12-02

P. G. Gibbs, G. D. Potter and B. D. Scott

&Racehorses Training

Feeding Race Prospects

in

E-533

*Professor and Extension Horse Specialist; Professor and Equine Science Section Leader, Department of Animal Science, Texas A&M University; AssistantProfessor and Extension Horse Specialist; The Texas A&M University System

In recent years, significant research attentionhas been directed toward the equine athlete,particularly racehorses and young horses des-

tined for the track. New information is becomingavailable and new concepts are being formedabout the physiology and nutrition of racehorses.

One reason for this attention is that over thepast 50 years, the physical performance of race-horses has improved very little. Although racingtimes over common distances have improvedsome, the magnitude of improvement has beenrelatively small compared to that of human ath-letes. This is in spite of efforts to breed horseswith greater racing ability. Further, too manyhorses continue to succumb to crippling injuriesbrought on by acute fatigue and a compromisedskeletal integrity.

Conversely, the performance of humansimproves yearly, monthly and in some cases evendaily during certain athletic competitions. Thisphenomenon is explained by the dramaticimprovements in the diet and training regimensbeing developed continually for human athletes.

Horses also can be expected to perform betterif they are properly conditioned and fed a bal-anced diet containing the fuel (energy) and othernutrients needed to do the work. A horse that is“dead fit” and fed a good ration will run as fastas genetically possible if that horse has any“heart.” The term “heart” in a horse may in fact

P. G. Gibbs, G. D. Potter and B. D. Scott*

be closely related to that horse’s fitness and diet.If the horse has the available energy and thenutrients to use that energy, it can voluntarily runfaster and perform at a higher level than horseswith insufficient fuel and other nutrients to per-form these tasks.

To ensure that racehorses can perform at opti-mum levels, trainers need to pay close attentionto nutrition, providing the appropriate amountsand forms of energy, protein, vitamins and miner-als for young prospects as well as for racehorsesin training. If the nutritional requirements are metaccurately and feeding management is conductedproperly, racehorses’ performances will beimproved over those horses fed imbalanced dietsin irregular amounts at inappropriate times.

Race-bred prospectsTo produce and maintain a successful race-

horse, you must begin with proper feeding andearly development of a young prospect. Thisprocess begins soon after a foal is delivered. Twovital goals are to promote early growth and soundskeletal formation. If these goals are to beachieved, weanlings cannot be fed the samerations as yearlings, and long yearlings in trainingmust be given nutrient mixes that are differentfrom those fed to yearlings not being exercised.16

A field study was conducted on the manage-

eedingRace

Prospects

F&Racehorsesin Training

1

ment practices of 58 Texas farms raising almost2,000 thoroughbred and quarter horse race-bredprospects.5 Most of the owners/managers of thosefarms identified nutrition, exercise and genetics asthree major factors contributing to problems suchas contracted tendons, epiphysitis or osteochon-drosis. Contracted tendons were reported moreoften in foals; most epiphysitis problems wereobserved in weanlings; and osteochondrosisappeared to be most prevalent in yearlings.

Recommendations for weanlings

The study uncovered one common feedingpractice that is detrimental to weanlings: Farmsare failing to provide the high ratio of concentrateto hay needed to meet the weanlings’ require-ments in a reasonable amount of daily feed. Infact, 90 percent of the farms are trying to growweanlings by feeding more hay than concentrate.

Furthermore, 22 to 44 percent of these younghorses are receiving a total daily diet that is eitherdeficient in amino acids or unbalanced in its min-eral concentration or mineral ratios. In short,weanlings and yearlings are being fed almostidentical rations. The feeding programs for year-lings are much more in line with NationalResearch Council (NRC)16 recommendations thanthose for weanlings (Table 1).

To develop properly, race-bred weanlings mustbe given a concentrate feed that provides at least0.7 percent lysine, which is the primary growth-limiting amino acid.16 They also need at least 0.7percent calcium and 0.5 percent phosphorus infeeds containing no more than 1.4 megacaloriesof digestible energy per pound.

Feeds with higher levels of energy need even

Once training or forced exercise begins, thefeeding program should be evaluated even morecarefully.

Horses in race trainingResearchers have recently found that the fuel

supply available in the muscles of a horse and thehorse’s ability to use that fuel may be altered byincluding different ingredients in the diet and byusing appropriate feeding management and train-ing regimens.

To achieve high performance, racehorses in

training must have adequate energy, protein, vita-mins and minerals, and overall feeding must bemanaged well.

Energy

Racehorses often require twice as much ener-gy (measured in calories) as do nonworking hors-es. You must ensure that the racehorses’ diet pro-vides enough energy to complete the assignedwork (Table 2).

A significant challenge in feeding a racehorseis to achieve and maintain ideal body conditionfor training and racing while providing enough

more lysine, calcium and phosphorus to ensurethat they have the proper nutrient-to-calorie ratio.The mineral-to-calorie ratio is more critical thanthe calcium-to-phosphorus ratio, which also mer-its some consideration.

A well-formulated balanced feed will mostlikely provide the minimum acceptable amountsof amino acids and minerals as well as trace min-erals and vitamins. Such a feed almost alwayseliminates the need for any supplements becausethe nutrient mix is balanced.

Conversely, a diet of straight oats and eitheralfalfa or grass hay is unsuitable because it:◗ Fails to provide the requirement for absorbable

lysine.6

◗ Provides less than desirable amounts or ratiosof minerals.5, 16

◗ Often jeopardizes skeletal development.Furthermore, overfeeding hay and feeding

unbalanced concentrates will combine to givefoals a “pot-bellied” appearance. Oats can be usedas the primary grain source if they are fortifiedwith a good amino acid source as well as themineral concentrations needed to provide theproper calcium:phosphorus ratio and to meet theneeds for trace minerals. Although most commer-cial feeds contain some oats, other grains are alsoused routinely.

Recommendations for yearlings

If not being conditioned for sale, yearlings canachieve a moderate rate of growth on good-quali-ty, improved pastures. The digestive tract of ayearling can process more roughage than that of aweanling. Good-quality grazing appears to sup-port acceptable growth and development at thisstage.7

However, yearlings being prepared for sale orbeing retained for placement into pre-race traininghave significantly different nutrient requirementswhen rapid growth and/or forced exercisebecomes part of the management scheme. Forthese horses, you must provide a balanced con-centrate.

These horses typically need to be fed a con-centrate with at least 14 percent crude protein,0.6 percent lysine, 0.6 percent calcium and 0.4percent phosphorus in a feed that contains 7 per-cent or more fiber and not more than 1.4megacalories of digestible energy per pound.Many companies manufacture horse feeds thatmeet or exceed these minimums.

2 3

TABLE 2.Approximate daily nutrient requirements of race-bred prospects and racehorses in training (1,100 pounds mature weight).

DigestibleEnergy (Mcals)

15.0

17.2

18.9

21.3

26.5

26.5

32.8

Weaning(moderate growth)

Weaning(rapid growth)

Yearling(moderate growth)

Yearling(rapid growth)

Longyearling

Two-year-old

Mature-intensework

CrudeProtein

(pounds)

1.7

1.9

1.9

2.1

2.6

2.5

2.9

Lysine

(grams)

32

36

36

40

50

45

45

Phosphorus

(grams)

16

20

16

20

27*

26*

29

Calcium

(grams)

29

36

29

34

49*

46*

40

Vitamin A

(IU)

10,000

10,000

15,000

15,000

18,000

20,000

22,000

Magnesium

(grams)

4.0

4.3

5.5

5.7

15.5*

17.6*

15.1

RACE-BRED PROSPECTS

RACEHORSES IN TRAINING

Source: National Research Council (1989) *Based on recent work of Nielsen et al,13 Stephens et al22 and Nolan et al.15

TABLE 1.Diet proportions for race-bred prospects of varying ages.

Weanling 70 30

Yearling 60 40

Long-yearling 60 40(in training)

Two-year-old 55 45(in training)

Age/Class % Concentrate % Hay

Source: National Research Council (1989)16

fuel to support performance at an intense level ofwork. Therefore, a primary concern is energy,which allows the horse to maintain optimumbody condition while performing at a heavy work-load.

To determine the types of diets to feed and theenergy substrates (carbohydrates and fatty acids)to make available, you need to understand theextent to which a horse depends on its system ofanaerobic energy metabolism. During regulartraining and racing, a racehorse must performboth aerobic and anaerobic work.

Aerobic work occursduring exercise in whichthe heart rate does notexceed about 150 beatsper minute. While per-forming aerobic work, ahorse is able to getenough oxygen to thetissues to burn fat as afuel source.

During anaerobicwork (heart rate is typi-cally above 200 beatsper minute), the horse isunable to rely totallyon fat for use as fuel.For this work, it mustrely primarily onblood glucose, andliver and muscleglycogen, which are produced from dietary carbo-hydrates. In a race, a horse performs mostlyanaerobic work using carbohydrates, but a combi-nation of carbohydrates and fatty acids in the dietcan help a horse work harder and delay fatigue.

To meet the short-duration, high-speed energydemands of anaerobic work, it is critical that race-horses receive enough readily available energyfrom dietary carbohydrates to maintain blood glu-cose and store energy in the form of muscleglycogen.12, 17, 18, 20, 25 During anaerobic exercise andcompetition, these are primary fuel sources forhorses.

Energy must be provided to racehorses in areasonable amount of daily feed that they canconsume safely. Depending on the level of activityand the energy concentration of the diet, a horsewill take in forage and concentrate in amountsranging from 2.0 to 3.0 percent of its body weightdaily.

Racehorses performing at intense levels have

very high energy requirements; they often havetrouble getting enough energy from conventionaldiets of hay and other fibrous feedstuffs. Theymust be fed grain-based concentrates. They alsoneed a comparatively large amount of highlydigestible starch in the diet to meet both aerobicand, particularly, anaerobic energy demands.

Most stables are very accustomed to usingconcentrates to supply soluble carbohydrates forenergy. Cereal grains such as oats, barley andcorn can be mixed together in a variety of ways toproduce concentrates of differing energy concen-

trations. Cereal grainsshould be processed topromote digestion ofstarch in the smallintestine and to ensurethat high amounts ofglucose are absorbed.Grain feeds provide car-bohydrates that can beused directly or storedin the muscles and liverin the form of glycogenfor later use.

By manipulating thediet and exercise regi-men of exercising hors-es, you can dramaticallyincrease the concentra-

tion of glycogen stored inthe muscles.23 Horses

deplete their muscle glycogen stores and becomeunable to work at a high level when they are fedtoo few carbohydrates and put into high levels oftraining. But their work performance can beimproved by feeding them high-energy diets withan adequate supply of carbohydrates.

Many studies have shown that adding fat tothe diets of horses in race training can improvetheir muscle glycogen storage and work perform-ance.12, 17, 20, 26 Fat provides a concentrated supply ofenergy in an amount of feed that can be con-sumed safely by the horses. You can incorporatefat or oil into a grain mix and increase it to 10percent of the concentrate without negativelyaffecting dry matter or fiber digestibility.

Although the amount of energy supplied dailyis important, it is equally important that signifi-cant amounts of that energy be supplied in a formthat promotes synthesis and storage of muscleglycogen in horses that are expected to do short-term, high-velocity, anaerobic work.

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Race prospects must be fed balanced concentrate in two or more feedings daily.

Note: To achieve maximum performance inracehorses, feed them a fat-supplemented, high-carbohydrate diet…not a high-fat, high-fiber diet.

When feeding a fat-supplemented diet, consid-er several factors:◗ Horses need time to become adapted to fat in

the diet, sometimes as much as 4 weeks.◗ Because a fat-supplemented diet provides more

energy, you should decrease the total daily feedintake if the work level and body condition areto remain the same.

◗ If you plan to top-dress fat or vegetable oil onthe feed, begin with a small amount andincrease it gradually, keeping an eye on eatingbehavior and general well-being. You mustreassess the total dietary nutrient balance (seesection on protein), especially for race-bredyearlings and 2-year-olds receiving exercise.Remember: The energy requirements for work

take precedence over the storage of energy as fatin the body. Animals that are not fed enoughenergy to maintain body weight will use the ener-gy stored in body tissues — including muscleglycogen stores — to meet the energy require-ments for work. A thin horse may not be physio-logically able to exercise strenuously because itdoes not have enough available energy.

To maintain reasonable amounts of body fatin horses in race training and being worked hard,you must increase the energy density in the dietand adjust the amounts of feed proportionally. Forthin horses that are exercising, adding fat to thediet results in higher muscle glycogen concentra-tions than in horses fed conventional diets.9, 20

Feeding some fat to racehorses helps protect themfrom fatigue even when their body condition isreduced.

When selecting a commercial feed, check theamounts of fat and fiber listed on the feed tags.The information will help estimate the energydensity of the grain mix. There is an inverse rela-tionship between fiber and the expected digestibleenergy content (Table 3); knowing this can helpyou choose concentrates that are a better buy perunit of energy.

Lower fiber feeds usually contain more energythan higher fiber feeds. If you feed good-qualityhay, there is no need to spend more money onadditional fiber in a bagged horse feed.

Some commercial feed manufacturers producefat-supplemented diets. If a feed tag lists a fatconcentration of 8 percent, in most cases about 4to 5 percent additional fat has been included.

At any given level of crude fiber, a grain mixwith 5 percent supplemental fat will have up to 8percent more energy than a similar feed with nosupplemental fat. This supplemental fat affectsthe relationship between crude fiber and expecteddigestible energy content by about 0.10 megacalo-ries or 100 kilocalories per pound of feed. Of iden-tical amounts of two concentrates — one withsupplemental fat and one without — the you withthe supplemental fat will contain significantlymore energy, meaning that you can feed less on adaily basis.

To be able to meet the nutritional needs ofracehorses, you need not only to know theamount of energy in a feed, but also to recognizethe caloric needs for training and racing. Horsesthat are calorie-deficient cannot run at the sameintensity as those with enough energy in the dietand stored in the muscles.

When a horse’s body weight is reduced signif-icantly, it often depletes its body energy reservesso that it has too few calories to perform at a highlevel for an entire race, regardless of the length ofthat race. The goal should be to achieve sufficientbody condition in the horses to maintain muscleglycogen reserves, but not so much as to causethermal stress.20

Although racehorses must have adequate bodycondition to do their job, excess body fat causesthermal (heat) stress on the horse. Regardless ofbody condition, feeding a fat-supplemented dietreduces the thermal stress on horses.18, 21 Thus, itis important that you maintain the horses in lean

TABLE 3.Relationship of crude fiber to expected digestible energy in conventional and fat supplemented grain mixes.

2 1.62 1.72

4 1.55 1.65

6 1.45 1.55

8 1.35 1.45

10 1.25 1.35

12 1.15 1.25

Fiber % (3-4% fat) (7-8% fat)Concentrate diet Fat-supplemented diet

DIGESTIBLE ENERGY (MEGACALORIES PER POUND)

condition but not “ribby.”21 Feed them a fat-sup-plemented diet with adequate carbohydrates andother nutrients. With proper training, the horse’sperformances are likely to improve, with fewerinjuries and less fatigue.

Protein

While some attention to protein is important,it generally should not be the most critical consid-eration for racehorses. Stables sometimes overfeedprotein because of the misconception that the per-centage of crude protein in the grain or concen-trate mix must be raised as a horse’s level ofactivity increases.

Horses do require a small increase in proteinin the diet for optimum production and work per-formance.4 But having a high concentration ofprotein in a mature racehorse’s diet can do moreharm than good. For racehorses in training, it isimportant to have a balance of amino acids in thediet. To receive the proper supply of these aminoacids, they need a source of high-quality proteinin the regular diet.

Although the effects of exercise on the aminoacid needs of an equine athlete are not complete-ly understood, stables should consider proteinintake in relation to energy intake. A properly bal-anced diet will provide enough protein at increas-ing levels of work, provided that the horse’s ener-gy requirement is being met through additionalfeed intake (Table 2).

In studying the nutritional effects of increasedexercise on horses, researchers have found thatwhen fed a diet that has a constant calorie:proteinratio, horses retain more nitrogen during the con-ditioning period than at rest. After conditioning isachieved and the work level reduced, the horsesstill retain more nitrogen than when not working.Exercising horses in a high state of conditionretain more nitrogen than sedentary horses, butthe additional nitrogen usage is comparativelysmall.8 Although it is unclear whether they usethe retained nitrogen for muscle synthesis or it islost in sweat, exercising horses do require somesmall increase in protein, particularly during con-ditioning.4

Changes in muscle composition have beenmeasured in conditioned horses fed varyingamounts of protein.3 The study found that condi-tioning changes the diameter of certain musclefibers and helps the muscles synthesize protein.Also, horses fed higher protein diets retain some-

what more nitrogen, but not much more.For mature racehorses receiving average-quali-

ty grass hay (7 to 8 percent crude protein),enough additional protein is provided if they arefed a 12 percent crude protein grain or concentratemix. However, a higher percentage of crude pro-tein may be warranted in two situations: whenhay quality is suspect, and when supplemental fatis being top-dressed onto the concentrate. Al-though adding fat or oils increases the energy den-sity concentration in the feed, it dilutes the pro-tein. If fat is added at 5 to 10 percent of the grainmix, the concentrate should contain about 14 per-cent crude protein. This is especially important for2-year-old racehorses that are still growing.

It is useless to feed high-protein feeds tomature racehorses. Giving a horse more proteinthan it requires creates metabolic stress on thehorse and is an unnecessary expense for the rac-ing facility.

Vitamins

Vitamin needs are not as well defined in hors-es as in other species. Nevertheless, vitamin sup-plementation is of great interest to many racehorseowners, to the extent that vitamins are oftengrossly overfed in the horse industry.5

Excess vitamin supplementation does notimprove performance and, in fact, may be toxicand dangerous. If a horse’s diet is well balancedand contains enough vitamins to meet its needs,over-supplementation of vitamins will notenhance its physiological performance in trainingor in a race.

Vitamin A: Horses obtain significant amountsof the fat-soluble vitamins A, D, E and K from top-quality fresh hays. In an athlete, vitamin A helpsmaintain normal eating behavior and respiratoryhealth. However, excessive vitamin A may eventu-ally contribute to bone weakness.

Reputable feed manufacturers balance concen-trate rations by supplementing vitamin A, often ina vitamin premix. Race stables mixing their ownfeed should usually add vitamin A at about 1,500to 2,000 international units (IUs) per pound offeed (see tables 4, 5 and 6 as examples).

Vitamin D: Dietary requirements for dietaryvitamin D in horses have not been identified.Horses that receive normal exposure to sunlightand that are fed sun-cured hay will have enoughvitamin D for calcium homeostasis and mineralabsorption.

This vitamin is usually supplemented in com-mercial horse feeds at no more than 10 percent ofthe concentration of vitamin A. Excessive vitaminD can cause calcification of soft tissues.

Vitamin E: Vitamin E has received increasedattention for its possible role in reducing tissuedamage and as an antioxidant. Most feed manu-facturers already provide supplemental vitamin E(Tables 4, 5 and 6). If it is not added to the com-mercial diet of racehorses, vitamin E will need tobe supplemented to provide at least 45 IU perpound of feed.

Vitamin K: Because Vitamin K is synthesizedand ab-sorbed in a horse’s large intestine, there isno dietary requirementfor it. Adequateamounts of this vita-min are produced byanaerobic bacteria ofthe hindgut.

Although vitamin Khas been added to thediets of performancehorses to treat or pre-vent exercise-inducedpulmonary hemorrhage(bleeders), its influ-ence on “bleeding”has yet to be docu-mented by equineresearch.

B-vitamins: Ofall nutrients usedin the horse indus-try, B-vitamins are the least understood yet mostwidely used, if not abused. Like vitamin K, the B-vitamins are synthesized in and absorbed fromthe large intestine. Stables often incorporate B-vitamins into feeding programs to promote “bloodbuilding.” However, excesses of water-solublevitamins such as B12 are quickly voided in theurine and do not increase packed cell volume orhemoglobin concentration. Instead of over-supple-menting these B-vitamins, you should rely moreheavily on conditioning and exercise to improveblood volume and oxygen-carrying capacity.

Some B-vitamins affect equine performanceand may need to be added to a horse’s diet if con-ditions warrant. Research indicates that exercisinghorses may need supplemental vitamin B1 (thi-amin) beyond what they would normally synthe-size in the intestine.25 Horses at the race tracksometimes develop a lethargic, depressed condi-

tion known as “track sour.” This condition ischaracterized by a dullness in attitude, generalunthriftiness and slowed performance. Loss ofappetite is one symptom of a thiamin deficiency.

Although enough thiamin can be synthesizedin the gut to meet the needs of most mature hors-es, it may not be adequate for racehorses in train-ing. Thiamin is part of an enzyme system invol-ved in energy metabolism in horses. Therefore,racehorses requiring high levels of energy couldbecome thiamin deficient if they take in too littlethiamin in the diet. Diets of only oats and grasshay may lack the amount of thiamin needed tomeet a horse’s requirements.

In many reportedcases of “track sour”horses, adding brewer’syeast to the diet appearsto stimulate the appetiteand return the horse to aspirited, energetic attitudewith improved work per-formance. One of thelargest components ofbrewer’s yeast is thiamin,among other B-vitamins.

Heavily worked horsesreceiving traditionaldiets benefit from hav-ing thiamin added tothe diet.25 If the com-mercial feed has notbeen supplemented withthiamin, stables should

include a good supplement containing the B-vita-mins, particularly thiamin, in the diet of racinghorses. However, there is no benefit in over-sup-plementing B-vitamins.

Another B-vitamin, biotin, is often added toenhance hoof growth or strength. Limited clinicalreports have claimed some improvement in aboutone-third of horses receiving biotin supplements.2

More recent research has demonstrated that d-biotin supplementation reduces the incidence andseverity of hoof wall defects, increases hoof wallintegrity and reduces the incidence of white linesyndrome.10

Note: In most cases, it takes from 9 months tomore than a year for the benefits of biotin supple-mentation to become observable. Although moreresearch is needed before exact recommendationscan be made about supplementing the diets ofhorses with poor hooves, providing horses about

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Racehorses can utilize calories from a combination of carbohydrate and fat sources to better perform anaerobic work with delayed onset of fatigue.

15 milligrams of biotin a day or about 1.5 partsper million in the diet appears to help.

Minerals

As high-performance athletes, racehorsesrequire a balanced supply of minerals for mainte-nance of skeletal tissue, muscle contraction andenergy transfer. It is much more critical for stablesto ensure that the horses have enough mineralssuch as calcium and phosphorus, relative to theamount of energy they take in, than to be con-cerned with exact calcium:phosphorus ratios.

However, the total diet of horses being trainedor raced should always contain at least as muchcalcium as phosphorus. Diets with inverted ratios(more phosphorus than calcium) can contributeto weakened bones and subsequent lameness in astressed horse. Because cereal grains contain morephosphorus than calcium, inverted or improperratios often occur in the horse industry.

Cafeteria-style and free-choice mineral feedingprograms do not meet a horse’s requirements forminerals.19 The only reliable way to achieve min-eral balance is through accurate ration formula-tion.

Recently, Texas A&M researchers studied themineral requirements of young horses in racetraining.13, 15, 22 They found that calcium, phospho-rus and magnesium requirements are affected by

the combination of growth and exercise.Young horses in race training are building

bone as a part of growth, and they are modelingand remodeling bone in response to exercise.During the initial stages of training, the calciumand phosphorus needs of juvenile horses in train-ing appear to be increased by 30 to 35 percent,and magnesium requirements increased by 80 to100 percent, over current NRC (1989)16 recommen-dations. These increases in mineral requirementsin early training are caused by the demands ofbone modeling and remodeling.14

Thus, during the early stages of training, a 2-year-old horse requires about 130 mg/kg/day ofcalcium, 70 mg/kg/day of phosphorus and 40mg/kg/day of magnesium. Juvenile horses intraining require total dietary concentrations of cal-cium of 0.60 percent; phosphorus, about 0.35 per-cent; and magnesium, 0.2 percent. See tables 4, 5and 6 for examples of rations with suitable miner-al levels.

Electrolytes: During workouts and racing,horses lose significant amounts of electrolytes —sodium, chloride and potassium — in the sweat.Usually it is not difficult to meet the increasedrequirements for these minerals in horses receiv-ing intense exercise. The majority of theseincreased requirements can be satisfied by good-quality forage, minerals provided in the concen-

trate mix and supplemental salts. However, com-mercially prepared horse feeds do not normallycontain enough electrolytes for horses that sweata lot, particularly in the summer. To compensatefor the loss of these electrolytes in the sweat,diets must be supplemented with sodium, chlo-ride and sometimes potassium.28 Even if a com-mercial feed contains salt, horses that work hardand sweat profusely will still need about 3 ounces(90 grams) of supplemental salt per day in addi-tion to the salt already in the feed.

Few studies have been conducted on the useof orally drenched electrolytes. The value of thispractice is questionable. Also, there is a chancethat adding electrolytes to the drinking watercould cause a horse to drink less water, whichcould result in dehydration. The most effectiveway to meet the electrolyte needs of horses is toselect roughage and concentrates that have a goodbalance of all the minerals required and to feedthem in adequate amounts to meet the animals’energy requirements. Horses that sweat excessive-ly will need additional salt, a total of about 1 per-cent of the horse’s daily ration. Also, give specificattention to meeting the potassium requirement of

exercising horses, which may be twice the main-tenance requirement, particularly if forages arenot of top quality. The potassium requirement forheavily exercised horses is about 1.2 percent ofthe total diet.28

Feeding management

To achieve the highest level of performancewith a minimum of digestive disturbances, it isimportant that feeding is managed well and thatrations are balanced. Horses must receive theproper amounts and ratios of nutrients and be fedat regular intervals.

It makes no difference whether a race stablechooses to balance rations by buying formulated,finished feed or by buying the ingredients andmixing them. The critical point is to provideenough nutrients to racehorses to meet their dailyrequirements and to maintain the ideal body con-dition for racing. Either approach will work ifcareful attention is given in the formulationprocess. Excessive amounts of nutrients must notbe fed because it results in nutritional imbalanceand metabolic stress on the horse.

98

TABLE 4.Example of a traditional ration for a mature racehorse (designed to be fed with a mix of good quality grass hay and alfalfa hay). Note: This feed contains no supplemental fat.

Important:See Table 7 on expectedfeed consumption, andalways introduce newgrain feeds gradually.Because this ration contains about 6 percentmore energy thanstraight oats, smalleramounts of this rationwill usually maintainsimilar body condition.

+ Percentages andweights of vitamins Aand E will vary, depend-ing on the vitaminpremix used.

Cracked corn 45.00 900

Whole oats 42.50 850

Soybean meal 7.50 150

Molasses 3.25 65

Calcium carbonate 0.75 15

TM salt 0.75 20

Vitamin A + +

Vitamin E + +

Calculated analysis

Crude protein = 12.0%Digestible energy = 1.39 Mcal/lbCrude fiber = 6.0%Crude fat = 3.7%Calcium = 0.36%Phosphorus = 0.32%Thiamin = 2.18 mg/lb.Vitamin A added at 2,000 IU/lbVitamin E added at 60 IU/lb

Ingredients Percent Pounds/Ton

TABLE 5.Example of a fat-supplemented ration for long yearlings and 2-year-olds in training (to be fed with a mix of grass and alfalfa hay).

Important:See Table 7 on expectedfeed consumption andalways introduce newgrain feeds gradually.This ration contains 15 percent more energythan the ration shown inTable 4 and about 25percent more energythan straight oats, sosmaller amounts of thisration will need to be fedto maintain similar body condition.

+ Percentages andweights of vitamins A andE will vary, depending onthe vitamin premix used.

Calculated analysis

Digestible energy = 1.6 Mcal/lbCrude protein = 14.8%Lysine = 0.7%Crude fiber = 6%Crude fat = 7.3%Calcium = 0.62%Phosphorus = 0.43%Thiamin = 2.57 mg/lbVitamin A added at 2,000 IU/lbVitamin E added at 60 IU/lb

Cracked corn 37.50 750

Whole oats 35.00 700

Fat or oil 5.00 100

Soybean meal 15.00 300

Molasses 4.00 80

Calcium carbonate 1.25 25

Dicalcium phosphate 0.25 5

Brewer’s yeast 1.25 25

TM salt 0.75 15

Vitamin A + +

Vitamin E + +

Ingredients Percent Pounds/Ton

❷ Similar feed with the same nutrient com-position and physical characteristics, espe-cially crude fiber.

❸ If none of those is available, buy goodclean oats as a last resort.

For horses that have been in strenuous train-ing during the week with Sundays off, reduce theconcentrate feed accordingly on the off day. Whencombined with some free exercise, this reductioncan help prevent metabolic disorders caused byfeeding high-concentrate feeds in the absence ofexercise.

Reduce the concentrates to about half the nor-mal amount and increase the hay allowances.This practice will help prevent feeding-relatedmuscular problems, azoturia (Monday morningdisease) and the feeding-related “tying-up” syn-drome.

Riders should take adequate time to warm upthe horses before strenuous work and cool themdown after strenuous work.

SummaryNutrition is one of the most important aspects

of overall development and management of hors-es. Feeding horses of economic significance is aneveryday responsibility.

On more than 55 percent of Texas farms, thesingle biggest cost of keeping race-bred prospectsand racehorses is nutrition.5 Although feedingracehorses successfully is a challenge, it can bedone. The primary focus should be on meetingthe energy and other nutrient needs in an amountof feed the horses can eat comfortably.

If a horse’s nutritional requirements are met,but not exceeded, its performance will beimproved over those horses that are fed imbal-anced diets in irregular amounts.

New research information currently availableoffers new approaches to ration formulation, feed-ing management and training regimens for race-horses. Adjustments in these areas offer the bestopportunity to improve athletic performance,delay fatigue and reduce injuries to the high per-formance horse.

In the future, stables that use research infor-mation and follow sound management practiceswill consistently achieve the highest level of per-formance in racehorses. Remember: Indiscrim-inate feeding of supplements will not result in topathletic performance. Rather, the focus should beon feeding racehorses correctly. It is complicated,but it can be done.

1110

Tables 4, 5 and 6 show examples of rationsthat contain differing sources of energy and arebalanced for protein, minerals and vitamins. Dailyfeed intake typically ranges from 2 to 3 percent ofa horse’s body weight. In some cases, extremelyhard-working horses may require feed at 3 per-cent of horse body weight; such high levels ofdaily feed must always be provided in two ormore feedings per day.

In general, concentrate intake should notexceed 0.75 percent of body weight per feeding,and time intervals between feedings must be thesame. If horses can be maintained with concen-trate intakes of 1.5 percent of body weight dailyor less, they can be fed twice daily at 12-hourintervals. If they require more feed, they shouldbe fed three times daily, at 8-hour intervals.

It is sometimes difficult to maintain appetiteand normal feeding regularity in horses that are inrace training or at the track. For these horses, ithelps to follow these recommendations:◗ Use only the highest quality feeds with very

high energy density, and try to feed the horsesthree times a day at regularly spaced intervals

around the clock, taking workout sessions intoaccount.

◗ Do not feed concentrates or hay to racehorseswithin 3 hours before a workout or race.Although you can offer hay after the workoutor race, do not feed concentrates for at least 2hours after exercise. Offer water free choiceafter exercise, but make sure that the horsesdrink slowly, initially, after a workout.

◗ If the normal feeding time is delayed, reducethe concentrate portion of the next ration at thelate feeding, then resume the normal amountsof feed at the next feeding. If feeding is delayedfor several hours after a very strenuous work-out or because of transport, feed the horse onlyhay at the next feeding and then offer the nor-mal concentrate allotments at the next regularscheduled feeding. Do not feed any extra con-centrate to compensate for feed missed becauseof travel or other interruption in normal man-agement.

◗ If a racehorse stable runs out of feed, buy feedin the following priority order:

❶ The same feed if possible.

TABLE 7.Expected daily feed consumption by racehorses and prospects in training (percent body weight)a.

AGE OF HORSE OR LEVEL OF WORK

Racing

Concentrate 1.00 – 1.5 1.0 – 1.5 1.50 – 1.75

Hay 1.00 – 1.5 1.0 – 1.5 0.75 – 1.00

Concentrate 0.5 – 1.00 0.75 – 1.0 1.25 – 1.5

Hay 1.0 – 1.5 1.00 – 1.5 0.75 – 1.00

Type of diet

Typical nonfat diet

Long yearlingIn training

Two-year-oldIn training

10% fat supplemented diet

aFeed consumptionby individual horsesmay vary furtheraccording to thelevel of activity and energy density of the feeds beingfed.

TABLE 6.Example of a high-fat supplemented ration (to be fed with a mix of grass hay and alfalfa hay).

Important:See Table 7 on expectedfeed consumption andalways introduce newgrain feeds gradually.This ration contains 16percent more energythan the ration shown inTable 4 and over 25 per-cent more energy thanstraight oats, so smalleramounts of this rationwill need to be fed tomaintain similar bodycondition.

+ Percentages andweights of vitamins Aand E will vary, depend-ing on the vitamin pre-mix used.

Calculated analysis

Cracked corn = 14.5%Digestible energy = 1.61 Mcal/lbCrude fiber = 5.25%Crude fat = 12.9%Calcium = 0.47%Phosphorus = 0.38%Thiamin = 2.45 mg/lbVitamin A added at 2,000 IU/lbVitamin E added at 60 IU/lb

Cracked corn 36.25 725

Whole oats 32.50 650

Fat or oil 10.00 200

Soybean meal 15.00 300

Molasses 3.25 65

Calcium carbonate 0.75 15

Dicalcium phosphate 0.25 5

Brewers’ yeast 1.25 25

TM salt 0.75 15

Vitamin A + +

Vitamin E + +

Ingredients Percent Pounds/Ton

12

1. Anderson, C., G. D. Potter, J. L. Kreider and C. C.Courtney. 1983. Digestible energy requirements for exercisinghorses. Journal of Animal Science. 56:91.

2. Comben, N., R. J. Clark and D. J. B Sutherland. 1984.Clinical observations on the response of equine hoof defects todietary supplementation with biotin. Veterinary Record. 115:642.

3. Freeman, D. W., G. D. Potter, G. T. Schelling and J. L.Kreider. 1985. Nitrogen metabolism in the mature physically con-ditioned horse. II. Response to varying nitrogen intake.Proceedings, 5th Equine Nutrition Physiology Symposium. p. 236.

4. Freeman, D. W., G. D. Potter, G. T. Schelling and J. L.Kreider. 1988. Nitrogen metabolism in mature horses at varyinglevels of work. Journal of Animal Science. 66:407.

5. Gibbs, P. G. and N. D. Cohen. 2001. Early managementof race bred weanlings and yearlings on farms. Journal of EquineVeterinary Science. Vol. 21, No. 6. p. 279-283.

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7. Hansen, K. D., F. M. Rouquette, G. W. Webb, G. D. Potterand M. J. Florence. 1987. Performance of yearling horses on pas-ture and supplemental feed. Proceedings, 10th Equine NutritionPhysiology Society. Ft. Collins, CO. p. 25-30.

8. Hinkle, D. K., G. D. Potter, J. L. Kreider and G. T.Schelling. 1981. Nitrogen balance in exercising mature horse fedvarying levels of protein. Proceedings, 7th Equine NutritionPhysiology Symposium. p. 91.

9. Jones, D. L, G. D. Potter, L. W. Greene and T. W. Odom.1991. Muscle glycogen concentrations in exercised miniaturehorses at various body conditions and fed a control or fat-supple-mented diet. Journal of Equine Veterinary Science. 12(5):287.

10. Linden, J., H. Josseck, W. Zenker, H. Geyer and J. Schulze. 1993. The effect of d-biotin supplementation on hoofcondition in Lipizzaner horses. Proceedings, 13th EquineNutrition Physiology Symposium. p. 58-61.

11. Meyer, H. 1987. Nutrition of the equine athlete. InEquine Exercise Physiology 2. ICEEP Publications, Davis, CA.p. 644.

12. Meyers, H. C., G. D. Potter, J. W. Evans, S. B. Smith, T. S. Taylor and W. S. Barnes. 1990. Physiologic and metabolicresponse of exercising horses to added dietary fat. Proceedings,19th Equine Nutrition Physiology Symposium. p. 107.

13. Neilsen, B. D., G. D. Potter, L. W. Greene, E. L. Morris, M. Murray-Gerzik, W. B. Smith and M. T. Martin. 1998.Response of young horses in training to varying concentrations ofdietary calcium and phosphorous. Journal of Equine VeterinaryScience. 18(6):397-404.

14. Nielsen, B. D., G. D. Potter, E. L. Morris, T. W. Odom,D. M. Senor, J. A. Reynolds, W. B. Smith and M. T. Martin. 1997.Changes in the third metacarpal bone and frequency of boneinjuries in young Quarter Horses during race training observa-tions and theoretical considerations. Journal of Equine VeterinaryScience. 17(10):541-549.

15. Nolan, M. M., G. D. Potter, K. J. Mathiason, P. G. Gibbs,E. L. Morris, L. W. Greene and D. Topliff. 2001. Bone density inthe juvenile racehorse fed differing levels of minerals. Pro-ceedings, 17th Equine Nutrition Physiology Symposium. p. 33.

16. NRC, 1989. “Nutrient Requirements of Horses.”National Academy of Sciences. Washington, D. C.

17. Oldham, S. L., G. D. Potter, J. W. Evans, S. B. Smith, T. S. Taylor and W. S. Barnes. 1990. Storage and mobilization ofmuscle glycogen in exercising horses fed a fat-supplemented diet.Journal of Equine Veterinary Science. 10(5):1-5.

18. Potter, G. D., S. P. Webb, J. W. Evans and G. W. Webb.1990. Digestible energy requirements for work and maintenanceof horses fed conventional and fat-supplemented diets. Journal ofEquine Veterinary Science. 10(3):214-218.

19. Schryver, H. G. et al. 1978. Voluntary intake of calciumby horses and ponies fed a calcium deficient diet. Journal ofEquine Medical Surgery. 2:337-340.

20. Scott, B. D., G. D. Potter, L. W. Greene, P. S. Hargis andJ. G. Anderson. 1992. Efficacy of a fat-supplemented diet on mus-cle glycogen concentrations in exercising. Thoroughbred horsesmaintained in varying body conditions. Journal of EquineVeterinary Science. 12(2):105-109.

21. Scott, B. D., G. D. Potter, L. W. Greene, M. M. Vogelsangand J. G. Anderson. 1993. Efficacy of a fat-supplemented diet toreduce thermal stress in exercising thoroughbred horses. Proceed-ings, 13th Equine Nutrition Physiology Symposium. p. 66.

22. Stephens, T. L., G. D. Potter, K. J. Mathiason, P. G.Gibbs, E. L. Morris, L. W. Greene and D. Topliff. 2001. Mineralbalance in juvenile horses in race training. Proceedings, 17thEquine Nutrition Physiology Symposium. p. 26.

23. Topliff, D. R., G. D. Potter, T. R. Dutson, J. L. Kreiderand G. T. Jessup. 1983. Diet manipulation and muscle glycogenin the equine. Proceedings, 8th Equine Nutrition PhysiologySymposium. p. 119.

24. Topliff, D. R., G. D. Potter and J. L. Kreider. 1983.Exercise physiology in horses – fitness vs. fatness. Proceedings,Texas A&M University Horse Short Course. p. 1.

25. Topliff, D. R., G. D. Potter, J. L. Kreider, G. T. Jessupand J. G. Anderson. 1981. Thiamin supplementation for exercis-ing horses. Proceedings, 7th Equine Nutrition PhysiologySymposium. p. 167.

26. Webb, S. P., G. D. Potter and J. W. Evans. 1987.Physiologic and metabolic response of race and cutting horses toadded dietary fat. Proceedings, 10th Equine Nutrition PhysiologySymposium. p. 115.

27. Webb, S. P., G. D. Potter, J. W. Evans and G. W. Webb.1990. Influence of body fat content on digestible energy require-ments of exercising horses in temperate and hot environments.Journal of Equine Veterinary Science. 10(2):116-120.

28. Hoyt, J. K, G. D. Potter, L. W. Greene and J. W. Evans.1989. Mineral balance in resting and exercised miniature horses.Journal of Equine Veterinary Science. 15(7):310.

References