Thank goodness for Premier 1 supplies! That firm has a good number of styles, colors and shapes of eartags for sheep and other critters. Which enables me to come up with new eartagging systems every few years.
Currently I use 2 eartags in each lamb's ears, in case of tag loss. About 2 years ago I decided that the tag in the RIGHT ear should be in the system used in Australia--- they have 8 different colors of ear tags that indicate the year. https://www.agric.wa.gov.au/livestock-biosecurity/nlis-and-identification-sheep
This year is WHITE in the system. Next year will be ORANGE. In Australia where the government forces you to use the system you can tell the age of a sheep by the ear tag. For the number, I use a letter plus numbers. This year's letter is G, and all or nearly all of lambs that get names will begin with G. I've been naming sheep alphabetically since I started and have gone through the alphabet once. Well, I quit at Y and started again with E or something like that. Not sure why I skipped some letters. It's fun every year to go through name books and dictionaries to make the official list of names with the right letter.
The LEFT ear tag indicates breed--- whether purebred Shetland or crossbred with hair sheep (Dorper or Katahdin).
white = single
salmon = triplet or better
spearmint = single
lime green = twin
green = triplet or better
In the Premier 1 catalog they say that they also use tags to indicate male or female. They put the 'main' tag in the right ear for males and left ear for females. I tried that, several tagging systems ago. It doesn't work for me. I always get a few males or females tagged wrong.
What I'm thinking of doing is this: I have a supply of tag pens. I thought I could make a mark with the tag pen on the male lamb's RIGHT ear tag--- the one that indicates the year. Tag pen marks don't last that long, but by the time the male sheep is old enough that the mark will have faded, you can tell he's a boy just by looking. I might also write the lamb's name on the inside of the tag, where the writing will be sheltered from sunlight.
I've also thought about adding a seventh color to the LEFT ear tag system--- gray to indicate male lambs which have been wethered and are going for meat.
As for the official government scrapie tags, when I started this new system I was not going to use them until the sheep was sold. That's what they do at Premier, according to their catalog. But at Premier they have a lot of help, and they have a sheep handling system. I don't have the help, and my 'sheep handling system' is a shed. I chase small groups into the shed to catch them in a small stall where I can grab them. So my LEFT ear tags are going to be official government Mark-of-the-Beast scrapie tags.
In my latest order of ear tags, I bought Q-flex 1.2 tags for the RIGHT ear tag and Q-flex 1.5 for the LEFT ear tag. So that even if I put the tags in the wrong ears I can tell which tag is which at a distance. Because most of my sheep don't like to come near enough for me to read the number on the tag.