COMMUNITY METHODS FOR THE ANALYSIS AND OFFICIAL CONTROL OF FEEDINGSTUFFS RULES *

COMMUNITY METHODS FOR THE ANALYSIS

AND OFFICIAL CONTROL OF FEEDINGSTUFFS

SUBSIDIARY LEGISLATION 437.76

COMMUNITY METHODS FOR THE ANALYSIS

AND OFFICIAL CONTROL OF

FEEDINGSTUFFS RULES *

8th July, 2005

LEGAL NOTICE 252 of 2005.

(1) The title of these rules is the Community Methods for

the Analysis and Official Control of Feedingstuffs Rules.

(2) The scope of these rules is to implement the provisions

found under European Union Council Directive 73/46/EEC

regarding official controls of feedingstuffs as regards moisture

contents of animal and vegetable fats and oils and magnesium and

crude fibre contents of feeding stuffs in accordance with the

methods described in the Schedule to these rules and in accordance

with article 22(c) of the Veterinary Services Act.

*These rules have been repealed by Legal Notice 37 of 2025.

(Rule 2)

Chapter I

Determination of Moisture in Animal and Vegetable Fats and Oils

1. Purpose and Scope

This method makes it possible to determine the water and volatile substances

content of animal and vegetable fats and oils.

Principle

The sample is dried to constant weight at 103 ºC. The loss in mass is determined

by weighing.

Apparatus

3.1. Flat-bottomed dish, of a corrosion-resistant material, 8 to 9 cm in diameter

and approximately 3 cm high.

3.2. Mercury thermometer with a strengthened bulb and expansion tube at the top

end, graduated from approximately 80ºC to at least 110ºC, and approximately 10 cm

in length.

3.3. Sand bath or electric hot-plate.

3.4. Desiccator, containing an efficient drying agent.

3.5. Analytical balance.

Procedure

Weigh out to the nearest mg approximately 20 g of the homogenized sample into

the dry, weighed dish (3.1) containing the thermometer (3.2). Heat on the sand bath

or hot-plate (3.3), stirring continuously with the therm ometer, so that the

temperature reaches 90ºC in about 7 minutes.

Reduce the heat, watching the frequency with which bubbles rise from the bottom

of the dish. The temperature must not exceed 105ºC. Continue to stir, scraping the

bottom of the dish, until bubbles stop forming.

In order to ensure complete elimination of moisture, reheat several times to 103ºC

± 2ºC, cooling to 93ºC between successive heatings. Then leave to cool to room

temperature in the desiccator (3.4) and weigh.

Repeat this operation until the loss in mass between two successive weightings no

longer exceeds 2 mg.

N.B. An increase in the mass of the sample after repeated heating indicates an

oxidation of the fat, in which case calculate the result from the weighing carried out

immediately before the mass began to increase.

Calculation of results

The moisture content, as a percentage of the sample, is given by the following

formula

(M1 – M2) .

Mo

where

Mo = mass, in grammes, of the test sample;

M1 = mass, in grammes, of the dish with its contents before heating;

M2 = mass, in grammes, of the dish with its contents after heating.

Results lower than 0ꞏ05% must be recorded as ‘lower than 0ꞏ05%’.

Repeatability

The difference in moisture between the results of two parallel determinations

carried out on the same sample must not exceed 0ꞏ05%, in absolute value.

Chapter II

Determination of Magnesium

- by atomic absorption spectrophotometry -

1. Purpose and Scope

This method makes it possible to determine the quantity of magnesium in feeding

stuffs. It is particularly appropriate for determining magnesium contents lower than

5%.

2. Principle

The sample is ashed and dissolved in dilute hydrochloric acid. If it contains no

organic substances, it is dissolved directly in dilute hydrochloric acid. The solution

is diluted and the magnesium content determined by atomic absorption

spectrophotometry at 285ꞏ2 nm, by comparison with standard solutions.

3. Reagents

3.1. Hydrochloric acid a.p. d: 1ꞏ16.

3.2. Concentrated hydrochloric acid a.p. d: 1ꞏ19.

3.3. Magnesium ribbon or wire, or magnesium sulphate heptahydrate, dried at

room temperature.

3.4. Strontium salt solution (chloride or nitrate) at 2ꞏ5 % (w/v) strontium

(= 76ꞏ08 g SrC12 ꞏ 6H2O a.p., or 60ꞏ38 g Sr (NO3)2 a.p.).

3.5. Standard magnesium solution: weigh out to the nearest mg 1 g magnesium

(3.3) which has previously had its oxide coating carefully removed, or the

corresponding quantity (10ꞏ143 g) of magnesium sulphate heptahydrate (3.3). Place

ina 1 000 ml graduated flask, add 80 ml hydrochloric acid (3.1), leave to dissolve

and make up to 1 000 ml with water. 1 ml of this solution contains 1ꞏ000 mg

magnesium.

4. Apparatus

4.1. Platinum, silica or porcelain ashing crucibles.

4.2. Thermostatically controlled electric muffle furnace.

4.3. Atomic absorption spectrophotometer.

5. Procedure

5.1. Preparation of the sample solution

5.1.1. Feeding stuffs composed exclusively of mineral substances

Weigh out to the nearest mg 5 g of the sample into a 500 ml graduated flask with

250 to 300 ml water. Add 40 ml hydrochloric acid (3.1), bring to the boil and keep

the liquid gently boiling for 30 minutes. Leave to cool, make up to volume with

water, mix and filter into a dry beaker through a dry pleated filter. Discard the first

30 ml of the filtrate. In the presence of silica, treat 5 g of sample with a sufficient

quantity (15 - 30 ml) of hydrochloric acid (3.2), evaporate to dryness on a water bath

and transfer to an oven at 105ºC for one hour. Proceed as from the third sentence of

5.1.2.

5.1.2. Feeding stuffs composed predominantly of mineral substances

Weigh out to the nearest mg 5 g of the sample into a crucible and ash at 550ºC in

the muffle furnace until an ash which is free from carbonaceous particles is obtained,

and leave to cool. In order to eliminate silica, add to the ash a sufficient quantity (15

- 30 ml) of hydrochloric acid (3.2), evaporate to dryness on a water bath and transfer

to an oven at 105ºC for one hour. Treat the residue with 10 ml hydrochloric acid

(3.1) and transfer to a 500 ml graduated flask using warm water. Leave to cool and

make to volume with water. Mix and filter into a dry beaker through a dry pleated

filter. Discard the first 30 ml of the filtrate.

5.1.3. Feedingstuffs composed predominantly of organic substances

Weigh out to the nearest mg 5 g of the sample into a crucible and ash at 550ºC in

the muffle furnace until an ash which is free from carbonaceous particles is obtained.

Treat the ash with 5 ml hydrochloric acid (3.2), evaporate to dryness on a water bath

and then dry for one hour in the oven at 105ºC in order to render the silica insoluble.

Treat the ash with 5 ml hydrochloric acid (3.1), transfer to a 250 ml graduated flask

using warm water, bring to the boil, leave to cool and make up to volume with water.

Mix and filter into a dry beaker through a dry pleated filter. Discard the first 30 ml of

the filtrate.

5.2. Measurement by atomic absorption

By diluting the standard solution (3.5) with water, prepare at least 5 reference

solutions of increasing concentration, corresponding to the optimal measuring range

of the spectrophotometer. Add to each solution 10 ml strontium salt solution (3.4)

and then make up the volume to 100 ml with water. Dilute with water one aliquot

part of the filtrate obtained from 5.1.1, 5.1.2 or 5.1.3, so as to obtain a magnesium

concentration which is within the limits of concentration of the reference solutions.

The hydrochloric acid concentration of this solution must not exceed 0ꞏ4 N. Add 10

ml strontium salt solution (3.4) and then make up the volume to 100 ml with water.

Measure the absorption of the solution to be determined and of the reference

solutions at 285ꞏ2 nm.

Calculation of results

Calculate the quantity of magnesium in the sample by relation to the reference

solutions. Express the result as a percentage of the sample.

Repeatability

The difference between the results of two parallel determinations carried out on

the same sample must not exceed 5%, in relative value.

Chapter III

Determination of Crude Fibre

1. Purpose and scope

This method makes it possible to determine fat-free organic substances in feeding

stuffs which are insoluble in acid and alkaline media and are conventionally

described as crude fibre.

2. Principle

The sample, defatted where necessary, is treated successively with boiling

solutions of sulphuric acid and potassium hydroxide of specified concentrations. The

residue is separated by filtration on a sintered-glass filter washed, dried, weighed

and ashed within a range of 475 to 500ºC. The loss of weight resulting from ashing

corresponds to the crude fibre present in the test sample.

3. Reagents

3.1. Sulphuric acid, c = 0,13 mol/l.

3.2. Anti-foaming agent (e.g. n-octanol).

3.3. Filter aid (Celite 545 or equivalent), heated at 500ºC for four hours (8.6).

3.4. Acetone.

3.5. Light petroleum boiling-range 40 to 60ºC.

3.6. Hydrochloric acid, c = 0,5 mol/l.

3.7. Potassium hydroxide solution, c = 0,23 mol/l.

4. Apparatus

4.1. Heating unit for digestion with sulphuric acid or potassium hydroxide

solution, equipped with a support for the filter crucible (4.2) and provided with an

outlet tube with a tap to the liquid outlet and vacuum, possibly with compressed air.

Before use each day preheat the unit with boiling water for five minutes.

4.2. Glass filter crucible with fused sintered glass filter plate pore size 40-90 µm.

Before first use, heat to 500ºC for a few minutes and cool (8.6).

4.3. Cylinder of at least 270 ml with a reflux condenser, suitable for boiling.

4.4. Drying oven with thermostat.

4.5. Muffle furnace with thermostat.

4.6. Extraction unit consisting of a support plate for the filter crucible (4.2.) and

with a discharge pipe with a tap to the vacuum and liquid outlet.

4.7. Connecting rings to assemble the heating unit (4.1), crucible (4.2) and

cylinder (4.3) and to connect the cold extraction unit (4.6) and crucible.

5. Procedure

Weigh out to the nearest 0,001 g, 1 g of the prepared sample and place it in the

crucible (4.2), (see observations 8.1, 8.2 and 8.3) and add 1 g of filter aid (3.3).

Assemble the heating unit (4.1) and the filter crucible (4.2), then attach the

cylinder (4.3) to the crucible.

Pour 150 ml of boiling sulphuric acid (3.1) into the assembled cylinder and

crucible and if necessary add a few drops of antifoaming agent (3.2).

Bring the liquid to the boil within 5 ± 2 minutes and boil vigorously for exactly 30

minutes. Open the tap to the discharge pipe (4.1) and, under vacuum, filter the

sulphuric acid through the filter crucible and wash the residue with three consecutive

30 ml portions of boiling water, ensuring that the residue is filtered dry after each

washing. Close the outlet tap and pour 150 ml boiling potassium hydroxide solution

(3.7) to the assembled cylinder and crucible and add a few drops of antifoaming

agent (3.2). Bring the liquid to boiling point within 5 ± 2 minutes and boil

vigorously for exactly 30 minutes. Filter and repeat the washing procedure used for

the sulphuric acid step. After the final washing and drying, disconnect the crucible

and its contents and reconnect it to the cold extraction unit (4.6). Apply the vacuum

and wash the residue in the crucible with three consecutive 25 ml portions of acetone

(3.4) ensuring that the residue is filtered dry after each washing.

Dry the crucible to constant weight in the oven at 130ºC. After each drying cool in

the desiccator and weigh rapidly. Place the crucible in a muffle furnace and ash to

constant weight at 475ºC to 500ºC for at least 30 minutes. After each heating cool

first in the furnace and then in the desiccator before weighing.

Carry out a blank test without the sample. Loss of weight resulting from ashing

must not exceed 4 mg.

6. Calculation of results

The crude fibre content as a percentage of the sample is given by the expression

(b-c) x_100

a

where

a = mass of sample in g;

b = loss of mass after ashing during the determination, in g;

c = loss of mass after ashing during the blank test, in g.

Repeatability

The difference between two parallel determinations carried out on the same

sample must not exceed

- 0,3 in absolute value for crude fibre contents lower than 10%,

- 3% relative to the higher result, for crude fibre contents equal to or greater

than10%.

Observations

8.1. Feedingstuffs containing more than 10 % crude fat must be defatted prior to

analysis with light petroleum (3.5). Connect the filter crucible (4.2) and its contents

to the cold extraction unit (4.6) and apply vacuum and wash the residue with three

consecutive 30 ml portions of light petroleum, ensuring that the residue is dry.

Connect the crucible and its contents to the heating unit (4.1) and continue as

described under 5.

8.2. Feedingstuffs containing fats which cannot be extracted directly with light

petroleum (3.5) must be defatted as shown in 8.1 and defatted once more after

boiling with acid. After boiling with acid and the subsequent washing connect the

crucible and its contents to the cold extraction unit (4.6) and wash three times with

30 ml acetone followed by three further washings with 30 ml portions of light

petroleum. Filter under vacuum until dry and continue the analysis as described

under 5, beginning with potassium hydroxide treatment.

8.3. If the feeding stuffs contain over 5% of carbonates, expressed as calcium

carbonate, connect the crucible (4.2) with the weighed sample to the heating unit

(4.1). Wash the sample three times with 30 ml hydrochloric acid (3.6). After each

addition let the sample stand for about one minute before filtering.

Wash once with 30 ml water and then continue as described under 5.

8.4. If an apparatus in the form of a stand is used (several crucibles attached to

the same heating unit) no two individual determinations on the same sample for

analysis may be carried out in the same series.

8.5. If after boiling it is difficult to filter the acidic and basic solutions, use

compressed air through the discharge pipe of the heating unit and then continue

filtering.

8.6. The temperature for ashing should not be higher than 500ºC in order to

extend the lifetime of the glass filter crucibles. Care must be taken to avoid

excessive thermal shock during heating and cooling cycles.