Proximate p[principles given by Stohman and Hennberg in 1865 at Weende Village in Germany

2. Overview
1. Introduction
2. Proximate Principles
3. Demerits of Proximate analysis
4. Merits of Proximate analysis
5. Conclusion

3. Introduction

4. Proximate principle
1.Water (moisture)
2.Crude protein
3.Crude fat (ether extract)
4.Crude fiber
5.NFE (Nitrogen free extract)
6.Ash

5. Water (Moisture)
Principle
It is determined by drying feed sample in hot air oven at
100 0C for a specified length of time
• DM,% = wt after drying/wt before drying x 100%
• % Moisture = 100 – DM,%

6. •Moisture determines the keeping quality of hay
•Moisture content determines the losses in silage
making
•Usefull in classification of feed in to succulent
and non-succulent
•Moisture content is significant in storage of feed
•Moisture content is important while purchasing
of feed
•Moisture content is directly related to nutritive
value of feed
Significance of moisture

7. Demerits
• Drying above 60 oC can create artifacts that
hinder lignin, fiber & ADF analysis
• Most likely underestimate dry matter
• Loss of volatile fatty acids (VFA's)

8. Crude protein
• Estimated indirectly by determining the nitrogen content
of feed and multiplying it with 6.25.
• Estimated by a process developed by a Danish chemist
Johan Kjeldahl.
• 100/16 = 6.25, therefore: NITROGEN x 6.25 = CRUDE
PROTEIN
Principle and Scope
In the presence of sulfuric acid, sodium sulphate and a
catalyst, the amino nitrogen of many organic materials is
converted to ammonium sulphate. The ammonia is distilled
from an alkaline medium and absorbed in standardized
mineral acid.

9. Assumptions of Kjeldahl analysis
1.All proteins contain 16% N. Hence uses
constant‘6.25’ to convert N to protein.
2.All N in the food comes from true protein.

10. Problems with assumption 1
All amino acids are
not created equal
Therefore, all proteins are
not created equal
Amino Acid % Nitrogen
Alanine 15.72
Arginine 32.16
Aspartate 10.52
Cystine 11.66
Glutamate 9.52
Protein % Nitrogen
Casein 15.9
Glycinin 17.5
Hemoglobin 16.8
Ovalbumin 15.5
Serum globulin 16.2
(Kaiser et al., 1995) (Kaiser et al., 1995)

11. Problems with assumption 2
True protein in the plant is overestimated by the
Crude Protein value (Maynard and Loosli, 1979).
• The use of concentrated sulfuric acid at high
temperatures poses a considerable hazard
• The technique is time consuming to carry-out

12. Crude Fiber
Principle
Two boiling processes simulate the pH conditions
of the digestive tract
• Crude fiber composed of cellulose,
hemicelluloses, and lignin
• Lignin is not a true carbohydrate
• The method has been widely used to determine
the fiber content of feed but it has some serious
shortcomings

13. Demerits
• C.F. - Indigestible and non nutritive residue
• Acid and base solubilize some of hemicelluloses,
pectin and lignin
• NFE of a feed therefore tends to be
overestimated
• Hence crude fiber underestimates true fiber

14. Crude fat
Principle and Scope
A dried, ground sample is extracted with diethyl
ether which dissolves fats, oils, pigments and other
fat soluble substances.
Demerit
• This process assumes all substances soluble in
ether are fats. Plant pigments, wax which are
also soluble in ether, but do not have the same
nutritional values of fats

15. Nitrogen free extract (NFE)
Principle
NFE represents the soluble carbohydrate of the
feed, such as starch and sugar.
% NFE = % DM - (% EE + % CP + % ash + % CF)
Demerit
NFE not determined analytically but is calculated
by difference.
Therefore, NFE accumulates all of the errors that
exists in other proximate analysis components.

16. Total Ash
Principle
When a sample is burnt in muffle furnace at 600oC for
2 hours, only mineral matter is left behind. This is the
total ash or mineral content of feed.
% Ash = wt. after ashing/sample wt. x 100%
Demerits
• No indication of amounts of individual minerals.
• Long time required(12-24 hours).
• Muffle Furnaces are quite costly to run
• Loss of volatile minerals e.g., Cu, Fe, Pb, Hg, Ni,
Zn.

17. Advantages of Proximate Analysis
• Comparison of feeds on a specific basis
• It is a common basis for the feed purchasing
and for ration formulation
• No substitute till today except for fiber
component
• It forms Starting point for specific analysis
• Used for analysis of feeds, faeces, urine,
body tissues, body fluids

18. Conclusion
• Proximate analysis is a system for approximating the
nutritive value of feedstuff without actually using it in
feeding trial
• It is simple and yet descriptive method for evaluating
the nutritive value of feeds
• Main demerits of this system are it underestimates dry
matter, assumes that all proteins contain 16% N,
crude fiber is considered as in indigestible non
nutritive residue, this process assumes all substances
soluble in ether are fats, it does not includes vitamins
and gives no indication about kind of minerals present
in Ash

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