Equine Nutrition & Feeding

Peggy M. Auwerda

Time-Budgets

Feral Horses

Select highest fiber, lowest protein content

70% of its day foraging

Stabled Horses

10% of their day feeding

Meal fed

Digestive TractThe Mouth- first part of digestive system.

Mouth has 2 main functions- masticate food and wet food with saliva.

Mastication•Jaw sweeps 60,000 times/day when grazing•Saliva contains little, if any amylase

Stomach –

9-15 liters

Trickle feeders

Transit time <2 hr

Cardiac sphincter does not relax to allow regurgitation

Digestive Tract

Digestive TractSmall Intestine

30% of digestive tract40-50 litersTransit time – 45 min to 8 hrsα-Amylase – low & varies widely between horses

Starch digestion occurs in the stomach and small intestinesAmino acids and fat digested and absorbed in small intestineVitamins/minerals absorbed in small intestine

Hindgut – 60% of digestive tract capacityCecum –

25-35 litersTransit time < 5 hr

Large Colon50-60 liters

Small Colon18-19 liters

Large & small colon transit time 48-72 hoursFiber digesters most active pH of 6.2-6.8Starch digesters prefer pH 5.2 – 6.0

Digestive Tract

Aspects of The Foal GI Tract

Small digestive tract

The small intestine does not increase in length from 4 wks of age

Cecum not fully functional until 15-24 mo of age

The large intestine increases with age even up to 20 yrs

Microbial Fermentation

Fibrous &Non-Fibrous

Carbohydrate

Microbe

Volatile Fatty Acids

Gas

B-vitamins & Vit. K

MetabolizedFor

Energy

WastedEnergy

Protein and Amino Acids?

StarchStarch is an important and valuable component of the equine diet.

Equine athletes need carbohydrates for efficient energy use.

Mares need carbohydrates to help produce healthy foals.

Mares need carbohydrates for milk production.

0102030405060708090

Starch Fats Protein SmallIntestineDigestion

LargeIntestineDigestion

Comparison of Corn and Oats

Corn

Oats

%

Postprandial Cecal pH Change

6.6

6.8

7

7.2

7.4

7.6

2 3 4 5 6 7

OatsCornHay

Starch OverloadStarch not digested in SI is delivered to hindgut for bacterial fermentation. Too much starch may…

Cause radical changes to hindgut flora

Increase VFA & lactic acid concentrations – hindgut acidosis

Cause laminitis, colic, endotoxemia, metabolic acidosis, behavioral problems (wood chewing)

Critical capacity for hydrolysable carbohydrate overload ~0.4% of BW

Cuddeford, D. 1999; Harris et al. 1999

How hindgut acidosis can occur in hindgut and how it can be attenuatedHigh Grain or High Fructans

Minimal decrease in pH

Significant decreaseIn pH

Increase in VFA&Lactic Acid of

Hindgut

Time ReleasedBuffer

Optimal VFA absorption

Optimal Energy forWorking & Breeding Horses

Decrease in fiber fermenting OrganismsIncrease in lactate producing organisms

Very low pH

Bacterial lyses

SubclinicalAcidosis

Irritation & damageTo intestinal mucosa

Inhibition of fiber fermentingOrganisms & lactateUtilizing organisms

Off FeedDecreased fiber

digestibilityColic Symptoms

Stereotypic Behaviors

Release of endotoxins

LaminitisPagan, J. 2007. Feedstuffs

Total CHO

Non-FiberCarbohydrates

Neutral DetergentFiber

NonstructuralCarbohydrates

Neutral DetergentSoluble Fiber Hemicellulose

Acid DetergentFiber

Sugars

Starches

Pectins

Fructans

β-Glucans

Cellulose

Lignin

Carbohydrates

Ingredient NSC Sugar StarchPectins

Beta-Glucans

% DM -------------------------- % of NSC ---------------------

Alfalfa hay 23.0 0.0 40.9 33.0

Grass hay 17.2 35.4 15.2 49.4

Barley 61.8 9.1 81.7 9.2

Corn 71.4 20.0 80.0 0.0

Oats 42.4 4.4 95.6 0.0

Wheat 73.8 8.9 80.2 10.9

Distillers 10.3 0.0 100.0 0.0

Corn gluten feed 24.7 3.7 71.2 25.1

Corn gluten meal 17.3 0.0 69.4 30.6

Soyhulls 14.1 18.8 18.8 62.4

Soybean meal, 44% 34.4 25.0 25.0 50.0

Wheat midds 31.2 10.0 90.0 0.0

Starch Comparisons (what’s low, what’s high)

Methods Of Maximizing Starch Digestion In Small Intestine

Properties of the starch granuleGrain processingPlant cell wallsTransit time through the small intestineAvailability & concentration of enzymes

REMEMBER!“The number one cause of deaths from

colic is from starch overload due to

feeding mismanagement.”Dr. John Reagor, PhDChief of ToxicologyTexas Veterinary Medical Diagnostic Laboratory

Glycemic Response Hyperglycemia occurs after

digestion of grain meals Affects substrates utilized

during exercise

Glucose & insulin peak 60-90 min after a meal Insulin promotes fat storage

Sugary meals before exercise will CHO to muscle & ↓ fat oxidation

Feed intake usually expressed as % of Body Weight Lbs feed/100 lbs body weight Free Choice

Forages – Maximize in the rationProvide fiber & energyMin. at least 1% of body weight (dm basis)

ConcentratesProvide energy

Supplements Provide protein, minerals and vitamins

Feeding Horses

Estimating Weight (lbs)

Heartgirth (in) x Heartgirth (in) x Body Length (in)

330

Body Condition Score Measures amount of body fat (1-9 scale)Determines balance between energy intake & expenditureSimple, repeatable, consistent methodComparison between animals

EnergyDetermines Weight & Condition Of Horse

Body Condition ScoreFat laid down in predictable patterns

Organs

Behind the shoulder

Ribs

Rump

Back

Withers

Head and Neck

Body Condition Score Evaluation

Visual assessment and actual touch

Palpate fat areas

Avoid mistaking longer hair covering for fat areas

Avoid being fooled by conformation differences

Body Condition Scoring1-3 Poor-Thin4 Can see ribs,

vertebra ridge evident5 Back flat, can’t see

ribs, but can feel them6 Crease down back, fat

deposits7-9 Fleshy - Extremely fat

Time & Additional Grain Required To Improve

BCS by 1 level

Improving 1 Condition Score

Days Needed Daily Gain Additional Grain Needed

60 0.75 lbs/day 4.5 lbs/day

90 0.50 lbs/day 3.0 lbs/day

120 0.40 lbs/day 2.3 lbs/day

Optimum Body Condition ScoreEach horse has its own ideal condition for the breed & use

Average horse 5-6

Broodmare 5-7

Breeding stallion 5-6

Performance horse 4-6

Building a Horse RationStart with horse needsMaximize forage Add energy if neededAdd protein & minerals if neededConsider adding vitamins & supplementsConsistency is key to good feeding practices

Feed concentrate that makes-up the difference between nutrients needed & nutrients in roughage

Forages are the FoundationPasture, Hay

GrassBromegrassOrchardgrassTall FescueTimothy

Grain HayOat HayWheat hay

Straw

LegumeAlfalfaBirds Foot trefoilCloversLespedeza

Ingredients Used In Place of Hay for Roughage

Good Quality Sources:

Beet Pulp

Soybean Hulls

Dried Citrus Pulp

Dried Apple Pectin Pulp

Alfalfa Meal

Poor Quality Sources:

Peanut Hulls

Oat Hulls

Ground Straw

Cottonseed Hulls

Rice Hulls

Rice Mill Feed

Forage Isn’t Everything

Most do not have all the minerals &/or vitamins a horse requires. Four ways to add these.

1. Add 1 to 4 oz mineral or mineral/vitamin supplement per day or

2. Add 1 to 2 lbs ration balancer (mineral plus protein) per day or

3. Feed 5 to 7 lbs fortified grain per day or

4. Feed 12 – 14 lbs complete feed (forage & grain)

Energy Sources - Grains

Oatsvariable

crimped vs. whole

Corncracked, steam rolled

Barley

Sorghum & wheatless than 30%

rolled, cracked, flaked,

Fat/Fatty Acids• No gall bladder

Horses can be safely fed up to 20% fat in the total diet Energy from fat is 90% utilizable

Often used to supplement calories for hard-working horses and hard keepers

Reduction in DM intake & bowel weight

Calmer temperament

Protein

Muscle & bone growth, milk production, fetal growth, normal metabolismMost horses requirements can be met with good quality hay or pasture forage

Protein Quantity = amount

Quality = amino acid balance

Very important for young horses

Lysine, methionine, tryptophan most limiting for growth & milk production

Sources of Protein for HorsesSoybean Oil Meal

Flax - Linseed Meal

Sunflower Meal

Cottonseed Meal

Peanut Meal

Corn Gluten Meal

Whey

Dried Skim Milk

Minerals Content in the diet

Determined by soil & waterQuality of feed & proportion of grain to hay

Macro-mineralsCa & P - quality forages usually provide adequate amount

This ratio is very important: 1.5:1 to 2:1 Grains are rich in P and low in Ca

NaCl (Salt)Salt block will meet many horse’s needsIf horses sweat a lot - need salt in the ration

Trace MineralsLook for iron, zinc, copper, selenium

MineralsMacro-minerals

– Ca & P - quality forages usually provide adequate amount

This ratio is very important: 1.5:1 to 2:1 Grains are rich in P and low in Ca

– NaCl (Salt)Salt block will meet many horse’s needsIf horses sweat a lot - need salt in the ration

– Trace MineralsLook for iron, zinc, copper, selenium

A guide to the recommended

concentrations of trace elements in

the diet, mg/kg dry matter. (Modified

fromthe NRC 2007).

These will need to be adjusted to suit

individual circumstances, growth rate and

appetite etc.

Vitamins

Fat soluble: - stored in body - A, D, E, K- Toxicity’s can occur if fed in excess

Water soluble: - must be continuously supplied - B-complex; niacin, thiamin, riboflavin

Vitamins

High quality fresh forages = High quality fresh forages = maintenance for mature horses maintenance for mature horses

Hay is poor in Vitamin AHay is poor in Vitamin A

Supplement Vitamin A in the rationSupplement Vitamin A in the ration

Exposure to sunlight provides Vitamin DExposure to sunlight provides Vitamin D

Guide to recommended levels of Fat-soluble vitamins (need to be adjusted according to individual

circumstances).

Nutrient Requirement Varies With Class of Horse – NRC 2007

Adult (no work)

Working

Light exercise

Moderate exercise

Heavy exercise

Very heavy exercise

Stallions

Pregnant Mares

< 5 mo

5th, 6th, 7th, 8th, 9th, 10th, 11th mo

Lactation1st, 2nd, 3rd, 4th, 5th, 6th mo

Growing 4, 6, 12 mo18 mo

Light exerciseModerate exercise

24 moLight exerciseModerate exerciseHeavy exerciseVery heavy exercise

Water Essential for all body functions

Temperature regulation

Feed digestion

Amount of water intakeLevel of exercise

Ambient temperature

Quality of feeds in ration

Proportion of diet that is forage

Minimum 1 gallon/100 lbs BW/day

Maintenance Size: body weight

Environment

Individual differences

Dry matter intake: 1.5% of the BW

Most - energy requirements are met with forage alone

Recommended Daily Feed Intakes as % of Body Weights

Class Forage Concentrate Total Example

1,000 lb horse

Mature (Idle) 1.5 - 2.0 0.0 - 0.5 1.5 - 2.0 15-20 lb

Geriatric 0.8 – 2.0 0.5 – 2.0 1.5 – 3.0 15-30 lb

Geriatric Horses Nutrient Considerations

Reduced salivation

CF digestibility ↓

Total fiber < 30%

CP digestibility ↓

10-14% CP

Energy:

Increase soluble carbohydrates, fats, & oils

Caloric Restrictions

Supplement minerals & vitamins including vitamin C

Selection of Feed For the Geriatric Horse

Highly palatable

Easy to chew & swallow

Forage - chopped, cubed, pelletized, or in a wafer

Grains - rolled, crimped, or flaked

28 yr old horse

32 yr old horse

Feeding The Athlete

Aerobic and Anaerobic Metabolism

During exercise, ATP is generated from breakdown of:

Glucose

Fatty acids

Amino acids

ATP low in muscles; essentially no storageContinuous ATP production vital for athletes

ATP

OxidativeMetabolismLactate

Free Fatty Acids

Creatine Phosphate CO2and

Water

Lipolysis

O2

Simplified Energy for Muscle Contraction

Pyruvate

Blood Glucose

Muscle Glycogen

Work

ENERGY, ENERGY, ENERGY!

Levels of Performance/Work

Light – Recreational riding, beginning of training programs, Show horses (occasional)

Moderate – School horses, Recreational riding, Show horses (frequent), Polo, Ranch

Heavy– Ranch, Polo, Show horses (frequent, strenuous events), Low-medium eventing, Race training (middle stages)

Very Heavy – Racing, Elite 3-day event

Performance/Work

Energy =

Activity DE (Mcal/d)

Maintenance 16

Light 20.0

Moderate 23.3

Heavy 26.6

Very Heavy 34.5

Feeding Guidelines for Performance Horses

Starch is necessary for replacing glycogen stores.Hay

Feed at least 50% of total ration as forage (pasture &/or hay)Preferably high quality grass hay or alfalfa/grass mix

Exercising horses do not need high levels of proteinMore important – quality of protein

Horses should be fed to meet their immediate needsCut grain on rest days

FAT SUPPLEMENTATION

Enhanced stamina capacity for uptake & oxidation

of fatty acids in muscle Concomitant decrease in use of

endogenous carbohydrate stores - Muscle glycogen sparing

Add 6-10 weeks before performance

Feeding Guidelines for Performance Horses

Hay requirementFeed at least 50% of total ration as forage (pasture &/or hay)Preferably high quality grass hay or alfalfa/grass mix

Exercising horses do not need high levels of protein

More important – quality of proteinHorses should be fed to meet their immediate needs

Cut grain on rest days

Breeding AnimalsMaiden mare

Barren mareFlushing- Increasing energy intake 20-25% ~3 wks prior to breeding.

Gestating mare

Lactating mare

Stallion

•Last 3 month of gestation: 60 % foals’ weight•Mare needs to gain 0.3 – 0.8 lb/d

Gestating Mares

Lactating Mare

Lactating Mare

Month 1 – 3 = milk is 3 % BW

Month 4 – 6 = milk is 2 % BW

Requirements of energy, protein, mineral, and vitamin double vs. maintenance

21

22

23

24

25

26

27

28

15 30 45 60 90 120 150

Time (days)

Dai

ly M

ilk P

rodu

ctio

n (lb

s)

Feed Consumption (% BW)

Mare status Forage Concentrate Total

Early pregnancy 1.5-2.0 0-0.5 1.5-2.0

Late pregnancy 1.0-1.5 0.5-1.0 1.5-2.0

Early lactation 1.0-2.0 1.0-2.0 2.0-3.0

Late lactation 1.0-2.0 0.5-1.5 2.0-2.5

•Adding concentrate to late pregnancy mares accounts for limited energy & acclimates microbes

•Allow 1 wk to 10 d for mares to adjust to intake changes•Heavy milkers may require as much as 1.75-2.0% of BW in concentrate feed/day

Body Condition ScoreMaximum Reproductive Efficiency

Moderately fleshy to fat mares can be expected to

Cycle earlier in the yearHave fewer cycles per conceptionHave a higher pregnancy rateMaintain pregnancy more easily

Mare prior to breeding should have a BCS of 6 or greater and fed to maintain weight.BCS of 5.0 is marginal especially for lactating mare.

Feeding The Growing HorseGoals

Maximize genetic potential for growth

Sound musculoskeletal system

•Nutrient Balance is important•Requires higher quality feeds•Growth rate & age determines requirements•Growing till reach 30 months

Average Daily Gain

0

0.5

1

1.5

2

2.5

3

3.5

0 2 4 6 8 10 12 14 16 18 20 22 24

Month of Age

Avg

. Dai

ly G

ain

, lb

s/d

Rations should be balanced to promote a consistent growth curve

Requires periodic updating of the ration

Nutritional Strategies Aimed at Minimizing DOD

www.Foalcare.com

Nutritional Strategies Aimed at Minimizing DODFeed selection

High quality forage is a must

Grain mix concentrates formulated specifically for growing horses

Improper use of supplements

Feed amounts

Forage

Minimum of 1 lb / 100 lb BW / d

Fed to appetite is best

Concentrate

~ 1 lb / 100 lb BW / d

Max. 8 to 10 lbs /d

Monitor The Growth Process

Daily Intakes

Body Weight

Average daily gain

Signs of Skeletal Abnormalities

Physitis

Joint effusion

Lameness

Feeding Guidelines & Strategies To Minimize Risk Of Hind Gut Dysfunction

Know Your Horse & Provide Feed Based on:

Class

Stage of production

Age

Activity level

Growth

Consider..Quality of feeds available

Body Condition

Feeding Guidelines & Strategies To Minimize Risk Of Hind Gut Dysfunction

Check for Refusals Change type &

amount of feed gradually. 7-10 d period

Provide Salt

Feeding Guidelines & Strategies To Minimize Risk Of Hind Gut Dysfunction

Feeding Guidelines & Strategies To Minimize Risk

Of Hind Gut DysfunctionControl amount of NSC (sugar, starch & fructan) the horse consumes. Minimize the flow of fermentable polysaccharide to the large intestine

Feed starch sources little and often i.e., less than 5g oats/(2g starch)/kg body weight/mealPre-feed forages

Feeding Guidelines & Strategies To Minimize Risk

Of Hind Gut DysfunctionMinimize the flow of fermentable polysaccharide to the large intestine

Limit rate of concentrate intake through physical obstructionMaximize substrate (glucose) availability to the performance horse

Ensure good occlusion of teeth through regular dentistry

Group Feeding Should Account for Dominance Hierarchies

Recognize Feeding-Related Behavior Problems

Feeding Guidelines & Strategies To Minimize Risk Of Hind Gut Dysfunction

REINSRelevant Equine Intensive

Nutrition Software

Peggy Auwerda & Garland Dahke

REINSTotal mixed ration (TMR) program that allows for evaluation and formulation of protein, energy, vitamin and mineral requirements of horse rations across multiple stages of production Based off of the 2007 NRC Nutrient Requirements of Horses Written in MS Visual Basic and uses MS Excel as the user’s interface to operate

REINSLeast cost formulator can be used or rations can be entered manually Extensive feed library – Up to 220 feedsMultiple feed libraries can be created which allows a use to assign a feed library to a farm Comprehensive appendixes