A small introduction:

The UK has an excellent reputation for high standards in animal welfare. The first legislation on animal welfare in the world was implemented here in 1822 by an "Act to Prevent the Cruel and Improper Treatment of Cattle" - and the UK has led the way ever since. Domestic and captive animals are now protected by the Protection of Animals Acts, 1911-2000, making it an offence to cause unnecessary suffering whether by commission or omission. Laws exist to protect performing animals, pets, to prevent cruel sports for example  cockfighting,  abandoning animals, to set standards in boarding and riding establishments, dog breeding and farriers, to monitor tethering, keeping of wild animals and so on.

In addition to the above, farmed animals are further protected by the Agriculture Act (Miscellaneous Provisions) 1968 and the Welfare of Farmed Animals Regulations (England) 2000 with similar legislation in Scotland, Wales and Northern Ireland. These regulations provide for farm inspections, requirement for record keeping, animal freedom of movement, standards of buildings and equipment and feeding and watering. No animal may be caused unnecessary pain or distress. Specific Codes of Recommendations have been approved by both houses of Parliament and while these do not lay down statutory requirements per se, the onus is on all attending to livestock to be familiar with and have access to the relevant codes for the species they are involved with.

Other Aspects of Welfare Legislation also exists to monitor the wellbeing of animals in markets (from the time of unloading to departure), during transport (from loading, to care during the journey to unloading) and at slaughter.