The ID numbers printed on them are allocated from the GB Livestock Unique Identification Service (LUIS) to suppliers of approved identifiers/ear tags.
Gwasanaeth Adnabod Unigryw Da Byw Prydain (LUIS) sy’n gyfrifol am neilltuo rhifau adnabod ac am eu rhoi i’r cyflenwyr cymeradwy iddynt gael eu printio ar y tagiau clust.