Animal nutrition - carbohydrates Flashcards
Percentage of Energy contribution from carbohydrates in farm animal nutrition is
70…80%
what fractions of DM are carbohydrates?
crude fibre
▪ plant cell wall substances
(not all of crude fiber is carbs though)
nitrogen-free extracts
▪ starch, sugars etc.
Classification according to van Soest system:
– Neutral detergent fibre (NDF)
– Acid detergent fibre (ADF)
name 3 Neutral detergent fibre (NDF) compounds
▪ Hemicellulose + Cellulose + Lignin
name 2 Acid detergent fibre (ADF) compounds
▪ Cellulose + Lignin
Classification of carbs in pig feeding and in human nutrition:
– mono- and disaccharides
– starch containing polysaccharides
– starch not containing polysaccharides → ration fibre
This distribution arises because monogastric animals can digest only starch (α-1,4 and α-1,6 glycosidic bond) of the polysaccharides.
Starch not containing polysaccharides contain different β-glycosidic bonds, which are not digestible due to lack of endogenous enzymes.
Classification of carbs in ruminant feeding:
– structural carbohydrates -> effective fibre
– non-structural carbohydrates
what are structural carbohydrates
▪ plant cell wall substances (cellulose, hemicellulose, lignin, but not pectin), most are hydrolysed by bacterial enzymes and ensure the necessary rumen environment (lignin is not)
what are non-structural carbohydrates
▪ mono- and disaccharides, starch
In nature, the most common Monosaccharides are (3)
– trioses – organism metabolism intermediates, amount in feeds is low (glycerol and
dihydroxyacetone)
– pentoses - arabinose, xylose, ribose
– hexoses - glucose, fructose, galactose, mannose
Monosaccharides chemically contain how many C atoms?
3, 4, 5, 6 or 7 C atoms
the main component of plant polysaccharides
the pentose arabinose
the main monosaccharide in hemicellulose
the pentose xylose
the pentose ribose is found in (3)
RNA, coenzymes, B12
monosaccharide Hexoses include (4)
– glucose
– fructose
- galactose
- mannose
– glucose also known as (2)
▪ grape sugar or blood sugar
▪ di- and polysaccharides, glycogen
– fructose also known as (1)
▪ fruit sugar, sweetest CH
– galactose found in
▪ in the composition of lactose
– mannose found in (1)
▪ component of glycoproteins
Disaccharides are formed when two monosaccharides are bound together (dehydration reaction), which leads to the loss of H2O and formation of a
glycosidic bond (α or β)
An alpha-glycosidic bond is formed when both carbons have the same stereochemistry, whereas a beta-glycosidic bond occurs when the two carbons have different stereochemistry.
Humans lack digestive enzymes capable of hydrolyzing most β-glycosidic bonds, which explains why amylose, a glucose polymer with α-1,4 glycosidic bonds, is digestible by human enzymes, while cellulose, a glucose polymer with β-1,4 glycosidic bonds, is indigestible.
what breaks a glycosidic bond and leads to
hydrolysis breaks the glycosidic bond and H2O is incorporated
Sucrose is
a Disaccharide composed of glucose + fructose, found in
– table/cane/beet sugar
– vegetative parts of plants
– sugar beet, fodder sugar beet
Lactose is
a Disaccharide composed of glucose + galactose, found in
– milk sugar, milk-based feeds
Maltose is
a Disaccharide called malt sugar,
composed of glucose + glucose,
is a starch hydrolysis product
found in
– more in germinating grains
how to tell a (α from β) glycosidic bond
1,4 alpha glycosidic bonds are formed when the OH on the carbon-1 is below the glucose ring; while 1,4 beta glycosidic bonds are formed when the OH is above the plane.
“Alpha linkage has the oxygen (on the aldehyde or ketone) below the ring and the beta has it above the ring. “
Oligosaccharides contain
3…10 monosaccharide residues
Which Oligosaccharides are common In feeds (3)
– raffinose – galactose + glucose + fructose
– stachyose – 2 x galactose + glucose + fructose
– verbascose – 3 x galactose + glucose + fructose
(the disaccharide sucrose is composed of glucose and fructose so all of these technically contain sucrose)
Oligosaccharides are found in (4)
plant seeds such as beans, peas, but also in sunflower seeds and in sugar beet
Oligosaccharides are not degraded by endogenous enzymes, but by
bacterial enzymes
MOS
Mannan-oligosaccharides are glycoproteins, which are used instead of antibiotics, increases the number of beneficial bacteria in the intestine so, prebiotics composed of complex carbohydrate molecules.
Produced from the cell wall of the yeast Saccharomyces cerevisiae.
▪ for example, by adding MOS into the ration of monogastric animals the pathogens (E.coli, Salmonella) do not attach to intestinal epithelial glycoproteins, but to the MOS
▪ as oligosaccharides not digested in the digestive tract of monogastric animals, the MOS is excreted with pathogens
Polysaccharides consist of
numerous monosaccharide residues -> could be thousands in one molecule
Polysaccharides in plants are mostly what type
mostly 6-carbon hexoses (glucose -> starch, cellulose),
but there are also pentoses, which are called pentosans
high concentrations of pentosans are found in
– barley, oats, wheat
(together with β-glucans, cause sticky faeces and hygienic problems in chickens)
– woody plants (grasses, legumes) and husks, wheat bran, cotton seeds
Pentosans are not degraded by
endogenous enzymes (β-glycosidic bonds that cannot be broken by mammals lacking the correct enzyme)
Starch is the main polysaccharide in
– cereals
(maize 70%, wheat 67%, rye 64%, barley 60%, oats 46%)
and potatoes 72%
Starch is the main energy source in the rations of
pigs and poultry
Starch consists of many molecules of
glucose
according to the chain structure of starch, it can be divided into:
– amylose - linear chain, α-1,4 glycosidic bond
– amylopectin – branched chain, α-1,6 glycosidic bond
In regard to starch - Rumen bacteria can only degrade
amylose and only the linear part of amylopectin (α-1,4),
the rest of the amylopectin (α-1,6) is digested in the small intestine
degradability in the rumen depends on the structure of the endosperm and on the number of α-1,6 glycosidic bonds
this is why barley, wheat and rye starch degrade faster (~3-5 h) versus maize and potato starch which degrades slower (~20 h)
In monogastric animals (pigs) starch is digested and absorbed at %?
90…100% (in cereals over 96%)
“animal starch”
Glycogen
is chemically similar to amylopectin, containing α-1,4 and α-1,6 glycosidic bonds
is only in animal-origin feeds so is therefore important only in feeding of
carnivores
Cellulose is the
most common polysaccharide in nature
is an important structural component of the cell wall
Mammalian endogenous enzymes do not digest cellulose!
Cellulose is linear, consisting of ?,
which are linked to each other by
glucose (up to 10,000), which are linked to each other by β-1,4-glycoside bonds
Hemicelluloses are relatively short, containing
50…2,000 monomer residues, which are linked by β-1,4 glycosidic bonds
the monomers that hemicellulose consists of are arabinose, mannose, galactose, glucose, and xylose.
have a branched chain
– penetrate the cell wall between cellulose and gives even
more strength to the plant due to the branched structure
name 3 Hemicelluloses
– xylans -> mainly found in wheat, rye, barley
– xyloglucans -> are found in grasses, cereals (50% hemicellulose)
– galactomannans -> are found in leguminous plants
Hemicelluloses are not digested by
endogenous enzymes, but are digested by bacteria (hydrolysis reaction) more
easily compared to cellulose (because smaller molecule)
Lignins are
derivatives of phenylpropane.
are not saccharides.
are in plant cells and cross-linked with cellulose and hemicellulose.
are completely indigestible, and also hinder the digestion of cellulose and hemicellulose.
Lignins are in plant cells and cross-linked with
cellulose and hemicellulose.
*There are two types of lignin:
guaiacyl and syringyl
Pectins are
plant polysaccharides, which are included in plant cell wall substances.
are not structural.
Pectins are not digested by
endogenous enzymes (β-1,4 glycosidic bonds), but are easily soluble and due do this digestible.
Legumes contain more what than grasses
lignin
Glycosinolates are found in …
C. rape seeds
The effects of cyanogenetic and mustard oil glycosides can be reduced in plants by …
A. heating
The effect of tannins on animals is …
A. negative
B. positive
C. both negative and positive
D. does not affect at all
C. both negative and positive
The effect of phytin on animals’ health is …
A. negative
B. positive
C. both negative and positive
D. does not affect at all
D. does not affect at all
just remains undigested
Lignin …
A. digests fast
B. digests at a medium speed
C. digests slowly
D. doesn’t digest at all
D. doesn’t digest at all
Starch content is highest in …
A. grass silage
B. maize silage
C. cereals
D. protein feeds
C. cereals
Endogenous enzymes that hydrolyse starch…
A. а-amylase
B. maltase
C. isomaltase
D. all named enzymes
D. all named enzymes
Di- and oligosaccharides are digested by endogenous enzymes?
A. Yes
B. No
B. No
degraded by bacterial enzymes!
• … decrease the nutritional value of feeds, are used as prebiotics in monagastrics (human, animal)
Micro-organisms hydrolyse…
A. а-1,4 glycosidic bonds
B. а-1,6 glycosidic bonds
C. both -1,4 and а-1,6 glycosidic bonds
A. а-1,4 glycosidic bonds
they do not possess isomaltase
Pectin content is higher in …
A. graminaceous plants
B. leguminous plants
B. leguminous plants
Lignin content is higher in …
A. graminaceous plants
B. leguminous plants
B. leguminous plants
Cellulose has a …
A. long and linear chain
B. short and branched chain
A. long and linear chain
What does starch consist of?
Starch normally contains about 20–30% amylose and 70–80% amylopectin.
Amylopectin is a water-insoluble polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose.
what is maltose
Maltose is a disaccharide which consists of two glucose units joined by glycosidic bonds.
In starch, the glucose monomers are linked by a glycosidic bond.
Amylopectin is a water-insoluble polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose.
Starch is a polysaccharide which smallest units are glucose.
Starch normally contains about 20–30% amylose and 70–80% amylopectin.
