Lecture 2 Part 2 Flashcards
non fibrous
starches and sugars
fibrous
cellulose
benefits of van soest fiber analysis
-useful
- accurate
- evaluating type of carbs
cell contents
- digestible fraction of CHO, protein, lipid, and some ash
- sugar and starch
- protein
- lipids
cell wall
structural fiber and lignin
- cellulose
- hemicellulose
- lignin
NDS
neutral detergent solubles
- cell contents
NDF
Neutral detergent fiber
- cell wall
cell contents vs cell wall
cell contents are the stuff that is easy to digest while the cell was is stuff that is not easy to digest
what do microbes posses to digest cellulose
enzymes
what do cellulose and hemicellulose make up
carbs
lignin
- structure and support
- doesn’t provide nutrients
- not digestible for microbes
as age increases cell wall becomes
- tougher/thicker because lignin and NDF increases while digestibility decreases
van soest method
- forage
- digest with neutral detergent
- cell contents removed and hemicellulose, cellulose and lignin remain
- digest with acid detergent (full picture)
- hemicellulose removed and cellulose and lignin remain
- digest with 72% sulfuric acid
- cellulose removed and lignin remains
why in the van sest method is there a step of digest with 72% sulfuric acid
only way to separate cellulose and lignin
what is under the category of NDF
- cellulose
- hemicellulose
- lignin
- silica
- heat damaged proteins
silica
- common in soils with a lot of sand
- could be potential contaminant
- increase NDF values
heat damage proteins
- change shape and structure
- may not be chemically analyzed the same way
- overestimate value of NDF
ADF
acid detergent fiber
what is ADF
- lignin and cellulose
- stuff that is hard to digest
- boil NDF in acid to remove hemicellulose
is lignin a carb
no, it’s a structural filler
- nonnutritive component of feedstuff
summary of fiber analysis
- NDF: cell wall components
- NDS: cell content & easy to digest
- ADF: cell wall components
- ADL: lignin portion of ADF
what does van soest explain
nutritional responses in terms of feed digestibility and intake
which is better CF or Van Soest
Van Soest
what does NDF predict
voluntary feed intake
- higher= less feed intake
what does ADF predict
- forage digestibility
- lower= more digestible
- decrease = decrease in cellulose
what is van soest more relative to
high fiber feeds
non fiber carbohydrate
- from van soest
NFC= 100-(NDF+CP+CFat+Ash) - highly digestible carbs
near infrared analysis (NIR)
- sample dried & ground
- expose sample to Near Infrared Light Source
- reflect infrared radiation measured
- each organic component absorb and reflect near infrared differently
benefits of NIR
- extremely detailed
- potential to provide instantaneous results
NIR challenges
- has to be calibrated based on wet chemistry
- very costly
- not recognized as an official analysis
specialized methods of feed analysis
- bomb calorimetry
- amino acid analysis (chromatography)
- gas-liquid chromatography (fatty acids)
- dumas combustion method (non metallic elements)
biological methods of feed analysis
test what is actually happening in animal
- in-situ
- digestibility trials
- passage rate trials
what procedure is also considered Kjeldahl Procedure and why?
Crude Protein because it measures the nitrogen in material
- Kjeldahl procedure also was a method for measuring nitrogen
