crude fibre

NSP dietary fibre

NDF ADF ADL

cellulose* cellulose cellulose cellulose cellulose

hemicel-lulose*

hemicel-lulose

hemicel-lulose

hemicel-lulose

lignin lignin lignin lignin lignin

pektin pektin

β-glucan β-glucan

arabinoxylan

arabinoxylan

* = not the total content

Dietary fibre

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 CH3

cellulose C=O

pectin COOH acetatestarch pyruvate propionatesucrose butyratelactose

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 > poultry12-20% 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 6,9corn silage 12,9hay (good quality) 25,8barley straw 35,6barley 4,9wheat 2,6corn grain 2,6full fat soybean 6,9extracted soybean meal 13,5sugar beet 1,2potato 0,7pumpkin 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)