1. Nutrients: Carbohydrates
EQS 125

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As discussed in the energy lecture, carbohydrates are the primary source of energy for the horse
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Defining Carbohydrates
Structural Carbohydrates
Non-Structural Carbohydrates
Carbohydrates in the Body
Carbohydrate Values
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3. Defining Carbohydrates

4. What are carbohydrates?
The term carbohydrate is a collective term for:
Starches
Sugars
Fiber
Carbohydrates can be broken down into 2 types – non-structural and structural

5. Structural Carbohydrates

6. Structural carbohydrates
Structural carbohydrates are part of the cell wall of plants and provide fiber in the diet
Structural carbohydrates cannot be broken down by enzymes in the small intestine – they must be fermented in the hindgut
In the hindgut, they are broken down into volatile fatty acids and glucose, which are absorbed by the body for energy
Forage (hay and/or pasture) is an excellent source of structural carbohydrates

7. Fiber is the most important ingredient in every equine diet
Fiber provides all the energy needed for maintenance metabolism and helps maintain a healthy GI tract
Except in strenuous circumstances, fiber should make up at least 50% (by weight) of the horse’s daily diet
Remember – grain is an optional part of the horse’s diet, fiber is not!
That means forage alone can meet energy requirements for maintenance horses
Compared to grain/concentrate, fiber sources provide a lower amount of digestible energy

8. Forage is an excellent source of structural carbohydrates
Knowledge check
Forage is an excellent source of structural carbohydrates
True
False
Incorrect
Structural carbohydrates are part of the cell wall of plants and provide fiber in the diet – forages (hay and/or pasture) is a great source of structural carbs!
Correct!

9. Knowledge check
Which classification of horse will be able to meet dietary energy needs on forage alone?
Growing Horse
Lacating Mare
Peformance
Maintenace
Correct!
Forage, which provides fiber, can help maintenance horses meet all dietary energy needs if it is good quality
Incorrect, Try Again
Incorrect, Try Again
Incorrect, Try Again

10. Non-Structural Carbohydrates

11. Non-Structural carbohydrates
Non-Structural carbohydrates (NSC) are stored inside of the plant…
These carbohydrates consist of…
Simple Sugars
Starch
Simple sugars can be readily utilized by the body during exercise – performance horses often require NSCs in higher amounts to fuel the required energy
Non-structural carbohydrates are broken down by enzymes and absorbed in the small intestine

12. Non-Structural carbohydrates
Non-Structural carbohydrates (NSC) are stored inside of the plant…
These carbohydrates consist of…
Simple Sugars
Starch
Once broken down, they become readily utilized for energy as glucose, which circulates in the bloodstream or is stored

13. Non-Structural carbohydrates
Non-Structural carbohydrates (NSC) are stored inside of the plant…
These carbohydrates consist of…
Simple Sugars
Starch
When compared to fiber sources, grain products contain higher concentrations of non-structural carbohydrates

14. Non-Structural carbohydrates
Non-Structural carbohydrates (NSC) are stored inside of the plant…
These carbohydrates consist of…
Simple Sugars
Starch
Because of high concentrations of NSCs, grain products generally provide higher dietary energy than fiber sources

15. NSC overload
When good microbes die due to the environment change, they react as poison in the bloodstream
This can result in colic, laminitis, and other illnesses
Non-structural carbohydrates are not meant to be digested in the hindgut
If a horse ingests too large of an amount they may overflow to the hindgut and destroy the microbial environment

16. Knowledge check
Feeding too many non-structural carbohydrates in one feeding could result in hindgut illness
True
False
Incorrect
Non-structural carbohydrates are not meant to be digested in the hindgut – if too much overflow to the hindgut the environment will change and kill microbes
Correct!

17. Carbohydrates in the Body

18. Utilizing Carbohydrates
Once broken down, carbohydrates may be stored if the body does not need to use them right away
The body will store them as:
Glycogen = storage form of glucose
Stored in the muscle and liver
Fat
Converted into fat if the muscle and liver are full
The hormone insulin acts as a glucose regulator – it determines how much remains in the bloodstream and how much gets stored

19. Utilizing Carbohydrates
Once broken down, carbohydrates may be stored if the body does not need to use them right away
During exercise, the horse’s muscle fibers receive energy from muscle glycogen stores and circulating blood glucose
Carbohydrates can be used as energy for aerobic and anaerobic work until depleted

20. The hormone _____ is a glucose regulator
Knowledge check
The hormone _____ is a glucose regulator
Cortisol
Insulin
Adrenalin
Endorphin
Incorrect, Try Again
Incorrect, Try Again
Correct!
Incorrect, Try Again

21. Carbohydrate Intolerance
A racehorse needs carbohydrates in the diet in order to meet the energy demands of exercise
On the other hand, if you are an athlete, carbohydrates are needed to fuel your performance
A person that ingests a large number of carbohydrates but doesn’t exercise will often see a weight gain
If you feed a maintenance horse (little to no exercise, not pregnant, not lactating, not growing) a diet too high in carbohydrates it will result in obesity
The best way to think about carbohydrates in the horse is think about how they work in a human

22. Carbohydrate Values

23. Carbohydrates on the feed label
There is no “true” carbohydrate value on a feed label because it depends on the type of carbohydrate you are looking at (structural vs non-structural)
When determining how many structural carbohydrates are present we look at:
Crude Fiber (CF)
The higher the crude fiber value, typically the lower overall dietary energy that feed will provide

24. Carbohydrates on the feed label
There is no “true” carbohydrate value on a feed label because it depends on the type of carbohydrate you are looking at (structural vs non-structural)
NSC values are not found on commercial feed labels – you will have to look on the company’s website for this information
Remember that NSCs provide more dietary energy, so the more NSCs present, the more energy

25. Carbohydrates on the feed label
There is no “true” carbohydrate value on a feed label because it depends on the type of carbohydrate you are looking at (structural vs non-structural)
NSC values are not found on commercial feed labels – you will have to look on the company’s website for this information
Picking grains that are under 10% are ideal for these types of horses
When discussing grain – horses that are overweight or prone to obesity should be on a diet low in NSC

26. Crude Fiber is a value the tells you how many NSCs are in a feed
Knowledge check
Crude Fiber is a value the tells you how many NSCs are in a feed
True
False
Incorrect
Crude Fiber is a structural carbohydrate value
Correct!

27. Horses that are obese should have a grain with a NSC value under 10%
Knowledge check
Horses that are obese should have a grain with a NSC value under 10%
True
False
Incorrect
Obese horses should have a grain with a NSC value under 10%
Correct!

28. Finish

29. End of Lecture
You have finished Lecture 4.2 – Nutrients: Carbohydrates. Complete Homework #4 prior to taking your Homework quiz in Blackboard