The damage caused by ear tags used for sheep identification was investigated in a two-part study. In Part I, ear tags classified as metal loop, golf-tee, single flex or lambtag were inserted into the ears of 62 ewes. The severity of ewe ear lesions was monitored until 20 weeks after ear tag insertion. In Part II, 351 lambs had tags classified as metal loop, plastic loop, golf-tee, double flex, single flap, lambtag and electronic, inserted in their ears. The behaviour of the lambs was observed for 30s after insertion of the ear tag. The severity of lamb ear lesions was monitored until 5 weeks after ear tag insertion. In both ewes and lambs there was a significantly greater risk of severe and persistent ear lesions following the use of metal loop tags as compared with the other types of ear tag (P < 0.001). The single flap tag was difficult to insert in a greater proportion of lambs (P < 0.001), and more lambs haemorrhaged (P < 0.001), vocalized (P = 0.002) and shook their heads (P = 0.004) with it, than with the other types of ear tags. All ear tags resulted in an inflammatory reaction and required correct positioning to minimize the severity of ear lesions.

Animal identification has been one of the most contentious issues for the last decade in the livestock industry. More specifically, at issue is the idea of a government-sponsored identification system, although it is unclear that an identification system forced on the industry by the market would be any more popular. Rancor over the issue has set livestock groups at odds over the merits of establishing such a framework; it has highlighted differences between species, within species, and by size and scale of agriculture. Given its politically sensitive nature, many groups without a tie to agriculture have been drawn in to lobby on the issue. This article examines the U.S. experience with the development of an animal identification system.

This article provides a brief history of the animal identification (ID) system that previously existed in Canada along with details on efforts to “reidentify” the country's cattle herd. The current state of ID for various species is summarized, and the state of regulations federally and for major agricultural province are outlined. A short background on the economics of animal ID is provided. Particular attention is paid to the operation of the Canadian Cattle Identification Agency, an industry-government initiative charged with identifying the national cattle herd. The animal ID system in Canada is found to have performed well when called on in times of animal health crises, although there have been notable deficiencies in its performance on occasion. Canada's animal ID system will continue to evolve as new technologies for tagging and database management (among others) are developed. It is expected the system will play an important role in future attempts to exploit traceability for value-added initiatives.

Specific PCR, amplifying a fragment of the mitochondrially encoded cytochromeb gene, are developed for discrimination of chicken, turkey, pig, cow and sheep. These PCR tests could be applied for detection and discrimination of animal food ingredients. For origin identification of milk, the bovine PCR is applied on DNA extracted with the DNeasy™ Tissue kit. A PCR of 30 cycles reached a sensitivity of 720 somatic cells in the PCR reaction corresponding to 2·9 × 104 cells per ml milk. A PCR of 40 cycles could detect 0·72 to 0·144 somatic cells in the PCR reaction corresponding to 29 to 2·9 cells per ml milk.