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ANSC 315 > Module 6- Nutrients & chemical analysis > Flashcards

Module 6- Nutrients & chemical analysis Flashcards

(62 cards)

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1
Q

what kg of composite sample so feed should you take

A

1-2kg

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2
Q

nutrient content expressed on a DM basis is always ( ) when expressed on as-fed basis

A

greater

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3
Q

proximate analysis

A

series of analytical procedures that partitions the feed into 6 fractions

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4
Q

6 fractions of proximate analysis

A

1) moisture or DM
2) Ash (minerals)
3) CP
4) EE
5) crude fiber
6) nitrogen free extract

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5
Q

crude protein

A

represents nitrogenous compounds contained in the feed

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6
Q

crude fiber

A

represents cell wall & less digestible components
- cellulose
- hemicelullose
- lignin

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7
Q

T or F: crude fiber is measured

A

F

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8
Q

purpose of moisture in a diet

A

provides texture

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9
Q

2 things that will occur with too much moisture in the feed

A

1) reduction in DMI
2) reduce storage life

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10
Q

moisture/DM determination procedure

A

drying feed to a constant weight by putting in oven at 55 C

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11
Q

DM content of a feed =

A

weight of dry feed / weight of wet feed x 100

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12
Q

4 methods of DM analysis

A

1) forced air oven
2) moisture meter
3) freeze drying
4) near-infrared reflectance spectroscopy

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13
Q

what is the most accurate DM analysis method? why?

A

freeze drying, do not lose any volatile materials

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14
Q

2 volatile materials in feed

A

ammonia + VFAs

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15
Q

1 disadvantage to oven drying of DM analysis

A

underestimate how much DM bc of ammonia & VFA loss from heat

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16
Q

koster moisture tester

A

small portable electric drying unit, used on farms

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17
Q

moisture tracker device

A

hand held NIR scanning device for silage

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18
Q

ash determination principle

A

completely combust sample in muffle furnace at 500-600C = residue left is the mineral content of feed

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19
Q

% ash =

A

weight of residue / weight of feed sample x 100

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20
Q

disadvantage to ash determination

A

lose iodine & selenium at high temps = underestimate ash content

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21
Q

wet ashing procedure

A

use concentrated percholric acid, do not any lose minerals

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22
Q

how is crude protein determined

A

Kjeldahl distillation

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23
Q

Kjeldahl distillation procedure

A

measures total N content of test feed & uses it to estimate CP content

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24
Q

during crude protein determination, all N is converted to

A

ammonium sulfate

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25
Kjeldahl factor
6.25
26
CP % =
N x 6.25
27
macro-kjeldahl apparatus disadvantage
time consuming, only 1-2 batches / day
28
titration
titrating boric acid with HCI
29
leco method for N analysis
combust sample in O2 rich environment
30
why is the conversion factor for CP 6.25?
assuming proteins contain 16% N molecular weight of N / total molecular weight x 100 + 16% 100/16 = 6.25
31
why is it called crude protein
it is a crude estimate of how much protein there is - contains other N compounds not in form of AA
32
Kjeldahl factor is actually
7.74
33
kjeldahl factor use for mixed feeds vs individual feeds
mixed- 6.25 individual- use specific kjeldahl factors for specific feeds
34
2 limitations to kjeldahl CP determination
1) assumes all protein contains 16% N 2) assumes all n comes from protein
35
why is CP a bigger deal in monogastrics vs ruminants
monogastrics need AA from true protein in the diet, while ruminants can use any source of N
36
principle of CP analysis
converting all N contained in the feed to ammonia and then use total content of N to calculate CP by N x 6.25%
37
urea as a NPN source contains ( ) %
45
38
2 limitations to using urea in the diet
1) urea is not very palatable 2) toxicity
39
principle of ether extract/crude fat determination
extract feed sample with diethyl ether to remove anything soluble - anything soluble is lipid
40
diethyl extract is a
organic solvent
41
%EE =
weight of residue / weight of original sample X 100
42
soxhlet extractor
heat sample to 35 C, vapor released is the ether, use organic solvent to extract
43
2 main energy sources in ether extract
triglycerides & free FA
44
why is it called crude fat
inclusions of resins & waxes
45
2 problems with ether extract determination
1) EE fraction is assumed to have high E content 2) if EE fraction contains high % of waxes & resins = overestimate E content
46
% CF =
weight of residue / weight of feed sample x 100
47
2 issues with crude fiber determination
1) some cellulose, hemicellulose & lignin ends up in NFE = underestimate CF 2) not highly repeatable
48
NFE
nitrogen free extract, contains digestible carb fraction (starch & sugars)
49
T or F: there is a chemical analysis for NFE
F
50
NFE =
100- (%CP + % EE + % CF + % ash + %H2O)
51
T or F: NFE is used today for diet formulations
F
52
T or F: TDN will not work without proximate analysis
T
53
3 disadvantages of proximate analysis
1) does not define individual nutrients -> ash components 2) time-consuming 3) no indication of digestibility
54
what replaced crude fiber analysis?
detergent extraction system
55
detergent extraction system
partitions fiber components into soluble & insoluble carbs - NDF & ADF
56
benefit of detergent extraction system
better indication of fiber content of feed
57
cell wall components (ADF vs NDF)
cell wall: cellulose, hemicellulose, lignin ADF= cellulose & lignin NDF = hemicellulose + cellulose + lignin
58
how does the detergent extraction system work?
1) digest forage with neutral detergent solution 2) extract cell contents from NDF 3) digest NDF with acid detergent 4) digest ADF with 72% sulfuric acid to get cellulose & lignin
59
what does sulphuric acid do in detergent extraction
dissolves cellulose, lignin is left
60
example of a neutral detergent solution vs acid detergent solution
neutral- EDTA acid- H2SO4
61
near infrared reflectance spectroscopy (NIRS)
uses 5g sample absorption of light by feed ingredient
62
NIR uses ( ) range of visible light
outside 700-2500nm

ANSC 315 (9 decks)

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