A Comparison of the Health and Production Effects of Local Anaesthetic and Non-Steroidal Anti-Inflammatory Drugs with and Without Xylazine Sedation for Calf Disbudding

Use of sedation for disbudding is common practice in a number European countries, with United Kingdom (UK) practices adopting its use. This study assessed the effects of disbudding with and without xylazine sedation on growth rates and calf health on a UK calf rearing unit. Data was collected from 485 dairy crossed with beef breed calves between April and August 2024 from a single calf rearing unit in England. Calves were purchased from multiple farms across the UK and arrived on site at approximately 21 days of age. Calves were disbudded—and, in the case of male calves, surgically castrated—at approximately three weeks after arrival on farm. Pens of calves were assigned to undergo disbudding with (SED, n = 238) or without (CTL = 234) xylazine sedation at a dose of 0.2 mg/kg administered intramuscularly. Calves from both groups were provided with local anaesthetic (procaine hydrochloride) as a cornual nerve block and a non-steroidal anti-inflammatory drug (meloxicam). While other studies have demonstrated some behavioural and physiological indicators of pain to be reduced with sedation, this study found that calves in the SED group had a reduced daily liveweight gain (DLWG) of 0.14 kg/day in the short term (mean 20 days) following disbudding (p < 0.001), but there was no difference in growth rates in the medium-term (mean 43 days) post-disbudding (p = 0.30). Some of this difference could be explained by the slightly higher DLWG pre-disbudding in the CTR group, and it is likely that the physiological impacts of sedation accounted for the rest of this difference. This initial reduction in DLWG following disbudding with sedation should be considered by vets, especially on farms where growth rates may already be compromised. In the sedated calves, 19.3% exhibited either some movement or entry into sternal recumbency. Specifically, a light plane of sedation with calves entering sternal recumbency was associated with a reduction in DLWG of 0.89 kg/day compared to 0.98 kg/day for those that remained in lateral recumbency throughout (p = 0.008). The light plane of sedation may have created additional calf stress, impacted feeding behaviours, and impinged welfare, with further work needed to establish the reasons for insufficient sedation. There was no difference in the number of post-disbudding treatment outcomes between calves disbudded with and without sedation (p = 0.97).