What is RFID and how does it work?
RFID stands for radio frequency identification. A tag holds a number, and a reader sends out a signal that the tag answers. No battery is needed in most tags. The reader shows the number on a screen or sends it to a computer or app.
Some tags are visual and electronic together, with a printed number you can read from a distance. Many farmers like both. Think through tag placement and timing with your veterinarian, since ears grow and tags that are right for a calf may need adjusting later. Different tag frequencies and standards exist, so ask the seller and your state veterinarian's office whether the tags you want will work with the readers you or your buyers use. Ask the seller how long the tags are expected to last and what the warranty covers.
- Passive tags have no battery
- A reader must be close to the tag
- Visual numbers still help
What can I do with tag numbers?
Link each number to records, such as birth date, dam, weights, vaccinations, treatments, breeding and sale. Then scan an animal in the chute and see its history. It cuts down on writing errors and helps you cull, select and treat the right animal.
Tag numbers are only useful if records are kept. A tag with no record gives little information. Keep tags clean and dry before applying, and follow the maker's directions to reduce infection and early loss. Spreadsheets and herd software both work. Choose one that lets you export your records, so you are never locked in.
What equipment do I need?
You need tags, an applicator, and a reader. Readers are handheld sticks or panels at a chute or alley. Software on a phone, tablet or computer stores records. Choose equipment that works together, and ask about support.
Plan to handle animals safely when tagging. Use a good chute or restraint, work with help, and keep calm. Ask your veterinarian or extension agent about proper tag placement and care of the ear.
Buy a few extra tags and an applicator for replacements. Test the reader on a few animals before the busy day, and keep spare batteries and a charger. Record a few numbers by hand in case the reader fails. Keep your applicator clean and disinfected between animals as advised, and replace worn parts.
What problems should I expect?
Tags can be lost, torn or become unreadable. Animals can catch an ear on a fence or feeder, and infections can happen if tagging is done unclean. Readers can have trouble with metal, wet tags or fast-moving animals. Keep a backup identification method, such as a visual tag and a paper record.
Check animals after tagging, and treat infection promptly with veterinary advice. Check the reader's range with the tag at different angles and in the chute, since metal gates and wet ears can reduce reads. Practice on a few animals first, and watch ears over the following weeks.
What are the official identification rules?
Identification rules depend on species, age, state and whether animals move or are sold. They can change. Do not assume what a neighbor or seller tells you is current. Your state veterinarian's office and USDA can say which identification is required and which tags are approved.
If you plan to sell animals, ask the buyer or market what they need, since requirements can differ. Keep records of tag numbers with sale papers. Record any tag you replace and link the new number to the old one, so history is not lost. Keep tag numbers with every sale, purchase and transport paper, so a trace can be completed if a health question arises later.
Is it worth it for a small herd?
For a very small herd, visual tags and a notebook may be enough. As numbers grow or if you want detailed performance records, electronic tags can save time. Weigh the cost of tags, a reader and software against how much you will actually use them.
Ask extension staff and other producers about their experience, and consider borrowing a reader before buying one. Talk with the market or buyer before sale day and ask what tags and papers they require. Talk with neighbors about sharing a reader, which can be a practical way to try the system.
Key takeaways
- RFID tags identify animals; records give the numbers meaning.
- Keep a backup visual identification.
- Tag safely and watch for infection.
- Check official identification rules with your state veterinarian.
- Weigh cost against how much you will use it.
Sources and further reading
Last reviewed: November 12, 2026. Written by the Rural Farm Life Editorial Team. See our editorial policy.