Although ear tags were developed as early as 1913 as a means to identify cattle when testing for tuberculosis, the significant increase of use of ear tags appeared with the outbreak of BSE in UK. Today, ear tags in a variety of designs are used throughout the world on many species of animal to ensure traceability, to help prevent theft and to control disease outbreaks.
The first ear tags were primarily steel with nickel plating. After World War II, larger, flag-like, plastic tags were developed in the United States. Designed to be visible from a distance, these were applied by cutting a slit in the ear and slipping the arrow-shaped head of the tag through it so that the flag would hang from the ear.
In 1953, the first two-piece, self-piercing plastic ear tag was developed and patented. This tag, which combined the easy application of metal tags with the visibility and colour options of plastic tags, also limited the transfer of blood-borne diseases between animals during the application process.
Some cattle ear tags contain chemicals to control insects such as buffalo fly etc. Metal ear tags are used to identify the date of regulation shearing of stud and show sheep. Today, a large number of manufacturers are in competition for the identification of world livestock population.
The United States Department of Agriculture maintains a list of manufacturers approved to sell ear tags in the USA for the National Animal Identification System.
The International Committee for Animal Recording (ICAR) controls the issue electronic tag numbers.
The National Livestock Identification System (NLIS) is Australia's system for tracing cattle, sheep and goats from birth to slaughter.