Chemical analysis of feed Flashcards
purpose of feed evaluation
diet formulation
economics
commerce
environmental impact
factors affecting nutrient concentrations
-geographical location/soil fertility
-management practices
-climate
-plant species
-stage of plant maturity
methods for chemical analysis
proximate analysis
van soest
nondestructive analysis methods
near infrared spectroscopy
animal based analysis methods
metabolism trials
feeding experiments
in vivo methods(cannula)
microbial analysis methods
nylon bag(in situ): forage held in rumen for 48 hours then examined
in vitro methods
what fractions does the proximate analysis system separate the feed into
water
crude protein
crude fat/ether extract
ash
crude fiber
nitrogen free extract
weakness of crude protein analysis
-not all protein contains exactly 16% nitrogen
-it does not distinguish between non-protein nitrogen and true protein
weakness of crude fat analysis
does not distinguish between true fat and waxes
weakness of crude fiber analysis
some cell wall contents get lost when separating the cell wall and the inner content
what does nitrogen free extract measure
highly digestible CHO
equation for nitrogen free extract
100 - CP - EE - CF - Ash
primary weakness of proximate analysis system
-CF recovers <100% cellulose, hemicellulose and lignin
-separation of CHO into CF and NFE is inconsistent
components of crude protein
protein
AA
amines
non-protein nitrogen
nucleic acid
nitrates
B-complex vitamins
components of crude fat
fats
oils
waxes
organic acids
pigments
fat-soluble vitamins
what are the fat soluble vitamins
A,D, E, K
components of crude fiber
cellulose
hemicellulose
lignen
components of NFE
starch
sugars
pigments
fructans
pectins
(some cellulose, hemicellulose, and lignin)
what percent of feed is the carbohydrate fraction
80-90%
how many NDF/in situ bags can the van soest machine hold
8 trays of 3 bags(24 total)
what equation is used to measure heat damaged protein
ADF - CP
how does forage become heat damaged
water on hay causes anaerobic reactions leading to heat damage
maillard(browning) reactions
heat-induced chemical reactions between proteins and AA that render protein less digestible
