Lecture 5 Flashcards
What is meant by the term dietary fibre?
Refers to carbohydrate polymers that are not able to be digested in the small intestine but can undergo complete or partial digestion within the large intestine.
Where is dietary fibre generally found?
Within the plant walls
What are the main components of dietary fibre?
- Non-starch polysaccharides (NSP)
- Resitant starch
- Lignin
- Small quantities of insoluble proteins, fatty acids, waxes
What are the two different types of non-starch polysaccharides?
Soluble NSP and insoluble NSP
What are the major effects of soluble non-starch-polysaccharides?
- decrease digestibility (of all nutrients across the diet)
- decrease nutrient absorption
- increase transit time
- increase growth of pathogenic bacteria
- from viscous gels
What is the effect of insoluble non-starch polysaccharides?
- decrease the transit time
- increase water holding capacity
- increase faecal bulk
Where are non-starch polysaccharides fermented?
Non-starch polysaccharides are fermented in the hindgut
What is benefit of resistant starch?
Escapes digestion in small intestine and is then fermented in the large intestine. It provides a susbtrate for “good bacteria” and “butyrate for colonocytes”.
What are the types of resistant starch?
- starch physically inaccesible to enzymes (e.g. inside intact cells)
- B-type starch granules (e.g. uncooked potatoes)
- Retrograde amylose in processed food
- Chemically modified starch
What are the limitations of the crude fibre measure?
- Least accurately determined component
- Variable availability for energy
- Better measures of fibre are available
What is the benefit of using a van soest analysis?
Better describes energy contribution from carbohyrdrates and nutritative value of high fibre feeds for herbivors.
Name the following blanks on the diagram below:
- Cell contents
- Cell wall
- Neutral Detergent Fibre (NDF)
- Acid Detergent Fibre (ADF)
- Neutral Detergent Solubles (NDF)
- Acid detergent solubles (ADS)
Label the blanks of the diagram below:
- Neural Detergent Solubles (NDS)
- Neural Detergent Fibre (NDF)
- ADF
Complete the table below:
What does a high acid detergent fibre value mean?
High ADF = Low digestibility = Low energy
What does a high NDF value mean?
A high NDF means lower intake
What does WSC mean?
Water soluble carbohydrates
What does NSC stand for?
Non-structural carbohydrates
What does NFC stand for?
Non-fibre carbohydrates
Fill in the table below:
What are the benefits of a moderate fibre inclusion for dogs?
- Few effects on nutrient availability
- VFA for the colon
- Good stool quality
- Cheaper ingredients = lower costs
What are the problems associated with a high fibre inclusion?
- Reduced nutrient digestibility and vitamin availability
- Gas production
- Poorer stool quality
- Increased frequency of defecation
What is the effect of the addition of exogenous food enzymes added to the diet?
- Enzymes not found in the intestinal tract
- Partially break down dietary fibre molecules
- Reduce viscosity
- Improve nutrient availability
- Facilitate the use of cheaper ingredients
How does the stage of maturity affect the digestiblity, energy and protein content of forages?
Increasing maturity means declining digestibility, energy and protein of roughages.
