Section 53. All commercial feed distributed in the commonwealth except customer-formula feeds shall be accompanied by a legible label bearing the following information: (1) net weight; (2) name or brand under which the commercial feed is sold; (3) guaranteed analysis of the commercial feed, listing the minimum percentage of crude protein, minimum percentage of crude fat, and maximum percentage of crude fiber. For mineral feeds formulated entirely or mainly from mineral ingredients the list shall include the following if added: Minimum and maximum percentage of calcium (Ca) and minimum and maximum percentages of salt (NaCl). Other substances or elements, determined by laboratory methods, may be guaranteed by permission of the commissioner or his deputy. When any items are guaranteed, they shall be subject to inspection and analysis in accordance with the methods and regulations that may be prescribed by the commissioner. Products sold solely as mineral or vitamin supplements and guaranteed as specified in this section need not show guarantees for protein, fat and fiber. In all cases the substances or elements must be determined by laboratory methods; (4) common or usual name of each ingredient used in the manufacture of the commercial feed, except, the commissioner or his deputy may, by regulation, permit the use of a collective term for a group of ingredients all of which perform the similar function, or he may exempt such commercial feeds or any group thereof from this requirement of an ingredient statement if he finds that such statement is not required in the interest of consumers and providing that a statement of the ingredients to be used is on file with the commissioner or his deputy; (5) name and principal address of the manufacturer or the person responsible for distributing the commercial feed; (6) adequate directions for the use of all commercial feeds containing drugs and for such other feeds as the commissioner may require by regulation as necessary for their safe and effective use; (7) such precautionary statements as the commissioner by regulation determines are necessary for the safe and effective use of the commercial feed.

When a commercial feed is distributed in the commonwealth in bags or other containers, the label shall be placed on or affixed to the container; when a commercial feed is distributed in bulk, the label shall accompany delivery and be furnished to the purchaser at time of delivery.

A customer-formula feed shall be labeled by invoice. The invoice, which is to accompany delivery and be supplied to the purchaser at the time of delivery, shall bear the following information: (1) name and address of the mixer; (2) name and address of the purchaser; (3) date of sale; and (4) kind or type of feed shall be affixed with a tag bearing the information required on the invoice except date of sale.

If a customer-formula feed contains a non-nutritive substance which is intended for use in the diagnosis, cure, mitigation, treatment or prevention of disease or which is intended to affect the structure or any function of the animal body, the commissioner or his deputy shall require the label to show the name and amount present, directions for use or warnings against misuse of the feed.