ear tag

An ear tag is a small, numbered or barcoded plastic or metal clip that pierces and sits permanently in the ear of cattle, sheep, goats, pigs, or other farm livestock. It serves as the primary identifier linking an individual animal to its owner, herd records, health history, and regulatory documentation. The tag remains visible and readable throughout the animal's life, making it the standard method for tracking animals in agricultural operations.

Most ear tags are made from flexible polyurethane or polycarbonate and measure roughly 30 to 50 millimeters along their longest edge. They come in pairs or singles and are installed using a hand-held applicator that pierces the ear cartilage between the top edge and the midline. The applicator works on a spring mechanism, driving a post through the ear while the tag body remains on the opposite side. Metal variants, typically aluminum or stainless steel, are less common but more durable for harsh conditions. Tags are color-coded by year, region, or herd protocol; a UK cattle tag, for example, uses specific colors to indicate the year of birth.

Ear tags carry either sequential numbers, unique identification numbers linked to national livestock registers, or increasingly, barcodes and RFID microchips readable by electronic wands. Many countries require ear tags for cattle as part of disease traceability and food safety regulation. The European Union mandates double tagging of cattle; if one tag is lost, the duplicate ensures the animal remains identifiable. RFID tags allow rapid herd counts and sorting at handling facilities without needing to read each tag manually.

Common problems include tag loss through rubbing, infection at the piercing site, and illegible or faded numbers on older plastic tags. Livestock handlers use backup identification methods, tags with wider bases to reduce snagging, and antimicrobial dips at application time to minimize issues. Tag loss is significant because it breaks the chain of custody for regulatory compliance and herd records.

The term "ear tag" reflects its simplicity: it is a tag affixed to the ear. The practice predates modern plastic tags by centuries; farmers historically cut notches into ears or applied dye marks. Plastic ear tags became standard from the mid-twentieth century onward as herds grew larger and record-keeping became more formalized. Today, ear tagging is intertwined with veterinary health schemes, export certification, and traceability requirements that define modern livestock management.