = 0.02) in KN calves compared to BA calves 2 to 4 h after castration, although no differences were seen between BA and KN compared to CT calves. In Exp. 2, a treatment × time interaction ( = 0.02) was observed for cortisol, where KN calves had greater cortisol concentrations 120 min after castration compared to BA and CT calves; KN calves also lay down and ate less ( < 0.01; = 0.02) and stood and walked more ( < 0.01; = 0.05) compared to BA and CT calves 2 to 4 h after castration. In Exp. 3, a treatment × time interaction ( < 0.01) was observed for cortisol concentrations in which all treatments were different from one another at 60 and 120 min, with BA calves having the greatest concentrations, KN calves being intermediate, and CT having the lowest concentrations. Overall, KN and BA castrated calves presented physiological and behavioral changes associated with acute pain; however, 2-mo-old BA calves presented the fewest behavioral changes and no physiological changes associated with acute pain compared to CT calves.

Effect of timing of subcutaneous meloxicam administration on indicators of pain after knife castration of weaned calves.

The newly revised Canadian Codes of Practice for the management of beef cattle requires that as of 2018, calves older than 6 mo of age be castrated using pain control. Castration is a husbandry procedure commonly done without pain control, and there is a lack of agreement on an effective pain mitigation strategy specific to castration. The aim of this study was to identify the optimal time of administration of meloxicam prior to castration. Thirty-four Angus and Angus crossbred bull calves (282 ± 28.0 kg BW) were randomly assigned to 1 of 3 treatments receiving a single s.c. injection of meloxicam (0.5 mg/kg BW): 6 h (6H; = 11), 3 h (3H; = 12), or immediately (0H; = 11) before knife castration. Measurements included visual analog scale (VAS), head movement (HM), accelerometer movement (AM) and strain gauge exertion force (EF) on the squeeze chute, stride length (SL), lying and standing behavior, salivary cortisol (SC), haptoglobin, serum amyloid A (SAA), substance P (SP), and scrotal temperature (ST). Samples were collected on d -7, -5, -2, -1, and immediately before castration (T0) and 30, 60, 120, and 240 min and 1, 2, 5, 7, 14, 21, and 28 d after castration, except for VAS, AM, EF, and HM, which were obtained at the time of castration. A time × treatment effect ( = 0.01) was observed for SP, where 0H had lower concentrations than 3H and 6H calves 1 d after castration, whereas 3H calves tended to have greater levels than 6H calves 5 d after castration. Mean ST was greater ( < 0.01) in 6H calves compared to 0H and 3H calves 120 min after castration, whereas 6H and 3H calves had greater ST compared to 0H calves 240 min after castration. On d 1 after castration, 6H calves had greater ST than 0H and 3H calves, whereas 0H calves had greater ST compared to 3H and 6H calves on d 28 after castration. The SL tended ( = 0.09) to be shorter in 3H and 6H calves than 0H calves 30, 60, 120, and 240 min after castration. Number of peaks from the AM between 2 and 3 SD above or below the mean were greater ( = 0.03) in 3H and 6H calves than in 0H calves. No treatment differences ( > 0.10) were observed for the number of peaks and area for AM and EF, VAS, HM, SC, or haptoglobin. On the basis of these results, the optimal time to administer s.c. meloxicam in 7- to 8-mo-old knife-castrated calves is immediately before castration (0H), as evidenced by fewer indicators of pain and inflammation compared to 3H and 6H calves.