THE WELFARE OF LIVESTOCK (PROHIBITED OPERATIONS) REGULATIONS 1982 (Statutory instrument 1982 No. 1884) and its 1987 amendment (SI No. 114) prohibits the following operations in the UK:

Penis amputation and other penial operations
Freeze dagging of sheep
Short-tail docking of sheep (this is allowed providing that enough tail is retained to cover the vulva in the case of female sheep and the anus in males).
Tongue amputation in calves
Hot branding of cattle
Tail docking of cattle
De-voicing of cockerels
Castration of a male bird by a method involving surgery
Any operation on a bird with the object or effect of impeding its flight, other than feather clipping
Fitting any appliance which has the object of limiting vision to a bird by a method involving the penetration or other mutilation of the nasal septum
Tail docking of a pig unless the operation is performed by the quick and complete severance of the part of the tail to be removed and either:
the pig is less than 8 days old, or
the operation is performed by a veterinary surgeon who is of the opinion that the operation is necessary for reasons of health or to prevent injury from the vice of tail biting
Removal of any part of the antlers of a deer before the velvet of the antlers is frayed and the greater part of it has been shed.
tooth grinding of sheep is prohibited.

The above prohibitions apply to animals “for the time being situated on agricultural land” and the provisions are made under the Welfare of Animals (Agricultural Provisions) Act 1968.

Exemptions

The above prohibitions, contained in regulation 3, shall not apply to:

Any act lawfully done under the Cruelty to Animals Act 1876(a)
The rendering, in an emergency, of first aid to save life or relieve pain
The performance by a veterinary surgeon of certain operations or necessary treatments.