Equine nutrition

Question 1

If in ruminants the hydrolysis of organic matter takes place mainly in the rumen then in horses it takes place in

Answer 1

the stomach and in the hindgut

Question 2

The part of the digestive tract that is most important in digestion depends on

Answer 2

the ration / type of feed

Question 3

If a horse’s ration is concentrate-rich the hydrolysis of organic matter takes place mainly in

Answer 3

the stomach, if hay-rich then in the hind gut.

Question 4

How long do horses spend eating if allowed to graze freely?

Answer 4

Usually, when horses are grazed, they spend 16-17 hours per day for eating.

Question 5

Biggest difference between ruminants and odd-toed ungulates is that

Answer 5

– in ruminants the hydrolysis of nutrients first takes place by microbial fermentation and secondly by endogenous enzymes

– in odd-toed ungulates this is vice versa, first endogenous enzymes act and then microbial fermentation takes place

Question 6

In horse nutrition, carbohydrates can also be divided into two parts

Answer 6

– hydrolysable (digested by endogenous enzymes)

– fermentable (digested by microbial enzymes)

Question 7

examples of hydrolysable carbs (3+)

Answer 7

disaccharides,
some oligosaccharides (e.g. maltodextrin)
and starch (amylose, amylopectin)

Question 8

examples of fermentable carbs (3+)

Answer 8

cellulose, hemicellulose
and some oligosaccharides (fructans, galactans etc.)

Question 9

an abundance of fructans can cause

Answer 9

issues in fermentation in the hindgut so,

need to be limited

hindgut acidosis, laminitis etc.

e.g. pasture-associated laminitis from lush young grasses containing fructans

Question 10

Generally, starch digestion in horses is similar to that in

Answer 10

monogastric animals (like pigs)

Question 11

Starch digestion takes place mainly where with what

Answer 11

in the small intestine where the enzyme α-amylase enters and acts with pancreatic juice

Question 12

α-amylase hydrolyses what exactly?

Answer 12

amylose α-1,4 glycosidic bonds,

but not the C-skeleton terminal α-1,6 glycosidic bonds (until only disaccharides are left)

Question 13

Small intestine enzyme isomaltase hydrolyses what exactly?

Answer 13

α-1,6 glycosidic bonds

Question 14

The final digestion of starch takes place where by what

Answer 14

in the small intestine by disaccharide enzymes (maltase, sucrase, lactase) which are produced in the small intestine

Question 15

The activity of lactase is remarkably high not only in foals but also in

Answer 15

adults, and therefore the grown up horses can easily digest lactose

Question 16

What is the first thing we need to take into account In the case of a starch-rich ration

Answer 16

The amount and activity of the produced α-amylase is limited, and the chyme passage rate in the digestive tract is high.

NB! Starch can remain partly undigested in the small intestine and enter to the hind gut, where active microbial fermentation takes place, which may cause acidosis.

Question 17

What is the max percentage of concentrates you can feed

Answer 17

No more than 0.2% (max 0.4%) concentrates of body weight per feeding time,
e.g. 1kg for a 500kg horse

Question 18

Due to the morphology of the horse GI tract, microbial fermentation of a starch-rich ration already begins in the

Answer 18

Due to the morphology of the horse stomach, some fermentation occurs in the highest part of the stomach.

The uppermost portion of the stomach is nonglandular.

Question 19

Are there lactic acid utilising bacteria or lactic acid producers or both in the equine stomach?

Answer 19

There is no lactic acid utilising bacteria in the horse stomach -> are only producers.

Question 20

What compound is a major cause of gastric ulcers?

Answer 20

Lactic acid is absorbed with great difficulty, and therefore, together with stomach HCl, it
destroys the mucosa cells of the stomach non-glandular region, which leads to gastric
ulcers.

Question 21

Horses use feed protein less effectively compared to

Answer 21

ruminants

Horses also need much less protein in their rations. Less than even dry cows.

Question 22

Why is hydrolysable protein important for covering a horses’ protein requirements?

Answer 22

Although, in horses, effective carbohydrate fermentation and microbial protein synthesis occurs in the hind gut, the horse cannot use the produced microbial protein.

Feed fermentation also occurs to some extent in the stomach, in which case it is possible that some of the microbial cell protein can be digested, but this is negligible in feeding practice.

Therefore hydrolysable protein is important to cover horses’ protein requirements.

Question 23

Horses, compared to cattle, are more sensitive to easily hydrolysable feed protein.
For example: when lucerne hay, rich in protein is fed, they..?

Answer 23

excrete most of the digested feed protein via urine when lucerne hay is fed

Question 24

Excessively fed feed protein increases horses’ what (5)

Answer 24

– energy requirement
– water requirement
– sweating
– heart beat rate
- Reduces the speed endurance of racing horses

Question 25

Problems occur when the fed protein requirement is exceeded by?

Answer 25

Problems occur when the protein requirement is exceeded by 20-30%.

Question 26

Protein requirement of dressage and show-jumping horses is almost equal to

Answer 26

their maintenance protein requirement – 8% in DM is sufficient

Question 27

Protein requirement for physically hard working horses is

Answer 27

10-12% – a lot of protein is excreted with sweat

Question 28

To excrete urea produced from deaminated AA, horses need

Answer 28

a lot of liquids

Question 29

For horses there are two essential FA, name them

Answer 29

– linoleic acid, C18:2, omega-6, (LA) – α-linolenic acid, C18:3, omega-3, (ALA)

Question 30

The content of ALA (α-linolenic acid) in a horse’s ration should be

Answer 30

0.5% in DM

Question 31

The ratio of the essential FA-s (LA : ALA = linoleic acid : alfa-linolenic acid) should be in balance, recommended to be

Answer 31

10:1 so, LA/linoleic acid 50 g and ALA/alfa-linolenic acid 5 g in kg DM

Question 32

Horses can obtain both LA & ALA)in the right proportions from

Answer 32

pasture grass

Question 33

Cereals contain more linoleic acid so therefore for sport horses its recommended to feed e.g. an

Answer 33

alfa-linolenic acid-rich linseed oil, to ensure the proper proportion between these FA-s

Question 34

Horses rations contain on average ?% lipids, but if we train them to consume more lipids, we can feed lipids up to ?% – feeding more lipids stimulates secretion of bile.

Answer 34

Horses rations contain on average 3-5% lipids, but if we train them to consume more lipids, we can feed lipids up to 20% – feeding more lipids stimulates secretion of bile.

Question 35

In horses, biohydrogenisation of unsaturated fatty acids

Answer 35

does not take place, and therefore their reserve fat has very specific FA content.

Question 36

Reserve energy sources (2)

Answer 36

triglycerides (muscle, adipose tissue) glycogen (muscle, liver)

Question 37

Which energy substrate is fastest at energy release?

Answer 37

phosphocreatine Phosphocreatine releases P quickly, which is added to ADP; substrate for oxidation is not needed

Question 38

Which energy substrate is slowest at enery release?

Answer 38

fatty acids are 10 times slower than phosphocreatine in releaseng energy for use Slow lipolysis, β-oxidation and mitochondrial oxidation

Question 39

which energy substrate is roughly doubly fast as glucose/aerobic glycolysis, in releasing energy?

Answer 39

glycogen via anaerobic glycolysis is roughly doubly fast Phosphorylation, glycose-1-phosphate produced without expenditure of ATP energy.

Question 40

Horses has three different types of muscles

Answer 40

– I muscle fibres contract slowly – IIA – IIB muscle fibres contract quickly in the latter two types

Question 41

types I and IIA muscles have a great --?-- and produce --?-- relatively high amounts of energy

Answer 41

types I and IIA muscles have a great oxidation ability and produce aerobically relatively high amounts of energy

Question 42

type IIB muscles have a low --?-- and mainly use --?-- produced energy (through glycolysis)

Answer 42

type IIB muscles have a low oxidation ability and mainly use anaerobically produced energy (through glycolysis)

Question 43

All muscles store glycogen. I and IIA type muscles can also store

Answer 43

a relatively high amount of triglycerides. which could be combusted due to oxidation ability

Question 44

the Arabian horse, whose body contains a relatively high amount of what muscle type

Answer 44

type I muscles muscle fibres contract slowly, endurance

Question 45

The idea behind feeding mainly starch-rich cereals 4-5 hours before competition is

Answer 45

to "charge" the horse with available glycogen Also Avoid excessive protein and restrict hay feeding. Digestion of hay produces a lot of heat, causes sweating and large loss of electrolytes. Hay is digested slowly and fills the digestive tract. Before competition, 0.5 kg of hay is recommended to avoid gastric ulcers.

Question 46

It is very important to restore the content of electrolytes lost by sweat and urine during competition and training (physical load). What proportions of what electrolytes are most important?

Answer 46

Important to balance Na–K–Cl -> proportionally -> 8-30-30

Question 47

3 points about Gastric ulcers in horses

Answer 47

* Mainly a sports horse disease (90-100% prevalence) * A roughage-rich ration protects the non-glandular part of the stomach wall against acid attack, but the concentrate-rich ration doesn’t * If horses ar active the abdominal muscles will tighten and press the stomach acids from the glandular part to non-glandular part of the stomach and cause ulcers

Question 48

3 points about acidosis in horses

Answer 48

* is caused when easily digestible carbohydrates, mainly starch, are overfed to horses * If more starch is fed to horses than the endogenous enzymes can hydrolyse in the small intestine then the undigested starch passes to the hind-gut and microbial fermentation of the starch takes place * acidosis occurs if the accumulation of lactic acid in the hind-gut exceeds the buffering capacity, after which the pH will fall

Question 49

Normal pH in the hind-gut is

Answer 49

6.4-6.7, but when starch is overfed the pH can drop to 6.0

Question 50

subclinical acidosis occurs, accompanied by (4)

Answer 50

osmotic diarrhoea, proliferation of undesirable bacteria and lysis of desirable bacteria, endotoxaemia and increased incidence of laminitis

Question 51

Laminitis aetiology

Answer 51

aetiology is very variable and therefore there are different types of laminitis, which can be caused by – toxicity – metabolic disorders – overload (mostly a heavy draft horse problem)

Question 52

why do metabolic disorders cause laminitis

Answer 52

feed sugars consumed by bacteria in the hind-gut lactic acid produced pH reduced endotoxins released as cellulolytic bacteria begin to die due to low pH inflammation in hindgut hindgut endothelium damaged bacterial endotoxins enter the blood stream toxins reach the hooves and induce laminitis circulatory system for the hooves contribute to their sensitivity; few and narrow vessels.

Question 53

The reason for Acidosis -> Laminitis in grazing horses is connected to

Answer 53

high fructans content in grasses fructans are not hydrolysed in the small intestine, but degraded by bacteria in the hind-gut sugars consumed by bacteria lactic acid produced pH reduced endotoxins released as cellulolytic bacteria begin to die inflammation in hindgut hindgut endothelium damaged bacterial endotoxins can enter the blood stream toxins reach the hooves and induce laminitis circulatory system for the hooves contribute to their sensitivity; few and narrow vessels

Question 54

Equine metabolic syndrome (EMS)

Answer 54

EMS is an endocrine condition that affects the body in three ways: obesity and/or localized fat deposits, insulin dysregulation, and laminitis.

Question 55

Because of obesity other problems also may appear in association with equine metabolic syndrome. Such as (4)

Answer 55

infertility, reduced function of the ovaries, increase of leptin and triglycerides in blood serum, and increase in blood pressure

Question 56

Equine rhabdomyolysis syndrome (ER) may also be called (4)

Answer 56

Monday morning disease, Tying-up, Azoturia, Myoglobinuria

Question 57

Equine rhabdomyolysis syndrome (ER) is connected with (5)

Answer 57

overfeeding of non-structural carbohydrates; overloading of muscles and disorders of Ca metabolism in muscles; lack and imbalance of electrolytes (especially K); deficiency of Se and vitamin E; virus infection

Question 58

Horses eat during grazing...? A. A little at a time, but often B. a lot at a time, but less often

Answer 58

A. A little at a time, but often

Question 59

Of the endogenous enzymes, the horse has the lowest activity for... A. α-amylase B. isomaltase C. sucrase D. lactase

Answer 59

A. α-amylase

Question 60

In the horse stomach live only ... A. Lactic acid utilising bacteria B. Lactic acid producing bacteria

Answer 60

B. Lactic acid producing bacteria

Question 61

In what part of the digestive tract can digested protein be used by the horse? A. Stomach B. Small intestine C. Large intestine

Answer 61

B. Small intestine

Question 62

Horses develop health problems when the dietary protein requirement is exceeded by... A. 10 -20% B. 20-30 % C. 30-40 % D. 40-50 %

Answer 62

B. 20-30 %

Question 63

Despite the absence of a gallbladder, the feed ration for horses may contain lipids at up to... A. 5 % B. 10 % C. 20 % D. 30 %

Answer 63

C. 20 %

Question 64

From which energy source is ATP energy obtained the fastest? A. Fatty acids B. Glycogen C. Glucose D. Phosphocreatine

Answer 64

D. Phosphocreatine

Question 65

How much hay should be fed to the horse just before competition? A. not at all B. 0.5 kg C. 1.5 kg D. freely

Answer 65

B. 0.5 kg

Question 66

Which elements’ loss via urine and sweat should be covered in horses after competition or training? A. Na ja K B. K, Cl ja S C. Ca, P, Na and Mg D. Na, K, Cl and Mg

Answer 66

D. Na, K, Cl and Mg

Question 67

max how much starch can you feed a horse in a day?

Answer 67

max 4 kg/day only 1-2kg in one sitting big no-no to give lots of water with it, speeds up the rate of passage and it can end up in the hindgut and ferment

Question 68

what causes laminitis in fresh frazed horses?

Answer 68

fructans in fresh, young grasses can cause hindgut acidosis via lactic acid production