1) wieght loss during drying is only water 2) no info on dry matter composition 3) most valuable in determining ingredient cost
dry matter intake
number of pounds consumed x %DM
highest percent of nutrients
%nutrient divided by DM= % of nutrient on DM basis
Kjeldahl procedure. actually measure amount of nitrogen and uses it to estimate ______.
assumptions of protein
1) all nitrogen is them 2) they have a constant nitrogen percent 3) no info on availability of nitrogen (digestibility) 4) no info on quality of protein (necessary/not)
Leco Protein Analysis
ignite sample, faster, safer, easier than Kjeldahl, expensive
crude fat, need to extract lipid from ingredient
assumptions of ether extract
1) all either soluble material is fat 2) no info on individual fatty acid (long, short, sat, unsat)
analysis is designed to simulate body's natural digestion process. weight of sample loss during burning of ash.
determines mineral content of feedstuff. inorganic material.
assumptions of crude fiber
1) all material is fiber (some stuff could dissolve so would be underestimated 2) no indication on individual fiber
assumptions of ash
no indication of individual mineral content
nitrogen free extract (NFE)
calculations of sugar and starches left over from other analyses. 100- % off all other procedures.
problems with NFE
errors in other analyses show up in nitrogen free extract
limitations of proximate analysis
1) sampling (getting a representative sample not stored to long and not only from certain area of feed 2) no indication of toxic compounds 3) no indication of individual nutrients 4) no indication of nutrient availability (digestible)
permitted analytical variation (PAV)
allowance for accuracy of individual analytical procedures