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AS-953 (Revised)

FeedingManagement

Recommended feeding management of horses differs from that of other

domestic livestock, primarily because of differences in digestive anatomy and

physiology. The digestive anatomy of the horse is classified as a monogastric

(simple stomach) animal with extensive post-gastric fermentation of

undigested feed residue. Pigs are an example of a monogastric animal that

does not have extensive hindgut fermentation capabilities, while ruminants

(cattle and sheep) have extensive fermentation in the rumen prior to gastric

digestion. The combination of a simple stomach and post-gastric fermentation

gives horses the ability to efficiently utilize both forages and concentrates.

Nonetheless, this combination can present some unique challenges that

need to be addressed with feeding management.

Greg Lardy Chip PolandDepartment of Animal and Range Sciences Dickinson Research Extension Center

North Dakota State University

HorseOwners

for

North Dakota State University, Fargo, North Dakota 58105

FEBRUARY 2001

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STOMACH9%

SMALLINTESTINE

28%CECUM

17%

LARGECOLON

35%SMALLCOLON

11%

FOREGUT37%

HINDGUT63%

■ Digestive Tractof the Equine

For domestic livestock, horses havea peculiar digestive tract (Figure 1).Functionally, the digestive tract can bedivided into two components (foregutand hindgut). Components of the foregutinclude the mouth, esophagus, stomach,and small intestine; while the hindgutincludes the cecum, large colon, smallcolon, and rectum. The foregut of thehorse accounts for approximately 35 to40 percent of the relative capacity of thedigestive tract. When compared to therelative capacity of the foregut in pigs (60to 65 percent) and cattle (85 to 90 percent;Figure 2); the uniqueness of the horses’digestive anatomy becomes apparent.

Horses have a small stomach in terms ofrelative size compared to other classes oflivestock. This makes the rate of passageof ingesta (feed) through the stomachrelatively fast. Horses are physicallyunable to vomit or belch. Consequently,overfeeding and rapid rates of intakeare a potential problem.

Meal size and physical form of the dietinfluence rate of passage of ingestathrough the foregut. Larger meals passmore quickly than smaller meals sincestomach emptying is controlled by mealvolume. Smaller feed particles (finelyground or pelleted grains) and liquidspass rather quickly to the hindgut. Exces-sively fast rates of passage can reduce theextent of digestion in the foregut since thefeed passes through too quickly for thedigestive processes to occur.

One of the unique features of the horsedigestive tract is the presence of a largemicrobial population in the cecum andcolon. These microorganisms are respon-sible for extensive fermentation of residuesremaining following digestion and absorp-tion in the foregut. The microbes have theability to utilize the cellulose present inforages. Consequently, even though horsesare monogastrics, they do have the abilityto utilize forages. The anatomy of thecolon (several flexures or folds which turnback onto itself) greatly reduces the rateof ingesta passage. Although this is anadvantage in utilizing roughages, it canpredispose the horse to digestive upsetswhen nutrient flow is abnormal.

Figure 1. Anatomy of the horsedigestive tract withrelative sizes.

Adapted from Feeding Managementof the Equine (F-3973). OklahomaCooperative Extension Service).

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4.8

66.5

2.1

16.9 17.4

2.4

25.4

7.42.3

8.92.6 0.4

0

10

20

30

40

50

60

70

Horse Cattle Pig

Rel

ativ

e C

apac

ity

(gal

lon

s)

Stomach

Small Intestine

Large Intestine

Cecum

■ Feeding ManagementThe basic feed requirements of the horseare relatively simple. As a general ruleof thumb, a horse will typically consume10 to12 gallons of water, greater than orequal to 1.0 percent of body weight inforage, and less than or equal to 1.0percent of body weight in concentrateper day. Horses should also be givenfree choice salt.

WaterClean water should be available at alltimes. A mature horse may drink 12gallons of water a day. Water consumptionhas a positive correlation to feed intake.If water intake is restricted, dry matterintake will also be reduced. Inadequatewater consumption can result from havingsnow as the only water source, faultywatering equipment, or unpalatable water

sources. Inadequate water consumptionalso increases the risk of impaction colic.

Reduced water consumption can be asign of unpalatable or low quality water.Horses do not readily consume stale ordirty water. High salinity (total dissolvedsalts) or high sodium concentrations canalso reduce water consumption. For moreinformation regarding water quality, seeLivestock and Water (NDSU ExtensionService publication AS-954).

Water that is supplied manually shouldbe changed at least twice a day toavoid becoming stale or contaminated.Automatic water sources should becleaned frequently. Clean and disinfectcommunity water sources if a sick horseis detected in a group. Sick horses shouldhave access to a separate water sourceuntil they are considered healthy again.

Figure 2. Relative capacities and proportional sizes of the digestive tracts of the pig, horse, and bovine.Numbers give size of various compartments in gallons.

Adapted from Ensminger and Olentine, 1978.

Relative Capacities for Digestive Tracts

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Horses that are hot from strenuousexercise should not have free access towater. They should be allowed only a fewsips every three to five minutes until theyhave adequately cooled down. Workinghorses and horses in strenuous exerciseprograms require more water than inactivehorses since large amounts of water arelost as sweat.

How much to feedIt is beneficial to know the actual weightof a horse when developing rations.This allows a more accurate estimate ofthe nutrient requirements and expectedintake of the horse being fed. Normally,horses will eat the equivalent of 1.5 to 2.5percent of their body weight as dry matterper day (this includes forage and grain).Heavily lactating mares, intensivelyworked mature horses and youngerweaned horses (4 to18 months of age)can consume up to 3 percent of theirbody weight as dry matter daily.Producers can assume horses grazingon adequate pasture, supplemented withgrain, will consume at least half of theirdaily dry matter intake from grazing.

It is also important to know the weight ofthe feeds when feeding horses. A volumeof feed (scoops of concentrate or flakes ofsquare-baled hay) is fine for instructingothers how to feed your horses. However,you must know the weight per unitvolume of each feedstuff to providethe proper proportions. Table 1 lists theweight of various feeds per unit volume.The true value for a specified feed mayvary as much as 35% from average values.A more accurate estimate of weight perunit volume can be obtained by weighinga known volume of the actual feed beingfed. This logic can be used to estimatethe weight of concentrates, grains orroughages (bales or flakes).

Long-stemmed foragesHorses evolved in a grazing environmentand their digestive systems can accom-modate large quantities of roughage.Although horses can consume largequantities of concentrates, includinglong-stemmed forage in the diet slowsthe overall rate of passage and increasesdry matter and water intake. A minimumof 1.0 percent body weight of roughage(pasture, hay, or other forage) should beoffered daily to ensure adequate intakeand digestive health. The use of long-stemmed forage in the diet may also helpprevent or curtail other managementproblems such as tail chewing, woodchewing, and coprophagy (feedingon fecal material).

Table 1. Weight per unit volume of selectedfeedstuffs.

Feed (as fed) lbs/qt

Alfalfa Meal 0.60Barley, whole 1.50Barley, ground 1.20Beet Pulp, dried 0.60Corn, grain, whole 1.75Corn, grain, cracked 1.60Distillers grains, dried 0.60Gluten feed, dried 1.30Linseed meal 1.00Milo, whole (grain sorghum) 1.70Molasses 3.00Oats, regular, whole 0.85Oats, heavy, whole 1.00Oats, dehulled, whole 1.40Soybean, whole 1.60Soybean meal 1.80Soybean hulls, ground 0.90Wheat, whole 1.80Wheat, ground 1.55Wheat midds 0.70

Forages cu ft/ton

Hay, baled 200-360Hay, cubed 60-70Hay, loose 450-600Straw, baled 400-500Straw, chopped 250-350Straw, loose 675-1000

The true value for a listed feed may vary by as much as35% above or below the value given. An accurate valueis only obtained by weighing a volume of the actual feed.

Adapted from Feeding and Care of the Horse, 1995. Lon D. Lewis.

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Nutritional quality of forages reflects therelative concentrations of energy, proteinand fiber. Forages which are higher inquality (higher in energy and protein)require less concentrate supplementationto meet the nutrient needs of the horse.Lower quality forages (those with higheramounts of indigestible fiber) tend torequire extensive (and expensive) concen-trate supplementation to meet the nutrientrequirements of certain types of horses.

It is generally recommended that horses befed long-stemmed rather than processed(pelleted, ground, wafered, cubed) forages.Feeding long-stemmed forages tends toreduce the rate of consumption, stabilizeingesta flow and maintain digestivehealth. If forages are processed, particlesize should be kept quite coarse to preventdigestive upset. Providing long-stemmedforages increases the amount of time spenteating, increases saliva flow, and reducesthe level of boredom and associatedbehavioral problems. Processed foragehas been used successfully in horse dietswith minimal problems when appropriatefeeding management and adequateexercise is provided.

Poor quality forages should not be usedin horse diets. Low digestibility, excessivedust, molds, weeds, foreign material, andinsect infestations are all factors that candramatically reduce the overall suitabilityof a forage. These types of quality detrac-tors can lead to a multitude of problemsthat range from low consumption of feedto irreversible respiratory disease and/ortoxicity.

Blister beetles (Epicauta species) are ofparticular concern when feeding horses.If blister beetles are present in a hay, itshould not be fed to horses. Blister beetlescontain a compound called cantharidin,

which is toxic to horses. The amount ofcantharidin present per beetle varies bysex and species, but as few as 100 beetlescan kill a 1200-pound horse. Symptoms ofblister beetle poisoning include blisters onthe tongue and in the mouth, colic, diar-rhea, blood or intestinal lining dischargein stools, and problems with urination orbloody discharge in urine. If blister beetlepoisoning is suspected, contact a veteri-narian immediately. In areas where blisterbeetles are a problem, poisoning potentialcan be reduced by using first cutting hayor by using hay harvested after first frost.Beetles are not typically active at thesetimes. Hay conditioning at cutting in-creases the risk of beetles being present inthe hay, since the beetles can be crushedduring the conditioning process anddirectly incorporated into the bale. Cuttinghay with a straight mower may reduce therisk of incorporating beetles into the hayby allowing the beetles time to move outof the windrow prior to baling.

Processing feed grains for horsesA number of factors should be consideredbefore deciding whether or not to feedprocessed grains to horses. Since grainprocessing tends to increase the overallcost of the concentrate, costs of processingneed to be offset by feeding advantages.Processing feed grains with relatively hardseed coats (barley, corn, sorghum) or smallkernel size (wheat) will aid in their diges-tion and increase their ultimate utilization.Fine grinding, however, is not recom-mended for any feed grain. Fine particlesize can lead to decreased overall palat-ability, increased dust associated with theration, and increased incidence ofdigestive problems. Processing of larger,soft-seeded grains (oats) is generallynot necessary. The soft kernel and largerkernel size allow ample processing duringnormal mastication (chewing).

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Dental soundness should be consideredin deciding whether or not to process feedgrains. Horses with poor dental soundness(a particular problem in older horses)tend to benefit more from processing thanyounger horses with sounder mouths andteeth. Horses fed high amounts of grainfor maximum performance may alsobenefit from processed feed grains.

Many different methods of processinggrain are acceptable. Some examplesinclude pelleting, rolling, flaking,cracking, wafering, and extruding.Desirable pellet size varies, but mostrecommendations range from 0.2 to0.75 inches in diameter.

Commercially prepared horse feeds,complete feeds, textured feeds, or totalmixed rations offer some benefits andare especially popular among part-timehorse owners due to the ease of feeding.The convenience and quality control ofcommercially available feeds needs to bebalanced against their relative cost. Thegeneral recommendation of maintainingat least 1.0 percent body weight inlong-stemmed forage is still applicable.

Frequency of feedingThe digestive health of the horse isenhanced with frequent feedings,particularly with respect to concentrates.When concentrates exceed 0.5 percent ofbody weight in the ration (5 pounds ofgrain for a 1000 pound horse) it is gener-ally best to feed the grain in two or morefeedings per day to reduce the risk ofdigestive upset. These meals should be fed10 to 14 hours apart. Idle, mature horsescan be fed up to 5 pounds of grain oncea day, if they have continuous access topasture. Young, growing horses consum-ing significant quantities of grain needto be fed concentrates at least twice a day.

Stabled (non-pastured) horses shouldalso be fed at least twice a day. Highperformance horses are often fed threetimes a day or more.

Feeding should occur during quiettimes of the day so the horse will notbe distracted and bolt (rapidly consume)its feed. A horse will learn to anticipatemealtime, so feeding at the same timeseach day is encouraged. Irregular feedingschedules can lead to feed bolting anddigestive problems. It may also causeundue psychological stress.

Equal amounts of concentrate should beprovided with each feeding. Hay shouldbe provided when offering concentratesto stabled horses, with the bulk of the haygiven in the evening, providing nighttime activity.

Changing the rationTo prevent digestive upset, be sure togradually adapt horses to any rationchange over several days. It takes time forthe digestive tract to adapt to significantration changes, especially when switchingfrom an all forage diet to one with alarge amount of concentrate. If grain orconcentrate levels need to be increasedsubstantially, do so incrementally overa period of several days. For example,increase the amount of grain by 0.5pounds per day every two to three daysuntil the desired level of grain is reached.

Teeth and dental soundnessSymptoms of improper chewing includefeed falling from the horse’s mouth duringchewing, wasted feed, excessive slobber-ing, indigestion, and large amounts ofwhole grain in the feces. A horse’s teethmay need to be checked if it is takinglonger than normal to clean up its feed.Conversely, sore spots in the mouth may

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cause horses to bolt their feed to reducethe amount of time the sore is irritated.Strong, sour odors from the mouth canbe indications of tooth cavities or foodparticles lodged in the mouth. Floating(filing) the teeth may be necessary toremove sharp edges produced fromexcessively worn teeth. A good manage-ment practice to follow is to check teethonce per year in adult horses and twiceper year in aged horses.

Vitamin and mineral supplementsThere are a variety of good quality mineraland vitamin supplements on the market.Horse owners may be tempted to fall intothe ‘if some is good, more is better’ trap.This is not the case with vitamin andmineral supplements. Excess levels ofmost vitamins and minerals can causeproblems for horses. Using commerciallyprepared mineral and vitamin supple-ments at the recommended levels willtake the guesswork out of proper mineraland vitamin supplementation. In manycases, commercially prepared concentratesupplements will provide all the necessaryvitamins and minerals, so no additionalsupplementation is necessary except inspecial cases.

Special concernsThe amount of hay fed to heavy workinghorses should be restricted immediatelyprior to exercise. Horses will normallyconsume a regular meal within an hour.Allow one hour between the time thehorse finishes a meal and heavy work.Also, remember to reduce the nutrientintake of a working horse during periodsof reduced activity. Tying-up, (‘Mondaymorning disease’ or ‘azoturia’) can occurin working horses that are being fed highgrain diets and given one or more daysof complete rest with no change in diet.

Although the exact cause of the problemis not known, it is likely that the conditionresults from exercise that exceeds the stateof training. The condition was commonin draft horses that were worked hardsix days a week and given rest on Sunday.Tying-up occurred following the resump-tion of work on Monday. Reducing grainintake during periods of inactivity andbeginning exercise programs slowlyfollowing extended periods of inactivityare recommended.

Reducing the rate of grain intake maybe necessary if horses bolt their feed or ifcompetition between horses for the samefeed becomes a problem (pen- or group-fed horses). Several methods can be usedto slow rate of intake. Grain can be spreadout in shallow troughs or feeders, or largestones can be placed in grain feeders sothat horses are required to eat aroundthem. If a pelleted feed is used, harderpellets will tend to increase the amountof time spent chewing and decrease theoverall rate of intake.

Individual feeding is the best way toassure each horse receives the necessaryamount of feed to meet its individualnutrient requirements. Competitionamong horses in group-feeding situationscan result in aggressive horses consumingmore than their share of feed while moretimid horses are not given the opportunityto receive adequate amounts of feed.In these types of situations, it may bebetter to feed less aggressive horsesseparately or to place feeding stations50 to 75 feet apart to reduce competitionduring feeding. When feeding groups ofhorses, you may also wish to use one morefeed bucket or trough than the number ofhorses. This will give the submissive horsea chance to eat next to an unoccupiedbucket or trough.

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Inherent nervousness caused byunfamiliar surroundings can often bereduced by offering the horse many smallmeals of hay during the day. Providingmineral blocks to the traveling horsemay also help dispel nervous activity.

Horses are also susceptible to nitratepoisoning and prussic acid poisoning.For more information on these problemsrefer to Nitrate Poisoning of Livestock(NDSU Extension Service publicationV-839) or Prussic Acid Poisoning (NDSUExtension Service publication V-1150).

■ SummaryHorses have a unique digestive tract incomparison to other species of livestock.Horses are monogastrics but can useforages effectively due to the presenceof the microbial population in thehindgut. Because of the unique natureof the digestive tract, proper feedingmanagement is important to ensure thatthe nutritional needs of the horse are met.

Long-stemmed forages such as haysor pasture are necessary in the diet toensure normal digestive function. Whenconcentrates are fed, consideration shouldbe given to grain processing, frequencyof feeding, the amount of concentratenecessary, and dental soundness. Rationchanges should always be made gradually.

Nutritional quality of hays and otherforages intended for horses is important.To ensure optimum health andperformance of your horse do not feedhays that are excessively dusty, moldy,weedy or have blister beetles present.As with any species of livestock, accessto good quality water is also important toensure optimum health and performance.

AS- 9532M-2-01

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