Potassium and Lactose in Milk in Relation to the Physiology of Milk Secretion

Abstract

IN a previous communication,¹ we reported the interrelationships of the concentration of sodium, potassium, lactose and water in samples of milk taken at intervals over a period of three months from shorthorn cows in mid-lactation. It was shown that the water of milk can be represented as a two-phase system: in one phase, referred to as the sodium-lactose phase, potassium is absent and sodium and lactose vary inversely; in the other, referred to as the sodium-potassium phase, lactose is absent and sodium and potassium vary inversely. The relative proportions of the two phases were calculated to be, on average, about 2.5: 1.0, but it was not possible to deduce from information then available whether, and to what extent, the relative proportions of the two phases varied from animal to animal, or within the milk of an individual animal from time to time.