Feeding Carbohydrates to Horses: Fibre

Question 1

What should be the main part of the horses diet?

Answer 1

fibre

Question 2

What is fibre?

Answer 2

• Carbohydrate
• Complex vs Simple

•Complex = Fibre and plant material
•AKA
–Structural CHO
–Complex CHO

Question 3

What are the fibre components present in plants?

Answer 3

•Fibre components present in plants:
–Lignin Cellulose
–Hemicellulose
–Pectin
–Lignin
–Ligno-Cellulose

Question 4

What is short fibre?

Answer 4

Short fibre
•Copra meal
•Sugar beet
•Soybean hulls
•Lupin hulls
•Oat hulls
•Specific high fibre compound feeds

Question 5

What is long fibre?

Answer 5

Long fibre
•Grass
•Hay
•Haylage
•Straw
•Lucerne/Alfalfa
•Sainfoin?
•Foggage(standing hay)

Question 6

What is a source of energy that is used to produce muscular movement for all disciplines?

Answer 6

–adenosine triphosphate = ATP

–ATP is mostly generated from food

Question 7

what are the storage forms of energy?

Answer 7

•Feed is converted into storage forms of energy:
–Glycogen
–Glucose
–Free fatty acids

these are converted to ATP during exercise

Question 8

What are the three key energy sources?

Answer 8

1. Fermentable fibre
2. Fats and oils
3. Hydrolysable carbohydrates (starch and sugar)

Question 9

What are hydrolysable carbohydrates?

Answer 9

•Hydrolysable CHO
–Digested in the foregut
–Sugars & starches
–Create ↓ intestinal pH & risk of colic

Question 10

What is fermentable CHO’s?

Answer 10

•Fermentable CHO
–Digested in the hindgut
–Sugar beet, alfalfa or soya hulls
–↓ glycogen usage

Question 11

What is fat?

Answer 11

•Fat
–Digested in the foregut
–2-3x the energy concentration of CHO
–Creates higher energy feed

Question 12

What is protein?

Answer 12

•Protein (minimal usage)

–Digested in the foregut

Question 13

What does spring grass supply?

Answer 13

•Spring grass
–Some simple and some complex carbohydrates
–Will supply some anaerobic and some aerobic energy

Question 14

What does hay, haulage and other forages supply?

Answer 14

•Hay, Haylageand other forages
–Mainly complex carbohydrates
–Will supply mainly aerobic energy

Question 15

What is plant matter?

Answer 15

• Forage contains plant material which cannot easily be broken down by enzymes
• Fibre =complex carbohydrates
• Inside the cell are the starches, sugars, proteins and fats
• Starches and sugars = simple carbohydrates

Question 16

What are monosaccharides, disaccharides, polysaccharides?

Answer 16

• Monosaccharides -onesugar unit
• Disaccharides-twosugar units, Tri-threesugar units
• Polysaccharides -four or more monosaccharides joined together

Question 17

What are simple sugars?

Answer 17

•They are “simple” because they are single units of sugar that are easy to digest
•Therefore they are rapidly digested, quick sources of energy for the horse
•Include:
–Monosaccharides = one sugar
•E.g. glucose, fructose, mannose
–Disaccharides = two sugars joined
•E.g. sucrose = 1 glucose + 1 fructose
•And lactose = 1 glucose + 1 galactose

Question 18

What is the structure of fibre?

Answer 18

•Structural polysaccharide
•Helps a plant maintain it’s structure
•β-1,4 linkages cannot be broken down by enzymes like starch and sugars
–Require microbial degradation in the hind gut
–Produce smaller energy units = VFAs
•Propionic, Acetic, Butyric

Question 19

What is cellulose?

Answer 19

•Chain of polymerised glucose molecules held together by β-1,4 linkages
–cannot be broken down by enzymatic hydrolysis like starch and sugars
•Digested by bacteria in the hindgut depending on lignin quantity

Question 20

What is hemicellulose?

Answer 20

• Hemicellulose
• Short, branched polymer of various sugars
• Embedded in the cell walls of plants
• Help absorb and retain water in the hind gut

Question 21

What is pectin?

Answer 21

•Pectin binds hemicellulose with cellulose to form a network of cross-linked fibres

Question 22

What is lignin?

Answer 22

•Chemically complex
•Protects plant from both chemical and biological attack -indigestible
•Not a carbohydrate but is closely linked to cellulose and hemicellulose in maintaining mechanical structure of the plant
•Can be chemically treated
–NaOH(sodium hydroxide) or NH3(anhydrous ammonia)
–Break bonds between lignin and carbohydrate eg.Nutritionally Improved Straw (NIS)

Question 23

What is the difference between simple and complex carbohydrates?

Answer 23

SIMPLE:

• easily broken down
• Enzymatic breakdown
• starch and sugar
• quick release energy

COMPLEX:

• Resistant to enzymes
• Microbial fermentation
• fibres
• slow release energy

Question 24

What is fibre?

Answer 24

•Also known as
–structural carbohydrates
–structural polysaccharide
–non-starch polysaccharide
–fermentable fibres
•= cell wall components
–Cellulose
–Hemicellulose
•Resistant to enzyme degradation in the SI
•Undergo bacterial fermentation in hindgut

Question 25

What factors effect nutritional content?

Answer 25

•Stage of maturity when harvested will affect: –Nutrient content –Energy content –Digestibility –Palatability •Earlier cut forages will have better nutritional value for performance horses •Higher forage:concentrateration is possible when high quality (energy) forage is fed

Question 26

How does the time of year that the forage was cut effect the digestibility of forage?

Answer 26

* Related directly to time of year it is cut and weather conditions when it is cut * Early cut -less mature -more digestible * Late cut-more mature -less digestible

Question 27

How is forage digested?

Answer 27

``` Forage is fermented by the gut microflora of the horse •Consist of: –Bacteria –Protozoa –Fungi ```

Question 28

How is forage utilised during exercise?

Answer 28

* Volatile Fatty Acids (VFA’s) are utilised during aerobic exercise * The VFA ProprionicAcid (proprionate) is the most available of the three as an energy source for the horse * It is converted to liver glycogen * Roughage fed horses therefore produce enough glucose to maintain good levels of blood glucose

Question 29

How does feeding short fibre differ from feeding long fibre?

Answer 29

SHORT FIBRE •Fermentable fibres in the form of sugar beet pulp and soya hulls containing highly digestible fractions including pectins, arabinans and galactans, readily fermented by gut microflora (Geor, 2004) •These feeds have a higher digestibility (91%) than traditional fibre sources such as hay •Higher energy content “superfibres” (Crandell et al., 1999) •Combined with a higher fat content can provide 90% energy provided by a grain ration LONG FIBRE •Hay/Haylage/Grass •Essential for facilitating adequate chewing and occupying time

Question 30

What is the importance of forage?

Answer 30

•Minimum 1.5% BW DM/day •Promotes healthy digestive system –Helps maintain a healthy microbial population –Fibre passing though the tract can push through any excess gas that may have formed –Increases pH of hindgut compared to starch –Acts as a reservoir for fluid and electrolytes. •Contains valuable nutrients. •Promotes a healthy mind!

Question 31

What is the difference between hay and haylage?

Answer 31

``` HAY +Increased chew time +Can be soaked/steamed +Feed lessvolume/weight +Can be stored for long periods with little nutrient loss +Lower urinary N (drier bedding?) -Low moisture -content=dust/mould spores -Storage needs to be undercover (travelling?) -Needs to be stored in dry conditions? ``` ``` HAYLAGE +More palatable +Practical choice for travelling etc +Easy storage +Higher moisture content +Potentially lower WSC? -Deteriorates when opened ```

Question 32

How do we know what the quality of our hay or haylage is like?

Answer 32

–Manual –Chemical Analysis –Representative sample

Question 33

How can we reduce respirable particles from forage?

Answer 33

•Steaming –Purpose made steamer KEY!! –Provides the greatest increase in hygienic quality •Soaking –10-30 minutes required to significantly reduce dust and mould particles

Question 34

How can we reduce WSC content from forage?

Answer 34

``` •For significant reduction recommended to soak for between 3 and 16 hours. •Especially useful in the absence of analysis •Practice variable in outcome Considerations: –Leached vitamins and minerals! –Bacterial proliferation? –High labour requirement –Steaming as well? –Palatability? Waste? ```

Question 35

How can we extend chew time when feeding forage?

Answer 35

* Absolute minimum 1.5%BW forage * Small holed/double/triple netting * Hay balls/Slow feeders * Compressed hay blocks * Physically stagger feeding * Choice of forage –Straw? * Placement of forage * Musculoskeletal considerations?

Question 36

How can you restrict horses intake?

Answer 36

``` •Grazing muzzles •Physically restricting grazing time –i.e. stabling •Bare paddock and conserved forage •Overall picture essential! –Beware of compensatory grazing! ```

Question 37

How would a forage only diet effect performance horses?

Answer 37

* Water intake higher on forage only diet (even though forage was higher quality) * BW higher on forage only * Plasma lactate recovery lower in those on forage only * No difference HR/Resprate/Rectal Temp * Muscle glycogen lower for before and after exercise for forage only diet in comparison to mixed. * Forage with higher protein gives better glycogen? Implications?

Question 38

Could horses have a sugar free diet?

Answer 38

•Horses evolved to utilise sugar as energy source •Undoubtedly some that require a low sugar diet •Sugar free diet impossible to achieve •Best we can do? –Minimise sugar intake from forage –Sugar contributions –context of the whole diet

Question 39

Why is forage essential in the horses diet?

Answer 39

•Forage is an essential part of the diet of the horse –To maintain gut health –Energy needs –Fulfil the horse’s essential need to chew –Should form the basis of any horse’s diet •Forage is often neglected for its role as a nutrient and energy source and poorly utilised in the UK