Disbudding under sedation stunts calf growth, study finds
Disbudding is painful for calves without sedation.
New research from the Royal Veterinary College (RVC) has highlighted the impact of sedation when disbudding calves.
An analysis of the procedure revealed that calves sedated for so-called ‘knockdown disbudding’ had a lower growth rate than calves which were disbudded while conscious.
Disbudding describes the process through which a calf’s horn buds are removed to prevent horn growth. This is intended to reduce the calf’s risk to other animals and its handlers throughout its life.
In the UK, hundreds of thousands of calves will undergo this operation each year.
However it is painful for the animal, with healing taking up to nine weeks. This has prompted many farmers to opt for knockdown disbudding, where the procedure is performed while the calf is under sedation with xylazine.
This is believed to make the process more comfortable for the calf, as well as enabling handlers to manage multiple procedures.
To assess the impact of such procedures, RVC researchers followed the disbudding of 485 calves in Somerset between April and August 2024. One treatment group received local anaesthetic and Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) with no sedation, whereas the other group also received xylazine sedation.
For the second group, researchers also recorded the sedation quality – whether it was sternal recumbency or lateral recumbency.
Statistics revealed that the sedated calves had grown 0.14kg per day less in the 20 days post-disbudding compared to conscious calves.
Within this sedated group, calves which had entered sternal recumbency grew the slowest, growing at a rate of 0.89kg per day. Meanwhile, calves which entered lateral recumbency grew at a rate of 0.98kg per day.
Additionally, almost 1 in 5 calves under lateral recumbency either showed movement or ended up in sternal recumbency. This could suggest that lateral recumbency is not always deep enough.
Researchers say that these findings not only pose an economic concern for farmers, but also suggest stress or welfare compromise. They encourage veterinary professionals to carefully consider sedation use in disbudding, particularly since sedation quality cannot be guaranteed.
Sophie Mahendran, lecturer in Farm Animal Health and Welfare at the RVC, said: “Knockdown disbudding is often used when calf handling facilities are poor, or to try and increase efficiency when disbudding large numbers of calves.
“However, this work has shown that it causes reduced calf growth rates for approximately 20 days following disbudding, and that this effect was worse in calves that only experienced a light plane of sedation and were able to enter sternal recumbency during the procedure.
“Therefore, vets should consider whether sedation should be used as a standard restraint method, or whether investment into appropriate calf handling facilities should be encouraged on farms.”
The full study can be found in the journal Dairy.
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