Dietary fibre
crude
fibre
cellulose*
NSP
hemicellulose*
lignin
hemicellulose
cellulose
dietary
fibre
cellulose
NDF
hemicellulose
lignin
hemicellulose
lignin
lignin
pektin
pektin
β-glucan
β-glucan
arabinoxyl arabinoxyl
an
an
* = not the total content
ADF
ADL
cellulose cellulose
lignin
Cellulose
• cell wall structure (10-15 thousand
glucose units)
• does not soluble in water
• higher animals and humans can’t
digest
• bacteria in the rumen and large
intestine produce cellulase enzyme
The structure of starch and
cellulose
starch
cellulose
Hemicelluloses
• closely associated with cellulose
• can bind water
• not homogenous structure
(glucose, galactose, mannose,
xylose, arabinose polymers)
• can metabolise only bacteria
Pectic subtances
• the first compound of primary cell
walls
• the linear chain of galacturonic acid
• good water absorbing capacity
• soluble in hot water, but animals can
not digest
• contains considerable gelling
properties (jam making)
Lignin
• is not a well defined compound
• alcohol polymer
• high résistance to chemical
degradation
• binding to cell wall polysaccharides,
mostly cellulose
• wood products and straw are rich
• do not solve in water
• from nutritional point of view has a
negative effect
Other fibre compounds
• -glucan, arabinoxylan (wheat, barley, rye, oats)
– anti-nutritive effect
– increasing the viscosity of the digesta
– decrease the digestibility of nutrients
– sticky droppings, Salmonella contamination of
eggs
• chitin
– a linear polymer of glucose amine, containing insects,
fungi, and green algae
• exudate gums
– produces from wounds of plants, contains arabinose,
galactose, glucuronic acid
The effect of fibre in the nutrition of
ruminants
• chewing, rumination, producing saliva,
rumen contraction
• structural fibre (min. 75% of crude fibre)
• only microbes in the digestive tract
produce digestive enzymes (cellulase,
hemicellulase etc.)
• energy source, precursor of volatile fatty
acids
• has an influence on the time of rumen
fermentation, the transport time of chyme
in the intestine
Rumen degradation of dietary
carbohydrates
hemicellulose
cellulose
pectin
starch
sucrose
lactose
CH3
C=O
COOH
pyruvate
acetate
propionate
butyrate
The effect of fibre in the nutrition of
monogastric animals
• bacterial degradation only in the caecum and
large intestine (horse, rabbits)
• peristaltic movement of the intestine
horse > rabbit > pig > poultry
12-20%
10-14% 3-8%
3-6%
• young animals need less
• high fibre decrease the digestibility of the other
nutrients
• increase endogenous losses
• chyme transport time decrease
• high fibre means less concentrated food
• satiety feeling
Symptoms of fibre
deficiency
•
•
•
•
rumen function disturbances
constipation
anorexy
oesophageal and stomach ulcers
Crude fibre content of some feedstuffs (%)
alfalfa
corn silage
6,9
12,9
hay (good quality)
barley straw
barley
25,8
35,6
4,9
wheat
corn grain
full fat soybean
extracted soybean meal
2,6
2,6
6,9
13,5
sugar beet
potato
pumpkin
1,2
0,7
0,8
Fibre requirement of different animal species (%)
young pigs (10-20 kg)
2,5
older pigs (70-110 kg)
3,5
broiler chick (0-3 hét)
2-3
broiler chick (5-6 hét)
3-4
laying hen
5
horse
12-16
rebbit
11-12
milking cow
17-23
Effect of dietary fibre in the human
nutrition
• requirement: 30-40 g/day
• consumption: 15-25 g/day
Consequences of fibre deficiency :
• large bowel problems, diseases
(constipation, diverticuloses,
colon or rectal cancer)
• metabolic disorders (obesity,
diabetes high blood lipid
parameters)