MILK is the secretion of the mammary glands (mammae) of the large class, the Mammalia, of vertebrate animals that suckle their young. Those animals the milk of which is commonly con sumed by man are the cow, the goat and the sheep.
The average composition of milk, according to Richmond is shown in the following table.
But the rapid increase in the supply of milk, and the growing facilities for its distribution provided by the development of motor transport, made it more and more difficult to maintain producers' prices; and by 1933 the whole condition of the milk trade was verging on chaos.
The pressing need for complete organization led the milk pro ducers in 1933 to set up the Milk Marketing Board for the pur pose of fixing the price at a level adequate to the producers, controlling distribution, and preventing overlapping and waste.
Milk is a complete food, containing as it does protein, fat, car bohydrates, mineral constituents, and water. Though deficient or lacking in certain metallic elements believed essential for normal adult health, the milk of any species is an adequate diet for the very young of that species in all respects, including its contents of vitamines (q.v.). On the other hand, it may not be equally satis
factory for the young of another species. Thus cow's milk is not always an absolute source of vitamine C for human infants. Nor mally cow's milk if produced under proper conditions is an ade quate source of vitamines A and B, and a reasonably good source of C and D. Its content of vitamine E is probably low.
Under the Food and Drugs Act milk (other than skimmed, separated or condensed milk) must contain not less than 3 per cent. of milk fat and 8.5 per cent. "solids not fat," until the con trary is proved. Skimmed or separated milk should contain not less than 8.7 per cent. total solids.