29. Effect Of Soil Moisture

The proportion of water in plants is influenced by the lack or excess of soil moisture. The soil, and not the atmosphere, is the source of supply of vegetation water, which, taken up by the roots, traverses the plant and passes into the atmosphere through the leaves. If the supply is abundant, the tissues are constantly fully charged, but if, by reason of drought, the soil becomes very dry, the outgo of water by evaporation may exceed the income. What farmer has not seen his corn with rolled leaves during an August drought! The vegetation water had fallen below the normal, or below what was necessary to maintain the tissues in their usual condition of rigidity.

30. Water In Dry Foods

The proportion of moisture in flour, meal, and other food materials has much to do with their preservation in a sound condition. New grains when packed in large masses are subject to fermentations, which injure their quality and diminish their food value. This is due to the fact that sufficient moisture is present to allow the growth of low forms of life with certain attendant chemical changes. Food materials containing 20 per cent or more of water, when stored in large quantities or in closed vessels, are almost certain to heat and become musty or moldy, always involving a loss of nutritive value. It is well if the moisture in flour and other stored cereal preparations does not exceed 10 or 12 per cent.

31. Water In The Animal

Water is an important and abundant constituent of animal organisms, from the lowest to the highest forms. The blood, which is one-twentieth or more of the weight of the human body is approximately four-fifths water. The soft tissues of farm animals have been found to contain from 44 per cent to 75 per cent, according to the species and conditions of the animal. The most extensive and complete analysis so far made of the entire bodies of animals were performed by Lawes and Gilbert at Rothamsted, England. In this country four steers were analyzed at the Maine Experiment Station, and in the study of human nutrition problems many determinations of water have been made of parts of the carcasses of bovines, swine, sheep, poultry, and game. The figures are as follows: -

Table VIII.Water In Entire Body

It is very evident that, in general, considerably more than half of the weight of the bodies of our domestic animals consists of water, the range in all species and conditions here mentioned being from 42.3 per cent to 67.5 per cent.

32. Effect Of Age And Condition

The percentage of water varies with the species, age, and condition. Swine carry a notably small proportion. The calf's body, even though fat, is comparatively watery. It is very noticeable that with oxen, sheep, and swine the lean animals contain a much larger proportion of water than do the fat. This does not mean that in the process of fattening the fat is substituted for water, and so expels it from the organism, but that the increase in fattening has a much smaller percentage of water than the body in its original lean condition. This is well illustrated by the data from two independent investigations at Rothamsted and at the Maine Experiment Station. The former investigation showed that when swine, sheep, and oxen are fattened, the increase contained from 20 per cent to 24 per cent of water, this being half the proportion found in the entire bodies of the lean animals. The Maine Station results established the fact that in the increase of two steers from the age of 17 months to 27 months, during which time a fattening ration was fed, there was 42 per cent of water, the bodies of the younger steers having 58.2 per cent. It is well understood that beef from mature animals "spends" better than that from young, the same observation being made in comparing lean and fat beef. Modern investigation shows clearly that the reason for this lies partly in the difference in water content. Dry matter, and not water, is the measure of food value.