Tagging lambs would be a step forward in tracing meat back to the individual animal. But, even with tagging in place, how can consumers be sure that the meat they are eating comes from a particular lamb?
The answer could lie in genetic fingerprinting. If a sample of skin, blood or even hair was taken from the lamb at the time it was tagged, that animal would be traceable right through to the shrink-wrapped chop on the supermarket shelf.
IdentiGEN, an Irish company in TCD's Institute of Genetics, has developed a system called TraceBack. This has been used by Superquinn for the past two years for beef-tracing, with more than 100,000 animals tested.
Superquinn has conducted trials with sheep, but it is not cost-effective at present, according to Ms Paula Mee, the company's nutrition adviser. Testing costs about £4 a head, and lamb is about £40 a carcass, she said.
Mr Ciaran Meghen, managing director of IdentiGEN, explained that when an animal goes to an abattoir its eartag number is logged but, with large-scale meat-processing, there is no way of linking a cut of meat with a particular animal.
DNA testing of the carcass and subsequently of the meat maintains that link through the slaughtering and butchering process.
The system is not currently used on live animals. Mr Meghen said it would be possible to extend it backwards to the farm, but the first step was for sheep to be tagged, as sheep did not have "passports" similar to those carried by cattle.
Cattle are tagged and then issued with a passport logging their history, including tests for diseases such as TB and brucellosis.
This is expensive, but not every animal would have to be tested, he said. The samples could be kept, and random quality assurance checks would be run.
Any particular problem could then be investigated by referring to the genetic database.
Mr Meghen suggested that the logical starting-point was with cattle. Cows have a product life of six or seven years and steers about 30 months; they could move many times in their lives.
The system is not particularly relevant for pork, as pigs tended to spend their lives in one production unit, he said.
Biological material could be taken from animals at the time of tagging, and they would then be traceable.
DNA testing would provide supplementary quality assurance, rather than replacing current systems, he said.