Equine nutrition Flashcards
If in ruminants the hydrolysis of organic matter takes place mainly in the rumen then in horses it takes place in
the stomach and in the hindgut
The part of the digestive tract that is most important in digestion depends on
the ration / type of feed
If a horse’s ration is concentrate-rich the hydrolysis of organic matter takes place mainly in
the stomach, if hay-rich then in the hind gut.
How long do horses spend eating if allowed to graze freely?
Usually, when horses are grazed, they spend 16-17 hours per day for eating.
Biggest difference between ruminants and odd-toed ungulates is that
– 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
In horse nutrition, carbohydrates can also be divided into two parts
– hydrolysable (digested by endogenous enzymes)
– fermentable (digested by microbial enzymes)
examples of hydrolysable carbs (3+)
disaccharides,
some oligosaccharides (e.g. maltodextrin)
and starch (amylose, amylopectin)
examples of fermentable carbs (3+)
cellulose, hemicellulose
and some oligosaccharides (fructans, galactans etc.)
an abundance of fructans can cause
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
Generally, starch digestion in horses is similar to that in
monogastric animals (like pigs)
Starch digestion takes place mainly where with what
in the small intestine where the enzyme α-amylase enters and acts with pancreatic juice
α-amylase hydrolyses what exactly?
amylose α-1,4 glycosidic bonds,
but not the C-skeleton terminal α-1,6 glycosidic bonds (until only disaccharides are left)
Small intestine enzyme isomaltase hydrolyses what exactly?
α-1,6 glycosidic bonds
The final digestion of starch takes place where by what
in the small intestine by disaccharide enzymes (maltase, sucrase, lactase) which are produced in the small intestine
The activity of lactase is remarkably high not only in foals but also in
adults, and therefore the grown up horses can easily digest lactose
What is the first thing we need to take into account In the case of a starch-rich ration
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.
What is the max percentage of concentrates you can feed
No more than 0.2% (max 0.4%) concentrates of body weight per feeding time,
e.g. 1kg for a 500kg horse
Due to the morphology of the horse GI tract, microbial fermentation of a starch-rich ration already begins in the
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.
Are there lactic acid utilising bacteria or lactic acid producers or both in the equine stomach?
There is no lactic acid utilising bacteria in the horse stomach -> are only producers.
What compound is a major cause of gastric ulcers?
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.
Horses use feed protein less effectively compared to
ruminants
Horses also need much less protein in their rations. Less than even dry cows.
Why is hydrolysable protein important for covering a horses’ protein requirements?
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.
Horses, compared to cattle, are more sensitive to easily hydrolysable feed protein.
For example: when lucerne hay, rich in protein is fed, they..?
excrete most of the digested feed protein via urine when lucerne hay is fed
Excessively fed feed protein increases horses’ what (5)
– energy requirement
– water requirement
– sweating
– heart beat rate
- Reduces the speed endurance of racing horses
Problems occur when the fed protein requirement is exceeded by?
Problems occur when the protein requirement is exceeded by 20-30%.
Protein requirement of dressage and show-jumping horses is almost equal to
their maintenance protein requirement – 8% in DM is sufficient
Protein requirement for physically hard working horses is
10-12% – a lot of protein is excreted with sweat
To excrete urea produced from deaminated AA, horses need
a lot of liquids
For horses there are two essential FA, name them
– linoleic acid, C18:2, omega-6, (LA)
– α-linolenic acid, C18:3, omega-3, (ALA)
The content of ALA (α-linolenic acid) in a horse’s ration should be
0.5% in DM
The ratio of the essential FA-s (LA : ALA = linoleic acid : alfa-linolenic acid) should be in balance, recommended to be
10:1
so,
LA/linoleic acid 50 g and
ALA/alfa-linolenic acid 5 g in kg DM
Horses can obtain both LA & ALA)in the right proportions from
pasture grass
Cereals contain more linoleic acid so therefore for sport horses its recommended to feed e.g. an
alfa-linolenic acid-rich linseed oil, to ensure the proper proportion between these FA-s
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.
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.
In horses, biohydrogenisation of unsaturated fatty acids
does not take place, and therefore their reserve fat has very specific FA content.
Reserve energy sources (2)
triglycerides (muscle, adipose tissue)
glycogen (muscle, liver)
Which energy substrate is fastest at energy release?
phosphocreatine
Phosphocreatine releases P quickly, which is added to ADP; substrate for oxidation is not needed
Which energy substrate is slowest at enery release?
fatty acids are 10 times slower than phosphocreatine in releaseng energy for use
Slow lipolysis, β-oxidation and mitochondrial oxidation
which energy substrate is roughly doubly fast as glucose/aerobic glycolysis, in releasing energy?
glycogen via anaerobic glycolysis is roughly doubly fast
Phosphorylation, glycose-1-phosphate produced without expenditure of ATP energy.
Horses has three different types of muscles
– I muscle fibres contract slowly
– IIA
– IIB
muscle fibres contract quickly in the latter two types
types I and IIA muscles have a great –?– and produce –?– relatively high amounts of energy
types I and IIA muscles have a great oxidation ability and produce aerobically relatively high
amounts of energy
type IIB muscles have a low –?– and mainly use –?– produced energy (through glycolysis)
type IIB muscles have a low oxidation ability and mainly use anaerobically produced energy (through glycolysis)
All muscles store glycogen.
I and IIA type muscles can also store
a relatively high amount of triglycerides.
which could be combusted due to oxidation ability
the Arabian horse, whose body contains a relatively high amount of what muscle type
type I muscles
muscle fibres contract slowly, endurance
The idea behind feeding mainly starch-rich cereals 4-5 hours before competition is
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.
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?
Important to balance Na–K–Cl ->
proportionally -> 8-30-30
3 points about Gastric ulcers in horses
- 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
3 points about acidosis in horses
- 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
Normal pH in the hind-gut is
6.4-6.7, but when starch is overfed the pH can drop to 6.0
subclinical acidosis occurs, accompanied by (4)
osmotic diarrhoea,
proliferation of undesirable bacteria and lysis of desirable bacteria,
endotoxaemia and
increased incidence of laminitis
Laminitis aetiology
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)
why do metabolic disorders cause laminitis
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.
The reason for Acidosis -> Laminitis in grazing horses is connected to
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
Equine metabolic syndrome (EMS)
EMS is an endocrine condition that affects the body in three ways: obesity and/or localized fat deposits, insulin dysregulation, and laminitis.
Because of obesity other problems also may appear in association with equine metabolic syndrome. Such as (4)
infertility,
reduced function of the ovaries,
increase of leptin and triglycerides in blood serum,
and increase in blood pressure
Equine rhabdomyolysis syndrome (ER) may also be called (4)
Monday morning disease,
Tying-up,
Azoturia,
Myoglobinuria
Equine rhabdomyolysis syndrome (ER) is connected with (5)
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
Horses eat during grazing…?
A. A little at a time, but often
B. a lot at a time, but less often
A. A little at a time, but often
Of the endogenous enzymes, the horse has the lowest activity for…
A. α-amylase
B. isomaltase
C. sucrase
D. lactase
A. α-amylase
In the horse stomach live only …
A. Lactic acid utilising bacteria
B. Lactic acid producing bacteria
B. Lactic acid producing bacteria
In what part of the digestive tract can digested protein be used by the horse?
A. Stomach
B. Small intestine
C. Large intestine
B. Small intestine
Horses develop health problems when the dietary protein requirement is exceeded by…
A. 10 -20%
B. 20-30 %
C. 30-40 %
D. 40-50 %
B. 20-30 %
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 %
C. 20 %
From which energy source is ATP energy obtained the fastest?
A. Fatty acids
B. Glycogen
C. Glucose
D. Phosphocreatine
D. Phosphocreatine
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
B. 0.5 kg
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
D. Na, K, Cl and Mg
max how much starch can you feed a horse in a day?
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
what causes laminitis in fresh frazed horses?
fructans in fresh, young grasses
can cause hindgut acidosis via lactic acid production
