Fig. 4–2. Grass hay. Note the fine stems, long leaves, and heads (below and to the right of the thumb), which distinguish it from legumes.

Fig. 4–3. Oat hay. Note the heads which contain the grain.

Legume hays are higher in nutritional value than grass and cereal grain hays, generally containing 2 to 3 times more protein and calcium, and more soluble or nonfiber carbohydrates (often referred to as nitrogen-free extract, or NFE), vitamin A precursor or beta-carotene, and vitamin E (Table 4–1). Because of the greater amount of these nutrients in legumes, and the increased need for these nutrients during growth, lactation, and the last three months of pregnancy (Appendix Tables 1 and 3), legumes are preferred by many during these periods, if it is good quality and available at a reasonable cost as compared to equalquality grass or cereal grain hay. If a good legume hay is not available at a reasonable cost, grass or cereal grain hay may be fed, and additional nutrients if needed may be added to a grain mix as described in Chapter 6.

In contrast to what is occasionally stated or believed by some, any of the three major types of hay may be safely fed as the only forage for the horse, or the only feed for the horse if a grain mix is not needed to provide additional amounts of certain nutrients. Some individuals recommend against feeding alfalfa, or other legumes, as the only hay. This recommendation is probably based on any one or more of a number of factors, including:

Most horses will generally consume more legume than grass hay, even if the legume hay is of poorer quality. Within the same type of hay, the amount consumed is directly related to hay quality, i.e., the higher the hay quality (the lower it is in weeds, dust, and mold; the higher its protein and energy; the lower its fiber content; and the higher its digestibility), the more of it the horse will consume. For equal quality hays, consumption of timothy by horses tends to be greater, and fescue and Bermuda grass lower, than for brome grass, canary grass, and orchard grass. Orchard grass tends to be preferred by horses over flaccid grass and Bahia grass. Bahia grass is not recommended for horses as it is sufficiently unpalatable that many will not eat enough to maintain their weight. Most grains are preferred by most horses over any forage.

TABLE 4–1 Hay Nutrient Content for Horses

Fig. 4–4. Illustration depicting the differences in appearance between a grass, such as timothy, and a legume, such as alfalfa. In the grass, note the long leaves, their attachment, fine stems, and heads. The stalks of the legume are much coarser, and the leaves less firmly attached. (Courtesy of Dr. R. Seaney, Cornell University.)

The leaves are less firmly attached to the stem in legumes than in grasses. This can result in a greater loss of leaves from legumes if they are not cut at the proper stage of maturity, handled properly after cutting, or fed in a feeder that prevents their loss. Since leaves contain two-thirds of the energy, three-fourths of the protein, and most of the other nutrients present in forages, the loss of leaves greatly decreases the nutritional value and therefore the quality of the hay. The firmer attachment of the leaves and the differences in their size and shape in grass hay makes leaf loss less of a problem with grass hay (Fig 4–4). This permits more latitude in the cutting and processing of grass hays without greatly decreasing their nutritional value. Grass hays also are usually less dusty, making them cleaner to feed and resulting in less coughing and chronic obstructive pulmonary disease or heaves. In addition, grass hays don’t contain blister beetles, whereas legume hays may when harvested in areas where, and during the season when, they occur (as discussed in Chapter 19).

The most important factor to consider in selecting the hay to feed is not the type of hay, or the form that it is in. but its quality, availability, and cost.

Hay Forms

There are five major ways that forages may be harvested and fed. These are: grazing, dried, green chop or soilage, haylage or silage, and acid treated. Hay dried to less than 20% moisture content prior to baling, stacking, or storage is by far the most common harvested forage fed to horses. If the moisture is much higher, molding and heating that decreases protein utilization occurs. Stored hay with excess moisture may even undergo spontaneous combustion. However, if hay is allowed to dry (less than 12% moisture prior to baling and storage), there is a greater loss of leaves, particularly with legumes. Drying may be done artificially but generally is accomplished by sun curing. This may be hastened by conditioning (crushing or crimping the plants) and adding drying agents as it is cut. Drying agents (usually a solution of sodium and potassium carbonate or potassium hydroxide) are sprayed on the for-age during mowing and conditioning, and can decrease drying time by more than one-half. They are effective only on legumes during favorable drying conditions. The presence of the drying agent on the hay has no effect on animals consuming it. The faster drying occurs, the lower the amount and risk of weather damage to the hay. Hay that is mowed and then rained on before harvest may lose 40 to 50% or more of its nutritional value.

Once sufficiently dried, the hay may be stacked, baled, chopped or, compressed into cubes, wafers, or pellets for storage and feeding. Most forage available commercially and fed to horses is in cubes, pellets, or most commonly long-stem hay in small square bales (45 to 100 lbs or 20 to 50 kg) versus large round or square bales weighing from 500 to 2000 lbs (227 to 909 kg) depending on the equipment used.

Large round bales and stacks of hay are sometimes fed by leaving them in the field and allowing animals free access to them. Doing this alleviates the need for daily feeding. However, this results in storage and feeding losses of 30 to 38% as compared to 8 to 9% loss from bales (4% from cubes and pellets) stored inside and fed in a feed rack (Table 4–2). However, storage losses from large bales may be greatly decreased by wrapping them in plastic, which is done as the hay is baled; a new procedure found to be quite effective is to spray the bale with melted tallow or animal fat. The tallow is sprayed on at a temperature sufficient to keep it liquid (usually about 120°F [49°C]). It congeals on the hay, providing a water-repellant covering that sheds rain, resulting in almost no loss due to weather spoil-age. It takes about 2 gallons (7.6 L) of melted tallow for most large round bales at a current cost of $1.50 to $3.00/ bale, as compared to $4.00/bale for plastic wrap. The fat on the hay not only protects it but also increases its dietary energy content and feeding value as described in the section “Fat and Oil Supplements for Horses” later in this chapter.

TABLE 4–2 Losses in Storage and Feeding of Different Forms of Hay

In contrast to ruminants, in which pelleting roughages decreases crude fiber digestibility, for horses the form in which hay is fed doesn’t appear to affect its digestibility. Chopping hay increases its rate of passage and intake in ruminants and probably horses, as indicated by a greater dry matter intake by horses fed pelleted alfalfa than when they are fed a coarse-chopped wafered alfalfa, and more of the wafered alfalfa than when fed unchopped long-stemmed alfalfa. In addition, it’s been reported that most horses prefer chopped to long-stemmed grass hay. But the major advantage of chopping hay is so that it can be mixed with grain to slow the rate of grain consumption. However, horses are able to separate grain from chopped hay and eat only the preferred feed (usually the grain).

If preferred, or conditions are unsatisfactory for drying following cutting, harvested forage may be fed that day, or treated with acid or ensiled at a high moisture content (40 to 70%). Not allowing forage to dry minimizes feed and nutrient losses during harvesting and feeding and reduces the inhalation of dusts and molds, generally present in varying amounts in most dry hay. This assists in decreasing respiratory problems such as coughing and heaves. If green forage is not fed immediately following cutting, acid treatment, ensiling, or drying is necessary to prevent mold and bacterial growth resulting in its spoilage. If one of these three procedures is not done, fresh forage must be fed the day it is cut or it will spoil.

Fresh forage cut, chopped, and fed that day is called green chop or soilage. It must be harvested daily, and for the best feeding value the forage must be harvested at its optimum stage of growth or maturity. This limits its duration of use. Because of these limitations, green chop is not commonly fed to horses.

Hay Cubes (Wafers) and Pellets (Dehy)

Hay is usually fed in loose form, but it may be compressed into cubes, wafers, or pellets. Pellets containing primarily or entirely grains and supplements that are large enough (about thumb size or larger) to be fed on the ground, are also commonly referred to as cake or cubes, generally as range cake or range cubes. They are most often fed to cattle on pasture or on the range.

In cubing, hay is generally sun cured and either unground or only coarsely ground before it is compressed into about 1¼-inch squares that break apart every 2 to 3 inches (3 cm by 5 to 7 cm) (Fig. 4–5). In pelleting, hay is finely ground and often artificially dried or dehydrated (and thus the common name “dehy” pellets) before being compressed into pellets of approximately ¼ to ⅜ inch in diameter by ½ inch long (0.6 to 1 by 1.3 cm) (Fig. 4–6). Cubing is done by farm equipment that moves across hay fields picking up windrows of hay, whereas pelleting is done in a pellet mill. In North America, dehy pellets are generally made from alfalfa and rarely a grass hay. Although heat is used in dehydrating and produced in pelleting hay, the amount of heat doesn’t appear to greatly affect the nutritional value of most hay pellets. Excessive heating of forages lowers nutritional value by destroying vitamins and inducing formation of undigestible protein-carbohydrate bonds. However, studies have shown no difference in nutrient digestibility by horses between loose, pelleted or cubed hay.

Fig. 4–5. Hay pressed into cubes. Cubes are 1 to 1¼ inches (3 cm) square and 1 to 3 inches (3 to 7 cm) long.

Fig. 4–6. Alfalfa or “dehy” pellets. These dark green pellets may be made from either sun cured or dehydrated alfalfa.

When pellets are made from good-quality alfalfa, they contain at least 17% crude protein as fed, and are often referred to as 17% dehy. When poorer-quality alfalfa is used, the pellets contain 15 to 17% crude protein as fed, and are referred to as 15% dehy. Generally, 15% dehy contains 26 to 28%, and 17% dehy 24 to 25%, crude fiber as fed.

Hay cubes offer the advantages of hay pellets with few of their disadvantages. The advantages of cubed and pelleted hay are the following:

It may take a few days for some horses to learn to eat hay cubes. However, once they do learn, they eat cubes and also pellets faster than loose hay. As a result of their more rapid rate of consumption, it is reported that some horses occasionally choke on pellets or cubes. Although this is an uncommon problem with hay cubes or pellets, their rate of consumption and, therefore, the risk of choking may be decreased in a number of ways as described later in this chapter (see end of section “Slowing Feed Consumption”).

Wood and tail chewing may increase when cubes or pellets are the only forage fed. When wood chewing was measured, this observation was verified for pellets but not for cubes. In one study, nearly 4 times more wood chewing occurred when pellets were fed than when long-stem hay was fed. In contrast, there was no difference in the amount of wood consumed by mature mares when they were fed the same alfalfa hay loose twice daily, or when it was fed cubed either twice or three times daily. Thus, wood chewing did not increase when hay cubes were fed, nor decrease by feeding cubes more frequently. However, feeding pellets 6 times versus once daily did decrease wood chewing by about one-half. Other causes of and procedures for treating and preventing behavioral problems such as wood and tail chewing are described in Chapter 20.

Major disadvantages of hay cubes and pellets are that harvesting costs may be higher for cubing and pelleting than baling, and it is difficult to evaluate the quality of the hay in cubes and pellets without a laboratory analysis. In addition to containing as much or more protein, and crude fiber equal to or less than that given in Appendix Table 6 for a similar type of hay, good quality cubes and pellets are quite firm, not crumbly, and are free of mold, weeds, and foreign material. If pelleted feeds are too soft and crumbly, most horses don’t like them, and they will break into fine material that is dusty, easily lost, and increases the risk of digestive problems. If they are well made, this is not a problem unless they get wet and then dry out. For this reason, pellets must be protected from the weather. If hay is cubed or pelleted when it is too dry, it will result in a soft crumbly cube or pellet; if it is too wet, mold growth and spoilage occur. The firmness and crumbling of feed pellets can be adjusted by adding varying amounts of binders and wet molasses. Too much wet molasses makes a soft pellet; too little results in a pellet that crumbles easily (7.5 to 10% generally results in a good pellet).

Horses’ fecal water content is lower when pellets instead of long-stem hay are fed—in one study, 75.2% versus 81.5%. The effect on the horse of a lower fecal water content when pellets are fed isn’t known. It theoretically may increase the risk of feed impaction in the intestinal tract. although there is no data indicating this. It has been reported that cattle fed only cubed or pelleted hay may develop a progressive indigestion and enteritis, but that feeding some loose hay (25% of the forage is the proportion recommended) will prevent this from occurring. Although this hasn’t been reported or known to occur in horses, it is recommended that all horses, whether being fed hay cubes or pellets, receive at least ½ lb of long-stem hay or pasture forage/100 lbs body wt (½ kg/100 kg) daily. This may decrease the risk of gastrointestinal problems and decrease wood chewing from when pellets only are fed.

Hay Cuttings

Depending on conditions, from one to as many as eight cuttings of hay per year may be obtained in some areas. The first cutting of the season is generally high in nutritional value if harvested at the proper time and if it does not contain large numbers of weeds that have grown up since the last cutting the previous season. It is also least likely to contain blister beetles, which may occur in alfalfa cut after midsummer in some areas, and which are quite toxic to the horse as described in Chapter 19. However, first-cutting hay frequently contains more weeds, and in many areas, putting it up at the proper time without getting it rained on after cutting is more difficult than it is for later cuttings of hay. Plant growth is generally fastest during the hottest part of the growing season, if moisture is not a limiting factor. Fast growth results in more stem and fewer leaves, which decreases the plant’s nutritional value. Later cuttings, when the temperature is cooler, generally have a higher leaf and nutrient content, the fewest weeds and, in many areas, the best opportunity of being harvested without being rained on after cutting, and, therefore, may have the highest feeding value. However, as shown in Table 4–3, there is no difference in either the appearance or nutrient content of different cuttings of alfalfa when only top-quality hay is evaluated. Thus, in selecting hay, the major consideration is not the type of hay or the cutting, but the quality of the hay, its availability, and its nutritional content in relation to its cost.

TABLE 4–3 Quality and Nutrient Content of Different Cuttings of Alfalfa Hay^a

Hay Quality

Hay quality refers to the hay’s nutritional value, its acceptability by the animal, and the type and amount of foreign material it contains. Good-quality hays are readily consumed in high amounts, are highly digestible, are high in available nutrients, and are low in foreign material. Characteristics of good-quality hay are that it is: (1) free of mold, dust, weeds, and other foreign material; (2) leafy, with fine stems; (3) soft and pliable to the touch; (4) of a pleasant, fragrant aroma; and (5) of a bright green, rather than a yellow or brown, color (least important criterion, although worth consideration). As a generality, the nicer that loose hay would be to sleep in, the better its quality. If it is nice and soft, lacks coarse stems, stalks, or weeds that would make it uncomfortable to sleep in, and has a nice, clean, fresh smell, with minimal dust or other particles, such as mold spores, that may be inhaled, it is probably good-quality hay.

The major factors that determine the quality of a hay are the stage of maturity when it’s cut, its weathering and handling during harvesting, and the duration and conditions of its storage (Fig. 4–7). As the plant matures, its digestibility and energy and protein content decrease. Just prior to the time legumes flower (the bud or vegetative stage), and when grasses begin to show heads through the sheath (early head to boot stage), their leaf development has been completed and they should be harvested (Fig. 4–8). At this time, field grasses will begin to change from a deep green to a slight gray as the heads begin to appear. Legumes consist of about one-half leaves and one-half stems at the full bud stage. Allowing the plant to stand after first flowering and past the boot stage increases crude fiber and reduces crude protein about ¼% per day, and decreases digestible energy nearly ½% per day. As legumes mature from full bud to full bloom, and grasses mature from the boot stage to complete heading out, one-half of their protein and one-third of their energy content is lost. This is also true of pasture forage. These factors result in decreased total digestible nutrient intake and feeding value of that forage. Grass hay that has heads over ½ inch (1 cm) long and legume hay that is past full bloom are too mature to make a good feed.

The appearance of hay is the most commonly used and practical means of determining the presence of mold, dust, weeds, and other undesirable contaminants. and generally in estimating beta-carotene and vitamin E content based on color. However, appearance is a poor indication of the content of other nutrients in a hay. The only accurate and reliable means of determining the nutrient content of a hay is to have it analyzed. The crude protein content may vary as much as 2 to 3 times in grass hays that appear to be similar. In assessing forage quality, it should be analyzed, at least for moisture, protein, and crude fiber content as described in Chapter 6 (see section on “Nutrient Content of Feeds”). The crude protein content of forages directly correlates with that forage’s digestible dry matter, NFE or nonfiber carbohydrate, and energy content, all of which directly correlate with the amount of that forage the horse will consume (i.e., the higher they are, the more the horse will consume, and, therefore, less is needed of the more expensive feed.

Fig. 4–7(A,B). Protect hay from the weather during storage. A 3-sided hay shed, as shown here, is adequate and relatively inexpen-sive. It will pay for itself within a few years in preventing weather-induced losses in the feeding value of the hay. If a hay shed or inside storage facilities are not available, waterproof canvas spread over the lop and partially down the sides of the stack, and peaked so water will run off may be used. Plastic, instead of a waterproof canvas. is not recommended. Plastic will frequently puncture and allow water into the hay, but prevent its evaporation, resulting in more spoilage than would have occurred if the hay had been left uncovered.

Fig. 4–8. Growth stages of a typical grass, limothy. The grass should be harvested no later than the boot stage, which is when the head begins to show through the sheath (center figure). (Courtesy EQUUS, 32(6), 1980.)

If a hay contains less protein or more fiber than the amounts given for that type of hay in Appendix Table 6, it is below-average-quality feed. It is important that this comparison be made on an equal moisture content basis, as described in Chapter 6. Average-quality forage contains 28 to 34% crude fiber and 0.9 to 1 Mcal digestible energy/lb (2.0 to 2.2 Mcal/kg) in its dry matter. A crude fiber content greater than 34 to 36% in dry matter indicates a poor-quality hay. If the moisture content of the feed is greater than 15% to 20% at baling or 15% when stored, excess heat is produced in the first few weeks of storage, which decreases protein digestibility, and it may become moldy during storage (Fig. 4–9). Moldy feed should not be fed. It may cause chronic obstructive pulmonary disease or heaves resulting in chronic coughing and decreased physical performance ability, and may contain mycotoxins, which can cause abortion and death (see Chapter 19). In addition, moldy feeds may be unpalatable and decrease growth rate.

The U.S. Department of Agriculture in 1946 set federal hay grades as U.S. Nos. 1, 2, and 3, and sample grade as an indication of the highest to the lowest hay quality. These grades, however, are based on an estimate of leafiness, color, and foreign material; they are not quantitative measurements of nutrient content. As a result, they are not a very)’ accurate indication of hay quality and are not commonly used. A more accurate measure of feeding and market value of hay developed and proposed by the American Forage and Grasslands Council is shown in Table 4–4. A1-though this system is based on the hay’s feeding value for ruminants, it would appear to be applicable to horses. As shown, a hay’s feeding value is based on its crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF) contents. The NDF is the best indication of forage intake, and ADF the best indication of forage digestibility. Both intake and digestibility decrease with increasing NDF and ADF content of the forage, respectively, as shown by the following formulas.

Fig. 4–9. Moldy hay. A white mold was present not only on the edges of this bale but throughout, and the hay was dusty. Moldy hay is unpalatable, contains fungal spores that cause heaves, coughing, and bleeders, and may contain mycotoxins. White dust in hay is usually fungal spores.

TABLE 4–4 Market Hay Grades and Relative Feed Value of Hays

Forage Digestible Dry Matter (%DDM) = 88.9 − (0.779 × %ADF)

Forage Dry Matter Intake (DMI) (as a % of body wt/day) = (120) ÷ (% NDF in forage dry matter)

Forage Relative Feeding Value (RFV) = (% DDM × % DMI) ÷ 1.29

The forage relative feeding value indicates the relationship between the feeding value and, therefore, economic value of different forages.

Although feeding good-quality hay is certainly preferred and recommended, if the only feed available is weathered, stemmy, weedy, or nutritionally deficient hay, lots of it should be fed. This allows the horse to sort through it and eat only the better portions. If lesser amounts are fed, the horse is forced to eat the poorer-quality portions of the feed, or consume inadequate feed to meet its needs. How-ever, moldy or dusty hay should not be fed.

CEREAL GRAINS FOR HORSES

Grains are seeds from cereal plants that are members of the grass family Gramineae. In addition to the seeds, the entire plant can be grazed as described in the next chapter or harvested as a cereal grain hay or haylage, as discussed previously in this chapter. The primary use of cereal grain plants, however, is the utilization of their seeds for feed and the rest of the plant as chaff, stover, or straw for high-fiber, low-energy, and low-protein feeds for ruminants or idle mature horses, or the straw for bedding as discussed in Chapter 9. The seed is the nutrient store for the embryo or germ from which a new plant develops. It consists of a coat, starchy endosperm, and germ. In milling, the coat is removed as bran. Rice, oats, barley, husked sorghum and husked millet have a fused husk or hull; corn (maize), wheat, rye, and grain sorghum (milo) and millet do not. Hulls are high in fiber; grains with hulls are therefore much higher in fiber than those without hulls.

The density, nutrient content, and characteristics of the cereal grains most commonly available are given in Table 4–5. In contrast to forages, the nutrient contents of cereal grains vary little from the values given. These values, there-fore, may be used in formulating diets for the horse. A laboratory analysis usually is not necessary. An exception to this is triticale, whose nutrient content is quite variable.

All cereal crops are annuals. Depending on the type and variety of grain, they may be either winter annuals (planted in the fall and grazed in the spring or harvested in the summer) or summer annuals (planted in the spring and harvested in late summer or early fall).

Wheat, corn, and rice each constitute about 25% of world grain production, barley 10%, and grain sorghum (milo), oats, millet, and rye 1 to 4%. How different grains are used varies from country to country. Corn, oats, grain sorghum, and barley constitute about 75%, 10%, 10%, and 4%, respectively, of the grains fed to livestock and poultry in the United States. However, production and feeding of corn is steadily increasing while that of oats is decreasing. Most wheat produced in the United States is consumed by people; in europe, large amounts are considered the primary feed grain for livestock and poultry. In Mexico, many consider corn primarily a food for people, while grain sorghum is considered the primary feed grain for livestock and poultry. In most of the world much of the rice is consumed by people, and barley and rye are used in the brewing and distilling industries. All of the cereal grains, however, and their by products, are sometimes fed to horses and other animals.

TABLE 4–5 Cereal Grains: Density, Nutrient Content,^a Relative Feeding Values, and Characteristics for Horses

Cereal grains have the following general characteristics. Compared to other horse feeds, cereal grains are:

Some of the starch in grain is digested and absorbed as the simple sugar, glucose, whereas most other carbohydrates in horse feeds are converted by microorganisms to and absorbed as volatile fatty acids. As a result, the horse’s blood-sugar (but not insulin) concentration increases more following consumption of grain than of hay. But there is no difference in the plasma concentration of either glucose or insulin in horses fed barley, corn, oats, or a sweet feed.

Starch digestibility by the horse is high (87 to nearly 100%) and similar in different feeds, but differs in where its digestion occurs. Starch not digested in the small intestine is converted by microbial organisms in the cecum to volatile fatty acids and lactic acid. A sufficiently rapid production of enough of these acids causes cecal acidosis. If cecal acidosis is severe, diarrhea, colic, and/or founder occur. The risk of this occurrence can be decreased by decreasing the amount of starch reaching the cecum. This can be done by each of the following procedures.

Regardless of whether these procedures are used, the consumption of a sufficient amount of any cereal grain at one time will result in diarrhea, colic, founder, or death. Even if excessive amounts at one time aren’t consumed, the consumption of excess amounts of grain results in excess dietary energy intake, which over time will result in obesity, frequently increased hyperactivity or nervousness, and may increase the risk of developmental orthopedic diseases in young horses (see Chapter 16). Because of these factors, grain or grain mixes should not make up over 50 to 70% of the total weight of the feed consumed by any horse, and need not be fed at all unless energy or nutrients in excess of that in the forages available are needed. A need for energy or other nutrients in excess of that in the forages available is the major reason nutritionally for feeding grains or grain-supplement mixes.

Grain Types

Any of the cereal grains given in Table 4–5 are nutritious, good feeds that may be fed to horses. Providing they are good quality and that excess amounts are not fed, none are harmful in any way. The major criteria that should be considered in determining which grain to feed are: (1) the quality of the grain, determined as described in the sections “Grain Quality” and “Grain Storage” later in this chapter, and (2) the characteristics of each grain most important for each feeding program and horses. When the amount of grain fed is not more than a few pounds (up to 6 or 7 lbs or 3 kg) daily, doesn’t vary greatly from day to day, and the chances of feeding too much are minimal, the major criterion in determining which of similar-quality grains to feed is the relative feeding value of the grains with respect to their cost. Other than as a carrier to ensure that the desired amount of a supplement is consumed, the major reason nutritionally to feed grain is to provide dietary energy. Therefore, barring differences in quality, cost with respect to energy provided is the most rational factor to consider in determining which type of grain to feed.

The relative feeding values of equal-quality cereal grains for horses are given in Table 4–5. The usefulness of these values is as an indication of the relative amount that each grain is worth. For example:

The feed preference of most horses from the most to the least preferred is a mixed-grain sweetfeed, oats, cracked corn, whole corn, good-quality alfalfa hay, wheat, barley, rye, and soybean meal. However, there are large individual variations in feed preferences by horses, just as there are in people. Although some horses may, for example, prefer rye to oats, just as some people may prefer liver to steak, for the majority the reverse is true. In addition, most horses prefer the type of feed to which they are accustomed. Thus, when the type of grain fed is changed, regardless of which type of grain is involved, initially most horses will show a preference for the one to which they are accustomed. This initial lack of preference for the newly introduced grain doesn’t, therefore, indicate that it is unpalatable, even for that horse, but only that the horse is unaccustomed to it.

Fig. 4–10(A,B,C). Cereal grains. These are grain sorghum or milo (A), wheat (B), and oats (C). Oats are similar in appearance to barley.

Oats

Oats (Avena sativa) are in many areas the most popular cereal grain fed to horses (Fig. 4–10) They are reported to make up 31% of all commercially prepared horse feed. Although they are fed to other livestock, they are less popular because of their lower energy density (Table 4–5), higher fiber content, greater variability in quality, and frequently higher cost. Oats are not as widely grown as many cereal grains and their production is decreasing because their yield per unit of ground is lower than it is for other cereal grains. Because oats require a low amount of water and a short season, and grow well in cool weather, their major production is in areas where other grains do less well, such as the northern plains states (Dakotas, Minnesota, Iowa, Wisconsin, Ohio, and Michigan). Their popularity as a food for horses is often due to habit, a lack of familiarity with feeding other cereal grains, and the fact that they are the safest and most palatable (in contrast to pigs) cereal grain for horses. Oats also have a relatively soft kernel that is easy for the horse to chew. Cooking and processing oats to crack the kernel aren’t necessary or of much benefit, except possibly for very young horses or horses with poor teeth. This is a benefit not only because it alleviates the need for processing, but also because nutrient deterioration during storage is slower than in grains that are processed.

Oats are safer to feed to horses than other types of grains because they are higher in fiber, lower in digestible energy, lower in density, and less likely to have molds and mycotoxins (Table 4–5). Because they are several times higher in fiber (10 to 12% vs 2 to 5% in most other grains), they are less likely to cause founder or digestive problems. In addition, because on a volume basis they provide only about one-half as much digestible energy as other types of grain, and because grain is most commonly fed to horses by volume, the risk and the problems of excess grain intake are reduced when oats are fed. Problems with excess grain intake include not only founder and digestive problems, but also the possibility that the horse will become too spirited or high and too fat. In contrast to what is occasionally stated or believed by some, the consumption of excess oats will cause any or all of these problems. But more oats than any other type of grain (2 times greater volume) must be consumed to cause any of these problems.

The advantages provided by oats are often expensive and unnecessary if precautions are taken to ensure that the grain fed is of good quality and that excess amounts are not fed. Generally, oats are the most expensive type of grain, particularly when their cost is compared to their feeding value or energy content, which is how their cost should be compared since the major reason grain is fed is to provide dietary energy. Because of this, the production and use of oats in the livestock industry is declining while that of corn, particularly, is increasing.

Three major types of oats may be available: regular, heavy, and hull-less. Heavy oats are of better quality than regular oats. They contain less foreign material and weigh more per unit of volume (e.g., 36 vs 32 lbs/bu)—thus the name—heavy oats. The nutrient content of regular and heavy oats, however, is quite similar. Because heavy oats are preferred and fed by many racehorse people, they are often called “racehorse” or “jockey” oats. They do vary less in quality than regular oats, which tend to be the most variable of all cereal grains in quality. The lower variation in quality is generally the only benefit of the additional cost of heavy oats over regular oats.

In contrast to the small differences between regular and heavy oats, hull-less oats are higher in feeding value (Table 4–5). Most of the fiber in oats is in the hulls that cover the grain kernels. Hulls are over 30% crude fiber and make up 23 to 35% of the grain. This variation in hull content accounts for much of the variability in oats. The removal of the hulls decreases oats’ fiber content similar to other grains that don’t have hulls (corn, wheat, rye, and grain sorghum), and increases the concentration and digestibility of other nutrients in oats. Dehulled, naked, or clipped oats, or groats, of which there are several varieties, including Pennula, Rhiannon, and Kynon, are occasionally available. In ponies, the digestibility of Pennula hull-less oats as compared to heavy oats was: 84 vs 68% for energy, 86 vs 71% for dry matter, 86 vs 83% for crude protein, 55 vs 34% for neutral detergent fiber (NDF), 40 vs 30% for acid detergent fiber (ADF), and 62 vs 40% for hemicellulose, respectively. The hull-less oats as compared to heavy oats weighed 52 vs 36 lbs/bu (67 vs 46 kg/hl) and in their dry matter provided 3.8 vs 3.0 Mcal digestible energy (DE)/ kg, 15.6 vs 10.6% digestible protein, 2.4 vs 12.9% cellulose, and 15.5 vs 34.2% NDF. Whether hull-less oats’ higher energy and protein content is worth the cost can be determined from their relative feeding value given in Table 4–5 and as described previously. The lower fiber and higher energy and density of dehulled or hull-less oats, however, decrease their safety from excess consumption similar to that of other grains that don’t have hulls (corn, wheat, grain sorghum, and rye).

Corn

Corn or maize (Zea mays) (Fig. 4 –11) is the leading crop in the United States in terms of amount produced and value, and its production and use are increasing steadily. Of that produced, over 80% is fed to livestock and poultry, and it constitutes over 80% of all grains fed in the United States. It is commonly fed to horses, for whom it is a nutritious, palatable, and good feed, providing it is of good quality and not fed in excessive quantities. For most horses, it is only slightly less palatable than oats, and is more palatable than other cereal grains. Corn, however, is more prone to moldiness and lacks the safety margin against the effects of excess grain consumption that oats provide. Mold is most likely to occur in processed (cracked or flaked) corn. Moldy corn may contain mycotoxins, which cause the highly fatal moldy corn disease or less commonly aflatoxicosis as described in Chapter 19. Thus, moldy or even questionable corn should not be fed.

Corn, like other grains without hulls, is low in fiber and higher in both energy content and density than oats. It provides twice as much energy as an equal volume of oats (Table 4–5). Because of this, some feel corn has a tendency to cause obesity or to make a horse high spirited. If equal volumes of corn and regular oats are fed, this is true, since the horse is receiving twice as much energy from the corn. However, if equal amounts of energy, not equal volumes of grain, are fed, corn does not have any greater tendency to cause obesity or to make a horse too high spirited than other cereal grains. How spirited a horse acts is directly related to how good it feels and how much energy it has consumed compared to its needs.

Contrary to another popular belief, corn is not a “heating feed.” It is sometimes fed during the winter and not during the summer because of this mistaken belief. Corn is a “hot feed” when hot implies high energy, but not when it implies high heat production. The heat produced in the utilization of corn is one-third less than that produced in the utilization of oats. Only 41% of the gross energy in corn is given off as heat, as compared with 66% of the gross energy in oats. This is because corn is lower in fiber, and the greatest amount of heat produced in feed utilization is from microbial fermentation of fiber; therefore, the lower a feed’s fiber content, the less heat produced in its utilization. However, because corn has a high energy density and because energy needs are increased during cold weather, it is a good winter feed (see Chapter 10 for cold-weather care of horses).

Fig. 4–11. Corn or maize—cracked, flaked or crimpled, and whole.

The risk of cecal acidosis, and as a result founder, diarrhea, and colic, is greater when corn than when oats is fed. This is because of corn’s higher energy density, which increases the risk of excess intake, its lower fiber content, and because less starch from corn is digested and absorbed in the small intestine than from oats. As a result more starch enters the cecum after the horse eats corn than oats. More starch in the cecum results in a greater production of volatile fatty acids and lactic acid, and increased cecal acidity. At a high com intake, a subclinical cecal acidosis occurred. However. no difference in founder, or in gastrointestinal disorders (including diarrhea and colic), occurred in horses in training that were fed corn as compared to those fed oats, with either grain making up 40% or 60% of the total diet.

Barley

Barley (Hordeum vulgare) has the distinction of being the most widely geographically cultivated cereal grain in the world, being suited for cool, dry climates. It can be grown in areas with too short a growing season for com and can tolerate limited rainfall in the summer. Over one-half of that grown and used in the world is in Europe and the former Soviet Union. In the United States, of the barley grown, over 50% is fed to livestock, about 25% is used for alcohol production, and most of the remainder is exported.

Barley grain looks similar to, but is somewhat harder than, oats (Fig. 4–10). Because of this, many recommend that it should be crimped or rolled for horses, although this doesn’t increase its feeding value for horses with normal teeth, and, therefore, processing barley is of questionable benefit. Like oats, most types of barley contain hulls. Because of the hulls, its fiber content is higher than the hull-less grains (corn, grain sorghum, wheat, rye, and dehulled or hull-less varieties of oats or barley). Barley might be best described as an in-between grain: in-between regular oats and com in fiber and energy content, safety, and heat produced in its utilization. However, it is more similar to corn in density (Table 4–5) and even slightly less of its starch is digested in the small intestine. If it is of good quality, barley is a nutritious, palatable, and good cereal grain for horses, and may be fed as the only grain in the diet with no detrimental effects. However, for most horses, like wheat and rye, barley is less palatable than oats and corn and, therefore, is best and most commonly used in a grain mix with either or both oats and corn, and frequently molasses.

Sorghum (Milo)

Sorghum (S. vulgare) encompasses a wide range of varieties, including grain, grass, syrup, and broom corn sorghums. Grass sorghums include Johnson grass and Sudan grass used as pasture, hay, or haylage. Sorgo is the principle syrup sorghum and is used for the production of sugar and syrup, but can be used for hay. Broom corn sorghums produce stems and panicles suitable for use in brooms. Some green grain sorghum plants may be high in cyanide or prussic (hydrocyanic) acid and, therefore, shouldn’t be grazed, as described in Chapter 18. However, many of the currently used sorghum species have been developed to have a low cyanogenic potential. Cyanide toxicosis is not a problem with feeding grain sorghum. Only grain sorghum is used as a cereal grain. In 1957, new, improved grain sorghum hybrids became available. Most were derived from milo-kafir crosses. Thus, this grain sorghum is often referred to as milo.

Grain sorghum is grown and used primarily in Asia and the United States, particularly in the central and southern plains states (Texas, Nebraska, Kansas, and Missouri). It is often considered to be a cereal grain suited to areas not conducive to corn due to inadequate or irregular rainfall, and where it is not too cold (mean temperature about 80°F [27°C]). Nearly all grain sorghum grown in the United States is fed to livestock, and it represents 6 to 8% of all grain fed. In a number of African and Asian countries it is primarily a food grain for people.

Grain sorghum, like wheat, has a small hard kernel (Fig. 4–10) that for efficient utilization must be steam flaked. Dry rolling is not adequate. Its feeding value varies with its tannin content. Tannins provide some degree of resistance to mold but decrease the grain’s protein digestibility and palatability, giving it an astringent taste—enough so that birds won’t eat it. High tannin content is present in brown-type grain sorghums (also called bird-resistant sorghums).

Under United States Grades and Standards there are four classes of grain sorghums. They are:

It can be difficult to differentiate between yellow and brown varieties on a strictly visual basis.

Good quality, low tannin grain sorghum is a nutritious, good cereal grain for horses, and may be fed as the only grain in the horse’s diet with no detrimental effects. How-ever, because it is less palatable for most horses than are oats and corn, it is best and most commonly used in a grain mix with them and often molasses. For good utilization it should be preferably steam flaked. Its small hard kernels are hard for the horse to chew and efficiently digest. Like corn, it is high in energy density and low in fiber (Table 4–5) and, therefore, carries the same risk as com in causing founder, colic, diarrhea, obesity, and too high a spirit if overfed. It is generally similar to oats and barley in protein content (Table 4–5) although it can vary from 8 to 14% depending on moisture adequacy during growth.

Wheat

Wheat (Triticum aestivum) is widely grown throughout the world. In the United States its production is second only to corn, with the greatest acreage being in the central plains and north central states. It is consumed primarily by people. Because of its high cost, it is not used extensively for animal feed, although at times it may be less expensive than other cereal grains. Most varieties of wheat grown for animal feeds are soft types. Even these types, however, have relatively small, hard kernels (Fig. 4–10), and, therefore, for efficient utilization by animals, including horses, they should be cracked, coarsely ground, or steam flaked. Fine grinding should be avoided because it increases wheat’s dustiness and decreases its palatability.

Wheat is even higher in energy density than corn and provides about 2.5 times more energy than an equal volume of regular oats (Table 4–5). The energy and dry matter digestibilities of wheat are 4 to 5% higher than oats, whereas protein content and digestibility are the same (71 to 72%). As a hull-less grain it is also quite low in fiber. Thus, the risk of excessive grain and dietary energy intake and the problems associated with this—such as founder, diarrhea, colic, obesity, and being too spirited—are even greater with wheat than corn. In addition, wheat flour has a stickier consistency than other cereal grain flours, which is what makes it so valuable to the baking industry. Because of this and the fear that the stickiness will increase digestive problems, it is commonly recommended that wheat not make up more than one-half of the grain mix fed. However, no digestive disturbances occurred in eight horses fed a diet consisting of 40% grass hay and 60% ground pelleted wheat. These horses did as well with no differences noted as when they were fed oats instead of wheat. Thus, wheat is a good, nutritious feed that may be fed to horses as the only grain without detrimental effects. However, it should be processed to break the small hard kernels, and caution must be used to ensure that it isn’t overfed. Because it is less palatable for most horses than oats and corn, it is best and most commonly used in a grain mix with them, often along with molasses.

Rye

Rye (Secale cereale) is not commonly grown or fed. It may be grown in poor sandy soils and in climates too cold for most other cereal grains. It is used primarily for pasture or hay but may be harvested and the grain fed. The grain is similar in energy, fiber, and feeding value to corn, but is higher in protein (Table 4–5). Like wheat and grain sorghum, rye kernels are small and hard and, therefore, for efficient utilization they should be cracked by some processing method. Rye may be fed to horses, but should be mixed with other grain as not over one-third of the grain mix because of poor palatability. Rye is the least palatable cereal grain for most animals. In addition, it should be inspected closely to ensure that it doesn’t contain ergot, which is quite toxic to horses (see “Equine Ergotism” in Chapter 19).

Rice

Rice (Oryza sativa) is one of the most important grain crops in the world. It requires a warm, long growing season with an abundance of water. It is used as a food primarily for people and only to a limited extent for animals. It contains a thick fibrous hull, which constitutes about 20% of its total weight and gives it a fiber content only slightly lower than oats (8% vs 11%). The hull is removed for human consumption. Rice hulls, without the grain and unground are unsuitable for feeding horses because the sharp edges may cause irritation. However, rough or unpolished rice, which is the grain before removal of the hull and the form generally fed to animals, is a suitable feed for horses. Its energy content is similar to corn on a weight basis (3.4 Mcal/kg) but on a volume basis is lower (2.0 Mcal/L vs 2.7 for corn and 1.4 for oats) (Table 4–5). Its protein content is lowest of all cereal grains (Table 4–5).

Millet, Emmer, Spelt, and Triticale

Millet (Panicum milaceum and Sataria spp.) is most commonly used as birdseed. It has a small hard seed covered ! by a hull. It should be ground for use in feeding horses. It has a feeding value similar to oats but is slightly lower in fiber (Table 4–5).

Emmer and spelt, like wheat, are Triticum spp. (T. dicoccum, spelta and vulgare, respectively) but have hulls, look like barley, and have a feeding value similar to oats. In the United States, emmer is grown primarily in the Dakotas, spelt in the East.

Triticale is a hybrid of wheat and rye. It is high in highquality proteins (usually 13 to 15% as fed) and in the essential amino acids lysine, threonine, and tryptophan, which are low in other cereal grains. However, it is lower yielding than wheat. Numerous studies have shown that it is a nutritious palatable feed for pigs, and probably also for horses.

Grain Processing

Grain, like harvested forages, may be dried, ensiled, or acid treated to prevent spoilage due to heating and molding during storage. High moisture ensiled and acid-treated feeds are discussed later in this chapter. Drying is most commonly accomplished by sun curing in the field. Artificial drying or dehydrating may be used but generally substantially increases the cost of the feed. Although drying to a moisture content of less than 20% is adequate for hay, less than 13% is necessary for grain because of grain’s higher and more fermentable soluble carbohydrate content. A moisture content below 10% stops the development of most insects. However, as moisture level decreases, especially below 12%, breakage of grain kernels increases.

Dry grains may be processed cold or hot. Cold processing is generally hammermill or rollermill grinding, but also includes milling. Hot processing is most commonly steam flaking or crimping (Fig. 4–12), but may be popping, micronizing, extruding, or pelleting. Hot processing is more expensive. In one study, e.g., steam flaking cost $5/ton versus about $2/ton for grinding. It’s reported that there is no advantage in cooking grains for horses that have good teeth and that steam treatment had no effect on the digestibility of ground corn for ruminants. However, protein digestion by the horse is 2 to 3% higher from both oats and milo when these grains are micronized than when they are crimped. In addition, it’s reported that steam flaking milo improves its utilization by cattle, whereas cold rollermill grinding does not. Heating and grinding sufficiently to disintegrate grain and its starch granule structure increases the amount of its starch digested in the small intestine. In one study, small intestinal starch digestion of popped, ground, cracked, and whole corn was 90%, 46%, 30%, and 29%, respectively. Thus, small intestinal starch digestion was increased three-fold by popping and 50% by grinding, but it wasn’t affected by cracking. Rolling oats or barley also does not increase the amount of their starch digested in the small intestine. Increasing the amount of starch digested in the small intestine decreases the amount of starch reaching the cecum, which decreases the grains risk of causing diarrhea, colic, or founder if excessive amounts are consumed.

Fig. 4–12. Oats. From left to right, whole, rolled or crimped, and steam flaked. Rolling and steam flaking don’t increase the feeding value of oats for most horses, but they do decrease the length of time oats should be stored.

Although crushed grain for horses has been reported to result in a faster growth rate and generally has been thought to have a higher feeding value than whole grain, controlled studies have failed to confirm this. Neither rolling nor pelleting had any effect on dry matter or gross energy digestibility of either oats or barley by mature horses. Crimping also had no effect on dry matter, protein, or neutral detergent fiber digestibility of either oats or corn by ponies. There was no significant difference between whole unprocessed regular oats and chopped vacuum– cleaned oats, with or without the hulls, in the digestibility of dry matter, protein, fat, acid detergent fiber, neutral detergent fiber or gross energy by mature quarter horses.

Thus, it appears that cold or hot processing of the large kernel grains, oats, barley, and corn, does not improve their digestibility or feeding value for mature horses with good teeth, but grinding and heat treating corn and barley does decrease their risk of causing diarrhea, colic or founder in the horse. Processing in any manner is reported to be important in utilization of the small kernel grains such as rye, wheat, and milo by the horse, and has been reported to increase the grain’s feeding value 10 to 15%. Thus, if processed milo, wheat, or rye can be purchased for not more than 15% above the cost of that grain whole, the processed feed is the best buy. If processing costs more than this, it isn’t worth the added cost. The exception would be when large amounts (over 8 to 9 lbs or 4 kg/day) of grain are fed, or when the grain is for foals or horses with poor teeth, such as some older horses that have trouble chewing feed properly. For these horses, all grains should be cracked, crimped, rolled, pelleted, or extruded and dental care provided as described in Chapter 9. Most horses, however, prefer processed to unprocessed grain, as has been shown for cracked versus whole corn.

Grain should not be finely ground. Utilization of fine ground grain generally is no better and may be worse than coarse ground grain. Fine grinding decreases palatability, increases dust and may increase the risk of gastric ulcers in horses as it does in pigs. Gastric ulcers commonly occur in both foals and young pigs, although their greatest incidence is in nursing foals who are generally consuming little grain. In addition, gastric acidity (an increase of which would increase gastric ulcers) is not affected by grinding or pelleting a grain mix.

Grain Quality

Cracking the cereal grain by any method decreases its stability during storage. Cereal grain with unbroken kernels, less than 13% moisture, and protected from insects and rodents may be stored for many years with little loss in feeding value. Cereal grains with broken kernels become oxidized during prolonged storage and develop a stale flavor that decreases their palatability. Mold and bacterial growth also occur more readily in grains containing broken kernels. The higher the temperature, humidity, and moisture content of the feed, the less time required for oxidation and for mold and bacterial growth to occur. The most important single factor is moisture. At 70% relative humidity or above, deterioration is almost certain to take place, even after only a few months and at temperatures as low as 4l°F (5°C). if oxidation occurs, it causes vitamin and essential fatty-acid deterioration. Once mold growth occurs, it generates metabolic water, enhancing further mold growth and water production; a vicious cycle occurs.

TABLE 4–6 Minimum Weight per Bushel in U.S. Grading Standards^a

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