[A]Calculated from analyses.
[B]Including salt, 4.1.
CHAPTER VII
MILK AND DAIRY PRODUCTS
99. Importance in the Dietary.—There is no article of food which enters so extensively into the dietary as milk, and it is one of the few foods which supply all the nutrients,—fats, carbohydrates, and proteids.[[36]] Milk alone is capable of sustaining life for comparatively long periods, and it is the chief article of food during many diseases. An exclusive milk diet for a healthy adult, however, would be unsatisfactory; in the case of young children, milk is essential, because the digestive tract has not become functionally developed for the digestion of other foods.
It is necessary to consider not only the composition and nutritive value of milk, but also its purity or sanitary condition.
100. General Composition.—Average milk contains about 87 per cent water and 13 per cent dry matter. The dry matter is composed approximately of:
| Per Cent | |
| Fat | 3.5 |
| Casein | 3.25 |
| Albumin | 0.50 |
| Milk sugar | 5.00 |
| Ash | 0.75 |
Fat is the most variable constituent of milk. Occasionally it is found as low as 2 per cent and as high as 6 per cent or more. The poorest and richest milks differ mainly in fat content, as the sugar, ash, casein, and albumin, or "solids of the milk serum," are fairly constant in amount and composition. Variations in the content of fat are due to differences in feed and in the breed and individuality of the animal.