N.Y. AGM Law § 52

§ 52. Presumptions in regard to cream and skim milk. When cream is\nseparated or skimmed from milk at any station or establishment where\nmilk is received from producers for the purpose of selling the same or\nshipping the same to market for consumption as food and the supply of\nmilk on hand thereat at the time of the next regular daily shipment of\nmilk therefrom, consisting of the total amount of milk in such shipment,\ntogether with that remaining on hand immediately after such shipment, is\nnot thereby decreased or correspondingly less than the total quantity\nreceived during any period extending from some point of time before such\nskimming was done until the time of such shipment, together with the\namount of milk on hand at the commencement of such period, and such\ndecrease is not equal in amount to the quantity of milk that must have\nbeen used in so separating such cream in addition to the quantity\notherwise there used or disposed of during such period, such fact is\nconclusive that skim milk or other foreign substance was added to such\nmilk supply within such period and shall be presumptive evidence within\nthe meaning of this section that the same was added to each can or\nvessel of milk in such shipment. When cream or skim milk is found to\nhave been on the premises of any such station or establishment or is\nsold or shipped therefrom, such cream or skim milk so found or so sold\nor shipped therefrom shall be presumed to have been produced by\nseparating or skimming at such station or establishment. In any action\nor proceeding relative to the adulteration of milk by removing cream\ntherefrom or adding skim milk or other foreign substance thereto, it\nshall be presumed that when cream has been produced by so skimming or\nseparating or butter has been manufactured, there was made at least five\nquarts of milk in the production of each quart of cream so produced and\nthere was necessarily so produced thereby at least four quarts of skim\nmilk to each quart of cream so produced, and that there was used at\nleast nine quarts of milk in the production of each pound of butter so\nmanufactured.\n