Swine Ear Notching Laws in Montana: What Pig Owners Need to Know

If you raise pigs in Montana — whether a small homestead herd, a 4-H project, or a registered purebred operation — understanding ear notching rules can save you from compliance headaches at the sale barn, the state fair, or the state line. Ear notching is one of the oldest swine identification methods in the United States, but its legal weight depends entirely on context: who recorded it, where the pig is going, and which other forms of ID accompany it.

Montana’s swine identification framework sits at the intersection of state administrative rules, USDA federal traceability requirements, and breed registry standards. This guide walks you through each layer so you can make confident, compliant decisions for your herd.

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

Ear notching is a permanent identification method in which small V-shaped cuts are made in specific positions on a piglet’s ears shortly after birth. Ear notching is widely used in the swine industry as a system of animal identification, with all systems identifying a pig by litter number and individual pig number. Because the notches are placed within hours or days of birth, they create a lifelong record that cannot be lost, fall off, or fade the way tags or tattoos sometimes can.

In Montana, ear notching is used in three main situations: as a permanent on-farm record-keeping tool for producers of any size, as an official identification method for purebred pigs enrolled in a breed registry, and as a supporting identifier when pigs move intrastate or interstate. It is especially common among producers who show pigs at county fairs and the Montana State Fair, where all cattle, sheep, swine, and goats need a Certificate of Veterinary Inspection issued within 30 days of exhibit.

The procedure is typically performed on piglets during the first few days of life, at the same time producers clip needle teeth and treat navel cords. For piglets of this size, a small (3/16- to 1/4-inch-deep) V-notcher is recommended. If you have never notched pigs before, working alongside an experienced producer or your local Montana State University Extension agent before your first litter arrives is strongly advisable.

Pro Tip: Perform ear notching within the first 24–48 hours of birth. Piglet ears are soft and small at this stage, healing is faster, and the stress on the animal is minimal compared to notching older pigs.

When Ear Notching Qualifies as Official Identification in Montana

Not every ear notch automatically counts as official identification under Montana or federal rules. The distinction matters enormously if you plan to move pigs across county lines, sell at a licensed market, or transport them out of state.

Ear notching qualifies as official identification when the ear notching has been recorded in the book of record of a purebred registry association. This is the federal standard set by USDA’s Animal and Plant Health Inspection Service (APHIS), and Montana’s rules align with it. In practical terms, this means a notch pattern on a commercial feeder pig with no registry paperwork does not meet the threshold for official ID — you would need an ear tag or tattoo bearing a Premises Identification Number instead.

Official individual identification is required for all pigs regardless of sex or age unless moved in a defined swine production system (ARM 32.3.219), and the ID must be listed on the health certificate. Montana’s Administrative Rules govern this requirement, and the Montana Department of Livestock enforces it at points of entry and at licensed livestock markets.

For purebred pigs with active registry enrollment, the ear notch pattern — once recorded with the appropriate breed association — satisfies the official ID requirement for breeding and exhibition movement. Ear notches can be used for breeding, feeding, and exhibition swine when properly documented. Always keep your registry paperwork with the animal during transport so inspectors can verify the notch record on the spot.

Important Note: Montana’s ARM 32.3.2002, which previously governed swine identification codes, was repealed effective October 6, 2018. Current swine ID requirements in Montana are governed primarily by ARM 32.3.219 and applicable federal APHIS rules. Confirm current requirements with the Montana Department of Livestock at 406-444-2976 before any interstate movement.

How the 1-3-9 Ear Notching System Works

The simplest method and the one recommended by most breed associations is ear notching, and the most common notching system is the 1-3-9 system. Once you understand the numbering logic, reading a pig’s identity from its ears takes only seconds — a skill that pays off every time you sort, treat, or register animals.

Each ear is divided into four parts, with each area representing the numbers 1, 3, 9, or 27. In each of the four areas, you can have up to two notches. The right ear is used for the litter mark, and all pigs in the same litter must have the same notches in the right ear. The left ear identifies individual pigs in the same litter, and all littermates must have different notches in the left ear.

To read a pig’s litter number, add up the values of all notches in the right ear. To read the individual pig number, add up the values of all notches in the left ear. A pig with a single notch in the “9” position of the right ear and a single notch in the “3” position of the left ear would be Litter 9, Pig 3 — written as 9-3.

There are five designated zones (1, 3, 9, 27, and 81) in the litter ear and three designated zones (1, 3, and 9) in the individual pig ear. In zones 1, 3, 9, and 27, there can only be two notches — two notches in all four zones would represent Litter 80 — and a notch in zone 81 doubles the system. Only one notch may be at the 81 position.

A few practical points worth knowing for Montana producers:

• Always orient the pig facing you when reading ears — the pig’s left ear is on your right as you face it.
• A good way to remember which is the left ear is to always look the pig in the face; read left-to-right, and it will always be litter number then pig number.
• Use a sharp, clean V-notcher and disinfect between animals to prevent infection spreading through a litter.
• Record the notch pattern immediately in your herd book — do not rely on memory.

Ear	Purpose	Notch Zones Available	Max Value (Without 81 Tip)
Right ear	Litter mark	1, 3, 9, 27, 81 (tip)	80 (before tip doubles system)
Left ear	Individual pig number	1, 3, 9	27

Ear Notching for Purebred Registry Compliance in Montana

If you raise registered purebred swine in Montana — Berkshire, Duroc, Hampshire, Yorkshire, Chester White, Landrace, or Poland China, among others — ear notching is not just a management convenience. It is a requirement for breed association registration, and that registration is what elevates a notch pattern from a farm record to an official form of identification under both state and federal rules.

The National Swine Registry and Certified Pedigreed Swine are two of the primary breed registry organizations that govern ear notching standards for purebred swine in the United States. Both require the standard 1-3-9 notching system, and both require that the notch pattern be submitted with the litter registration application. Notches in the left ear identify individual pigs in the same litter, all littermates will have different notches in the left ear, and no more than two notches may be made at any position.

Tattoos on the ear or inner flank of any swine qualify as official ID if the tattoos have been recorded in the book of record of a swine registry association — and the same principle applies to ear notches. The key phrase is “recorded in the book of record.” If you notch piglets but never submit the litter registration, those notches carry no official weight for movement or disease traceability purposes in Montana.

January 1 and July 1 of each year are the starts of each farrowing season for registry purposes with Certified Pedigreed Swine, which affects how litter numbers are assigned and tracked. Check with your specific breed association for their current farrowing season calendar and litter submission deadlines before your sow farrows.

Pro Tip: Submit your litter registration application to your breed association as soon as piglets are notched and weighed. Early registration ensures the notch record is in the association’s book of record before you need to move or sell any animals.

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

Montana swine producers have several official identification options, and the right choice depends on your operation type, where your pigs are going, and whether you raise registered purebreds or commercial stock. Understanding how ear notching compares to other methods helps you build a compliant ID strategy from the start.

ID Method	Official Status	Best For	Key Limitation
Ear notch (registry-recorded)	Official for purebreds	Registered breeding/exhibition swine	Must be recorded with registry to count as official
Ear tag (840 RFID / AIN)	Official	Commercial, feeder, and slaughter swine	Tags can be lost or removed
Premises ID tattoo	Official	Slaughter and feeder swine	Requires legibility; fades over time
Breed registry tattoo	Official for purebreds	Registered breeding/exhibition swine	Must be recorded with registry association
Microchip (ISO-compliant)	Official	High-value breeding animals	Requires reader; higher upfront cost

For slaughter swine and feeder swine, an ear tag or tattoo bearing the Premises Identification Number assigned by the State Animal Health Official to the premises on which the swine originated is the required form of official ID. If you are selling feeder pigs at a Montana livestock market or consigning pigs directly to a packing plant, a registry-recorded ear notch alone will not satisfy this requirement — you need a tag or tattoo with your Premises ID Number (PIN).

For producers running both registered purebreds and commercial feeders on the same operation, a dual-ID approach makes sense: notch all piglets at birth for registry and record-keeping purposes, then apply a PIN ear tag to any pig that will leave the farm as a commercial animal. This keeps you compliant across both tracks without redundant effort. You can learn more about Montana’s broader livestock movement rules in this guide to transporting livestock laws in Montana.

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

Montana’s swine identification rules are administered by the Montana Department of Livestock (MDOL), which operates under the Board of Livestock and enforces the Administrative Rules of Montana (ARM) Title 32. The Montana Department of Livestock is statutorily charged with exercising supervision to protect the livestock interests of the state from disease. For swine producers, this translates into specific ID and documentation requirements that apply at several points in a pig’s life.

Intrastate movement: Montana does not require a Certificate of Veterinary Inspection (CVI) for all intrastate swine movement, but official ID is still expected when pigs pass through licensed livestock markets or change ownership. Keep your herd book and any registry paperwork accessible whenever pigs leave your farm.

Interstate movement: Official individual identification is required for all pigs regardless of sex or age unless moved in a defined swine production system (ARM 32.3.219), and the ID must be listed on the health certificate. For purebred pigs moving to another state for a show or sale, your registry-recorded ear notch qualifies — but the notch pattern must appear on the CVI, and the registry documentation must travel with the animal. If moving livestock to another state, know the regulations for the destination state.

Exhibition at the Montana State Fair: Department of Livestock Inspectors check all consignments upon arrival at Montana State Fair for compliance with Montana Animal Health Import and Brand Laws. Swine exhibitors must have a valid CVI issued within 30 days of the show, and official ID — including a registry-recorded ear notch for purebreds — must be listed on that certificate.

Feral swine reporting: Montana takes feral swine prevention seriously. Feral swine are not currently present in Montana, and Montana law requires that any sighting of potential feral swine be reported immediately to the Montana Department of Livestock by calling 406-444-2976. Penalties for violation of Montana law include fines of at least $2,000 but not more than $10,000 for each violation. Properly identified, ear-notched domestic pigs help investigators quickly distinguish owned animals from feral ones during any investigation.

Defined swine production systems: Large integrated operations that move pigs between sites under a single ownership umbrella may qualify for the defined swine production system exemption under ARM 32.3.219, which relaxes individual ID requirements for those internal movements. Contact MDOL directly to confirm whether your operation qualifies.

Key Insight: Montana’s ARM 32.3.2001 governs brands and earmarks for livestock broadly, while the swine-specific identification code rule (ARM 32.3.2002) was repealed in October 2018. This means swine ID in Montana now falls primarily under federal APHIS standards and ARM 32.3.219 for movement. When in doubt, call the MDOL Animal Health Bureau at 406-444-2976 or email livpermits@mt.gov for current guidance.

Montana’s livestock regulatory environment also intersects with other animal ownership rules worth knowing. If you keep multiple species on your property, review the state’s goat ownership laws in Montana and backyard chicken laws in Montana for a broader picture of how the MDOL and local zoning rules affect mixed-species operations. For import-specific questions, the pet import laws in Montana page covers companion animals, while the MDOL import requirements page handles livestock. Producers moving pigs to or from neighboring states should also check Montana’s livestock transport rules before loading the trailer.

Ear notching remains a practical, low-cost, and permanent identification tool for Montana swine producers — but its legal value is only as strong as the paperwork behind it. Record every notch pattern in your herd book on the day of birth, submit litter registrations promptly to your breed association, and pair notches with a PIN ear tag for any pig moving in commercial channels. Those three habits will keep you compliant under both state and federal rules and make every trip to the sale barn or show ring straightforward.