Tags

 An ear tag is designed to survive some harsh treatment; it gets hot, cold, wet, frozen, bitten, pulled, scraped and squeezed - whatever the ear endures the tag must too.

The challenge is to keep the electronics safe, not just from the weather and animals but from the application process itself.

A one-piece EID tag is quite a feat of engineering – the plastic must be flexible enough to bend without breaking, rigid enough to punch a hole through a sinewy old ear, tough enough to protect the electronics inside, plus small and light enough for a newborn lamb to carry.

Two-piece tags have a harder grade of plastic in the spike than in the rest of the tag, making this design more suitable for older animals with tougher ears.

The consequences of losing a tag can be serious so it's important that tag retention is as good as possible.

Tag retention is influenced by:

• Correct placement in the ear
• Ensuring the male and female parts of the tag lock together properly
• Infection – affected by cleanliness, flies, flock/herd health
• Environmental hazards – twine, wire, fence and feeder design

The size of the puncture hole can also affect the retention rates between different kinds of tags. Loop tags such as the SET tag experience very little movement if properly positioned in the ear, and are unlikely to snag on wire, twine or net.

Low Frequency RFID tags have no internal power source such as a battery. Instead the microchip in the tag is energized by the radio frequency of the tag reader. The electrical current is very small but just strong enough to power up the microchip to transmit the ID number stored back to the reader.

Several factors affect the read range of an electronic tag.