1. Equine Nutrition & Feeding
Peggy M. Auwerda

2. Time-Budgets Feral Horses Select highest fiber, lowest protein content
70% of its day foraging
Stabled Horses
10% of their day feeding
Meal fed

3. Digestive Tract The Mouth- first part of digestive system.
Mouth has 2 main functions- masticate food and wet food with saliva.

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

6. Digestive Tract Stomach – 9-15 liters Trickle feeders
Transit time <2 hr
Cardiac sphincter does not relax to allow regurgitation
Horse ingests food thru mouth, goes down esophogus to stomach. Horse has no olfactory response. Horses can not regurgitate. Stomach – 2 gallons, SI – 10 gallons/ feet, Cecum – 7 gallons/ 4 ft, Large colon- 14 gallon, 12 feet, small colon – 5 gallon, 10 ft. Vitamins K&B produced in the cecum. Stomach and SI function like a pig using enzymes to digest starch, fat, protein, and carbohydrates while the hindgut functions like the rumen of a cow utilizing microbes or good bugs to digest fiber, structural carbohydrates and certain vitamins. Stomach and SI function like a pig using enzymes to digest starch, fat, protein, and carbohydrates while the hindgut functions like the rumen of a cow utilizing microbes or good bugs to digest fiber, structural carbohydrates and certain vitamins

7. Digestive Tract Small Intestine 30% of digestive tract 40-50 liters
Transit time – 45 min to 8 hrs
α-Amylase – low & varies widely between horses
Starch digestion occurs in the stomach and small intestines
Amino acids and fat digested and absorbed in small intestine
Vitamins/minerals absorbed in small intestine

8. Digestive Tract Hindgut – 60% of digestive tract capacity Cecum –
25-35 liters
Transit time < 5 hr
Large Colon
50-60 liters
Small Colon
18-19 liters
Large & small colon transit time hours
Fiber digesters most active pH of
Starch digesters prefer pH 5.2 – 6.0

9. 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 mo of age
The large intestine increases with age even up to 20 yrs

10. Microbial Fermentation
Metabolized
For
Energy
Volatile
Fatty Acids
B-vitamins & Vit. K
Gas
Microbe
Wasted
Energy
Protein and Amino Acids?
Fibrous &
Non-Fibrous
Carbohydrate

11. Starch
Starch 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.

12. %

13. Postprandial Cecal pH Change

14. Starch Overload
Starch 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

15. How hindgut acidosis can occur in hindgut and how it can be attenuated
Pagan, J Feedstuffs

16. Carbohydrates

17. Starch Comparisons (what’s low, what’s high)
Ingredient
NSC
Sugar
Starch
Pectins
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
Oats
42.4
4.4
95.6
Wheat
73.8
8.9
80.2
10.9
Distillers
10.3
100.0
Corn gluten feed
24.7
3.7
71.2
25.1
Corn gluten meal
17.3
69.4
30.6
Soyhulls
14.1
18.8
62.4
Soybean meal, 44%
34.4
25.0
50.0
Wheat midds
31.2
10.0
90.0

18. Methods Of Maximizing Starch Digestion In Small Intestine
Properties of the starch granule
Grain processing
Plant cell walls
Transit time through the small intestine
Availability & concentration of enzymes

19. REMEMBER!
“The number one cause of deaths from colic is from starch overload due to feeding mismanagement.”
Dr. John Reagor, PhD
Chief of Toxicology
Texas Veterinary Medical
Diagnostic Laboratory

20. Glycemic Response Hyperglycemia occurs after digestion of grain meals
Affects substrates utilized during exercise
Glucose & insulin peak min after a meal
Insulin promotes fat storage
Sugary meals before exercise will  CHO to muscle & ↓ fat oxidation

22. Feeding Horses Feed intake usually expressed as
% of Body Weight
Lbs feed/100 lbs body weight
Free Choice
Forages – Maximize in the ration
Provide fiber & energy
Min. at least 1% of body weight (dm basis)
Concentrates
Provide energy
Supplements
Provide protein, minerals and vitamins

23. Estimating Weight (lbs)
Heartgirth should be taken at highest point of the wither.
Length should be taken from the point of the shoulder to the point of the buttock (1/2 way between the corner to the tail).
Don’t use this formula on pregnant mares or horses with extreme conformation irregularities.
The average error is +/- 24 pounds.
Heartgirth (in) x Heartgirth (in) x Body Length (in) 330 23

24. Energy Determines Weight & Condition Of Horse
Body Condition Score
Measures amount of body fat (1-9 scale)
Determines balance between energy intake & expenditure
Simple, repeatable, consistent method
Comparison between animals
Body Condition Scoring measures the amount of body fat present on a particular horse. Fat = stored energy. It thus determines the balance between the amount of energy intake and expenditure – i.e.. if a horse has a negative energy balance it will lose weight, and if it has a positive energy balance it will gain weight. 24

25. Body Condition Score Fat laid down in predictable patterns Organs
Behind the shoulder
Ribs
Rump
Back
Withers
Head and Neck 25

26. 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
BCS evaluation is meant to be determined by both visual assessment and palpation.
This will help to avoid mistaking a longer hair covering from areas of extra fat, and being fooled by conformation differences (a taller horse may appear thinner than a smaller pony). 26

27. Body Condition Scoring
1-3 Poor-Thin
4 Can see ribs, vertebra ridge evident
5 Back flat, can’t see ribs, but can feel them
6 Crease down back, fat deposits
7-9 Fleshy - Extremely fat

28. 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

29. Optimum Body Condition Score
Each 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
For an average horse – 5-6 is good 29

30. Building a Horse Ration
Start with horse needs
Maximize forage
Add energy if needed
Add protein & minerals if needed
Consider adding vitamins & supplements
Consistency is key to good feeding practices
Feed concentrate that makes-up the difference between nutrients
needed & nutrients in roughage

31. Forages are the Foundation Pasture, Hay
Grass
Bromegrass
Orchardgrass
Tall Fescue
Timothy
Grain Hay
Oat Hay
Wheat hay
Straw
Legume
Alfalfa
Birds Foot trefoil
Clovers
Lespedeza

32. 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

33. Forage Isn’t Everything
Most do not have all the minerals &/or vitamins a horse requires. Four ways to add these.
Add 1 to 4 oz mineral or mineral/vitamin supplement per day or
Add 1 to 2 lbs ration balancer (mineral plus protein) per day or
Feed 5 to 7 lbs fortified grain per day or
Feed 12 – 14 lbs complete feed (forage & grain)

34. Energy Sources - Grains
Oats
variable
crimped vs. whole
Corn
cracked, steam rolled
Barley
Sorghum & wheat
less than 30%
rolled, cracked, flaked,

35. 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

36. Protein
Muscle & bone growth, milk production, fetal growth, normal metabolism
Most horses requirements can be met with good quality hay or pasture forage

37. Protein Very important for young horses
Quantity = amount
Quality = amino acid balance
Very important for young horses
Lysine, methionine, tryptophan most limiting for growth & milk production

38. Sources of Protein for Horses
Soybean Oil Meal
Flax - Linseed Meal
Sunflower Meal
Cottonseed Meal
Peanut Meal
Corn Gluten Meal
Whey
Dried Skim Milk

39. Minerals Trace Minerals Content in the diet Macro-minerals
Determined by soil & water
Quality of feed & proportion of grain to hay
Macro-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 needs
If horses sweat a lot - need salt in the ration
Trace Minerals
Look for iron, zinc, copper, selenium

40. Minerals Macro-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 needs
If horses sweat a lot - need salt in the ration
Trace Minerals
Look for iron, zinc, copper, selenium

41. A guide to the recommended concentrations of trace elements in the diet, mg/kg dry matter. (Modified from the NRC 2007). These will need to be adjusted to suit individual circumstances, growth rate and appetite etc.

42. Vitamins Fat soluble: Water 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
Good balance of green hay, grain & sunlight provides adequate amounts of vitamins
High quality fresh forages = maintenance for mature horses
Hay is poor in Vitamin A
Supplement Vitamin A in the ration
Exposure to sunlight provides Vitamin D
Vitamin B is synthesized in the horse’s cecum

43. Vitamins High quality fresh forages = maintenance for mature horses
Hay is poor in Vitamin A
Supplement Vitamin A in the ration
Exposure to sunlight provides Vitamin D
Good balance of green hay, grain & sunlight provides adequate amounts of vitamins
High quality fresh forages = maintenance for mature horses
Hay is poor in Vitamin A
Supplement Vitamin A in the ration
Exposure to sunlight provides Vitamin D
Vitamin B is synthesized in the horse’s cecum

44. Guide to recommended levels of Fat-soluble vitamins (need to be adjusted according to individual circumstances).

45. 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
Lactation
1st, 2nd, 3rd, 4th, 5th, 6th mo
Growing
4, 6, 12 mo
18 mo
Light exercise
Moderate exercise
24 mo
Heavy exercise
Very heavy exercise

46. Water Essential for all body functions Temperature regulation
Feed digestion
Amount of water intake
Level of exercise
Ambient temperature
Quality of feeds in ration
Proportion of diet that is forage
Minimum 1 gallon/100 lbs BW/day

47. Maintenance Size: body weight Environment Individual differences
Dry matter intake: 1.5% of the BW
Most - energy requirements are met with forage alone

48. Recommended Daily Feed Intakes as % of Body Weights
Class
Forage
Concentrate
Total
Example
1,000 lb horse
Mature (Idle)
15-20 lb
Geriatric
0.8 – 2.0
0.5 – 2.0
1.5 – 3.0
15-30 lb

49. 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
Highly palatable
Easy to chew & swallow
Clean & dust free
Contain enough high quality fiber to aid digestion
Highly digestible pellets or extruded feeds

50. Selection of Feed For the Geriatric Horse
28 yr old horse
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
32 yr old horse

51. Feeding The Athlete

52. Aerobic and Anaerobic Metabolism
During exercise, ATP is generated from breakdown of:
Glucose
Fatty acids
Amino acids
ATP low in muscles; essentially no storage
Continuous ATP production vital for athletes

53. Simplified Energy for Muscle Contraction
Blood Glucose
Free Fatty Acids
Lipolysis
Muscle Glycogen
Oxidative
Metabolism
Pyruvate
Lactate
Blood glucose- simple sugar broken down from CHO’s - the most accessible type of fuel
Glycogen- two unit stored form of glucose stored in muscles or liver As exercise increases and glucose decreases, glycogen is used )
Creatine
Phosphate
ATP
CO2and
Water O2

54. Work
ENERGY, ENERGY, ENERGY!

55. 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
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

56. Performance/Work Energy = Activity DE (Mcal/d) Maintenance 16 Light
20.0
Moderate
23.3
Heavy
26.6
Very Heavy
34.5

57. 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 protein
More important – quality of protein
Horses should be fed to meet their immediate needs
Cut grain on rest days

58. 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

59. Feeding Guidelines for Performance Horses
Hay requirement
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 protein
More important – quality of protein
Horses should be fed to meet their immediate needs
Cut grain on rest days

60. Breeding Animals Maiden mare Barren mare Gestating mare Lactating mare
Flushing- Increasing energy intake 20-25% ~3 wks prior to breeding.
Gestating mare
Lactating mare
Stallion

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

62. Lactating Mare

63. Lactating Mare Month 1 – 3 = Month 4 – 6 =
milk is 3 % BW
Month 4 – 6 =
milk is 2 % BW
Requirements of energy, protein, mineral, and vitamin double vs. maintenance

64. Feed Consumption (% BW)
Mare status
Forage
Concentrate
Total
Early pregnancy
0-0.5
Late pregnancy
Early lactation
Late lactation
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 % of BW in concentrate feed/day

65. Body Condition Score Maximum Reproductive Efficiency
Moderately fleshy to fat mares can be expected to
Cycle earlier in the year
Have fewer cycles per conception
Have a higher pregnancy rate
Maintain 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.

66. Feeding The Growing Horse
Goals
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

67. Average Daily Gain
Avg. Daily Gain, lbs/d
Month of Age

68. Nutritional Strategies Aimed at Minimizing DOD
Rations should be balanced to promote a consistent growth curve
Requires periodic updating of the ration

69. Nutritional Strategies Aimed at Minimizing DOD
Feed 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

70. Monitor The Growth Process
Daily Intakes
Body Weight
Average daily gain
Signs of Skeletal Abnormalities
Physitis
Joint effusion
Lameness

71. 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

72. Feeding Guidelines & Strategies To Minimize Risk Of Hind Gut Dysfunction
Consider..
Quality of feeds available
Body Condition

73. Feeding Guidelines & Strategies To Minimize Risk Of Hind Gut Dysfunction
Check for Refusals
Change type & amount of feed gradually d period
Provide Salt

74. Feeding Guidelines & Strategies To Minimize Risk Of Hind Gut Dysfunction
Control 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/meal
Pre-feed forages

75. Feeding Guidelines & Strategies To Minimize Risk Of Hind Gut Dysfunction
Minimize the flow of fermentable polysaccharide to the large intestine
Limit rate of concentrate intake through physical obstruction
Maximize substrate (glucose) availability to the performance horse
Ensure good occlusion of teeth through regular dentistry

76. Feeding Guidelines & Strategies To Minimize Risk Of Hind Gut Dysfunction
Group Feeding Should Account for Dominance Hierarchies
Recognize Feeding-Related Behavior Problems

78. REINS Relevant Equine Intensive Nutrition Software
Peggy Auwerda & Garland Dahke

79. REINS
Total 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

80. REINS
Least cost formulator can be used or rations can be entered manually
Extensive feed library – Up to 220 feeds
Multiple feed libraries can be created which allows a use to assign a feed library to a farm
Comprehensive appendixes