Pain management and weight gain of calves when disbudding

Disbudding and dehorning are painful procedures for calves and cattle.

This is taken directly from the Guide to Animal Welfare from MPI:

"From 1 October 2019, local anaesthetic must be used when disbudding and dehorning cattle. If you disbud calves without using effective local anaesthetic you could face a criminal conviction and a fine"

Because of these new regulations coming in over the next few weeks, we thought it would be timely to summarise some NZ research on disbudding in calves.

Disbudding with local anaesthesia is effective for reducing responses to pain during disbudding, however, around 2-3 hours after disbudding once the local anaesthesia wears off, calves can show signs of discomfort and pain (ear flicking and head shaking) with these pain-associated changes lasting for at least 24 hours after disbudding.

This study looked at the use of local anaesthetic paired with no pain relief, a topical anaesthetic or meloxicam for calves when being disbudded either under sedation (veterinary standard practice) or while restrained in a crate (farm standard practice).

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Key Points

1. Sedating calves for disbudding reduced the measures of pain experienced in the following 24 hours.

2. There was a benefit to providing calves with topical anaesthetic following disbudding on their behavioural responses and measures of pain sensitivity.

3. Using topical anaesthetics had similar responses to pain sensitivity to that of treating calves with meloxicam.

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Photo provided by Lucy Coleman.

Calves were aged between 2 and 6 weeks at the time of the study from three Waikato farms. On each farm, calves were split into 6 treatment groups for disbudding.

All 6 groups were given a local anaesthetic (Bomacaine, Bayer New Zealand), with half of the calves restrained in a crate and the other half were sedated with xylazine (Xylazine; Phoenix Pharm Distributors, Auckland, NZ).

Within these 2 groups, calves were split into 3 further groups;

1. No further treatment "control", or

2. Injection of meloxicam (Metacam20; Boehringer Ingelheim NZ Ltd, Auckland, NZ) before disbudding, or

3. Topical anaesthetic applied on the horn area after disbudding (Tri-Solfen; Bayer New Zealand Ltd)

See below for a nice flowchart that shows the 6 different treatment groups:

Figure 1. Flow diagram showing the allocation of calves to each group for disbudding.

Half of each of the 6 groups were monitored for behaviours after disbudding and the other half of each group had pain sensitivity testing completed.

Pain sensitivity testing

A pressure algometer was applied to 2 positions around the calf's horn bud (1 and 2 in the diagram below) in the first 24 hours after disbudding to measure the force that was able to be applied before the calf moved away (higher values mean less pain sensitivity).

Figure 2. Diagram showing the position of measurement for pain sensitivity of calves

A greater value (or force) from the algometer indicates the calf was in less pain (the calf did not move away from being touched) and a lesser value indicates the calf was in more pain (moved away quickly from having horn bud touched).

The force required to cause a response was lower between 6–11 hours after disbudding compared with 22–24 hours after disbudding. This indicated that calves had a reduced pain sensitivity by 24 hours after disbudding.

Pain sensitivity (as measured by a higher algometer reading) was low in the first hour after disbudding; due to all calves receiving the local anaesthetic.

Pain sensitivity was lower in all sedated calves (solid bars in Figure 3 below) than in the calves that were restrained and not sedated (speckled bars). The responses to pain were similar between calves that were given the topical anaesthetic or meloxicam (purple and grey) for both groups of calves that were restrained (crate) or sedated.

Figure 3. The mean algometer readings for pain sensitivity measurements in dairy calves (higher values mean less pain sensitivity). Calves were disbudded while restrained in a crate or they were sedated. Within those 2 groups calves either recieved no further treatment (control) or meloxicam or a topical anaesthetic (TA).

Behavioural Observations

The calves that were video recorded for 24 hours after disbudding for monitoring of ear flicking, head shaking and head scratching. These 3 behaviours are common indicators of pain resulting from disbudding and are used in many research studies, an increase in any of these behaviours is associated with increased pain.

Calves in the crate-control group had the greatest number of ear flicks per minute compared with the other 5 groups. Additionally, calves treated with meloxicam or topical anaesthetic had a similar number of ear flicks per minute.

Calves that were sedated and then treated with either meloxicam or with a topical anaesthetic had less head scratches compared to calves in the crate-control group.

For calves that were disbudded when they were restrained in a crate, the use of meloxicam or a topical anaesthetic did not reduce the number of head scratches per minute. For calves that were disbudded when they were sedated, the use of meloxicam or a topical anaesthetic did reduce the number of head scratches per minute compared with calves that were restrained in a crate with no further treatment.

Across the 24-hour study period, the number of head scratches per minute was reduced by 53% in sedated calves compared to non-sedated calves.

Sleeping calves. Photo provided by Lucy Coleman.

From 0 to 12 hours, there were no statistically significant differences in the number of head shakes for each treatment group. At 22 hours after disbudding, calves that had topical anaesthetic (both sedated or restrained) had less head shakes per minute compared with the crate-control calves.

Furthermore, calves that were sedated-control had less head shakes than calves that were restrained-control (i.e. had no additional treatment other than local anaesthetic).

Calves that had meloxicam (both sedated or restrained) and crate-control calves had similar numbers of head shakes per minute.

Weight gain

Calves were weighed before disbudding, 7 days and 28 days after disbudding to determine their average daily gain (ADG).

Days 0 to 7 after disbudding

As can be seen in Figure 4 below, the ADG between days 0–7 was on average 0.14 kg/day greater in sedated calves that were treated with meloxicam (solid grey and starred) than in calves in the crate-control group (black reference line).

All the other groups were similar to each other, this is shown clearly in Figure 4 by the error bars overlapping the black reference line for all groups except for sedate-meloxicam (solid grey).

Figure 4. Average daily gain (ADG) from 0 to 7 days after disbudding of calves that were disbudded while restrained in a crate or sedated and treated with meloxicam, topical anaesthetic (TA) or no further treatment (control). Black line represents the ADG of calves in the crate-control group as the reference value.

The ADG from day 0 to 7 of calves disbudded under sedation was on average 0.10 kg/day more than for calves that were disbudded by restraining in a crate.

Days 0 to 28 after disbudding

There were no significant differences among the 6 groups for ADG in the 28 days after disbudding, as seen in Figure 5 by the error bars overlapping the black reference line for all groups.

Figure 5. Average daily gain (ADG) from 0 to 28 days after disbudding of calves that were disbudded while restrained in a crate or sedated and treated with meloxicam, topical anaesthetic (TA) or no further treatment (control). Black line represents the ADG of calves in the crate-control group as the reference value.

Similar to the ADG from day 0 to 7, the ADG from day 0 to 28 of sedated calves was on average 0.05 kg/day more than for calves that were disbudded by restraining in a crate.

What does all this mean?

The results from this study suggest that if calves are to be disbudded by farmers or contractors (who cannot use sedatives), there may be some benefit of using a topical anaesthetic or meloxicam.

If the budget allows, getting a vet to come and disbud calves under sedation may minimise the pain-associated behaviours after disbudding, more so than using topical anaesthetics or meloxicam. As an added bonus, using sedatives for disbudding was associated with increased growth rates.

The New Zealand Veterinary Association recommends that:

"a combination of sedation, local anaesthetic, and systemic non-steroidal anti-inflammatory drugs should be considered in order to provide the best management of pain and distress caused by such procedures"

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Full Paper:

Cuttance EL, Mason WA, Yang DA, Laven RA, McDermott J, Inglis K 2019. Effects of a topically applied anaesthetic on the behaviour, pain sensitivity and weight gain of dairy calves following thermocautery disbudding with a local anaesthetic. New Zealand Veterinary Journal 10.1080/00480169.2019.1640651: 1-26.