Ear tags are an incredibly helpful tool when it comes to keeping flocks healthy and happy. Not only do ear tags make it easier to record data and keep track of individual sheep, they are also helping eradicate the spread of the disease Scrapie, or
Paraplexia enzootica ovium.
Scrapie is a fatal degenerative disease in sheep and goats that affects the nervous system. Since it affects the nervous system, it can cause changes in behavior, locomotor incoordination, intense rubbing and scratching, and eventually death. It is very contagious and there is currently no known cure or vaccine.
The USDA has instituted a program to help stop the spread of this disease. One part of the program is ear tags containing a scrapie identification number so that if if a positive case arises it can be traced back to the flock of origin. Each farm that registers with the program is given their very own scrapie identification number and lambs born on that farm are tagged with that number. Detailed records are taken and kept for at least five years to help with the history.
Ear tags are useful for more than just disease prevention!
Not only do our tags contain a scrapie number, each tag has a unique number for each individual sheep. For instance, Alfalfa's personal ID number is 1001 and only he has that number. Tags also have the name of our farm and a blank spot where we write info like their dam's name or number. This way, if mom and baby get separated we know who belongs with who and we can make sure that they get reunited.
Personal ID numbers are also essential for data collection and records. We use a software that uses ID numbers to organize who is related to who, so no accidental inbreeding occurs. The software also uses ID's to tell us how fast twins from one ewe are growing in comparison to twins from another ewe. In addition, we have multiple grey sheep. If I'm away on vacation and tell Sarah to "take the grey ewe's temperature", she likely wouldn't know which one I was referring to. Our sheep have names, but sometimes it's hard to keep track of them all, whereas ID numbers are always on the sheep and because everyone has their own number, they won't be confused with anyone else.
We put ear tags in the left ear for ewes and the right ear for rams. This is helpful because you can tell their gender from afar, but it's multi-purposed. When larger scale operations sort sheep, they usually use a system of chutes and gates. Most of the time these chutes are set up so that the animal's left side is facing you. Since most people have much more ewes than rams and it's easier to read tags that are closer to you, ewes get tags in their left ear for a better view.
Does it hurt?
I liken it to getting your ears pierced : There's a momentary pinch and then it's over. The ear might be a little sore if the sheep were to touch it or hit it on something, but other than that it doesn't seem to bother them too much! Lambs grow and heal very fast and usually it doesn't get in their way at all! It's a brief unpleasantness to aid them in the long run.
This might not be what every farm does in terms of ID tags, but it works for our farm and flock :-)