Effects of feed processing and carbohydrases on fibre degradatoin in pigs and poultry

Fibres contribute to nutritonal value of the diet

Direct and indirect, positive and negative

What is fibre

Non-digestible fraction of plant material

resistant starch RS, non-starch polysaccharides NSP, lignin

partly fermented by microbiota in the gastrointestinal tract

fibre is not fibre

diverse group of polymers

• non-starch polysaccharides

  • pectic polysaccharides

  • hemicellulose

  • cellulose

• resistant starch

• lignin

chemical composition doesn’t tell it all

• structural arrangements int he cell wall determine physicochemical properties

What fraction to consider in feed formulation

Commonly used gravimetric fibre analyses

• crude fibre - weende analyses

• neutral detergent fibre

• acid detergent fibre

• acid detergent ligning

→ van soest method

part of the fibre fraction not measured, depending on material

depeinding on physicochemical properties of the material

method determines ranking of ingredients

Particle size interferes with CF and NDF

Variation in fibre degradation

Chickens - soluble material

In chickens, NSP degradation generally low

Cell wall architecture limits nutrient degradation

Fibre degradability

• in pigs considerable

• In chickens generally low

  • minor role in energy supply

cell way may hamper digestibility of other nutrients

• 10 procent of total nitrogen (N) in common broiler diets contained NDF, 5%-29% lupins to sorghum

Fibre

Antinutritional effects

beneficial effects

Anti-nutritional effects

• increased digesta viscosity → reduced fat, starch, protien digestion

beneficial effects

• e.g. gastrointestinal tract development and function, gut microbiome, faeces/litter consistency, satiety

structure required for gizzard development and function

coarse diet

• thick muscular wall

• low ph

fine diet

• reduced size, weight, thickness of muscular wall

• impaired ph barrier, dilation of proventriculus, reduced retetion time, reduced grinding activity

Digesta matrix affects digestive processes

e..g transit behaviour, nutrient accesibility by enzymes, enzyme secretions, intestinal mucus secretions, epitheial cell proliferation, bacterial colonization and fermentation → digestibility and nutritional value

why modifying fibres using processing and enzyme technologie

improve fermentability of recalcitrant fibres

release nutrients encapsulated in cell wall

reduce anti-nutritioanl effects

exploit beneficial effects

mode of action of modifying fibres

processing technoloiges

• disruption cell wall matrix, depolymerization, breaking crosslinks

• chaning physicochemical properties: e.g. particle size, solubilituy, rheologicla properties, hydration properties

cell wall degrading enzymes

• specifically cleave polymers: depolymerization, remove side-chains

mechanical, thermal, chemical treatments

processing and enzymes to disrupt cell wall matrix

Can NSP fermentability be improved

Processing technologies

• common tehcnologies effective for easy NSP: +4-16 units

• not sufficient for more reclacitrant NSP as often present in agricultural by-products

• hydrothermal processes increase viscosity of cereals with high soluble NSP contents

enzymes

• mainly optimized for viscous cereal fibres, + 6-18% units

  • contradictory results: mismatching enzyme activities, side-activities, concentration

modifying fibre degradation suing enzymes

Best of both?

processing opens cell wall matrix, thus better accesibility by enzymes

processing may increase viscotiy, enzymes can counteract

enzymes after processing?

• viscosity: 3-4 fold decrease

  • ATTD NSP: effect 2-6 times greater in processed diets

Fiber structrers in rapeseed meal

Fermentation of NSP from RSM by broilers

Processing and enzyme technologies

How to modify NSP from rapeseed meal

enzymes increased NSP solubilisation

Solubilisation of fibre -. more fibre in ceca

wet-milling and enzymes increased NSP in ceca

But solibilzed does not mean degraded

enzymes increased NSP degradation

no enhanced degradation with wet-milling, despite reduced particle size and increased NSP in ceca

Apparently, solubilized NSP could not be degraded by cecal microbiota

Fibre doest not equal fibre, fermentation depends on

chemical composition, e.g. chain lenght, linkages b/w sugar molecules

strucutral arrangements in cell wall: crosslinks b/w polysaccharides, protein and lignin. Related to solubility

considerable in pigs, limited in chickens

unfavourable and beneficial effects of fibre

fibres contribute to physicochemical and rheologicla properties of feed/digesta, affecting e.g. digesta transit behaviour, nutrient accesibility, GIT development and function

solubilisation/particle size reduciont during processing complicate analyses

fibre before does not equal after

common processing technologies

effectiv for easy NSP

not sufficnet for more recalcitrant NSP, e.g. RSM > relatively unexplored

can fibres modify solubilisation

but solubilisation does not equal degradation in vivo

in RSM: rigid matrix of ester-linked or H-bound pectins linked to cellulose/ligning seem to be involved in reclacitrance of NSP

alkaline treatments, ferulic acid esterases, ligninolytic enzymes (fungi)

unfermented NSP from RSM