If you’re slaughtering the first-born, you can part the hair and even pluck a hair for the sake of smoother slaughtering. That is, plucking is not considered to be shearing. This might complicate matters for a red heifer — if one trimmed red hair that had some black, which is allowed, in this case, without actually shearing. So that task is also unintended beyond its actually purpose. Note that cows are not considered “shorn,” because their hairs are not wool. Plus, a historical account of 9 red heifers. Also, a new mishnah! A blemished first-born, who has shed hair, and then the animal is slaughtered (or it dies), can that hair be used in the way the body would be allowed for use after the slaughtering? It’s a machloket.