Ear tagging or notching allows you to identify your pigs by sight. Notching is easy to do and costs nothing. You can identify up to 121 pigs in this way. This method can be used to identify other animals, e.g. sheep and goats.
If you have a few pigs or other animals, identifying them is no problem. You will be able to identify them by sight and may well have given them a name. You will need some way to identify a large number of animals especially if you are going to keep records. There are many ways to identify animals including numbered collars, tattoos and plastic tags. Notching the ear is easy and is the cheapest way.
A V-shaped notch can be cut out of the edge of the ear using a pair of clean scissors. Make the notch a few centimeters deep so in future you will be able to read it from a distance.
The notches on the left ear are for single numbers and on the right ear the notches are for tens.
Look at the notches on the right and the left ears then add up the number on each ear to give the number of the animal.
Source : Pashu Sakhi Handbook