ALL pigs require pig identification marks for various purposes. Pedigree pigs have individual marks so it is possible to be certain of their breeding.
Pedigree identification: tattooing, ear-notching (which is being discussed at the moment) and ear tagging.
Tattoos small tattoo administered with small pliers.
Ear tags button tags are preferable to me as they do not get caught and are permanent and also show your herd number, personal identification mark and also a requirement for designated slaughter animals.
Ear notching whilst writing this there is a lot of controversy of this method and I believe the BPA are looking for an alternative to this identification as it is deemed by some as mutilation. Also worth noting, as of January 2010 Oxford Sandy & Black pigs are to be notched. Again there is some controversy over this and as yet i have not heard that this is compulsory.
Slap-marks like a tattoo that is slapped on the side of the pig with a metal plate with small spikes, which are pressed into an inkpad before slapping the pig also suitable for slaughter. Although it sounds gruesome it is best done when the pig is feeding and they dont even notice it.
Temporary marks these are so temporary and are solely for the intensive farming practice where they are moved from one farm to another at different stages of their lives for the different purposes. So identification could be a painted line, a number painted onto its back or a cross.
As of 2013 double tagging is permitted for the identification of a pedigree OSB BUT should you wish to show then the BPA have allowed tattooing this may change for this year but i will confirm once i know.