Lecture quiz 05/01/23 (monday) Flashcards
how do we calculate how much protein per gram in cat food?
100 (weight) X cru
weight X crude protein = grams of protein
protein peer gram =
why is it important to put the moisture content in cat food?
When water is given, how do we get dry matter?
100- moisture
What should we know about when preparing for chemical/proximate analysis?
- dry 55-60C = only needed for high/wet moisture samples
- grind (1mm particle size)
when do we use 105C when drying?
dry feedstuffs
how do we do proximate analysis for ash?
what represents the total mineral content of the feed?
ash
what method do we use for ash?
combust at 500-600C for 4 hours
how do we calculate ash%?
ash remaining wt/ sample wt x 100
how do we get the organic matter in ash?
% organic matter = 100 - %ash
what aree implications of ash content?
assh tellsss you nothing about the concentration of individual minerals
acts as diluent for other nutrients and enrgy
What are the are sourcess of error in ash proximate analysis?
high temp may volatize ssome minerals (zinc, chlorine, selenium and iodine)
is there energy in ash?
no it reduces energy intake
is ash underestimated?
yess
what do we use to combust ash?
muffle furnace then put in a desiccator
what is a muffle furnace?
advanced high temp heating elements
programmable temperature controller
temp can go up to 1,200 celsius
- we use crucibles because they are resistant to high temps
what does it mean when we say ash is a diluent?
more ash = less of other things (nutrients)
what does it mean if ther is more than 12% of ash in feedstuff in horses?
over 12% is alarming not baad but low energy
Proximate analysis of ether extract
fat is soluble in ether = extract fat
- EE is supposed to represent the lipids in a feedstuff
what is the method in EE?
reflux the sample with boiling ether to remove the fatt
what is the calculation used in EE?
%EE = residue after evaporation of ether/ sample wt X 100
what are the implications of EE conc?
- EE represents the fraction of feed with the highest energy value, Higher ether extract should imply that the feed has high energy conc.
what is the limitation of the procedure?
crude fat contains true fat - in addition it contains non-nutritive EE components (chlorophyll, pigments and waxes)
If EE overestimated or underestimated?
Overestimated the fat content
what system do we use for crude fat analysis?
Automated Soxtec Extraction System
Where are samples placed in for EE?
thimbles
