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

Ear notching has been a standard pig identification practice for generations, but Wisconsin law draws a clear line between using it as a farm management tool and using it as legally recognized official identification. Get that distinction wrong and you could face compliance problems at a sale barn, a state fair, or an interstate shipment checkpoint.

Whether you raise purebred Berkshires, run a commercial feeder operation, or show hogs through 4-H or FFA, understanding where ear notching fits — and where it falls short — under Wisconsin’s Department of Agriculture, Trade and Consumer Protection (DATCP) rules will save you real headaches. This guide walks through the full picture, from the basics of the practice to the state code sections that govern it.

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

Ear notching is a permanent identification method in which small V-shaped cuts are made in specific locations on a pig’s ears. Each position on each ear corresponds to a number, and the combination of notches creates a unique code that identifies both the litter and the individual pig within that litter. The procedure is typically done at one to three days of age, when the task is far easier and healing is faster.

Ear notching is considered a permanent ID system that provides individual identity for all animals and an inexpensive means of identification, enabling producers to keep an accurate set of records. In Wisconsin, producers use it most often in three situations: purebred breeding programs where registry compliance is required, youth livestock projects for county fairs and state exhibitions, and small-scale farrow-to-finish operations that want a no-cost, low-tech way to track litters.

If pigs are notched at one to three days of age, the task is much easier. If you allow pigs to become large — around 100 pounds — the task is considerably more demanding mentally and physically. For Wisconsin producers managing farrowing seasons, that timing window also lines up conveniently with tail docking and iron injections, making it easy to handle identification in a single session.

Pro Tip: Always disinfect your notching tool between litters and dip it in fresh surgical spirit or alcohol each day it is in use. Clean equipment prevents cross-contamination and keeps wounds healing cleanly.

It is worth noting that Wisconsin administrative code defines “swine” as a domestic hog or any variety of wild hog, so the identification rules discussed throughout this article apply broadly — not just to conventional farm pigs.

When Ear Notching Qualifies as Official Identification in Wisconsin

This is the section most Wisconsin producers need to read carefully. Ear notching does not automatically qualify as official individual identification under state law. Its legal standing depends entirely on the category of swine and whether the notch pattern is backed by a registry record.

Under Wisconsin Administrative Code ATCP 10.01(71)(g), for breeding swine, official individual identification may consist of an official ear tag attached to the animal, or ear notches for registered swine. That second option — ear notches for registered swine — is the key phrase. The notch must be recorded in a recognized breed registry’s book of record to carry legal weight.

According to the USDA Animal and Plant Health Inspection Service (APHIS), ear notching qualifies as official identification only if the ear notching has been recorded in the book of record of a purebred registry association. Wisconsin state rules mirror this federal standard. If your pig’s notch pattern is not on file with a recognized breed association, the notch alone does not satisfy the state’s official ID requirement.

For feeder swine — pigs weighing 80 pounds or less kept for feeding prior to slaughter — the rules work differently. Under ATCP 10.01(71)(f), for swine weighing 80 pounds or less, a tattoo or ear tag applied to the animal including a premises identification code, or a state-registered feeder pig premises tattoo number issued by the department, or the authorized animal health agency in the state of origin, or an official ear tag attached to the animal satisfies the identification requirement. Ear notching is not listed as a standalone option for feeder pigs — premises-based identification is the standard here.

Important Note: Microchips are not accepted as official identification for any swine in Wisconsin, including pet pigs. This is confirmed in Wisconsin DATCP’s Animal Health Regulations for Fairs and Shows (revised March 2026). Plan accordingly if you are entering a show or moving pigs across state lines.

How the 1-3-9 Ear Notching System Works

The 1-3-9 system is the standard used by virtually all breed associations and recognized by Wisconsin producers, county extension offices, and 4-H programs statewide. The most common notching system is the 1-3-9 system. Once you understand its logic, reading a pig’s identity becomes straightforward.

The litter number is notched in the pig’s right ear, and the individual pig number is in the pig’s left ear. Each ear is divided into zones, and each zone carries a numerical value. You add the values of all notches in each ear to arrive at the litter number and the individual pig number.

Here is how the zones break down:

• Right ear (litter number): The litter mark ear is divided into five sections, and each section has a numerical value — either 1, 3, 9, 27, or 81. Each section, except for 81, can have one or two notches only.
• Left ear (individual pig number): The left ear is used for notches to show an individual pig’s number in the litter. Each pig will have different notches in the left ear. The left ear is divided into three sections, with values of 1, 3, and 9.

To read any pig’s identity, face the animal and add up the notch values in each ear. In zones 1, 3, 9, and 27, there can only be two notches; if there are two notches in all four zones, that represents litter 80. A notch in zone 81 essentially doubles the system. This means the system can accommodate large operations with many litters per year.

A practical example: if a pig has notches at the 9 and 3 locations on the right ear, the litter number is 12. If the left ear has a single notch in the bottom inside (3) location, that pig is individual number 3 from litter 12. That pig’s identity is written as 12-3.

Remember that the reference to left and right ear refers to the pig’s own left or right ear, as viewed from the rear of the pig — not the viewer’s left or right when the pig is facing you. This is one of the most common mistakes beginners make. A useful trick: always look the pig in the face, then read left-to-right — litter number first, individual pig number second.

Ear	Purpose	Zone Values	Max Notches per Zone
Right (pig’s right)	Litter number	1, 3, 9, 27, 81	2 per zone (except 81: 1 only)
Left (pig’s left)	Individual pig number	1, 3, 9	2 per zone

Equipment matters too. Small notchers typically make a notch that is 3/16 to 1/4 inch deep, which is the preferable size for pigs under 25 pounds. For larger pigs, a notcher that makes notches 1/2 inch deep is recommended. 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.

Wisconsin 4-H and FFA participants should also review the Purdue Extension ear notching reference guide for illustrated examples that are widely used in Midwest youth livestock programs.

Ear Notching for Purebred Registry Compliance in Wisconsin

If you raise registered pigs — Berkshire, Duroc, Hampshire, Yorkshire, Chester White, Landrace, or Spotted breeds, among others — ear notching is not just a farm practice; it is a breed association requirement that also feeds into Wisconsin’s official ID framework.

The connection between registry compliance and legal ID status is direct. Ear notching qualifies as official identification if it has been recorded in the book of record of a purebred registry association. Tattoos on the ear or inner flank of any swine also qualify if they have been recorded in the book of record of a swine registry association. Both methods require that registration paperwork.

When you import registered swine into Wisconsin, the state’s DATCP rules require that official identification accompany the animal. For commercial swine entering Wisconsin, official identification options include a USDA ear tag number, a USDA “840” ear tag number, or an ear notch if the pig is a purebred and the ear notch is registered. The ear notch alone — without the registration record — will not satisfy the import requirement.

Certified Pedigreed Swine (CPS) is one of the major registry organizations whose members frequently raise pigs in the upper Midwest, including Wisconsin. Each ear is divided into four parts, each area representing the numbers 1, 3, 9, or 27, with up to two notches in each area. The right ear is used for litter mark, and all pigs in the same litter must have the same notches in the right ear. The left ear identifies the individual pig. CPS uses a slightly simplified four-zone version of the system, which is compatible with the broader 1-3-9 standard.

Keep your registration certificates with your animals whenever you move them. A tattoo on the ear or inner flank of any swine qualifies as official identification under Wisconsin code if the tattoo has been recorded in the book of record of a swine registry association. The same logic applies to ear notches: the physical mark is only as good as the paperwork behind it.

Wisconsin producers who raise purebred swine for shows, breeding sales, or interstate movement should also review the Certified Pedigreed Swine ear notching guidelines to confirm their breed association’s specific notching requirements before the next farrowing season.

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

Ear notching occupies a narrow lane in Wisconsin’s swine identification system. For most commercial movement scenarios, official ear tags — particularly USDA “840” RFID tags — carry broader acceptance and fewer conditions. Understanding the practical differences will help you choose the right method for each category of pig on your operation.

ID Method	Accepted for Breeding Swine	Accepted for Feeder Swine (≤80 lbs)	Registry Required	Accepted for Interstate Movement
Ear Notch	Yes (registered only)	No	Yes	Yes (purebred/registered only)
Official Ear Tag (USDA)	Yes	Yes	No	Yes
840 RFID Tag	Yes	Yes	No	Yes
Premises ID Tattoo	Yes (with individual ID)	Yes	No	Yes (with individual ID)
Breed Association Tattoo	Yes (if registered)	No	Yes	Yes (if registered)
Microchip	No	No	N/A	No

Under Wisconsin code, an “official ear tag” means an identification ear tag approved by the federal bureau that meets the requirements of the national uniform eartagging system or the animal identification number developed by USDA consisting of 15 digits with the first three digits of 840. These RFID-enabled 840 tags are the most widely accepted form of official ID for swine moving in commercial channels.

For sows, boars, and stags heading to slaughter, the rules are more streamlined. Whenever an animal dealer, animal market operator, or animal trucker receives any sow, boar, or stag for sale or shipment to slaughter, that person shall immediately identify the swine with an official swine back tag or premises identification ear tag and record the back tag number. A back tag or premises ID ear tag is sufficient for slaughter-bound animals — no registry record needed.

To avoid purchasing the wrong tags, be sure to order 840 RFID official tags made by approved manufacturers. Approved tags will be imprinted with the 15-digit animal identification number with the first three digits being “840.” Wisconsin producers can find the current list of approved tag manufacturers through the Wisconsin DATCP Official ID and Traceability page.

For producers who need to register their premises to order official 840 tags, the Wisconsin Livestock Identification Consortium (WLIC) at wiid.org handles premises registration. A valid Premises Identification Number (PIN) is required to order tags manufactured specifically for your operation.

Pro Tip: If you sell pigs at a Wisconsin auction market and do not know whether the buyer plans to move them out of state, talk with the market veterinarian before the sale. The buyer may need a Certificate of Veterinary Inspection (CVI) and official individual ID — and sorting that out in advance is far easier than doing it after the gavel drops.

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

Wisconsin’s swine identification framework is governed primarily by ATCP Chapters 10 and 12, administered by DATCP. Several state-specific rules directly shape when and how ear notching fits into your compliance picture.

Intrastate movement of commercial swine. No person may move commercial swine within Wisconsin unless the herd of origin has tested negative on a porcine reproductive and respiratory syndrome (PRRS) and porcine epidemic diarrhea virus (PEDv) test conducted not more than 90 days prior to the intrastate movement, and documentation of the test reports are made available at the time of sale and to the department upon request. Identification method — whether ear notch, ear tag, or back tag — does not exempt you from this disease-testing requirement.

Fairs and exhibitions. Wisconsin fair and exhibition regulations apply to all swine, including pet pigs and racing pigs. Swine from within Wisconsin need a Wisconsin intrastate certificate of veterinary inspection (CVI or health certificate). Swine from outside Wisconsin need a certificate of veterinary inspection that includes additional information under ATCP 10.30 and 10.87. Microchips are not accepted as official ID for any swine, including pet pigs.

Exhibition swine returning from out-of-state events. If commercial exhibition swine originate from Wisconsin and return to Wisconsin after an exhibition in another state, the exhibitor must notify DATCP of the movement before returning. The department may quarantine the returning swine and herd of origin. This requirement does not apply if the out-of-state exhibition organizer requires all participating swine to test negative for PRRS and PEDv within 90 days prior to the event.

Dealers, markets, and truckers. Animal identification requirements for animal truckers, animal markets, and animal dealers are specified under ATCP Chapter 12. If you sell through a licensed Wisconsin market, the market operator takes on specific identification and recordkeeping obligations. Improper or unauthorized use of any official tag, brand, or tattoo is a violation under ATCP 12.02(7)(f). That prohibition covers misuse of ear notch records as well as physical tags.

For the most current movement requirements — which can change as disease conditions warrant — check the Wisconsin DATCP Swine Movement page before any sale or transport. The fair and exhibition rules document was last revised in March 2026, so that source reflects current DATCP guidance.

Wisconsin producers raising other livestock alongside their swine will find related animal law topics covered in our guides on goat ownership laws in Wisconsin and backyard chicken laws in Wisconsin. If you show animals at county fairs, the rules around animal movement and health certificates intersect with broader pet and animal import laws in Wisconsin when you bring animals in from out of state.

For producers who also deal with livestock-related legal questions beyond animal health, our coverage of dog bite laws in Wisconsin and rooster laws in Wisconsin addresses other common rural property and animal ownership issues that Wisconsin landowners frequently encounter.

Key Takeaway: Ear notching is a legitimate and cost-effective identification tool in Wisconsin, but its legal standing as official ID is limited to registered purebred swine with notches recorded in a breed association’s book of record. For commercial, feeder, or unregistered pigs, official ear tags — including USDA 840 RFID tags — are the reliable path to compliance across all movement, sale, and exhibition scenarios.