Hay netting that has been mowed and dried to a moisture level of 15 17 percent or less; one of the basic feeds for ruminant farm animals during stabling. The nutritional value of hay depends on its botanical composition, the place the grass was grown, the time and method of harvesting, and the length and conditions of storage.
The following types of hay netting are distinguished: legumes, cereals, forbs, legume-cereals, legume-cereal-forbs, cereal-forbs, and legume-forbs. The nutritional value of plants in these groups differs, and therefore the quality of hay netting is determined by their quantitative ratios. The most valuable hay comes from such legumes as alfalfa, clover, common vetch, and bird s-foot trefoil; such cereals as Kentucky bluegrass, meadow fescue, ryegrass, timothy, orchardgrass, and wheatgrass; and such forbs as prostrate knotweed and meadow salsify.
Hay netting made from coarse sedges, rushes, Saint-John s-wort, ferns, and horsetails is low in nutritional value and virtually inedible. Hay made from plants raised in the steppe is generally richer in nutrients than hay from plants grown in swampy regions. Hay grass from grasses harvested in the early phases of development contains more nutrients and vitamins and is easier to digest than hay from grasses harvested in late stages. The best hay from legumes is obtained when the plants are mowed during budding or early flowering. The best cereal hays are made from grasses mown during ear formation. The nutritional value of hay grass is also affected by the leafiness of the plants, since the leaves have significantly more protein, fats, and mineral substances than the stems; the digestibility of these substances in the leaves is higher. The nutritional value of high-quality leguminous hay approaches that of concentrated feeds. One hundred kilograms contain approximately 50 feed units, 9.2 kg of digestible protein, 1,000 1,500 g of calcium, and 200 220 g of phosphorus. Leguminous hay also contains carotene, and vitamin B1, vitamin B2, and vitamin D. Hay from cereal grasses contains less protein and calcium; 100 kg of meadow hay averages 45.8 feed units, 4.9 kg of digestible protein, 600 g of calcium, and 210 g of phosphorus.
Hay is usually fed without any processing to cattle, sheep, and horses; hogs and poultry are fed hay meal or grass meal. The quality of hay is determined by evaluating its color, odor, dust content, and softness. High-quality hay is green. Late-harvested hay, hay that has lain in the sun for a long time, hay that has been rained on during the drying process, and hay that has undergone self-warming in stacks and shocks may be greenish yellow, yellow, pale white, light or dark brown, or dark cinnamon. Correctly harvested dry hay has a pleasant, fresh odor; hay sometimes takes on the distinctive odor of certain grasses (sweet vernal grass, wormwood). A musty and moldy odor appears when grass is dried in rainy weather and stored while too moist. The dust contained in hay results from slight heating. Hay is stored in shocks or stacks in the open air, in hay barns, or under canopies. It is baled for convenient transporting and storage. In the USSR hay accounts for roughly 40 45 percent of feed units in the winter diet and up to 50 percent of the digestible protein. In 1965, 78.2 million tons of hay was fed to livestock, and in 1973, 80.8 million tons.