Swine Ear Notching Laws in Wyoming: What Every Producer Needs to Know

If you raise pigs in Wyoming — whether on a small homestead outside Laramie or a commercial operation near Torrington — understanding swine ear notching rules is not optional. Wyoming’s livestock identification framework, administered by the Wyoming Livestock Board (WLSB), intersects with federal Animal Disease Traceability (ADT) requirements, purebred registry standards, and 4-H project rules in ways that can catch producers off guard.

Ear notching has been a standard swine identification practice for decades, but its legal weight depends entirely on context. A notch recorded with a breed registry carries official status for interstate movement; the same notch on an unregistered pig does not. Knowing the difference protects you from compliance problems at the sale barn, the state line, and the show ring.

This guide walks through every layer of Wyoming’s swine ear notching landscape — from the basics of the 1-3-9 system to how notching stacks up against RFID tags under current federal rules.

What Is Swine Ear Notching and When It Is Used in Wyoming

Ear notching is a permanent identification method in which small V-shaped cuts are made in specific positions on a pig’s ears. It provides a permanent ID system that gives individual identity to all animals and offers an inexpensive means of identification that enables producers to keep an accurate set of records. In Wyoming, where ranching and small-farm swine operations are common, ear notching remains the go-to method for producers who raise registered purebreds or show pigs through 4-H programs.

The simplest method, and the one recommended by most breed associations, is ear notching. Wyoming producers typically apply notches at birth — or within the first few days of life. If pigs can be notched when their tails are docked, or at one to three days old, the task is much easier. Waiting too long creates problems: if you allow pigs to become large (100 lbs), the task can become considerably demanding mentally and physically, and if notching ears on older or larger pigs, it may be necessary to house them in separate pens until the notches heal.

In Wyoming, ear notching is used in three main situations: on-farm litter and individual pig recordkeeping, purebred registry enrollment, and 4-H swine project validation. Outside those contexts — particularly for commercial feeder pigs or slaughter animals moving through Wyoming markets — ear notching alone does not satisfy official identification requirements. You need to understand which category your animals fall into before relying on notches as your primary ID method.

Pro Tip: Notch piglets during the same processing session as tail docking and needle teeth clipping. Combining procedures minimizes stress on the litter and ensures your records are complete from day one.

When Ear Notching Qualifies as Official Identification in Wyoming

Not every ear notch is an official form of identification under Wyoming or federal law. The distinction matters most when you move animals across county or state lines, sell at auction, or enter pigs in sanctioned shows. Ear notching qualifies as official identification only if the ear notching has been recorded in the book of record of a purebred registry association. An unregistered notch — even a perfectly executed one — carries no official legal weight for traceability purposes.

For slaughter swine and feeder swine, an eartag or tattoo bearing the Premises Identification Number assigned by the State Animal Health Official to the premises on which the swine originated is required instead. This means that if you are selling market hogs or feeder pigs in Wyoming, a PIN-based ear tag — not a notch — is the correct identification tool.

The Wyoming Livestock Board administers swine import requirements under Chapter 8 of its animal health rules. The WLSB’s Chapter 8 covers import regulations for swine, with specific requirements outlined at page 8-13 of those rules. Before moving swine into Wyoming from another state, contact the WLSB or your accredited veterinarian to confirm whether the animals’ existing identification — notched or tagged — satisfies Wyoming’s entry requirements. You can also review Wyoming’s livestock transportation rules for a broader look at movement compliance.

Important Note: Wyoming does not have a standalone state statute that specifically mandates ear notching for swine. Official status for ear notches flows from federal ADT regulations and purebred registry requirements — not a Wyoming-specific notching law. Always verify current requirements with the WLSB before assuming a notch alone satisfies your identification obligations.

How the 1-3-9 Ear Notching System Works

The most common notching system is the 1-3-9 system. It uses a positional numbering code applied to both ears to encode two pieces of information on every pig: its litter number and its individual number within that litter. Think of an ear notch like the pig’s first and last name — the right ear identifies the litter number (last name), and the left ear identifies the individual pig within that litter (first name).

The Right Ear (Litter Number): The right ear designates litter number, and it has five locations for notches, each assigned various numbers: 1, 3, 81, 9, or 27. There are five designated zones (1, 3, 9, 27, and 81) in the litter ear, and in zones 1, 3, 9, and 27, there can only be two notches — thus if there are two notches in all four zones, that would represent litter 80. The 81 zone effectively doubles the system’s capacity, allowing litter numbers well above 160.

The Left Ear (Individual Pig Number): The left ear is used for notches to show an individual pig’s number in the litter, with each pig having different notches in the left ear. The left ear is divided into three sections, with values of 1, 3, and 9. You add the values of all notches in each ear to arrive at the final number. For example, the notches on the left ear indicate pig number — there are three locations for these notches, and their numerical values are 1, 3, and 9, and as with litter number, the number values are added.

Reading the Ears Correctly: The reference to left and right ear refers to the pig’s left or right ear as viewed from the rear of the pig — left and right does not refer to the viewer’s left or right when the pig is facing the viewer. A simple trick from Purdue Extension’s ear notching reference guide: always look the pig in the face — then, if read left to right, it would always be litter number then pig number.

Equipment and Technique: Use a V-ear notcher to notch piglets weighing less than about 25 pounds — these notchers typically make a notch that is 3/16 to 1/4 inch deep. Avoid making notches too shallow, as they may become hard to read or possibly heal shut. Leave at least 1/4 inch between notches, and avoid making notches too close to the head. Disinfect your notcher between litters to prevent disease transmission across your herd.

Ear	Purpose	Notch Zones	Max Value per Zone
Right (pig’s right)	Litter number	1, 3, 9, 27, 81	2 notches (except 81: 1 notch)
Left (pig’s left)	Individual pig number	1, 3, 9	2 notches per zone

Ear Notching for Purebred Registry Compliance in Wyoming

If you raise registered swine in Wyoming — Durocs, Yorkshires, Berkshires, Hampshires, or other recognized breeds — ear notching is not just a farm management habit. It is a registry requirement. Ear notches are typically made within the first few days of birth, and they help breeders maintain accurate records in regard to registration and health records on the farm, including vaccination records.

Ear notches, using the Universal Ear Notching System, must be recorded with a breed registry association, and breed registration papers must accompany the animals. This is the step that converts a physical notch into official identification. Without that registry recording, the notch is simply a management mark — useful on your farm, but not legally recognized for interstate movement or official health certificates.

Organizations like the Certified Pedigreed Swine (CPS) registry and the National Swine Registry (NSR) each maintain their own ear notching guidelines that align with the Universal Ear Notching System. Wyoming producers registering purebreds should confirm their breed association’s specific notching chart, since minor variations exist between registries in how they assign zone values or handle litter numbering beyond 160.

For 4-H members in Wyoming showing swine at county fairs or state competitions, proper ear notching is also part of project validation. 4-H members and their families need to understand the ear notching system and be able to read the ear notches of their pigs to properly enroll their 4-H swine projects. County extension offices across Wyoming can assist first-time exhibitors with notching technique and registry paperwork. You may also find it helpful to review Wyoming livestock fence laws if you are setting up a dedicated swine operation on your property.

Pro Tip: Keep a litter record book from day one. Write down the notch combination for each pig alongside its birth date, dam, and sire information. This documentation speeds up registry enrollment and provides the paper trail your accredited veterinarian needs when issuing health certificates for out-of-state sales.

Ear Notching vs. Ear Tags, Tattoos, and RFID in Wyoming

Wyoming swine producers have several identification options, and choosing the right one depends on where your animals are going and what regulatory framework applies. Each method has a specific legal role under the USDA’s Animal Disease Traceability (ADT) program and Wyoming’s own import and movement rules.

ID Method	Official Status	Best Use Case	Wyoming Notes
Ear Notching	Only if registry-recorded	Purebred registration, 4-H projects	No standalone state notching mandate
PIN Ear Tag	Yes (for slaughter/feeder swine)	Market hogs entering harvest channels	Required for non-registered swine movement
Tattoo (registry)	Yes (if registry-recorded)	Purebred breeding stock	Must match registration papers
RFID / 840 Tag	Yes (federally approved)	Interstate movement, shows, sales	Must begin with “840,” carry US shield

Tattoos on the ear or inner flank of any swine qualify as official identification if the tattoos have been recorded in the book of record of a swine registry association. For slaughter swine and feeder swine, an eartag or tattoo bearing the Premises Identification Number is required. This means tattoos and notches share the same condition: registry recording is what makes them official, not the physical mark itself.

RFID tags are increasingly the preferred option for animals moving across state lines. Official electronic ID tags must have the U.S. shield and the ability to be read by an electronic reader, and the first three numbers of an official electronic ID must be “840.” The Wyoming Livestock Roundup reported that as of November 5, 2024, metal tags placed after that date are no longer considered official ID under the updated ADT rule — electronic tags are now required for new applications on covered species.

These are the only swine identification methods considered official for interstate movement. Other identification types, such as brands, unregistered notches/tattoos, or farm/ranch tags are not considered official identification for the purpose of interstate movement. If you plan to sell registered breeding stock to buyers in Colorado, Nebraska, or any other neighboring state, make sure your animals carry either a registry-recorded notch with accompanying papers or a USDA-approved 840 RFID tag. You can also explore Wyoming’s goat ownership laws if you manage a mixed small-livestock operation, as similar identification principles apply.

Due to a continued emphasis on livestock traceability within state and federal agencies and the livestock industry, the National Swine Registry requires all animals being exhibited at NSR or National Junior Swine Association events to be identified with an official, permanently-numbered ear tag. If your Wyoming-raised pig is heading to a national show, a registry-recorded notch alone may not be enough — verify the event’s specific tag requirements before loading the trailer.

State-Specific Swine Identification Rules That Affect Ear Notching in Wyoming

Wyoming does not have a single, consolidated swine identification statute the way some states do. Instead, the rules that govern whether your ear notch matters legally come from three overlapping frameworks: the Wyoming Livestock Board’s animal health chapters, USDA APHIS federal ADT regulations, and breed registry requirements. Understanding how these layers interact is what keeps Wyoming producers compliant.

Wyoming Livestock Board Requirements: The WLSB administers swine import rules under Chapter 8 of its animal health regulations. The WLSB’s Chapter 8 covers swine import requirements, including health certificate and identification standards for animals entering the state. Any swine moving into Wyoming from out of state must meet these requirements, which typically include a Certificate of Veterinary Inspection (CVI) and official identification. A registry-recorded ear notch can satisfy the ID requirement for purebred breeding stock, but the CVI must still accompany the animal.

Brand Inspection and Movement Rules: Wyoming is a brand inspection state with some of the most robust livestock movement oversight in the American West. While brand inspection requirements apply primarily to cattle, no person may cause livestock to be removed from any county in Wyoming to any other state or country unless each animal has been inspected for brands and ownership at the time of delivery or removal by an authorized Wyoming brand inspector and a proper certificate of inspection or clearance has been issued. Swine moving out of Wyoming for sale or breeding purposes are subject to this inspection framework. Review Wyoming’s livestock transportation laws for the full scope of movement requirements that apply to your operation.

Federal ADT Program and Wyoming: The USDA Animal Disease Traceability (ADT) program defines official animal identification and recording requirements for the interstate movement of animals. Wyoming operates within this federal framework, and the WLSB works alongside USDA APHIS to enforce it. Official ID under the ADT rule includes eartags that are both visually and electronically readable, a group or lot ID, breed registry tattoos and/or breed registration certificates, and a registered brand with an official brand inspection certificate. Ear notching fits into this framework only through the “breed registry” pathway — again underscoring that the registry recording, not the notch itself, is what counts.

Premises Identification Numbers: Premise identification (Premise ID) is part of the Animal Disease Traceability Framework (ADT) designed to help identify animals to the locations they have been raised on or passed through during their lives, and this number along with accurate movement records can serve as a critical piece of information in quickly tracing back an animal to a location in the event of an animal health emergency. Wyoming swine producers who have not yet registered a Premises ID with the WLSB should do so before moving animals commercially. Your PIN ties your operation to every tagged animal that leaves your farm.

Shows, Fairs, and 4-H Events: Each state in which the NSR or NJSA hosts events has regulations for animal health and the identification of swine that move across state lines to come to shows, and these regulations vary from state to state. Wyoming county fairs typically require a valid health certificate and official identification for swine entered in competition. Check with your local University of Wyoming Extension office or the Wyoming State Fair office for current show requirements, as these can change annually. For related animal law topics in Wyoming, see our guides on backyard chicken laws and beekeeping regulations in the state.

Key Insight: The single most important action you can take as a Wyoming swine producer is to obtain a Premises Identification Number from the Wyoming Livestock Board. This number links your operation to every animal you raise, sell, or move — and it is the foundation for PIN tags, health certificates, and ADT compliance. Contact the WLSB at wlsb.state.wy.us to register your premises.

Ear notching in Wyoming sits at the intersection of practical farm management and legal compliance. When done correctly — with proper technique, timely application, and registry recording — it gives your registered swine a permanent, readable identity that holds up at the sale barn, the show ring, and the state line. When done without the registry step, it is simply a useful on-farm tool that carries no official weight. Know which situation applies to your animals, keep your paperwork current, and connect with the Wyoming Livestock Board whenever you have questions about movement or identification requirements. For a broader look at how Wyoming regulates animals on your property, explore our coverage of livestock fence laws, pet vaccination requirements, and rooster ownership rules across the state.