Following our exit from the EU, the UK went from a member state to a third country, and this required an amendment for the livestock identification country code prefix from UK to GB.
Ar ôl ymadael â'r UE, aeth y DU o aelod-wladwriaeth i drydedd wlad, ac roedd hyn yn gofyn diwygio'r cod gwlad ar gyfer adnabod da byw o'r Deyrnas Unedig (UK) i Brydain Fawr (GB).