Abstract PROBABLY no feedstuffs have greater prestige than milk and milk products. Mechanical equipment for preparing dried milk products has been improved during recent years and lowered production costs have resulted in increased supplies. It is estimated that in 1930 over 20,000 tons of dried buttermilk and 70,000 tons of dried skimmilk were produced in the United States alone. Dried whey is at present, however, produced in only limited quantities. More research work has probably been carried on with milk and its products than with any other food or feedstuff, but even so the problem of relative nutritive values should be approached with what one research worker expresses as “conscious ignorance and active curiosity.” Many questions concerning milk and milk products still remain unanswered. Milk by-products differ somewhat in chemical composition, depending upon the primary product. Manufacturing and processing methods are as yet not standardized, for little is known of the . . .