Mich. Comp. Laws § 288.717

Sec. 157. (1) Only a grader approved by the department shall grade butter. (2) Standards for grading are those described in 7 C.F.R. 58. (3) As used in this section, "grade" means the classification of butter by its examination for flavor, aroma, body and texture, color, salt, package, and such other factors as may be approved by the department.