Why do we ID an animal?
It is a beautiful December morning. The sun is shinning and the breeze is brisk. I bundle up in my Carhartt and stocking cap as I head to check the cows. I listen and hear a hoarse cough coming from over by the hay ring. As I walk closer to investigate, I notice it is cow number 32. I make mental note to check on Cow 32 tonight to make sure the cough hasn't worsened. Animal identification is in place to help the farmer keep records and to ensure animal health.
There are many different forms of identification and farmers may use one or more of the variety of methods to best suit the needs of their farm. We use ear tags on our family farm. According to Wikipedia, "An ear tag is a plastic or metal object used for identification of domestic livestock and other animals. If the ear tag uses Radio Frequency Identification Device (RFID) technology it is referred to as an electronic ear tag."
Farmers number the ear tags in many different ways. We have a small cow/calf herd and therefore the cow and calf have the same number but some farmers will use a combo of numbers and letters. The letter might refer to a year or line of genetics. Farmers may utilize the right or left ear to identify gender, making it easier to glance at the calf and determine if it is a steer or heifer.
Another form of tracking/identification takes it one step further. Many dairy farmers use monitoring devices on a collar or ankle bracelet, very similar to a Fitbit. It keeps track of steps, how much they eat, how active, how often they rest and how much milk they produce daily.
Paint markers can be used temporarily to keep track of livestock as you sort them, etc.
Other forms of identification like tattooing and microchipping are more permanent. This method is used for animals like cattle, sheep, goat, donkey and rabbit. Permanent methods have long term advantages, for example, many of the temporary forms, like ear tags can fade or fall out of the cows ear.
Animal identification is in place to help both the animal and farmer!
The importance of animal identification includes (What are the benefits of cattle identification? | CattleTags.com):
It makes record keeping easy for a livestock farmer or animal breeder.
Selecting genetic traits for future breeding stock.