Also known as raddle not every Ram or Tup will tolerate a harness, so sometimes powdered raddle is mixed with vegetable oil and smeared over his chest.

It gives the farmer quite a lot of information, by changing the color every 17 days (a ewe's cycle), they can detect a infertile tup, predict lambing dates, etc.

In modern dairy operations, you chalk the tail of the heifers/cows you want bred. When the animal comes into heat, other female cattle will mount her and rub off the chalk. The artificial insemination tech then knows who should get inseminated.