Biological identification systems: genetic markers.

Individual animals differ from each other on a number of biological levels. At the most basic level, the deoxyribonucleic acid (DNA) of each animal is different, and transcription of the DNA code yields variations at the protein level, which in turn give rise to individual diversity at the physical level. In recent years, accessing the primary genetic code of individual animals has become straightforward. The authors briefly review the development of biological identification technologies and then consider in more detail the application of current DNA testing technologies to issues of traceability of live animals and derived products. Although largely focused on cattle and beef traceability, the principles described are relevant to ovine, porcine and equine traceability. The accelerating pace of innovation and development within the field of molecular genetics suggests that the technologies described may soon be superseded. However, the principles of genetic identification will remain unchanged.