N.J. Stat. § 4:12-41.8
All samples of milk or cream that are taken for the purpose of determining the per centum of butter fat to be used as a basis of payment for milk or cream purchased shall at all times remain on the premises where taken, except that a sufficient amount may be transferred to approved test bottles and the butter fat tests be completed at approved laboratories with the director's written permission. When tests are made at such approved laboratories each fresh or composite sample is to be treated to disperse the butter fat content evenly throughout the sample and two test bottles are to be charged on the premises where the fresh or composite sample was originally taken. Unless such permission is granted, the butter fat tests shall be completed on the premises where the samples were originally taken.
N.J.S. § 4:12-41.8