Cattle wear metal ear tags, pigs have indelible tattoos applied before slaughter. Only sheep in the Republic go unidentified; a shortcoming exposed by foot-and-mouth. However, the Government insists that next month a national sheep-tagging policy will be implemented.
The tags are basic plastic tip tags about the size of a paper clip and costing 15p to 20p, and more permanent triangular tags costing around 25p to 30p.
The two tags are not guaranteed to last permanently in normal sheep-rearing conditions, nor are they impossible to change if a farmer/dealer wishes.
Electronic tagging is seen by the Department of Agriculture and the IFA as a more advanced system.
But as Mr Aidan Murray, principal officer in the animal health and welfare section of the Department, pointed out, problems remain with electronic tagging. Effectiveness, efficiency, reliability and cost are issues still not resolved.
"Even if we could surmount some of the existing problems, it's not approved under EU law at the moment.
"It's certainly something for the future and the not-too-distant future. One to two years, it could be as early as that. We would be very pleased to move down the road of more technologically advanced systems of identification. We have no difficulty with electronic means of identification," he said.
Two systems being studied are microchips, which would be implanted in the sheep's ear and in horses under the mane and a stomach capsule.
Mr Kevin Kinsella, secretary of the IFA's livestock committee, said there were problems with animals destined for the food chain. "There are concerns. When you put something under the skin in an animal, you can't determine the exact location or whether it will move around, and you can't introduce foreign matter into an animal and guarantee that animal," he said.
"At operational level, if you're dealing with lambs or sheep in a field and you have electronic identification that's not visible, you may need some visual identification," Mr Murray said.
"It's not simply pushing a microchip into them and away you go. There have been cases where microchips have migrated within the body of an animal. You have to be very careful with a food-producing animal."
The Government's priority is to have every lamb, ewe and ram identified visually. Tagging of sheep has been compulsory in the EU for several years, and only Britain and Ireland have failed to implement the regulation, opting instead for a flock mark on the fleece and a piece of paper that travels with the animal when it moves from the farm.
Britain introduced tagging only in January and allowed 12 months for it to be put in place. The tags are flock-based and not individual, like the French or Irish systems, and are to be inserted in all animals at 12 months or when they move from their farm of origin.
This meant not all animals were tagged when foot-and-mouth broke out. In addition, tagging on a flock basis and not individually is, British authorities have admitted privately, not a tight system.
Mr Murray said British authorities had a problem tracing the movement of sheep around the country. Demands of supermarket multiples and the closure of small abattoirs necessitated the moving of animals long distances to central slaughterhouses. .
"It's a function of the way in which food is traded nowadays. Multiples want large volume and have set specifications for what they want. But it's too simplistic to turn back the clock to small abattoirs. They simply couldn't cover their costs, and hygiene in some of them would be horrendous," Mr Murray said.
Government and farmers have agreed on individual plastic ear-tagging, with a permanent tag in the case of a breeding ewe or a store animal to be sold at a livestock mart, and a tip tag when a young animal leaves the farm of origin for an abattoir at eight or nine months.
Farmers will have to keep a flock register of individual animal numbers, and sheep will always have to be accompanied by a movement document.