Horse Nutrition
March
29,
2013
M.E. Persia
Iowa State University
4/16/2012
Digestive Anatomy
Type of
Digestion
Foregut
Capacity
% of
the
GIT
Enzymatic
Stomach
8-15 L
8
Enzymatic
Small Intestine (70
feet)
68 L
30
Hindgut
Microbial
Cecum (4 feet)
28 – 36 L
15
Microbial
Large colon (10 – 12
feet)
86 L
38
Microbial
Small colon (10 – 12
feet)
16 L
9
Adapted: Atlas of Topographical Anatomy of the Domestic Animals,
Popesko, P., W.B. Saunders
Purpose of Feeding
• Physiological Stage
• Growth, pregnancy, lactation
• Geriatrics
• Environment
• Health & Well Being (body condition)
• Clinical Conditions
• Exercise
Feeding Behavior and General Considerations
• Feeding behavior affects feed intake
• Forages of considerable variety are primary diets consumed by wild horses
• 65% Grasses and Sedges
• 25% Shrubs
• 5% forbs (such as wildflowers)
• Preference between wild and
domestic horses for grasses is
similar but difficult to measure and
data are inconsistent.
• Highly selective grazers and will
graze down to ground level.
• Prefer young, rather than mature
plants
• Grasses are preferred to legumes
and herbs.
Appropriate & Palatable Forage Species
• Cool Season Grasses
– Perennial ryegrass, meadow fescue, timothy, orchardgrass,
creeping red fescue, Kentucky bluegrass, brome grass, tall fescue
• Warm Season Grasses
– Bermuda grass, crabgrass, prairie grass, India grass, canary grass,
wheat grass, switch grass
• Legumes
– Alfalfa, white clover, vetch
• Herbs
– Dandelion, ribgrass, chicory
• Cereals
– Oats, barley
Soft brome
Forage quality
Forage
DE (Mcal/Kg)
TDN, %
CP, %
DP, %
Alfalfa – early bloom
2.42
55
17.2
13.4
Alfalfa – full bloom
2.16
49
15.0
10.1
Bluegrass
2.15
50
15.0
12.6
Orchardgrass
2.2
50.0
16.0
13.5
Anti – Nutrients in Forage
• Oxalates & Phytates
– Many warm season grasses
– Calcium/Phosphorus concerns
• Cyanogenic glycosides
– high in Sorghum, Sudan grass, hybrid Johnson
grass, and Sorghum – Sudan hybrids; therefore,
not recommended for horses.
Anti-Nutrients in Forage
• Clostridium, Listeria can be issues with ensiled
forages
• Endophyte contamination
• Mycotoxins
• Yellow and White Sweet Clover – Penicillium
spp. – product dicoumarol poisoning
• Toxic plants
Insect Contamination - Blister beetles
• 2 species of concern
– Epicauta vittat
– Epicauta pennsylvanica
• Toxin = cantharidin
• Fatal
Grazing Time
•
•
•
•
•
Constant Grazers
– http://www.youtube.com/watch?v=s5FJgsHx6gY
– Accounts for up to 1.5 – 3 miles per day
– Move more than cattle (damage to pasture)
Horses will graze for 10 – 17 hours per day
– Compared to cattle?
– http://www.youtube.com/watch?v=L5xRBoyNIzc
Affected by light and season
– 20 – 50% nocturnal (higher in summer)
Affected by group
– Herd animals > single
Affected by gender, age, breed
– Mares > stallions
– Mature > weanlings
– Yearlings > 2 year olds
– Arabians > Thoroughbreds
Crowell-Davis, et al., 1985; Kaseda, 1993; Mesochina et al., 2000, Rogalski, 1977
How much will a horse eat?
Classification
DMI (Kg per 100 Kg BW)
Mature horses
1.8 – 3.2
Growing horses
2.0 – 3.0
Mature ponies
1.5 – 5.2
Donkeys
2.3 – 2.6
Diet type
Hay
2.0 – 2.4
Corn silage
0.97
Mixed forage + concentrate
> 2.0
Maximal DMI = 3 – 3.2% Body weight
General Feeding Considerations
• Meet nutrient needs while maintaining
normal feeding behaviors.
• Forage based rations
– Benefits?
– Grain by-products, pasture, harvested forages
– Forages should be a minimum of 1% of the body
weight.
– Example: 1,000 Lb horse
• 1% = 10 Lb forage minimum
Feeding Considerations
• What is the management system?
Feeding Considerations
• Does diet affect behavior?
• http://www.youtube.com/watch?v=NyYLfUlwfMs
– Goal is to prevent boredom that could lead to stable
“vices” and “sterotypies”
• Orosensory sensations of feeds are extremely
important for horses and contribute to
palatability.
– Smell, texture, and taste
– Prefer variety
Feeding considerations – oral behaviors
• Lack of fiber, too much grain in the diet
– Reduce gastric pH (3.3 compared to 5.5)
– Lower saliva production
– Associated with increase oral behaviors such as “cribbing”
• Hay should be at least 14 Lb per day if pasture can’t be
offered.
• Feed at least 2 types of forage, provide pasture if
possible.
• Feeding frequency of grain (more often is not better)
• Limit concentrate feeding
– http://www.youtube.com/watch?v=b4lmVaIqZIo&feature=
related
Considerations for Senior Horses
• Age related changes in nutrient digestion,
absorption and metabolism may occur
– Reduction in digestion and absorption in the large
intestine (5% lower digestion of CF)
– 5-10% reduction in protein digestibility
• Supplemental lysine (20 g/d) and threonine (15 g/d) – may
help reduce the lean tissue loss
• Dental issues
• Energy requirements – decrease 15 – 20%
– In the absence of disease
– With disease can increase as much as 40%
Considerations for heat and cold stress
• Water – during hot periods, voluntary water
intake increases 30 – 75%
• Salt should be available during hot weather
• Additional vitamins and minerals do not seem
to be useful
• During cold weather – DE should be increased
2 – 3%
• Hay should be offered ad lib to allow horses to
feed to energy requirement
Considerations for exercise
• How exercise is defined
• Light
• 1-3 hours weekly
• Mean heart rate is 80 beats/min
• Recreational trail riding
• Moderate
• 3-5 hours weekly
• Mean heart rate is 90 beats/min
• Show horses, light ranch work
• Heavy
• 4-5 hours weekly
• Mean heart rate is 110 beats/min
• Eventing, race training
• Very Heavy
• 6-12 hours weekly (or 1 hour speed work)
• Mean heart rate is 110-150 beats/min
• Elite eventing, racing
Exercise Considerations - Energy
• Digestible Energy
–
–
–
–
Light work
Moderate work
Heavy work
Very heavy
= (0.0333 x BW) x 1.20
= (0.0333 x BW) x 1.40
= (0.0333 x BW) x 1.60
= (0.0363 x BW) x 1.90
Ex. 500 Kg race horse
= (0.0363 x 500) x 1.9 = 34.5 Mcal per day
(> 70% more energy than light working)
Exercise Considerations - Protein
• Protein requirement for maintenance
– BW x 1.26g CP/Kg BW
– 500 Kg horse x 1.26 = 630 grams Crude Protein
– Range of 1.08 – 1.44 as the multiplier
• Exercise losses in protein are due to:
– Muscle gain
– Nitrogen lost as sweat
– Add protein to basal requirement
•
•
•
•
Light = BW x 0.089 g CP (630 + 44.5 g = 675 g CP)
Moderate = BW x 0.177 g
Heavy = BW x 0.266 g
Very heavy = BW x 0.354 g (630 + 177 = 807 g CP)
– 20% more protein needed than lightly worked horses
Clinical Nutrition
•
•
•
•
•
•
•
•
•
•
Hyperkalemic periodic paralysis (HYPP)
Polysaccharide storage myopathy (PSSM)
Developmental orthopedic disease (DOD)
Laminitis
Nutritional Secondary Hyperparathyroidism
Gastric ulcer syndrome
Colic
Enterolithiasis
Recurrent airway obstruction
Obesity
Laminitis
• Multifactorial – inflammatory
• Associate with carbohydrate overload including over feeding
of grains, lush pastures
– Frosted pastures
• Nitrogen compound overload
– Pastures where nitrate fertilizers used
– Pastures high in clover
Body Condition Scoring
• Necessary means of managing weight when
weighing isn’t possible.
• Farm/Stable Dependent.
• What is function?
• It is dependent on
structure
BCS = 1
BCS = 2
BCS = 3
BCS = 4
BCS =5