ANIMAL FEED

ANIMAL FEED

Feed

AGRICULTURE

WRITTEN BY: John K. Loosli Palmer J. Holden

See Article History

Alternative Title: animal feed

Feed, also called animal feed, food grown or developed for livestock and poultry. Modern feeds are produced by carefully selecting and blending ingredients to provide highly nutritional diets that both maintain the health of the animals and increase the quality of such end products as meat, milk, or eggs. Ongoing improvements in animal diets have resulted from research, experimentation, and chemical analysis by agricultural scientists.

Animals in general require the same nutrients as humans. Some feeds, such as pasture grasses, hay and silage crops, and certain cereal grains, are grown specifically for animals. Other feeds, such as sugar beet pulp, brewers’ grains, and pineapple bran, are by-products that remain after a food crop has been processed for human use. Surplus food crops, such as wheat, other cereals, fruits, vegetables, and roots, may also be fed to animals.

History does not record when dried roughage or other stored feeds were first given to animals. Most early records refer to nomadic peoples who, with their herds and flocks, followed the natural feed supplies. When animals were domesticated and used for work in crop production, some of the residues were doubtless fed to them.

The first scientific effort to evaluate feeds for animals on a comparative basis was probably made in 1809 by the German agriculturist Albrecht von Thaer, who developed “hay values” as measures of the nutritive value of feeds. Tables of the value of feeds and of the requirements of animals in Germany followed and were later used in other countries.

Preservation of green forages such as beet leaves and corn (maize) plants by packing them in pits in the earth has long been practiced in northern Europe. The idea of making silage as a means of preserving and utilizing more of the corn plant was gradually developed in Europe and was taken from France to the United States in the 1870s. When the mature, dried corn plant was fed to cattle in the winter, much of the coarse stem was wasted, but when it was chopped and ensiled (made into silage), everything was eaten. During the 20th century, concrete bunker silos for storage of silage became a common sight in many rural areas worldwide.

Basic Nutrients And Additives

The basic nutrients that animals require for maintenance, growth, reproduction, and good health include carbohydrates, protein, fat, minerals, vitamins, and water. The energy needed for growth and activity is derived primarily from carbohydrates and fats. Protein will also supply energy, particularly if carbohydrate and fat intake is inadequate or if protein intake exceeds the needs of the body.

Animals need a source of energy to sustain life processes within the body and for muscular activity. When the energy intake of an animal exceeds its requirements, the surplus is stored as body fat, which can be utilized later as a source of energy if less food becomes available.

Proteins

For immature animals, protein is also needed for growth of the muscles and other parts of the body. Since milk, eggs, and wool contain much protein, additional amounts are needed in the feed of animals producing these. All animals require a small amount of protein for maintenance—i.e., the daily repair of muscles, internal organs, and other body tissues.

Proteins are composed of more than 20 different amino acids, which are liberated during digestion. Animals with a simple single stomach (monogastric), including humans, monkeys, swine, poultry, rabbits, and mink, require correct amounts of the following 10 essential amino acids daily: arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. In addition to these, poultry need glycine and glutamic acid for growth. Cystine can replace up to half of the methionine requirement, and tyrosine can replace up to half of the phenyalanine requirement. High-quality protein, such as that supplied by eggs, milk, fish meal, meat by-products, and soybean meal, contains high concentrations of the essential amino acids in the proper balance for their full utilization. Poor-quality protein, such as that in most grains, including corn, barley, and sorghum, contains too little of one or more essential amino acids. Feeds having poor-quality proteins are useful when blended with other feeds that restore the balance in essential amino acids.

A protein source’s amino acid profile is of secondary importance to ruminants, such as cattle, sheep, goats, and the other animals that have four stomachs, because the bacteria that aid in the digestion of food in the rumen (first stomach) use simple nitrogen compounds to build proteins in their cells. Further on in the digestive tract, the animals digest the bacteria. By this indirect means, ruminants produce high-quality protein from a food that might originally have contained poor protein or from urea (a nitrogen compound). Very young ruminants, such as calves, lambs, and kids, however, need good-quality protein until the rumen develops sufficiently for this bacterial process to become established.

Carbohydrates and fats

Most animals get energy from carbohydrates and fats, which are oxidized in the body. These yield heat, which maintains body temperature, furnishes energy for growth and muscle activity, and sustains vital functions. Animals need much more energy (and more total feed) for growth, work, or milk production than for simple maintenance.

Simple carbohydrates such as sugars and starches are readily digested by all animals. The complex carbohydrates (cellulose, hemicelluloses) that make up the fibrous stems of plants are broken down by bacterial and protozoal action in the rumen of cattle and sheep or in the cecum of rabbits and horses. Such complex carbohydrates cannot be digested by humans or, to any appreciable extent, by dogs, cats, birds, or laboratory animals. Thus, ruminants and some herbivorous animals obtain much more of the energy-giving nutrients from the carbohydrates of plants than do monogastric carnivores and omnivores, for which fibrous materials have little or no energy value.

Fat in feeds has a high nutritive value because it is easily digested and because it supplies about two and one-quarter times as much energy as an equal weight of starch or sugar. While fat has a high nutritive value, it can be replaced by an equivalent amount of digestible carbohydrates in the feed, except for small amounts of essential fatty acids. Very small amounts of the unsaturated fatty acid linoleic, contained in some fats, are necessary for growth and health. Animal feeds typically supply ample amounts of this acid unless it has been removed by processing.

Minerals

Minerals essential for animal life include common salt (sodium chloride), calcium, phosphorus, sulfur, potassium, magnesium, manganese, iron, copper, cobalt, iodine, zinc, molybdenum, and selenium. The last six of these can be toxic to animals if excessive amounts are eaten.

All farm animals generally need more common salt than is contained in their feeds, and they are supplied with it regularly. Of the other essential minerals, phosphorus and calcium are most apt to be lacking, because they are heavily drawn upon to produce bones, milk, and eggshells. Good sources of calcium and phosphorus are bonemeal, dicalcium phosphate, and defluorinated phosphates. Eggshells are nearly pure calcium carbonate. Calcium may readily be supplied by ground limestone, ground seashells, or marl, which are all high in calcium.

Small amounts of iodine are needed by animals for the formation of thyroxine, a compound containing iodine, secreted by the thyroid gland. A serious deficiency of iodine may cause goitre, a disease in which the thyroid gland enlarges greatly. In certain regions, goitre has caused heavy losses of newborn pigs, lambs, kids, calves, and foals. Iodine deficiencies can be prevented by supplying iodized salt to the mother before the young are born. Almost all commercial sources of salt for animals contain iodine as a routine additive.

In some areas, soil and forage are deficient in copper and cobalt, which are needed along with iron for the formation of hemoglobin, the oxygen-carrying pigment of the red blood cells. In these areas, farm animals may suffer from anemia unless the deficiency is corrected by means of a suitable mineral supplement. Ruminants are usually fed cobalt in the diet so they can then synthesize vitamin B12. Monogastric animals, such as pigs, require a direct source of vitamin B12 in their diet.

Iron, used in hemoglobin formation, is amply supplied in most animal feeds, except milk. The only practical problem with iron deficiency occurs in young suckling pigs before they start to consume other feeds in addition to milk. They require an iron injection or access to fresh soil to meet their iron needs.

Manganese is essential for animals, and the usual diets for all farm animals supply sufficient quantities. A lack of manganese may cause the nutritional disease of chicks and young turkeys called slipped tendon (perosis) and also may cause failure of eggs to hatch. Normal diets for swine are often deficient in zinc, especially in the presence of excess calcium. Fortifying feed by adding 100 parts per million of zinc, as zinc sulfate or zinc carbonate, prevents zinc deficiency symptoms, which include retarded growth rate and severe scaliness and cracking of the skin (parakeratosis). While trace amounts of selenium are necessary for normal health, excessive amounts, which can be found in forages and grains in some regions, are toxic and may cause death. To furnish both calcium and phosphorus, grazing livestock may be allowed free access to such a mixture as 60 percent dicalcium phosphate and 40 percent common salt. Trace mineralized salt is used when copper or cobalt may be deficient. Livestock usually are given access to common salt separately, so they will not be forced to eat more of the other minerals than they require to get the amount of salt they need. Swine diets usually contain prescribed levels of calcium, phosphorus, salt, and essential trace minerals that may be deficient in the grains they are fed.

Vitamins

Known vitamins include the fat-soluble vitamins A, D, E, and K, and the water-soluble B group of thiamin, riboflavin, niacin, pantothenic acid, choline, biotin, folic acid, and vitamins B6 and B12 and vitamin C.

Vitamin A, the one most apt to be lacking in livestock feeds, is required for growth, reproduction, milk production, and the maintenance of normal resistance to respiratory infections. All green-growing crops are rich in carotene, which animals can convert into vitamin A. Vitamin A supplement is added to animal diets to ensure a supply when livestock are not fed green forages and are not on good pasture.

Vitamin D enables animals to use calcium and phosphorus; a deficiency causes rickets in young growing animals. The ultraviolet rays of sunlight produce vitamin D from the provitamin in the skin. Field curing of hay develops vitamin D through the action of the sunlight on ergosterol in the hay crops. Certain fish oils are very rich in vitamin D. Livestock that are outdoors in the sunlight much of the time have a plentiful supply of vitamin D. Under winter conditions in cold regions, cattle, sheep, and horses ordinarily get ample amounts from the hay they are fed; pigs, poultry, and laboratory animals that are raised indoors will be deficient unless a supplement is added.

The vitamin B group is not important in the feeding of cattle, sheep, and other ruminants, because the bacteria in their rumen synthesize these vitamins. Very young calves, however, and poultry, swine, and other monogastric animals require the B vitamins in their diets. Of these, riboflavin, niacin, pantothenic acid, and vitamin B12 are most likely to be deficient in ordinary feeds; special supplements are needed by pigs, poultry, and laboratory animals. Choline may also be deficient in poultry feeds.

Vitamin E is necessary for normal hatching of eggs. It plays a role along with selenium in preventing muscle stiffness and paralysis (dystrophy) in lambs, calves, and chicks under certain conditions. Vitamin C, which prevents scurvy in humans and guinea pigs, can be synthesized in the bodies of most other animals and need not be supplied in their food. Vitamin K is synthesized by bacteria in the intestinal tract and can be absorbed, and, if livestock can ingest feces, a dietary supply is usually not important. Today many animals are raised without fecal contact, though, so vitamin K is often added to their diets as a safety factor.

Antibiotics and other growth stimulants

Antibiotics have been used in livestock diets since the early 1950s. They and other growth stimulants are non-nutritive substances added to animal feeds to treat diseases, to improve the efficiency of feed utilization and feed acceptance, or to improve the health or metabolism of the animal in some way. The use of antibiotics can be broadly divided into two categories, therapeutic and subtherapeutic, in which the distinction purely depends on the amount added to the feed. In therapeutic use, enough antibiotics are used to control bacterial infections within an individual or animal population; in subtherapeutic use, antibiotics are given in relatively low doses to enhance the performance (typically growth and feed efficiency) of the animals. The addition of subtherapeutic antibiotics to the diets of young pigs improves growth performance by 10 to 15 percent or more. Because the subtherapeutic use of antibiotics does not completely eradicate bacteria populations, over time the practice leads to antibiotic-resistant bacteria, which forces the search for new antibiotics for both livestock and humans. Some countries in the European Union have banned the subtherapeutic use of antibiotics, and there is growing pressure in the United States to ban the subtherapeutic use of penicillin and tetracyclines, the most important antibiotics for human use. The most commonly used antibiotics in feed are chlortetracycline, oxytetracycline, bacitracin, penicillin, and tylosin.

Other growth enhancers added to the feed do not have a disease-reducing affect but rather change the animal’s metabolism. Most are related to hormones produced by the animals. These include lasalocid for cattle and sheep, melengestrol acetate and monensin for cattle, and ractopamine for swine. Several ear implants are approved for delivering hormones or other drugs to feedlot cattle in the United States. For example, these products typically increase daily gain by 10 to 15 percent and feed efficiency by 5 to 10 percent. Other countries, particularly those in the European Union, severely restrict or prohibit the use of implants in meat-producing animals because of opposition from some consumer groups.

Composition And Valuation Of Feeds

The usual chemical analyses of feeds provide information on the amount of dry matter, protein (with its amino acid composition), fat, fibre, minerals, and vitamins contained in the feed. Various energy values (digestible, metabolizable, and net) of the feed, which depend on the species of animal being fed, are included in complete tables of feed composition.

Determination

Digestion and balance experiments measure the degree to which the various components of a feed are absorbed and retained by the animal body. Proteins are composed of varying quantities of amino acids, which are ultimately used by the animal to develop muscle and other body tissues. Microbes in the rumens of cattle and sheep can synthesize amino acids from the various nitrogen sources in their feed. In contrast, monogastrics such as pigs and poultry must have the proper amounts of the essential amino acids provided in their diet. Thus, ruminants typically have simple protein requirements, while monogastrics have amino acid requirements.

Protein and amino acid requirements are expressed as the amounts of digestible protein or amino acids needed for growth or other body functions, either as a percentage of the diet or as the total grams or units required per day. The amounts of energy needed are measured as digestible energy (DE), metabolizable energy (ME), net energy (NE), or total digestible nutrients (TDN). These values differ with species. The gross energy (GE) value of a feed is the amount of heat liberated when it is burned in a bomb calorimeter. The drawback of using this value is that a substance such as wood and corn may have a similar GE but vastly different nutritional values because some or all of it passes through the body without being digested. Furthermore, some of what is digested gets excreted in the urine as urea. Still more energy is lost from the heat of digestion and as gas produced by bacteria in the digestive tract. This loss is appreciably greater in ruminants than in pigs, chickens, and other monogastric animals. The work of eating, digesting, and metabolizing food may also be subtracted from the food energy, resulting in the NE value, or useful energy value of a feed that can be used for production (growth, reproduction, or milk) or for maintenance (basal metabolism, activity, keeping warm). The TDN value of a feed represents the sum of the digestible protein, digestible ether extract (fat) times 2.25, digestible nitrogen-free extract (carbohydrate), and digestible crude fibre. Its use as a measurement factor has declined in recent years because it considers neither the fermentation and heat losses during digestion and metabolism nor the fact that energy is utilized more efficiently for maintenance or milk production than for growth and fattening.

Optimization of nutrient-cost ratio

Feed costs vary widely from season to season; it is often possible for producers to realize substantial savings through wise selection of the feed ingredients used to formulate complete diets. It is much easier for large commercial feed companies with widespread operations to take advantage of regional variations in feed prices than it is for individual relatively small-scale livestock producers who must rely on locally produced feeds.

Least-cost formulation of feed mixtures makes it possible to use computers to select the correct amounts of competitively priced feed ingredients that will combine to fully satisfy the nutrient requirements of a specific type of animal at a particular stage of development. When used by a qualified nutritionist, computer programs can successfully formulate diets that yield maximum production at the lowest possible cost.

Basic Types Of Feeds

Animal feeds are classified as follows: (1) concentrates, high in energy value, including fat, cereal grains and their by-products (barley, corn, oats, rye, wheat), high-protein oil meals or cakes (soybean, canola, cottonseed, peanut [groundnut]), and by-products from processing of sugar beets, sugarcane, animals, and fish, and (2) roughages, including pasture grasses, hays, silage, root crops, straw, and stover (cornstalks).

Concentrate foods

Cereal grains and their by-products

In the agricultural practices of North America and northern Europe, barley, corn, oats, rye, and sorghums are grown almost entirely as animal feed, although small quantities are processed for human consumption as well. These grains are fed whole or ground, either singly or mixed with high-protein oil meals or other by-products, minerals, and vitamins to form a complete feed for pigs and poultry or an adequate dietary supplement for ruminants and horses.

The production of grains is seasonal because of temperature or moisture conditions or a combination of both. It is necessary to produce a full year’s supply during the limited growing season. The grain is dried to 14 percent or less moisture to prevent sprouting or molding; the grain is then stored in containers or buildings where insects and rodents cannot destroy it. It is generally desirable to store more than a year’s supply of the grains to be used as feed, because crop failures sometimes occur.

High-protein meals

Vegetable seeds produced primarily as a source of oil for human food and industrial uses include soybeans, peanuts (groundnuts), flaxseed (linseed), canola, cottonseed, coconuts, oil palm, and sunflower seeds. After these seeds are processed to remove the oil, the residues, which may contain from 5 percent to less than 1 percent of fat and 20 to 50 percent of protein, are marketed as animal feeds. Cottonseed and peanuts have woody hulls or shells, which are generally removed before processing—if the hulls or shells are left intact, the resulting by-product is higher in fibre and appreciably lower in protein and energy value. The protein quality of these meals for monogastrics varies greatly depending on the levels and availability of the amino acids present. Ruminants in general require only protein or nitrogen sources for the rumen microbes to synthesize amino acids.

These high-protein feeds supplement inexpensive roughages, cereal grains, and other low-protein feeds in order to furnish the protein and amino acids needed for efficient growth or production. The supplement chosen for a particular diet depends largely on the cost and availability of supply.

By-products of sugar beets and sugarcane

From the sugar beet industry come beet tops, which are used on the farm either fresh or ensiled, and dried beet pulp and beet molasses, which are produced in sugar factories. Cane molasses is a residue from cane sugar manufacture. These are all palatable, high-quality sources of carbohydrates. Sugarcane bagasse (stalk residue) is fibrous, hard to digest, and of very low feed value. In Europe, beets and some other roots are grown as animal feed. Citrus molasses and dried citrus pulp, which are generally available at low cost as by-products of the citrus juice industry, are often used as high-quality feeds for cattle and sheep.

Other by-product feeds

Large quantities of animal feed are by-products or residues from commercial processing of cereal grains for human consumption. The largest group of these by-product feeds comes from the milling of wheat, including wheat bran, wheat middlings, wheat germ meal, and wheat mill feed. In some areas, bakery wastes, such as stale and leftover bread, rolls, and various pastry products, are ground and used as filler or feed for pets and farm animals. Rice bran and rice hulls are obtained in similar fashion from the mills that polish rice for human food. Corn gluten feed, corn gluten meal, and hominy feed are produced as by-products from the manufacture of starch for industrial and food uses.

Brewers’ grains, corn distillers’ grains and solubles, and brewer’s yeast are useful animal feeds and are collected from the dried residues of the fermentation industries that produce beer and distilled spirits. Waste products from pineapple-canning plants include pineapple bran or pulp and the ensiled leaves from the plant. By-products from the abattoirs and meatpacking plants that process animals into meat include such feeds as meat and bonemeal, tankage (animal residue left after rendering fat in a slaughterhouse), meat scraps, blood meal, poultry waste, and feather meal. Various types and qualities of fish meals are produced by fish-processing plants. These animal by-products typically contain 50 percent or more high-quality protein and the mineral elements calcium and phosphorus. Steamed bonemeal is particularly high in these important minerals. Dried skim milk, dried whey, and dried buttermilk are feed by-products from the dairy industry.

Roughages

Pasture

Pasture grasses and legumes, both native and cultivated, are the most important single source of feed for ruminants such as cattle, horses, sheep, and goats. During the growing season they furnish most of the feed for these animals at a cost lower than for feeds that need to be harvested, processed, and transported. Hundreds of different grasses, legumes, bushes, and trees are acceptable as feeds for grazing animals. The nutritive value of the cultivated varieties has been studied, but information is incomplete for many of those that occur naturally.

Hay

Hay is produced by drying grasses or legumes when they approach the stage of maximum plant growth and before the seed develops. This stage has been shown to give maximum yields of digestible protein and carbohydrates per unit of land area. The moisture content is typically reduced below 18 percent in order to prevent molding, heating, and spoilage during storage. Legume hays, such as alfalfa and clovers, are high in protein, while the grasses (such as timothy and Sudan grass) are lower in protein and vary considerably depending on their stage of maturity and the amount of nitrogen fertilization applied to them. Stored hay is fed to animals when sufficient fresh pasture grass is not available.

hay

hay

Bales of hay.

Silage

Silage is made by packing immature plants in an airtight storage container and allowing fermentation to develop acetic and lactic acids, which preserve the moist feed. Storage may be in upright tower silos or in trenches in the ground. The initial moisture concentration of the forage should be between 50 and 70 percent, depending on the type of silage. Lower moisture levels can cause difficulty in obtaining sufficient packing to exclude air and may result in molding or other spoilage. Too high a moisture content causes nutrient losses by seepage and results in the production of excessively acidic, unpalatable silage. Ensiled forage can be stored for a longer period of time with lower loss of nutrients than dry hay. The nutritive value of silage depends on the type of forage ensiled and how successfully it has been cured. Corn, sorghums, grasses, and sometimes leguminous forages are used in making silage.

Root crops

Root crops are used less extensively as animal feed than was true in the past, for economic reasons. Beets (mangels), rutabagas, cassava, turnips, and sometimes surplus potatoes are used as feed. Compared with other feeds, root crops are low in dry-matter content and protein; they mostly provide energy.

Straw and hulls

Quantities of straw remaining after the harvesting of wheat, oats, barley, and rice crops are used as feed for cattle and other ruminants. The straws are low in protein and very high in fibre; digestibility is low. Straw is useful in maintaining mature animals when other feeds are in short supply, but it is too low in nutrition to be a satisfactory feed for extended periods unless supplemented with other feeds that supply the protein, digestible energy, and minerals needed for growth and production. Treatment of straw with alkali markedly increases the digestibility of the cellulose, augmenting its value as a source of energy for animals.

Corncobs, cornstalks, cottonseed hulls, and rice hulls can also be used as sources of fibre in ruminant diets. Rice hulls are lower in value, while the others are similar to straw.

PASTURE AND RANGE IN LIVESTOCK FEEDING

by P. V. Cardon, W. R. Chaplme, L E. Woodward, E. W. McComas, and C. R. Enlow i i n K t t classes of feed available for livestock—pasture and range forage, harvested forage, and miscellaneous feeds—are discussed in the following three articles. This one deals with pasture and range, telling about kinds of pasture, grazing methods, pasture management, the relationship between pasture and other feeds, range forage, the maintenance of production on the range, and some of the research on soils and fertilizers as related to pastures. PRIMITIVE MAN, dependent as he was on game for his food, must have recognized the ^^miversal beneficence of grass." It is easy to imagine that he came to associate the differences in the forage upoji which his quarry grazed with the differences in the quality of his meat. With the domestication of cattle, sheep, and horses, the provision of suitable grazing for his animals became one of man's chief respousibilities. History is replete with tales of combat in which neighbors, tribes, and nations contended for grass for their flocks and herds. Recent range wars in our West are modern versions of man's age-long struggle for grass. In the United States today that struggle has entered a different phase—in some respects a new phase. With no virgin grasslands beyond the horizon, the eyes of the grazier are turned back upon the grass within his own fence lines or upon controlled public ranges. His hope lies now in grass restoration and maintenance and in providing not only more but better grass—better in a nutritional sense. For even within the last decade developments in the field of nutrition have shown that the nutritive properties of green plants are not only beneficial but essential to health, growth, and reproduction in livestock. The factors controlling the nutritional values of green forage are ' p. V, Cardon is Assistant Chief, formerly Principal Agronomist in charge of the Division of Forage Crops and Diseases, Bureau of Plant Industry; W. R. Chapline is Principal Inspector of Grazing, in charge. Division of Range Research, Forest Service; T. E. Woodward is Senior Dairy Husbandman, Division of Dairy Cattle Breeding, Feeding, and Management, Bureau of Dairy Industry; E. W. McComas is Animal Husbandman, Bureau of Animal Industry; and C. R. Enlow is Principal Agronomist, in charge. Agronomy Division, Soil Conservation Service. 925 926 YEARBOOK OF AGRICULTURE, 1939 Figure 1.—Major graining regions of the Liiited States. as complex as they are numerous, and present knowledge of them is admittedly limited, as will become plain in the following pages; but enough is known to point the w^ay to better grass and its more effective use. As we move in that direction, new facts and greater knowledge will develop to guide further progress. GRAZING REGIONS AND PRINCIPAL PLANT SPECIES ^ Approximately 60 percent of the total land area of the United States is grazed at least part of the year (1167). The type of grazing land, as well as its carrying capacity and seasonal use, varies according to topography, soil, and climate, all of which govern the number and kind of species constituting the forage. Regional differences witli respect to those factors characterize large geographic areas such as the Great Plains. The approximate boundaries of the major grazing regions of the United States are shown in figure L This map is supplemented by table 1, which lists the more abundant pasture species in each region. Many more species are recognized as being of importance, but it is not practicable in this article to present a complete list. WHY PASTURE AND RANGE ARE TREATED SEPARATELY There is a distinction, though not a basic difference, between farm pastures and the range. Farm pastures as a rule are relatively limited grazing areas, usually privately owned, which are units of farm enterprises, especially in humid or irrigated regions. Ranges, on the other hand, are relatively large grazing areas, either privately or publicly owned or controlled, located on nonfarming land, mostly in the semiarid and forested parts of the United States. Unharvested herbage includes all feed gathered directly by animals. TAKLIí \. MCO —i C m > Z O > z Q No TABLE L -Most abundant grasses and legumes comprising the forage in each of the genirally recognized grazing regions of the United States as shown in figure 1—Continued iTitermountain North Pacific coast South Pacific coast Grasses Legumes Grasses Legumes Grasses Legumes VVheatgrasses {Agropyron Alfalfa (Medicago sativa). Ryegrasses (Loiium spp.). Red clover {Trifolium Fescues (Festuca spp.). California bur-clover spp.). White clover (Trifolium re- Kentucky bluegrass {Poa pratense). Bromes (Promus spp.). (Medicago hispida). Gramas {Bouteloua spp.). pens),'^ pratense). White clover (Trifolium Wild oats (Avena spp.). Alfalfa (Medicago sativa). Bromes {Bromiis spp.). Sweetclovers(Melilotusspp.). Bents (Agrostis spp.). repens).^ Bermuda (Cynodon dacty- White clover (TrifoGalletas, tobosa, and curly Alsike clover (Trifolium hy- Reed canary (Phalaris arun- Hop clover (Trifolium Lon). lium repens) .^ mesquite {Hilaria spp.) bridum). dinacea). dubium). Sudan {Sorghum, vulgäre var. Black medic (Medicago Bluegrasses {Poa spp.). Red clover (Trifolium pra- Orchard (Dactylis glomer- Alsike clover ( Trifolium sîidanense). lupuLina), Timothy {Phleum pra- tense). ata). hyhridum). tense) . Black medic (Medicago LIL- Meadow fescue (Festuca alaRedtop {Agrostis alba). pulina). tior). Bermuda (Cvnodon dactv- California bur-clover {Medi- Redtop (Agrosths alba). ion). cago hispido). Timothy (PhLeuin pratense). Beardgrasses or bluestems Strawberry clover {Triformrn Tall oatgrass (Arrhenather- (Andropngon spp.) fragiferum). wm elafins). Meadow foxtail (Alopecurns pratensis^. 1 Includes Ladino clover. - DO O o o-n > C) n c c m O PASTURE AND RANGE 929 The same physical and biological factors influence, though perhaps in varying degrees, the nutritional value of plants whether tho}^ are in farm pastures or on the range. Pasturage consists principally of mixtures of tame grasses and legumes. Range forage usually consists of a mixture of herbaceous species, mainly native grasses and legumes, but often includes an admixture of sedges, rushes, and other grasslike plants, of weeds—the forbs of the scientist—and sometimes of woody plants as well. The forage gathered from shrubs or trees is called browse. Nuts that have fallen from trees and are used as feed are called mast. Mast and browse are important chiefly on ranges. In some areas and in certain seasons weeds constitute an important part of pasturage. Occasionally the weed of today may be classed as an important forage plant tomorrow. The major differences, then, between pastures and the range pertain to geographic distribution, size of units, kind of vegetation, and use. Pasture management usually aims at maintaining maximum production of young palatable growth, while this is not ordinarily possible on range lands, where drier conditions limit regrowth of plants after grazing. These difterences are considered of sufficient importance to justify in this article a separate section on the range to meet the special interests of range users. FARM PASTURES ECONOMIC IMPORTANCE AND MAJOR USES No accurate estimate can be made of the proportion of the total feed supply of the United States that is derived from pastures. Roughly, however, it would appear that pastures provide about one-third of the nutrients used by dairy cattle, while beef cattle and sheep probably obtain half of their feed from pastures and livestock on the range considerably more than half from range forage. Semple and others {1027) ^ cite the results of cost studies made by the United States Department of Agriculture to show that pasturage furnished nearly one-third of the total sustenance of cows in market milk production while constituting only one-seventh of the total feed cost. They show also that on 478 Corn Belt farms producing beef calves— the breeding cows obtained practically their entire hving from pasture for 200 days and from roughage and concentrates for 165 days. The pastures which were furnishing a little more than half of the total sustenance were credited with only one-third of the feed bill. Misner {791}) has shown that in New York the total cost of milk production on pasture was 9.7 cents per cow per day, with returns of 34 cents. The cost of winter feed, on the other hand, was 38 cents per cow per day, with the same returns as on pasture.^ 2 Italic numbers in parentheses refer to Literature Cited, p. 1075. 3 The practical importance of information as to the nutritive value of pasturage in terms of other feed crops and the relative cost of the nutrients derived from pasturage and from other crops is so great as to command the interest of various scientific groups in the United States and Canada, such as the American Society of Animal Production, the American Dairy Science Association, the American Society of Agronomy, and the Canadian Committee on Pasture and Hay Production. These four groups are considering joint effort designed to assemble and evaluate available data to serve as a guide to farmers in planning feed production. In the meantime certain European countries, especially the Scandinavian and Germanic countries, have assembled data of this type on the feed crops of those countries that are widely used there.* 4 PTETERS, A. J. A DIGEST OF SOME WORLD PASTURE RESEARCH LITERATURE. U. S. Dept. Agr., Div. Forage Crops and Diseases, Bur. Plant Indus. 1937. [Mimeographed.! 141394°-—39 60 930 YEARBOOK OF AGRICULTURE, 1939 The economy of pastures in livestock farniing lias been shown by similar results of cost studies in several other States. It should be remenibered in this connection that even p-eater returns might be expected on improved pastures under good management, although adequate cost data oii this poijit are not available. Vai'ious studies in Europe and some in this country indicate notable increases in forage yields and animal products on pastures following good management, including the use of improved pasture species, the proper use of fertilizers, or suitable grazing practices. These and other studies indicate also that through good management the pasture season may be extended and made to produce more satisfactory seasonlong returns. Pastures ma}^ serve as the total source of feed or, more often, as the principal seasonal source for different classes of livestock. They can be depeiided on for the total feed recpiirement only in limited areas where yearlong or continuous grazing is possible. In most regions of the United States it is possible to graze only during limited periods, so that pasturage does not pmvide as much of the total annual feed requirements as hay, silage, and concentrates combined, although it usualty provides the major portion of feed for the time it is used. In the United States pastures are grazed chiefly by cattle, sheep, and horses, and also to some extent by hogs, especially alfalfa pastures. In some areas, the use of pastures by poultry is becoming more common. In this country there is less tendency to graze cattle and sheep on the same pasture than in some other countries—in Great Britain, for instance, mixed grazing is commonly practiced in the belief that the herbage is thus more completely utilized. In certain sections of the United States, however, mixed grazing is practiced regularly, as on the Edwards Plateau of Texas, where cattle, sheep, and goats use the same pastures. ^^^,^^ ^^ „.c^-mnr*. KINDS OF PASTURES Pastures may be classified {926, 1027) as permanent, temporary, and supplemental, according to the length of time they are to be used ; or on the basis of the plants that make up the pasturage, as tame and wild, although the latter are now commonty classified as range. Permanent pastures in the United States are found most commonly on land that cannot be used profitably for the culture of field or horticultural crops. They occur on hill lands, in marshes, and in the woods and forests. The western ranges, also, may be regarded as permanent pastures. The common characteristic of permanent pastures is that they are seldom if ever broken by cultivation, except as their surfaces may be disturbed by renovation practices. Temporary pastures are of diverse character, but include all crop fields used as pastures for a short peiiod. Fallow land is sometimes pastured to utilize and control weed growth. Fields of seedling-grahi crops, as oats, barley, and wheat, are often pastured in the fall oi' spring without damaging the stand or reducing the ultimate yield of grain. Stubblefields likewise are pastured, as are meadows after the hay crop is removed. Again, such crops as cowpeas, velvetbeans, so3^beans, rape, and peanuts may serve as temporary pastures at some time during their growth periods. Supplemental pastures include those which are seeded to some crop such as Sudan grass or lespedeza, for tJje ])urpose of providing pas- >en—I 70m > Z O 70 > Z o Fígurp 2.—Temporary pastures lo supplcuenl pcnnaiK-.u paslurcs when ihe latter are relatively uiipruductive afford a means of maintaining o milk flow at a high level throughout the season. ^ 932 YEARBOOK OF AGRICULTURE, 1939 : PASTURES PERMANENT FERTILIZED UNFERTILIZED TEMPORARY RYE (FALL-SEEDED) SUPPLEMENTAL I SWEETCLOVER (2ND YEAR) i SWEETCLOVER (1ST YEAR) I SUDAN GRASS I MEADOW (2ND CROP) ; ALFALFA (2ND CROP) Figure 3.—Srhemalic represen la (ion ol' combined nse of permanent, temporary, and supplemental pastures designed to provide adequate pasturage throughout the season. Originally planned for Iowa, this scheme could be used as a guide in other Stales, substitviting temporary and supplemental pasture crops adapted to the locality. (Adapted from Iowa State College Extension Circular DH 46.) The rectangles black show the periods when the pastures are utilized. turage to supplement permanent pastures during the season when the latter are relatively unproductive, a condition characteristic of Kentucky bluegrass pastm-es in midsummer (fig. 2). Tame pastures may include any of the foregoing types when composed principally of domesticated grasses, as Kentucky bluegrass, redtop, timothy,^ orchard grass, and Bermuda grass, alone or in mixtures with white clover or other legumes. By a combined use of permanent, temporary, and supplemental farm pastures, fanners are able ordinarily to provide adequate seasonlong pasturage (fig. 3). Such a plan is generally less feasible in range country, but to some extent the same end often is accomplished by moving the hvestock from one range to another, as from springfall, to summer, and thence to winter range. In pasture experhnents conducted in Missouri (337) it was found that beef cattle on permanent bluegrass pasture made almost 60 percent of their total gains in weight during the first 60 days; abo tit two-thirds of the total season's gains were made from the first ojiethird of the full pasture season. By suppletnenting permanent pasture with Korean lespedeza, the carrying capacity and nutritive value of the pasture herbage has been increased. The Korean lespedeza furnished grazing from late June until late September, when permanent bluegrass pastures are practically dormant. GRAZING METHODS Grazing may be seasonlong or, in some favorable areas, yearlong. Either seasonlong or yearlong grazing may be continuous, or it may PASTURE AND RANGE 933 be intermittent with no attempt at regularity. Again, a pasture or range may be divided into two parts which are grazed alternately ; this is called alternate grazing. When a pasture or range is divided in such a way as to rotate the use of the various segments in regular order, grazing is referred to as rotation grazing. Deferred grazing— keeping the animals off the pasture until after the grasses, including the seed crop, are mature—is sometimes practiced to insure natural reseeding or to stimulate vegetative reproduction. In actual practice, especially on the range, deferred and rotational grazing are frequently combined. In the practice of any of the foregoing methods, the pasture may be adversely affected by premature grazing, that is, grazing too early in the season, before the ground is firm or the grasses have made sufficient growth; or by overgrazing, which results in the loss of vigor of desirable vegetation and creates a condition favorable to replacement of such vegetation by weeds and other less desirable plants. The herbage available determines the carrying or grazing capacity of an area, that is, the ratio of animals to the unit of area that will furnish ample sustenance, as one cow to 2 acres, three sheep to 1 acre, one steer to 20 acres, and so on. Overgrazing, or grazing beyond carrying capacity, ordinarily is inadvisable. The serious consequences of overgrazing have been emphasized, during recent 3^ears, in many publications pertaining to soil conservation, erosion control, and range improvement. It has received less emphasis in literature pertaining to farm-pasture management, although overgrazing is as much to be avoided on farm pastures as upon the range. It weakens desirable species, thereby making way for less desirable species, including weeds. Grazing short of carrying capacity may also be inadvisable under some conditions, especially where the grass tends to ^^get away,^^ and become with maturity relatively less palatable, digestible, and nutritious. If, under such conditions, the grass could be clipped and ensiled, as is commonly done in some countiies and to an increasing extent in this country, much good feed might be saved and the pasture left uninjured. In an experiment on methods and rates of grazing at Beltsville, Md. {502), it was found that the crude protein in the herbage under continuous light grazing averaged 13.04 percent as compared with 14.56 under continuous heavy grazing and 13.40 under alternate heavy grazing. The calcium and phosphorus contents were 0.59 and 0.30 percent, respectively, under continuous light grazing, 0.75 and 0.32 under continuous heavy grazing, and 0.60 and 0.34 under alternate heavy grazing. The Washington Agricultural Experiment Station {520) reports that rotation grazing did not improve the quality of herbage as measured by chemical composition when compared with the herbage obtained from continuous grazing, but it did increase the yield. It would appear from these experiments that the relative advantages in rotation and continuous grazing are dependent upon differences in local soil, climate, and management factors. A 6-year experiment conducted at Beltsville, Md. {1270), in which permanent pastures were grazed by dairy cattle in a six-field rotation o o o-n > o c c 70 Figure 4.—Good |>U!^liira^r |ir( \ idi's a pirrcci raliciii for rows proiliirinp a iiiciliiirii or -TIKIII (|iiarilily ol iiiilk, bul even good pasturaje may require biipplenieiit^ for iii*:h>|iro(liicing eow». PASTURE AND RANGE 935 and contiiuiously, showed a 10.4-percent greater yield under rotation grazing. NUTRITIVE VALUES OF PASTURAGE Besides providing cheap succulent feed, pasturage is of great importance as a source of proteins, minerals, and vitamins {1027). The immature plants are much richer in protein than the same plants at a later stage of growth. The young plants are also softer and more tender, and the dry matter, being less fibrous, is more easily digestible. Most if not all of the minerals of importance in animal nutrition may occur in pasture herbage, although, as will be shown, this depends in large measure on differences in the soil environment and the inherent ability of species of plants to extract nutrients from the soil. Influence of Physical Factors Rainfall is probably the greatest single factor influencing the yield and nutritive value of grasses. Most species are m.ore palatable, digestible, and nutritious under favorable moisture conditions than when the moisture supply is inadequate. Many of the grasses of the dry Great Plains region, how^ever, have in their physiological make-up the ability to retain their palatability and nutritive value at mature stages of growth when their moisture content is low. In addition to moisture, temperature plays an important part in influencing the nutritive value of many perennial pasture grasses. As the temperature increases during the summer months, production decreases and the ratio of stem, to leaf increases, with an increase in crude fiber and a decrease in crude protein. High temperature reduces the quality of adapted varieties of pasture herbage to the greatest extent in the north humid regions. Grasses grown in the South are adapted to and withstand high temperatures. Bermuda grass, Dallis grass, Bahia grass, molasses grass, and other southern species all require high temperatures for their most rapid growth, but at the same time they must have ample moisture and fertile soil. Buflalo grass, crested wheatgrass, and grama grass, all adapted to regions of limited rainfall such as the Great Plains, make ample growth with limited moisture and at reasonably high temperatures. Influence of Management Practices Among the various factors influencing the nutritional value of herbage, the management factor is of primary interest to the grazier, because it is one that he can control. Through intelligent management he is able to derive from his pastures the maximum returns possible under the environmental conditions governing his operations. Pasture management involves among other things (1) choice of species, (2) use of fertilizers, and (3) grazing practices employed. Choice of Species Species are chosen to provide a desired mixture of grasses and legumes. Because of differences in habits of growth and seasonal response to environmental influences, several grasses are more likely to insure grazing over a longer season than will any single grass. Through the proper selection of grass species it may be possible to 936 YEARBOOK OF AGRICULTURE, 1939 have one or more of them growmg througlioiit the grazing season. Legmnes m the mixtiu-e are iniportant in that they increase the yield of the herbage and in the more mature stage add to its nutritive vahie by increasing the ijrotein content. Because of their abiHty to supply to the soil nitrogen extracted from the air through their root nodules, legumes also stimulate the growth of the associated grasses and increase their protein content. Johnstone-Wallace {690) reports that the protein content of Kentucky bluegrass grown alone averaged 18 percent while that of the same grass grown in association with white clover averaged 25 percent—an increase of more than one-third. Timothy grown alone averaged 24 percent, but with white clover 30; orchard grass averaged 23.5 percent alone, but 29.3 with clover.^ Choice of species is also important with respect to palatability—a term commonly used but little understood. Graziers know that domestic animals display marked preference for certain pasture plants, whereas they avoid others except when forced b}^ hunger to eat them. Moreover, they prefer a given species when at a particular stage of growth, as shown by Stapledon (1099) and by Forsling and Storm on a Utah range (378), The same chscrimination has been obseiwed among rodents and insects. Whether or not animals smell or taste a difference in pasture plants and to what that difference may be ascribed aj^e points that remain to be determined. Yet palatability cannot be ignored in pasture management. Whatever it is, it influences the grazing value of any pasture. It is important, therefore, to choose species that are palatable and to graze them when they are most palatable, that is, in early immaturity. Bromegrass, Kentucky bluegrass, and timothy are genei'ally regarded as highly palatable, whereas such grasses as red top, bentgrass, and many natives species are relatively low in palatabihty, at least in certain stages of growth. Less palatable grasses may often be used advantageously, however, if their growth habits arc such as to provide herbage in seasons when more palatable species are dormant. The relationship between palatability^ and nutritive value is not clear, but it is generally conceded tliat palatable species are more nutritious than unpalatable species, possibly because of the greater quantity consumed or some related qualitative factor. Use of Fertilizers Because different species of pasture plants respond differently to various nutrients in the soil and because their use of nutrients influences their composition, it is plain that the application of fertilizers should be governed by plant requirements as well as by soil analysis. In other words, although soil analysis may reveal certain deficiencies which may be corrected through the use of fertilizers, experiments indicate that these fertilizers should be applied with a view to satisfying the requirements of the different grasses and legumes in the pasture mixture if the greatest benefits from fertilizer use are to be realized. This, however, would require knowledge not yet sufficiently developed to warrant definite recommendations. Lacking specific knowledge on this subject, the farmer can proceed only in the light of more > to —t C 73m > Z > z m Figure 5.—Beef cattle gains are made at less expense on bigli-qiialil^ pasture than by dry-lot feeding. 938 YEARBOOK OF AGRICULTURE, 1939 i:^onoral mformation. It is known, for instance, that grasses usually respond better than legumes to nitrogen, whereas legumes are more responsive than grasses to phosphorus and potash. Nitrogen not only stimulates grass but increases its protein content. The stinuilus to legmne growth afforded by applications of lime^ phosphorus, and potash, where deficient, also increases the protein content of the herbage. Overstimulation of legumes, on the other hancl^ may be detrimental to tlie associated grasses. In applying nitrogen it is important also to avoid excessiA^e stimulation of grass growth, since this may prove injurious to legumes growing in the mixtm-e. The objective should be to keep both grasses and legumes in the herbage. It is advisable in this connection to consult the county agricultural agent, who usually has access to information from the State agricultural experiment station or the United States Department of Agriculture relative to the various soil t^^pes in the county and their fertilizer requirements. If such information is not available the county agent may be able to make arrangements for obtaining it. Robinson and Pierre {975) emphasize the importance of consideiing the costs of pasture fertilization and liming as a long-time investment: Although the initial cost of improving a depleted pasture may range from So to $10 an acre, it should be remembered that once a good sod is reestablished, the cost of maintaining such a sod will be relatively low. This statement is supported by data showing the residual effects of lime and superphosphate treatments on yield and composition of the herbage, A more technical discussion of the results of research on the effects of soil and fertilizers on pasture herbage will be found at the end of this article. Grazing Practices Grazing practices also influence the botanical composition of pastures and hence the mitritive value of the herbage. Since pasture species diffei' in palatability, some are more readily grazed than others, which tends to jeopardize the more palatable and to protect the less palatable species. Likewise, some species are naturally more persistent than others, so that even though equally palatable the more persistent tend to survive while the less persistent tend to disappear under grazing, xlgain, species differ in their ability to recover after grazing, some requiring more time than others. The time and intensity of grazing with respect to the stage of growth also affects persistency, especially that of species dependent upon natural reseeding for reproduction. If these are grazed in a manner to prevent seed formation they do not survive. McCarty's studies with mountain brome (713) show that early spring growth is made at the expense of carbohydrates stored in the roots and stem bases during the previous autumn, but that subseciuent normal growth and yield are independent of stored carbohydrates, being ihe products of current carbohydrate manufacture by the plant. Excessive early grazing, therefore, tends to deplete stored reserves of carbohydrates and to reduce the vigo]' of the plants. These findings further hidicate the advisability of moderate grazing designed to leave enough herbage after each grazing period ^'to permit sufficient PASTURE AND RANGE 939 manufacture and storage of carbohydrates to maintain the hfe and proper vigor of the plants." Time of grazing with respect to the stage of maturity of the herbage is of the utmost importance. Young, succulent herbage is richer in protein than mature plants of the same species, contains more calcium and phosphorus, and is higher in vitamins, and the dry matter is more digestible. In South Carolina (322) it was found that, as indicated by chemical composition, rapidly growing plants produce greater yields and have superior feeding value ; also that the feeding value of pasture herbage is lower during the latter part of the growling season because of changes in chemical composition. Mortimer and Ahlgren (822) report that Kentucky bluegrass cut to 8 to 10 inches high was lower in phosphorus and calcium than the same grass cut to 4 to 5 inches. In studies conducted in North Dakota (54^) with many grasses both introduced and native, it was found that in general protein and ash (mineral content) decreased and carbohydrates increased as plants approached maturity. Use of Hay and Concentrates to Supplement Pasturage Dairy Cattle Studies made of seasonal milk production in 12 States show that the most favorable time for the production of milk is in the spring when the pasture grass is at its best. They show also that after tb.e flush of the pasture season, which lasts for only a month or so, the production declines rapidly. The first growth in the spring is tender, palatable, and abundant. Cows will eat as much as 150 pounds a deij. If no deduction is made for the energy used in grazing, this amount is enough to support a production of 40 pounds of milk with an average percentage of butterfat. The grass soon becomes either tougher, less palatable, and more fibrous, or it becomes more scarce. The result is that cows do not eat as much as they did earlier in the season. This fact is advanced as the principal explanation of the rapid decline in production during the summer. Aside from common salt, which is needed with all rations, young pasturage grown on a fertile soil provides a perfect ration for cows producing a medium or small quantity of milk (fig. 4). The content of protein, vitamins, and minerals is ample both in kind and quantity. Some dairy cows, however, have been developed to a state of productivity where they cannot obtain enough of the energy-producing constituents from pasturage alone to maintain their weight and at the same time produce the quantities of milk of which they are capable. Sucb cows should have supplementary feed. In the spring when the grass is eaten in large quantities and the cows maintain a good fill of forage, the supplementary feed should be concentrates and should be given to all cows producing more than, say, 25 or 30 pounds of averagetesting milk. As the pasturage becomes shorter or tougher following the early fiush growth, the decrease in forage consumed in the form of pasturage should be made up with hay or silage or both. Even if cows are Ï-À > JO CO o o 4% #'. • :? -^^ Figure 6.—Good lciii|>or¡iry |iabliir<'s lo Kii|i|>lrMi.-iil |) O n c c PASTURE AND RANGE 941 allowed all the hay and silage they will eat in addition to pasturage, the intake of nutrients will hardly equal the intake when they have access to flush pasturage. This means that while concentrates ma}^ be required for only that production over and above 25 or 30 pounds in the early part of the pasture season, they wdll be required for all production over and above a smaller quantity later in the season, even if the pasturage is supplemented with hay or silage, or both. The intake of protein is usually less in the summer and fall than in the spring, because the herbage is either more mature or less abundant. In the spring any of the farm-grown cereal grains will be satisfactor}^ to use as supplements because the need is for energy-producing feeds. Later in the season the protein content of the concentrate feed must be increased unless the protein needs are met by the generous feeding of legume hay. Vitamins A and D are the only ones in the cow^s ration the deficiencies of which have been shown to be serious enough at times to affect health. All fresh green pasture herbage has a high content of carotene from which vitamin A is formed in the animal body. No other common feed is equal to pasture herbage in content of carotene, and no other w^ill increase the carotene content—as indicated by yellow color—or the vitamin A content of the butterfat to as great an extent as pasture herbage. Fresh, green pasture herbage is devoid of vitamin D, but this vitamin is synthesized within the body when the animal is exposed to direct sunlight. Because grazing cattle are usually in the sun, vitamin D need not be considered in estimating the adequacy of rations being fed to cows on pasture. Pasturage is valuable for young dairy stock of all ages, but until the calves are about 1 year of age it should not constitute the sole ration, else the development of the calves will be arrested. The younger the calf the greater the need of supplementary feed. Probably for about the first 3 months of their lives calves should be fed about the same kind and quantity of feed whether or not pasturage is available. After this age the calf eats progressively larger quantities of grass and the proportion of supplementary feed can be correspondingly reduced until the calf is about 1 year old, when the supplementary feed may be discontinued. However, if quick maturity is desired a large-sized supplementary feeding should be continued. The supplementary feed of calves under 1 year on pasture should be both hay and grain, but of those over 1 year it need be only grain. If for any reason the pasturage becomes short or otherwise inadequate to keep the calves in a thrifty growing condition the supplementary feed should, of course, be increased. Beef Cattle It is generally agreed that beef cattle make gains at less expense on high-quality pasture than by lot feedhig, yet much more time is usually required to get cattle fat enough for market by the use of pasture only (fig. 5). The success of a combination of pasturage with one or more concentrates has been demonstrated in the Corn Belt by Black and Trowbridge (117, 118) in fattening calves prior to weanhig. That this practice, involving what is known as creep feeding—the use of a feeding device in the field—is good economy^ in parts of the Appalachian region is indicated by McComas and Wilson {726). 942 YEARBOOK OF AGRiCULTURE, 1939 Black and Wilson (12Ï) found that it is possible to speed up the rate of finishing 3-year-old steei's by feeding a mixture of corn and cottonseed meal while on. good bluegrass pasture. Feeding a supplement increased tlie steer gains 37 percent over gains from pasture alone. Subsequent work at the same station has shown that it is possible to put a marketable finish on 2-year-old steers by supplementing their pasturage with a mixture of pi'otein and carbohy^drate concentrates. Moreover, steers fed a grain supplement during the last 84 of their 140 days on pasture were more profitable than those fed a supplement the entire time. In order to get yearlings ready for slaughter in midsummer by feeding them a grain supplement on pasture, it is usually necessary to winter them on a ration somewhat liigher than that on which older steers are wintered und considerably liigher than that yearlings ordinarily receive. Hogs, Sheep, and Horses In swine production it frequently is advisable to supplement pasture with certain concentrates, although pasture is an important source of vitamin A and furnishes considerable protein and varying amounts of other nutrients. For example, if the pasture is composed largely of legumes, less calcium supplement will be needed. Robinson (977) and others have determined that swine are not only likely to be more thrifty, but also may be fattened more rapidly and more economically by feeding them supplements of carbohydrate and protei]i concentrates and a mineral mixture containing calcium and phosphorus on pasture, than when they are fattened in a dry lot. For fattening lambs, average-quality pasture will give better results when supplemented. Harper (475) at the Indiana Agricultural Experiment Station reported that it did not pay to supplement good temporary pasture used in fattening lambs (fig. 6), but that permaaient pasture alone gave less favorable results. It appears from subsequent research by Harper (476) that using good-quality temporary pasture as a supplement to permanent pasture in midsummer is probabty a more profitable practice than feeding a supplement of concentrates to lambs on permanent pasture. Permanent pastures and most kinds of temporary pasture when not overgrazed are important factors hi keeping horses healthy and maintenance costs at a minimum. Such pastures do not, as a rule, need to be supplemented with hay or grain in order to nourish idle mares and young stock adequately. In the Corn Belt, work horses are pastured about 6 months of each year, but much of this time they are turned out only at night and on Sundays and holidays or during other short periods of idleness. Under these practices, pasture may be considered a supplement to the work-horse ration (fig. 7). In tlie Cotton Belt, pasture is used to a relatively small extent for work stock. In the Mississippi Delta, for example, it is reported that a mule is pastured an average of only about 34 days a year. Use of Pasturage to Supplement Hay and Concentrates Pasturage is not extensively used as a supplement to other feed, usually when animals are on pasture the feed obtained there consti- -o >to —I a 73m > Z D X) > Z O ?'- ';. Figure r. "For idle mares and young stock, good pasliires usually are adequate, bul for work horses the pastures should be supplemented by concentrates. 944 YEARBOOK OF AGRICULTURE, 1939 tutes the larger share of the total ration and for that reason the other feeds are considered siipjDlenientary rather than the pasturage. In those sections of the country where the winter weather is not too severe, some of the clovers, grasses, and cereal grains may be seeded in the fall for winter pasturage. The amount of grazing provided by such crops is often limited and the continuity of grazing is often interrupted by inclement w^eather or soft ground. Winter pasturage cannot be depended on to provide any certain amount of grazing every year, although sometimes after crop failures pastin-es of winter cereals have been used to especially good advantage. A few dairymen make a practice of feeding their herds on harvested forage and grain the entire year with very little pasturage. The pastures in such cases are regarded as convenient places to put their dry eow^s and young stock in order to lessen the labor of caring for the stock, although the pasturage, because of its content of vitamins, minerals, and protein, makes an especially good feed for both the young stock and the dry cows. The milking cow^s, too, are benefited by even small quantities of pasturage, particularly if the roughage fed in the barn is of poor quality. THE RANGE EXTENT AND SIGNIFICANCE OF THE WESTERN RANGE The western range, pivotal in the economic and social structure of the far West, is a vast area covei'ing 728,000,000 acres of forested and nonforested land mostly west of the one hundi^edth meridian (fig. S). Because of its meager jjrecipitation. rough topography, and other adverse conditions, most of the range is suitable only fo]* grazing. The importance of this area in animal nutrition is enormous—it furnishes cheap feed, costing one-fifth to one-tenth as much as hay or supplements, to appj'oximately 11,000,000 cattle and horses and 27,000,000 sheep and goats for the equivalent of yearlong grazing. The range territory produces 75 percent of the Nation's output of wool and mohair, 55 percent in pounds of live weight of the sheep and lambs, and nearly 33 percent of the cattle and calves {1158). This vast area is not under single ownership but includes private as well as Federal, State, and county lands. In fact, certain areas show a bewildering complex of ownership, which greatly complicates the problem of use and management. A considerable acreage of public land is grazed part of the year by farmers and ranchers whose personally ow^ned lands do not supply a sufiicient amount of forage for the livestock they possess. It is extremely important that the range be maintained in such manner as to assure a continuous supply of forage. If it is improperly used, the direct result is not only unstable livestock production, but far-reaching adverse effects upon watersheds, irrigation, wildlife, recreation, and other resource values. Range livestock production is today definitely a part of western agriculture in which range use is integrated with crop farming. It is estimated that 35 percent of the feed consumed by western range livestock is supplemental feed raised on croplands or irrigated j^astures. In parts of the South also, forest ranges are an indispensable part of the agricultural set-up. PASTURE AND RANGE 945 MAJOR USES OF THE RANGE Cattle and sheep and, to a less extent, goats and horses are the principal kinds of livestock grazed on the western range. Elk, deer, and other wild species are dependent upon range forage and occasionally are overabundant on the range. Although cattle and sheep may be grazed on the same range unit, cattle prefer range predominantly grass, on not too steep a slope, and where there is daily access to water. Sheep feed on mixed grasses, weeds, and browse and are able to graze fairly steep and high ranges with infrequent watering places. Goats do well on good range lands, but are able to use forage on rough, brushy areas. Forage requirements of elk and deer are much the same as those of cattle and sheep, with preference for weeds and browse. An abundance of succulent forage in the spring is particularly important to give lambs, kids, and calves a proper start. Many western range lands are used seasonally in order to obtain maximum value from the forage. Where the winter climate is mild and the grasses cure well on the stalk, thus providing nutritious dry forage, the range may be grazed yearlong, as in parts of the Great Plains. Other areas where grasses cure well, or where there is palatable browse, are used only in winter. Many foothill and high plateau ranges where growth starts rather early are used for spring grazing. Often livestock are brought back onto these spring ranges in the fall. The tender, green, luscious growth on the cooler, moister, higher mountain ranges is in great demand for summer grazing. On these, lambs and steers fatten readily. Herds are frequently driven long distances between summer and winter ranges—often 50 to 150 miles, and in extreme cases as far as 300 miles. Figure 8,—The western range occupies roughly three-fourths of the land area west of the irregular line extending the length of the Great Plains. 141394°—:iy 01 946 YEARBOOK OF AGRICULTURE, 1939 FORAGE PRODUCED ON THE RANGE Range Types and Species As forage for grazing animals, the range offers onl}^ the natural wild vegetation. Some reseeding has been attempted, but on an acreage insignificant in comparison with the range as a whole. Owing to major differences in the soil, temperature, and rainfall, the vegetation naturally falls into 10 readily recognizable types, listed in table 2. Some of the more important forage species that characterize each are also given. The most extensive area (198,092,000 acres) is occupied by the short-grass plains, which rather abruptly succeed the tall-grass prairies, toward the west, in direct response to decreased total annual rainfall. To be sure, minor variations in soil and topography within any given type cause important local modification of the plant cover— for example, the growth of trees along a stream in an otherwise grassland area. TABLE 2.—Range types and grazing capacity Range type Some dominant species Extent Acres 18, 51B, 000 198, 092, 000 4*2. 534,000 89, 274, 000 9(5. 528, 000 2Ö, 896. 000 40.858, 000 75, 72S, 000 J3, 406, 000 126,367,000 Average per cow (5 sheep) per month Tall grass -- Short grass Pacific bunch grass Slender wheatgrass (Agropyron paacifloram) Beardgrasses, or bluestem {Andropogon spp.). Porcupine grass (Sfipa sparten). Bluestem wheatgrass {Agropyron smithii) Blue grama (Bouteloua gracilis). Buffalo grass (Buchloe dactyloides). Curly mesquite (Hilaria belangeri). Bluebuueh wheatgrass (Agropyron spicatum) Sandberg bluegrass (Poa secunda). California needlegrass (Stipa pulchra). Giant wild-rye (Èlymus condensntus). Gramas (Bouteloua spp.)-.- _ - Acres 2.4 4. L 4.5 6,4 Sagebrush-grass Mesquite (Prosopis spp.). Sacaton (Sporobolus wrightü). Bluebunch wheatgrass (Agropyron spicatu m) Sagebrush (Artemisia spp.). Indian ricegrass (Oryzopsis hymenoides). Needlegrasses (Stipa spp.). Saltbush (Atriplex spp.) 8,9 Southern desert shrub 11,5 Salt-desert ^hrub Yucca (Yucca spp.). Various cacti. Black sagebrush (Artemisia nova) 17.8 Piñon-juniper Woodland chaparral open foresrs -. . _ _ Shadscale (Artrîplex confertifolia). Winterfat (Eurofia lanata). Gramas (Bouteloua spp.j S. 4 Junipers (Juniperus spp.). Muhly grasses (Muhlenbergia spp.). Pinion (Pinus edulis). Chamise {Adenostoma fasciaulahim) California oatgrass (Danthonia californica). Alfileria (Erodium ciciUarium). Oaks (Quercus spp.). Largely ponderosa pine (Pinus ponderosa) timber,.. Fescues (Festuca spp.). Bromes (Promus spp.). 9.8 5.9 Total 728,196, 000 PASTURE AND RANGE 947 A balance in the range vegetation of the various climatic units would exist more or less indefinitely, notwithstanding occasional temporary upsets due to drought years, so long as no outside interference occurred. But, man and his grazing animals have disturbed the normal balance. With few exceptions, the principal perennial grasses once dominant and plentiful on the range were those most palatable to livestock, but these have often given way to less palatable plants. In general, out of a total of at'least 10,000 species growing on the range, probably only about 1,000 are of major or secondary importance {69S). Each range type is a complex of species, but only a comparatively small number furnish the bulk of the forage. Generally speaking, perennial species, especially grasses, are the backbone of the range. With the exception of certain legumes, California oatgrass, some bromes, and fingergrasses, range annuals are, on the whole, of inferior palatability and forage value. Furthermore, annuals are subject to wade fluctuation in forage production. Nutritive Values of Range Plants Many palatable range plants, such as some of the wheatgrasses, saltbushes, and native clovers, compare favorably with alfalfa and other cultivated feeds in their chemical composition, as indicative of nutritive value; indeed, some have an even higher ratio of minerals or protein. Chemical values of plants are, however, not constant; there is a higher protein and phosphorus content in the early stages of growth, which gradually decreases as the plants approach maturity {1098), ^ The chemical content of individual plants of the same species also varies with soil, exposure, altitude, and other ecological factors. In general, range plants of higher altitudes, whether grasses or weeds, are higher in crude protein and lower in fiber than plants of lower altitudes {972), The composition of forage plants as it affects their actual nutritive value to the animals themselves, that is, the relation to animal metabolism, is of great significance. Research along this line on range forage plants is of rather recent development and much work remains for the future. Greaves {433), working with 16 species of range plants in Utah, found that a total phosphorus determination is a good indication of the nutritive value of the plant, because sulfur, protein, and crude fat all vary directly with phosphorus. The Arizona Experiment Station has shown that blue grama is an extremely potent source of vitamin A, especially in the early stages of growth {1081). It has been found' in California that vitamin A deficiency in the range-forage diet contributes to reproductive failure of cattle {496), The California Agricultural Experiment Station is continuing its investigations of vitamin A and mineral déficiences at the San Joaquin Experimental Range in cooperation with the California Forest and Range Experiment' Station. Unpublished results of these studies show that with the drying of the annual type of plants on the range during the summer period nutritional values fell well below the minimum level for normal nutrition about the first of July, with both vitamin A and protein deficiencies. The phosphorus content of the plants was found to decrease with the protein, but the blood phosphorus of the animals remained normal. There was a severe loss 948 YEARBOOK OF AGRICULTURE, 1939 in weight of animals and supplements were required to keep them gaining'. Similar nutritional studies are now being made in a number of States. MAINTAINING RANGE FORAGE AND LIVESTOCK PRODUCTION Sustained livestock production on range lands depends on maintaining productivity of the range forage. Maintenance alone is not sufficient, however, since past drought and overuse have seriously depleted the grazing value and curtailed possible production. At the same time, the thinner stand of perennial grasses on the depleted range has exposed the land to increased erosion, which if left unchecked would further decrease productive values. It is of prime importance, therefore, if the productivity of the range is to be maintained and a continuous and ample forage supply for livestock assured, to graze the range in accordance with the life history and growth requirements of the most important palatable species. It is also important to be able to evaluate cotiditions at all times in order to adjust grazing to the capacity of the range {1120), The perennial range grasses and other plants that furnish the forage for the livestock grazing on the range, manufacture in their green leaves the food they utilize in their growth. The start of growth in perennial grasses in the spring, as exemplified by mountain brome, depends primarily on carbohydrates manufactured and stored in their roots the previous autumn, while further production of herbage and of flowers and fruit depends on the manufacture of sufficient carbohydrates currently through the season {71S). It will readily be seen, therefore, why it is essential to have a reasonable growth of grass in the spring before grazing begins and why too close utilization of the herbage at an}^ time is detrimental to sustained forage production. Close use of the range at the same spring period each year is especially detrimental {2S8), However, grazing closely twice or even three times in a summer season, provided the first grazing is late enough and the intervals are sufficient for the vegetation to recover from each cropping, ordinarily does not serio uslv affect the yield and vigor of the plant cover {1008), Forage production on the range must be accomplished under moisture conditions far more adverse than in humid pastures. Average precipitation in the range area is one-third that of the Middle West and East, and in 1 to 4 years out of every 10 there is less than 7b percent of this normally low average rainfaíL How^ever, range plants utilize their limited suppty of available water with remarkable efficiency. Some native grasses require less than 400 pounds of water to produce 1 pound of dry material, in contrast with alfalfa which, in the same section, requires over 800 pounds {1030). Furthermore, it has been shown that soils from a Utah mountain range seriously depleted by erosion require approximately twice as much water to produce a given unit of dry plant weight of peas and wheat as do comparable soils not so depleted {1004, 1005). During severe droughts, as in 1934, range grasses such as the gramas of Montana and New Mexico either fail to grow appreciably or dry up early in the season. Growth in height is greatly restricted in practically all species during drought years. Severe losses in density also follow droughts, as in southern New Mexico where black grama, even under protection from PASTURE AND RANGE 949 grazing, dropped in 1919 to 41 percent and in 1923 to 11 percent of its 1915 stand, following the droughts of 1916 to 1918 and 1921 to 1922 respectively {SJj^l). Overgrazing resulted in even lower stands of black grama during drought and in some cases killed it out entirely. Because of the rather wide fluctuation in forage production from one year to another, ranges should normally be stocked on a conservative basis of 20 percent below^ their forage production in average years. Such conservative stocking not only provides a reserve of forage in case of drought, but also affords added soil protection and enables more rapid recovery of vegetation following drought or on otherwise depleted ranges (fig. 9). Also to insure most satisfactory use of forage by livestock without detriment to forage production, the range should be managed with full recognition of the suitability of various range types for the different classes of livestock, the best season for grazing, and suitable distribution of the animals over the area to avoid concentration {198^ 584)' Deferred and rotation grazing allows deteriorated range to recuperate and often produces greater grazing values on range in good condition. Many examples mig:ht be given of the value of desirable rangemanagement practices in better livestock production. At the United States Range Livestock Experiment Station near Miles City, Mont., in studies handled cooperatively by the Forest Service, the Bureau of Animal Industry, and the Montana State Agricultural Experiment Station, 0-year-old cows grazing conservatively w^eigh from 40 to 90 pounds more than on range slightly overgrazed; an 84-percent calf crop was produced on the conservatively grazed range as compared to 70 percent on the overgrazed; the calves from the former range were heavier at birth, and one-third more pounds of calf at w^eaning time was produced per cow on the conservatively grazed range {564), On the Jornada Experimental Range in southern New Mexico grazing capacity is twice as great, calf crops are half again larger, and losses are one-fifth as great under conservative management as on comparable nearby unmanaged ranges. It is the overcoming of heavy losses during drought and extremely low calf crops which follow that accounts for the major differences {S77), Livestock in a poor and emaciated condition are more subject to losses from malnutrition, disease, predatory animals, straying, and poisonous plants. Ordinarily animals do not eat a sufficient amount of poisonous plants to be of serious consequence unless they fail to obtain from their forage an adequate supply of the nutrients essential for their needs. In parts of the West where breeding cattle are wintered on the range, supplemental feeding is particularly desirable. Experiments in Montana {IIS) showed that approximately 1 pound of cottonseed cake a head fed daily for 73 days during the winter as a supplement to the range enabled the cows to come through the winter in better condition than cows on range w^ithout a supplement, and they consistently produced calves heavier at birth and at weaning time. Lantow {663) found that feeding cottonseed cake at the rate of 1 pound a head daily to breeding cows on range in New Mexico was a highly desirable practice and usually more economical than feeding a supplement of corn. The relative price of corn and cottonseed cake would, of course, have to be considered in ranch practice. At the > CO O o O-n > o 7¡ Fißire 9.—Summer range conservatively grazed provides abundant excellent feed for sheep with adequate range conservation. PASTURE AND RANGE 951 same station Lantow (661) reported that feeding from }( to 1 pound of cottonseed cake a head daily gave best results with calves on winter range—the rate of feeding depending on the quality of the range. A supplement of 1 pound of cake a head daily was adequate for yearlings. Black and Mathews (111) showed that it is much more economical to winter yearling steers on range in the northern Great Plains with a supplement of concentrates or dry roughage w^hen the weather is severe, than to winter them in a lot on harvested feeds. Management that sustains forage production is of benefit to the stockman as well as to the economic welfare of the West generally. Overgrazing necessitates excessive use of supplemental feed, especially during droughts when hay and other available feeds are apt to be at a premium. The only alternative is starvation losses or forced shipments of livestock on markets depressed by many such efforts to dispose of surplus animals. Sustained livestock production on the basis of conservative grazing and other phases of good range management reduces the unit cost of production and assures more profit to the stockman {2^3). SOUTHERN FOREST RANGES The range picture would not be complete without reference to the extensive forest lands of the South producing native forage that is grazed. These forests of the South comprise some 200 million acres, most of which is grazed to some extent. Little attention is given to livestock on unfenced forest ranges, but fires set to ^^burn off the rough'' often damage forest values. Intensive livestock raising as well as intensive forest management will demand independent use of land for the best development, but at present there are large areas of forest land on w^hich grazing and forestry might well be combined under extensive management. Grazing should ordinarily be eliminated from hardwood forests, where feed values are low and reproduction is apt to be damaged severely. Through proper coordination of grazing of piney woods range with improved pastures and harvested feed, and by improving the type of cattle, livestock production could more nearly meet the milk and meat requirements of the region, and aid living standards of tlie farmer-stockmen. On cut-over pinelands of southern Mississippi it has been found that the abundant native forage available while the pine reproduction is developing has fairly good feed values in the spring and early summer (1176). Cattle make reasonably good gains during that period, but when left on the land until late in the fall or throughout the year without supplements, as is the common practice, they lose this weight. By removing the livestock in the fall to improved pastures, which can be rather readily established on the limited area of highly productive soils, gains in weight and satisfactory calf production could be attained. Needed management features include control of grazing through fence laws, leasing of range privileges on private lands, and other means for placing responsibility on owners of lands and livestock that will aid in overcoming the promiscuous burning and widespread unrestricted grazing now prevailing. Although there is much general information on the nutritive values of range forage and some very good work is under way, the detailed 952 YEARBOOK OF AGRICULTURE, 1939 knowledge of nutritive values of range plants and of management requirements based thereon which will make possible most satisfactory range and livestock management on both western and southern ranges is still lacking. RESEARCH ON THE EFFECTS OF SOIL AND FERTILIZERS ON PASTURES^ To research workers it is apparent that the nutritional values in herbage are modified by a complexity of physical and biological factors concerning which, particularly as to their interrelationships, present knowledge is inadequate. Pasture species, for example, vary structural!}^ and inherently, not only as species but within each species. Various strains of a given species may differ as widely in habits of growth as varieties of wheat or corn. Associated with variability in structure and growth habits among species is a difference in their ability to utilize nutrients in the soil. Much remains to be learned about this selective ability of plants and its relation to chemical composition—much more with respect to the relation between chemical composition and nutritional values. But an increasing volume of literature clearly indicates the existence of these relationships and further research will clarify them, EFFECTS OF SOIL AMENDMENTS Since plants vary in their ability to select and utilize different soil nutrients, the type of soil—its physical and chemical composition—apparently plays a basic part in modifying the growth habits and composition of the plants. This emphasizes the importance of intelligent use of soil amendments, such as fertilizers, lime, and inoculants, calculated to provide a suitable soil environment. Very little is known, however, as to what effect any particular fertilizer will have on the mineral content of the same plants grown on different soils. In general the amount of any fertilizing element in the soil is reflected in the chemical composition of the plant grown on the soil and also in the physical condition of the animals grazed on these plants. Where deficiency in calcium, nitrogen, potash, or phosphorus occurs in the soil and when increased growth results from the application of one of these elements, the increased growth is usually correlated with an increase in the plant of the particular element applied to the^ soil. Not infrequently the application of a fertilizing element results in an increase in the plant of a constituent other than that applied as a fertilizer. Adding phosphates to a certain soil may affect the amount of potassium in the plants growing on that soil without adding materially to the phosphorus content, w^hile on another soil applications of phosphate may result only in an increase in the phosphorus content of the plant. Instances have been reported in which applications of phosphorus and potash increased the nitrogen content of the plant very materially. On the other hand, applications of nitrogen alone have in some instaiices reduced the calcium and phosphorus content of grass. The association of bromegrass with clover is known to result in an increase in the protein content of the grass. In general, however, as first stated, the fertilizing elements in the soil are reflected in the chemical composition of the plant. Vinall and Wilkins {1168) report that nitrogen applied to Kentucky bluegrass increased the crude protein 12.34 percent (average of 56 comparisons). The addition of phosphorus and potash also resulted in increased crude protein. When phosphorus w^as applied as a fertilizer it effected an average increase of 25.64 percent of elemental phosphorus in the herbage, while the calcium was increased 16.67 percent. When nitrogen was applied to white clover its calcium content decreased 10.64 percent, while the addition of phosphorus to white clover produced small increases in crude protein and an increase of 22.22 percent in phosphorus content and 11.9 percent in calcium, Vinall and Wilkins conclude ''that if statistical methods are sound these results prove beyond reasonable doubt that the composition of grass may be changed appreciably by applications of fertilizer to the soil on which it is grown." Work done in Connecticut {160) shows that distinct changes in the composition of herbage have been caused by the various fertilizer treatments. The percentage = The material in this section applies almost wholly to farra pastures rather than to range lands. Studies to date raise considerable question as to the practical value of using fertilizers on range land. The section is intended primarily for students and others technically interested in the subject. PASTURE AND RANGE 953 of dry matter, crude fiber, and the more soluble carbohj^drates, organic acids, etc., is high in the herbage from unphosphated plots and lowest in that from plots treated with phosphate plus lime or nitrogen. The reverse was true of ash, nitrogen, fat, and potash. Calcium was depressed by the addition of nitrogen and by the omission of phosphate. Midgley {787) cites a number of references showing that plants are materially affected by the nature of the soil in which they grow. If the soils are high in available plant nutrients, this is reflected in the ciiemical composition of the plants and the physical condition of the grazing animals. Cases are cited of pasture areas that are known to produce nutritional disorders because of lack of certain minerals in the herbage, such as calcium, phosphorus, iron, copper, and iodine; in other cases such disorders are due to an excess of certain elements, as fluorine and selenium. A study of 775 pastures in West Virginia {923) and analyses of the soils showed that the most important factors responsible for the poor type of vegetation found there were soil acidity and lack of available phosphorus. Eighty-five percent of the area was found to be in need of lime and 94 percent was deficient in available phosphorus. The effect of adding phosphates, however, will vary with different soils. Adding phosphates to some soils may decrease the potassium content of plants without adding materially to the phosphorus content, while on other soils applications of phosphate may result in increases in the phosphorus content of the plants, Wrenshall and McKibbin {1272) in a pot experiment found that the phosphorus intake by pasture plants "is not to be wholly attributed to the utilization of readily soluble phosphate. The phosphorus obtained by the plants was in all cases considerably more than could be attributed to decreases in the amount of readily soluble phosphate in the soil. ... It is suggested that a considerable proportion of the phosphorus obtained by the plants came from the nucleotides (classes of compounds consisting of carbohydrates, certain nitrogen bases, and phosphoric acid) known to exist in the soil. Decomposition of nucleotides would result in the release of phosphoric acid in the soil, thus providing a notable source of phosphorus for plant nutrition and the replenishing of inorganic phosphates in the soil.'' In Michigan (^40) the phosphorus content of both the stems and leaves of alfalfa grown on soil which did not require lime was increased by the application of phosphate alone or in combination with potash. On another soil that required lime, applications of lime and phosphate did not increase the phosphorus content, whereas the addition of lime to one soil type increased the nitrogen content. In some cases very marked differences occurred in the calcium and phosphorus contents of alfalfa grown on different soil types. Alfalfa grown on heavy-textured soils contained more nitrogen and less phosphorus than that grown on lighttextured soils. The Utah Agricultural Experiment Station {928) found that, on a calcareous soil high in total phosphorus but low in available phosphorus, wherever the use of manure or phosphorus fertilizers gave an increase in yield of alfalfa it also gave a marked increase in its phosphorus content. Samples from the Uintah Basin Experiment Farm showed no response to the use of phosphorus either in yield or in phosphorus content of the alfalfa, though some other trials in the same general locality showed an increase in yield. The phosphorus content of this alfalfa was not high as compared with many other samples tested. Sewell and Latshaw {1028) found that on an acid Cherokee silt loam from southeastern Kansas phosphorus alone did not increase the percentage of phosphorus in alfalfa but phosphorus and lime did. The calcium increased in proportion to the amount of lime applied. The various lime and phosphorus fertilizer treatments had little effect on nitrogen content. With an increase in rate of liming a decrease was shown in the percentage of potassium in the dry matter. Nitrogen, phosphorus, and potassium fertilizers applied alone or in combination to western Washington soils {1163) in most cases had no appreciable effect on the percentage of those elements in the alfalfa, but when they were applied to eastern Washington soils the phosphorus and potassium contents of the alfalfa had a tendency to increase as a result of phosphate and potash fertilization. The calcium content did not seem to be affected by fertilization but varied inversely with yield. On an average, alfalfa from eastern Washington contained the highest percentages of nitrogen and calcium and that from western Washington the highest percentage of phosphorus. In work in Wisconsin {822) it was found that nitrogen fertilizers lowered the 954 YEARBOOK OF AGRICULTURE, 1939 calcium and phosphorus content of Kentucky bluegrass while the nitrogen content varied directly with the amount applied. Kentucky bluegrass receiving 1,160 pounds of sulfate of ammonia per acre produced 4.44 times more crude protein than grass not fertilized with nitrogen. Phosphate fertilizers increased the phosphorus content, while phosphorus and potash increased the nitrogen content. Emerson and Barton (330) found that the amoimt of potassium taken up by red clover from a soil varied with the treatment applied. Application of manure increased the solubility of potassium and the amount taken up by the plants. Adams and others (i^), studying the effect of fertilizers on the composition of soybeans, found that certain fundamental relationships are indicated: "(1) The CaO and nitrogen coiitents of the forage are in proportion to the phosphate applied; (2) the K2O content varies with the sulfate of potash and indirectly with the phosphate used ; (3) the P2O5 content is a reflection of the potash and phosphate in the fertilizer, with the former dominating; and (4) the relation of calcium and potassium depends on the level of nitrogen, phosphate, or potash offered to the plant by the fertilizer.'' The Kentucky Experiment Station (620) made complete analyses of 34 samples of lespedeza hay from different localities in the State. All of the hay from the poorer soils was low in phosphorus a,nd unusually low in protein, whereas hay from the better soils was much higher in phosphorus and protein. Annual and perennial lespedeza grown on the State Experiment Station farm at Lexington, Ky., contained 0.80 and 0.62 percent of phosphorus pentoxide, respectively, while plants of the same maturity harvested from an unproductive soil on the western substation at Princeton contained only 0.28 percent (619). West Virginia (9^4) reports that herbage from unproductive soil was only 60 percent as high in phosphorus as herbage from more fertile soils. The percentage increase of phosphorus in broomsedge when treated with phosphate fertilizer was approximately the same as in bluegrass similarly treated. Lime increased the percentage of calcium in broomsedge an average of 19 percent, while the calcium content of Kentucky bluegrass increased 36 percent. Lipman and Blair (690) report that liming increased the percentage of nitrogen in alfalfa grown in New Jersey, In an experiment in southern Illinois, Snider and Hein {1088) found that sweetclover contained 35 percent less nitrogen and 67 percent less phosphorus per acre on soil receiving lime alone than on soil receiving lime, phosphorus, and potassium. On certain soils in the West applications of sulfur are essential to satisfactory yields of alfalfa, indicating that this element is not present in amounts required by the crop. On the other hand, some other crops are not benefited by such treatment. Whether this means that these plants do not take up sulfur or that enough is present in the soil to meet the limited demands is not known. Studies conducted by the Washington Experiment Station {839) indicated that the apphcation of sulfur where needed, as shown by increased yields of legumes, resulted in an increase in nitrogen as well as of sulfur in the plants. On some of the muck soils in Florida, light applications of copper are very beneficial to alfalfa. It is known that where selenium is present in the soil certain forage plants take up enough of this element to poison livestock, while other plants grown on the same soil take up very little if any. Instances have been reported in which light applications of boron have benefited alfalfa, but where boron is present in excessive quantities it is injurious to plant growth. CORRELATION OF FORAGE AND ANIMAL YIELDS Forage yields are difficult to measure or evaluate since such yields must be determined by indirect methods and interpreted in terms of animals or animal products. Experimental technique for measuring pasture yields has not been developed to eliminate experimental error as in other fields of research. Efforts are being made to develop methods which would not require extensive land areas and a large number of animals with the object of determining the value of pasture herbage in terms of animal products. In a preliminary report of the 5 years' work at Kylertown, Pa. {4-08), in which pasture yields have been determined by calculating the total digestible nutrients in the herbage yields and the total digestible nutrients required by the grazing animals for gain in weight and milk produced, it is stated: "If the yield of clippings is considered as 100 percent, or the true yield of the PASTURE AND RANGE 955 pastures, the grazing animals utilized 70 to 80 percent of the T. D. N. (total digestible nutrients) available.'' A similar study in West Virginia {976) showed a ratio between herbage harvested and total digestible nutrients, calculated from grazing animals, of 1:0.61. While these relative yields do not correspond with those from Kylertown, Pa., the difference may be due to the fact that the pastures in West Virginia were continuously grazed while those in Pennsylvania were rotation-grazed. Results obtained at Beltsville, Md., as indicated in unpublished data, are in general agreement with Pennsylvania results with one exception—the yield of herbages obtained from a pasture which contained a high percentage of annual lespedeza as estimated from hand-harvested plots was less than that estimated to have been obtained by grazing animals. These differences indicate the need for further study on the effect of grazing management on forage yields.