Pigs’ ears are notched as a permanent identification system. Small V-shaped wedges are cut from specific locations on each ear within the first few days of life, creating a unique numeric code that identifies both which litter a pig belongs to and which individual pig it is within that litter. Unlike plastic ear tags, which can fall out or be torn off, ear notches last the animal’s entire life.
How the System Works
The Universal Ear Notching System assigns different numerical values to different positions along the edge of each ear. The outer edge of the ear is divided into sections, and each section represents a specific number: 1, 3, 9, 27, or 81. By cutting a small notch at one or more of these positions, a farmer creates a number. If notches appear at the 3 and 9 positions, for example, that ear reads as 12. The tip of the ear typically represents its own value as well.
The key to the system is that each ear serves a different purpose. The right ear (from the pig’s perspective) carries the litter number. Every piglet born in the same litter gets identical notches in its right ear. The left ear carries the individual pig number, so each piglet in the litter gets a different combination of notches in that ear. When someone reads or records the identification, the litter number is listed first, followed by the individual number.
This means a pig marked 7-3 belongs to litter number 7 and is the third individual pig in that litter. The system can represent a wide range of numbers by combining notch positions, making it practical for operations with many litters per year.
Why Notching Instead of Tags
Ear tags are common in cattle, but pigs present a different challenge. Pigs root in dirt, squeeze through tight spaces, and interact physically with pen mates in ways that can rip tags out. A lost tag means a lost identity, which creates serious problems for breeding records, health tracking, and regulatory compliance.
Ear notching solves this because it’s built into the animal. There’s nothing to fall off, corrode, or become unreadable. For purebred pigs, the USDA recognizes ear notching as an acceptable form of official identification when the notching has been recorded in the book of record of a purebred registry association. This makes it especially important for breeders who register animals with organizations like the National Swine Registry.
Cost is another factor. A V-notcher is an inexpensive, reusable tool. There are no ongoing expenses for replacement tags, and the procedure takes seconds per piglet.
When and How Piglets Are Notched
Piglets are typically notched between one and three days of age, when they’re small and easier to handle. A V-shaped ear notcher removes a small wedge of skin at the appropriate location on the ear’s edge. For piglets under about 25 pounds, a standard V-notcher works well. Larger pigs require a notcher that cuts about half an inch deep to ensure the notch remains visible as the ear grows.
The wounds from notching are small and typically heal within 7 to 10 days. Proper hygiene during the procedure helps prevent infection. Clean, sharp notchers produce cleaner cuts that heal more predictably than ragged ones.
Pain and Welfare Considerations
Ear notching is considered a painful procedure. The AVMA has acknowledged this in its review of standard piglet processing practices. Research into the timing of the procedure has produced some nuanced findings. One study found that one-day-old piglets of average birth weight were less reactive during ear notching compared to three-day-old piglets. However, for piglets born at low body weight, researchers recommended waiting until day three, since very small piglets are less likely to survive to weaning and the brief delay allows them to stabilize.
The AVMA’s position is that when painful procedures remain necessary, pain relief through analgesics or combined therapies should be used. In practice, pain management during ear notching varies widely across operations. Some farms apply antiseptic to the notch site but don’t use local anesthetics, while others are beginning to incorporate pain relief protocols as welfare standards evolve.
Reading Ear Notches in Practice
Reading a pig’s ear notches requires you to face the pig and identify which ear is its right and which is its left. This trips up a lot of beginners because the pig’s right ear is on your left when you’re facing it head-on. Once you’ve oriented correctly, you add up the values of each notch on the right ear to get the litter number, then add up the values on the left ear to get the individual number.
This skill matters for anyone involved in 4-H or FFA livestock programs, where youth are expected to identify pigs by their ear notches. It’s also essential for breeders maintaining accurate pedigree records, since a misread notch can lead to incorrect breeding pairs or faulty lineage documentation. The system is simple enough that once you’ve practiced a few times, reading a pig’s ID becomes almost automatic.