Proximate in dairy technology

1. Agriculture
University,
Jodhpur
1
Topic: Proximate principles of feed
by
Dr. Rashmi Bhinda
Assistant Professor (Animal Production)
College of Agriculture, Jodhpur
(Agriculture University, Jodhpur)

2. Agriculture
University,
Jodhpur
2
What is a Proximate ?
 A method for the quantitative analysis of the different macronutrients in feed.
 It is the Weende or proximate analysis, Chemical analysis of feed and fodders.
 Developed in 1865 by Henneberg and Stohmann.
 At weende experimental station in Germany.
Components
Proximate Analysis is a partitioning of compounds in a feed into six categories
based on the chemical properties of the compounds.
The six categories are:
1. Moisture
2. Crude protein (CP)
3. Crude fibre (CF)
4. Nitrogen-free extracts (NFE, digestible carbohydrates)
5. Ether extract (EE)
6. Total Ash

3. Agriculture
University,
Jodhpur
3
Moisture: It represents the water content of feedstuff. The portion of
feedstuff other than moisture is called as dry matter (DM).
Crude protein (CP): It represents the total amount of Protein in the
feedstuff. The crude protein include true protein as well as non-protein
nitrogenous substance like urea, biuret, and amides. Crude protein is
determined by measuring the nitrogen content of the feed and
multiplying it by a factor of 6.25. This factor is based on the fact that
most protein contains 16% nitrogen. Crude protein is determined by
kjeldahl method. The method involves: Digestion, Distillation and
Titration.
Crude fibre: it includes less digestible carbohydrates like pectins,
cellulose, and hemicellulose and non-carbohydrate fraction like lignin.
Nitrogen-free extracts (NFE): It includes more digestible carbohydrates
like starch sugars and also cellulose and hemicellulose in minor
quantity.
Ether extract: it represents liquid portion of feedstuff. Thus it contains
fats, fatty acids, pigments, waxes etc.
Total Ash: It represents inorganic portion of feedstuff like minerals and
silica.

4. Agriculture
University,
Jodhpur
4
Feed sample analysis method

5. 5
Agriculture
University,
Jodhpur
Principle
If a sample of feed is heated and dried in a hot air oven at the temperature of boiling
water (100°C ± 5 °C) for 12-18 hours , the water present in feed sample escapes as
vapour. the loss in weight is considered as moisture and the residue is termed as dry
matter (DM).
(W1 - W2)
Moisture (%) = ---------------------------------------------X100
W1-W
Where, W = wt. of moisture cup
W1 = wt. of moisture cup + sample
W2 = wt. of moisture cup + sample after drying
Dry matter (%) = 100 – Moisture (%)
Requirement
1. Aluminium moisture cup, 2. Analytical balance, 3. desiccator, 4. Hot air oven, 5. Metal tongs
6. spatula
Determination of Dry matter

6. 6
Agriculture
University,
Jodhpur
It is estimated by micro-Kjeldahl method.
2-3 g samples take and digest in the Kjeldahl flask with 20-30 ml of
concentrated H2SO4 in presence of 3g digestion mixture (potassium sulphate
and copper sulphate in the ratio of 9:1).
After completion of digestion, the content are cool and transfers to a 100 ml
volumetric flask and volume make-up with distilled water.
An aliquot (10 ml) is transfers to micro-Kjeldahl assembly; sufficient amount
of 40% NaOH is added to make contents alkaline.
The distillate collected in a 100 ml flask containing 20 ml 2% Boric acid
(with mixed indicator, Methyl red + Bromocerol green in the ratio 2:1 added
up to cherry colour developed).
The distillate titrates against 0.01N H2SO4. The quantity of nitrogen
estimates, on the basis of fact that 1.0 ml of standard 0.01N H2SO4 is
equivalent to 0.00014 g nitrogen.
Crude protein estimation

7. 7
Agriculture
University,
Jodhpur 140 x V x n
Nitrogen (per cent) = ———————— on moisture free basis
m (100-M)
where, V = volume in ml of the standard H2SO4 used
n = normality of the standard used H2SO4 used
m = sample weight in g
M = moisture percentage
For conversion on nitrogen into crude protein
where, CP (%) = n (%) x 6.25
CP= crude protein (%) content of feedstuff
n = total nitrogen (%) present in feedstuff
Organic nitrogen + H2SO4 -------------------------- (NH4)2SO4 (During digestion)
(NH4)2SO4 + 2NaOH -------------------Na2SO4 + 2NH3 + 2H2O (During distillation)
2NH3 + H2SO4 (Standard) --------------------------- (NH4)2SO4 (during titration)

8. 8
Agriculture
University,
Jodhpur

9. 9
Agriculture
University,
Jodhpur
Total fat/ ether extract
Principle
When a sample of feed is extracted continuously with fat solvent like
petroleum ether, the vapour from the ether boiling in the flask passes into the
condenser where it condenses and drops back on the sample which dissolves
ether soluble materials such as fat, sterols, lecithins, resins and volatile oils in
the extraction flask. The extract is termed as crude fat or ether extract (EE)
because it also contains other fat like substances.
It is analyzed with the help of Soxhlet’s apparatus. Two gram dried and
ground feed sample was placed to in a weighed extraction thimble. Petroleum
ether (60-80⁰C) continuously volatilized (8-10 hrs), condensed and allowed
pass through the samples in a Soxhlet’s apparatus. The loss in weight of the
sample as the result of the ether treatment takes as the measure of the total
fat.

10. Formula for Ether Extract
10
100 (w1 – w2) 100 x wt of ether extract
Ether extract, per cent on as such basis = ———————— or ————————
m wt. of sample
where, w1 = wt. in g of oil flask + extracted material
w2 = wt. in g of empty oil flask
m = wt. in g of sample
If the thimble with sample has not been dried in hot air oven at 80-100°C for 10-12
hours prior to extraction, the crude fat (ether extract) value can be converted into dry
matter basis.
Crude fat x dry matter per cent
Ether extract on DM basis = ———————————————
100
N.B.-The digestible ether extract is multiplied by 2.25 because
on oxidation fat provides 2.25 times more energy as compared
to carbohydrates.

11. 11
Agriculture
University,
Jodhpur
Crude fiber
When a sample of moisture and fat free feedstuff is boiled with dilute
acid followed by dilute alkali, the soluble carbohydrates and proteins go into the
solution and are extracted. the undissolved residue left behind represents cellulose,
hemicellulose, lignin and mineral matter. the cellulose, hemicellulose and lignin
put together are called crude fibre (CF). When the residue after drying and
weighing is ignited, the fibre being organic in nature is burnt whereas the ash or
mineral matter is left over. obtained by deducting the weight of ash from the
weight of the dried residue. In poultry feeding, the analysis of crude fibre content
is very essential because the amount of crude fibre predicts the digestibility of the
feedstuff. Higher the fibre content lesser will be the digestibility. The fibre content
is
A-B
Crude fiber content (%) = ------------- x100
C
Where, A= weight of crucible with dry residue (g)
B= weight of crucible with ash (g)
C= weight of sample (g)

12. 12
Agriculture
University,
Jodhpur

13. 13
Agriculture
University,
Jodhpur Total ash
Principle
Total ash (TA) is the inorganic residue which remains after a feed stuff is
ignited to carbon free at 550-600°C in a muffle furnace for four hours (AOAC,
2000). The previously recorded empty crucible weight was subtracted from the
weight of crucible and its contents after ignition to determine weight of ash
and expressed as percent of the dried sample.
Calculation of Nitrogen-Free Extract (NFE)
NFE (%) =100 – (CP% + CF% + EE% + Total ash)
Where, CP = Crude protein
CF = Crude fibre
EE = Ether extract.

14. 14
Agriculture
University,
Jodhpur Total Digestible Nutrients (TDN)
A term used in animal feeding that designates the sum of all the
digestible organic nutrients. (Digestible fat is multiplied by 2.25 because of its
higher energy content) TDN is a feed is the sum of the digestible crude protein,
digestible crude fibre, digestible nitrogen free extract and 2.25 times digestible
ether extract. TDN requirements are given as Kilograms (Kg.). TDN is a way of
expressing the energy content of feed. The TDN is calculated by the following
formula: -
TDN = DCP + DCF + DNFE + DEE X 2.25
Where,
TDN = Total digestible nutrients (kg.)
DCP = Digestible crude protein
DCF = Digestible crude fibre
DNFE = Digestible nitrogen free extract
DEE = Digestible ether extract

15. Agriculture
University,
Jodhpur
15