Under Irish legislation, a variety of measures are needed when dehorning or disbudding calves according to their age range.

If the calf is over four weeks of age, then a local anaesthetic needs to be administered before dehorning starts and this needs to be done under veterinary supervision.

Calves disbudded under two weeks old do not require any mandatory local anaesthetic.

Report on timeframe

The observations on legal requirements were made during a report on the optimum timeframe to dehorn calves, entitled Horn bud size of dairy-bred and suckler-bred calves at time of disbudding.

The report also noted that: “Administration of a local anaesthetic as a prescription only medicine (POM) by a non-veterinarian stockperson is permitted under Irish legislation for the disbudding of calves from two weeks to four weeks of age.”

A total of 279 calves were used as part of the study, with 88 dairy-bred Holstein Friesian bulls and 191 suckler-bred animals.

Difficult to set definite ages

Essentially, the study found that setting definite ages for disbudding calves was difficult, especially as the diameter of horns on dairy-bred versus suckler-bred animals of the same age could vary significantly.

It said that more work needed to be done, but had some words of advice for farmers.

It stated: “…the calf should be old enough to have a horn bud, but not so old that their horns are too large, as this would greatly increase trauma and prolong wound healing time”.