About buying tags Breeding Pairs If you are keeping sheep longer than 12 months, you must identify them using one electronic tag and one visual tag, both printed with your unique flock number. The electronic tag must be yellow. Slaughter Tags Sheep intended for slaughter within 12 months of birth must carry an electronic tag with the unique flock mark printed on the tag and the individual animal's number contained electronically within the chip of the tag. The electronic slaughter tag must be yellow. Replacement EID tags Only red tags may be used as replacement tags (EID and visual).