The Feeding of Dairy Cattle

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III THE ELEMENTARY COMPOSITION OF FEEDS In a consideration of the feeding problem, little attention is, as a rule, given to the individual elements which, in combination, form the complex compounds of the plant and animal tissues; yet the science of chemistry shows that all substances are ultimately derived from the simple chemical elements. The feeding stuffs used for farm animals are generally vegetable products, though a few animal products, such as tankage and skim milk, are utilized. These feeding stuffs consist of complex compounds, and a knowledge of the source of these compounds is of value. The animal elaborates the constituents of its body from the compounds existing in plants or animal products, but the plants used as sources of feeds must elaborate these compounds from simpler substances. As will be noted later, the carbohydrates, fats, proteins and ash are the main constituents derived by the animal from the plant products it consumes; the first problem, therefore, is to locate the source from which the plant obtains these substances. The plant makes them from the elements and from some simpler compounds elaborated from the elements. A very large number of elements are found in plants, in the form of compounds, but only a few of them need be considered, as all of them are not essential for animal life. CARBON The element, carbon, which is the main constituent of coal, and in the practically pure state forms such widely differentsubstances as diamonds and lampblack, forms about 50 per cent of the dry matter of plants and animals. It occurs in the air as a constituent of the gas, carbon dioxide, which when present in appreciable amounts in buildings may lead to difficulties, as it is poisonous to animals. Green plants have the power of absorbing t...