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Veterinary Services Act, 2001 (Act Xxiii Of 2001) Methods Of Analysis For The Official Control Of Feedingstuffs Rules, 2005 (L.N. 99 Of 2005 )

VETERINARY SERVICES ACT, 2001 (ACT XXIII OF 2001)

Methods of Analysis for the Official Control of

Feedingstuffs Rules, 2005

IN exercise of the powers conferred by article 22 of the Veterinary Services Act, 2001 the Minister for Rural Affairs and the Environment has made the following regulations>-

1. The title of these regulations is Methods of Analysis for Official

Control of Feedingstuffs Regulations, 2004.

(2) The scope of these regulations is to implement the rules found under EU Commission Directive 71#393#EEC establishing EC methods for the official control of feedingstuffs.

(3) The Member States shall require that analyses for official controls of feedingstuffs as regards their contents of moisture, volatile nitrogenous bases, total phosphorus and crude oils and fats be carried out according to the methods described in the Schedule to these Regulations.

Title, Scope and

Applicability.

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SCHEDULE

I. DETERMINATION OF MOISTURE

1. Purpose and Scope

This method makes it possible to determine the moisture content of feedingstuffs. It does not cover the analysis of milk products as straight feedingstuffs, the analysis of mineral substances and mixtures composed predominantly of mineral substances, the analysis of animal and vegetable fats and oils or the analysis of the oil seeds and olaginous fruit defined in Council Regulation No 136/66/EEC (1) of 22 September 1966 on the establishment of a common organization of the market in oils and fats.
The determination of the moisture content of oil seeds and oleaginous fruit is described in Annex III to Commission Regulation (EEC) No 1470/68 (2) of 23
September 1968 on the drawing and reduction of samples and the determination
of the oil content, imp1u7riptiaegs easndScmhoeidstuulree in oil seeds.

2. Principle

The sample is desiccated under specified conditions which vary according to the nature of the feedingstuff. The loss in mass is determined by weighing. It is necessary to carry out preliminary drying when dealing with solid feedingstuffs which have a high moisture content.
3. Apparatus
3.1. Crusher of non moisture-absorbing material which is easy to clean, allows rapid, even crushing without producing any appreciable heating, prevents contact with the outside air as far as possible and meets the requirements laid down in 4.1.1. and 4.1.2. (e.g. hammer or watercooled micro-crushers, collapsible cone mills, slow motion or cogwheeled crushers).
3.2. Analytical balance, accurate to 0·5 mg.
3.3. Dry containers of non-corrodible metal or of glass with lids ensuring airtight closure; working surface allowing the test sample to be spread at about 0·3 g/cm2.
3.4. Electrically heated isothermal oven (± 1 ºC) properly ventilated and ensuring rapid temperature regulation 3.

3 (3) For the drying of cereals, flour, groats and meal, the oven must have a thermal capacity such that, when pre- set at 131 ºC, it will return to that temperature in less than 45 minutes after the maximum number of test samples have been placed inside to dry simultaneously. Ventilation must be such that, when as many samples of common wheat as it can contain are dried for two hours, the results differ from those obtained after four hours of drying by less than 0·15%.

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3.5. Adjustable electrically heated vacuum oven fitted with an oil pump and either a mechanism for introducing hot dried air or a drying agent (e.g. calcium oxide).
3.6. Desiccator with a thick perforated metal or porcelain plate, containing an efficient drying agent.
4. Procedure

N.B.: The operations described in this section must be carried out immediately after opening the packages of samples. Analysis must be carried out at least in duplicate.

4.1. Preparation
4.1.1. Feedingstuffs other than those coming under 4.1.2 and 4.1.3
Take at least 50 g of the sample. If necessary, crush or divide in such a way as to avoid any variation in moisture content (see 6).
4.1.2. Cereals and groats
Take at least 50 g of the sample. Grind into particles of which at least
50% will pass through a 0·5 mm mesh sieve and will leave no more than
10% reject on a 1 mm round- meshed sieve.
4.1.3. Feedingstuffs in liquid or paste form, feedingstuffs predominantly composed of oils and fats
Take about 25 g of the sample, weigh to the nearest 10 mg, add an appropriate quantity of anhydrous sand weighed to the nearest 10 mg and mix until a homogeneous product is obtained.
4.2. Drying
4.2.1. Feedingstuffs other than those coming under 4.2.2 and 4.2.3
Weigh a container (3.3) with its lid to the nearest 0·5 mg. Weigh into the weighed container, to the nearest 1 mg, about 5 g of the sample and spread evenly. Place the container, without its lid, in the oven preheated to 103 ºC. To prevent the oven temperature from falling unduly, introduce the container as rapidly as possible. Leave to dry for four hours reckoned from the time when the oven temperature returns to 103
ºC. Replace the lid on the container, remove the latter from the oven,

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leave to cool for 30 to 45 minutes in the desiccator (3.6) and weigh to the nearest 1 mg.
For feedingstuffs composed predominantly of oils and fats, dry in the oven for an additional 30 minutes at 130 ºC. The difference between the two weighings must not exceed 0·1% of moisture.
4.2.2. Cereals, flour, groats and meal
Weigh a container (3.3) with its lid to the nearest 0·5 mg. Weigh into the
weighed container, to the nearest 1 mg, about 5 g of the crushed sample and spread evenly. Place the container, without its lid, in the oven preheated to 130 ºC. To prevent the oven temperature from falling unduly, introduce the container as rapidly as possible. Leave to dry for two hours reckoned from the time when the oven temperature returns to
130 ºC. Replace the lid on the container, remove the latter from the oven, leave to cool for 30 to 45 minutes in the desiccator (3.6) and weigh to the nearest 1 mg.
4.2.3. Compound feedingstuffs containing more than 4% of sucrose or lactose: straight feedingstuffs such as locust beans, hydrolyzed cereal products, malt seeds, dried beet chips, fish and sugar solubles; compound feedingstuffs containing more than 25% of mineral salts including water of crystallization.
Weigh a container (3.3) with its lid to the nearest 0·5 mg. Weigh into the weighed container, to the nearest 1 mg, about 5 g of the sample and spread evenly. Place the container, without its lid, in the vacuum oven (3.5) preheated to between 80 ºC and 85 ºC. To prevent the oven temperature from falling unduly, introduce the
container as rapidly as possible.
Bring the pressure up to 100 Torr and leave to dry for four hours at this pressure, either in a current of hot, dry air or using a drying agent (about
300 g for 20 samples). In the latter instance, disconnect the vacuum
pump when the prescribed pressure has been reached. Reckon drying time from the moment when the oven temperature returns to 80 ºC to 85
ºC. Carefully bring the oven back to atmospheric pressure. Open the
oven, place the lid on the container immediately, remove the container from the oven, leave to cool for 30 to 45 minutes in the desiccator (3.6) and weigh to the nearest 1 mg. Dry for an additional 30 minutes in the vacuum oven at 80 ºC to 85 ºC and reweigh. The difference between the two weighings must not exceed 0·1% of moisture.
4.3. Preliminary drying
4.3.1. Feedingstuffs other than those coming under 4.3.2

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Solid feedingstuffs with a high moisture content which makes crushing difficult must be subjected to preliminary drying as follows:
Weigh 50 g of uncrushed sample to the nearest 10 mg (compressed or agglomerated feedingstuffs may be roughly divided if necessary) in a suitable container (e.g. a 20 × 12 cm aluminium plate with a 0·5 cm rim). Leave to dry in an oven from 60 ºC to 70 ºC until the moisture content has been reduced to between 8% and 12%. Remove from the oven, leave to cool uncovered in the laboratory for one hour and weigh to the 10 mg. Crush immediately as indicated in 4.1.1 and dry as indicated in 4.2.1 or 4.2.3 according to the nature of the feedingstuff.
4.3.2. Cereals
Grain with a moisture content of over 17% must be subjected to preliminary drying as follows:
Weigh 50 g of unground grain to the nearest 10 mg in a suitable container (e.g. a 20 × 12 cm aluminium plate with a 0·5 cm rim). Leave to dry for 5 to 7 minutes in an oven at 130 ºC. Remove from the oven, leave to cool uncovered in the laboratory for two hours and weigh to the nearest 10 mg. Grind immediately as indicated in 4.1.2 and dry as indicated in 4.2.2.
5. Calculation of results
The moisture content, as a percentage of the sample, is calculated by using the following formulae:
5.1. Drying without preliminary drying
(E – m). 100
E
where:
E = initial mass, in grammes, of the test sample, m = mass, in grammes, of the dry test sample.
5.2. Drying with preliminary drying
(M'
m)M
M'
E M .
100
E
100 1
Mm
EM '
where:
E = initial mass, in grammes, of the test sample,

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M = mass, in grammes, of the test sample after preliminary drying, M' = mass, in grammes, of the test sample after crushing or grinding, m = mass, in grammes, of the dry test sample.
5.3. Repeatibility
The difference between the results of two parallel determinations carried out on the same sample should not exceed 0·2% of moisture.
6. Observation
If crushing proves necessary and if this is seen to alter the moisture content of the product, the results of the analysis of the components of the feedingstuff must be corrected on the basis of the moisture content of the sample in its initial state.
II. DETERMINATION OF VOLATILE NITROGENOUS BASES
A. MICRODIFFUSION
1. Purpose and Scope
This method makes it possible to determine the content of volatile nitrogenous
bases, expressed as ammonia, in feedingstuffs.
2. Principle
The sample is extracted with water and the solution clarified and filtered. The volatile nitrogenous bases are displaced by microdiffusion using a solution of potassium carbonate, collected in a solution of boric acid and titrated with sulphuric acid.
3. Reagents
3.1. 20% (w/v) solution of trichloroacetic acid.
3.2. Indicator: dissolve 33 mg of bromocresol green and 65 mg of methyl red in
100 ml of 95%—96% (v/v) of ethanol.
3.3. Boric acid solution: in a 1 litre graduated flask dissolve 10 g of boric acid A.R. in 200 ml of 95%—96% (v/v) ethanol and 700 ml of water. Add 10 ml of indicator (3.2.). Mix and, if necessary, adjust the colour of the solution to light red by adding a solution of sodium hydroxide. 1 ml of this solution will fix a maximum of 300 µg of NH3.

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3.4. Saturated potassium carbonate solution: dissolve 10 Og of potassium carbonate A.R. in 100 ml of boiling water. Leave to cool, filter.
3.5. Sulphuric acid 0·02 N.
4. Apparatus
4.1. Mixer (tumbler): approximately 35 to 40 r.p.m.
4.2. Glass or plastic Conway cells (see diagram).
4.3. Microburettes graduated in 1/100 ml.
5. Procedure
Weigh 10 g of sample to the nearest 1 mg and place with 100 ml of water in a
200 ml graduated flask. Mix in the tumbler for 30 minutes. Add 50 ml of
trichloroacetic acid solution (3.1), make upto volume with water, shake vigorously and filter through a pleated filter.
Using a pipette, introduce 1 ml of boric acid solution (3.3) into the central part of the Conway cell and 1 ml of the sample filtrate into the crown of the cell. Cover partially with the greased lid. Drop 1 ml of saturated potassium carbonate solution (3.4) quickly into the crown and close the lid so that the cell is airtight. Turn the cell carefully rotating it in a horizontal plane so that the two reagents are mixed. Leave to incubate either for at least four hours at room temperature or for one hour at 40 ºC.
Using a microburette (4.3), titrate the volatile bases in the boric acid solution with sulphuric acid 0·02 N (3.5).
Carry out a blank test using the same procedure but without a sample to be analysed.
6. Calculation of results
1 ml of H2SO4 0·02 N corresponds to 0·34 mg of ammonia. Express the result as a precentage of the sample.

Repeatibility

The difference between the results of two parallel determinations carried out on the same sample should not exceed:

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10%, in relative value, for ammonia contents of less than 1·0%;
0·1%, in absolute value, for ammonia contents of 1·0% or more.
7. Observation
If the ammonia content of the sample exceeds 0·6%, dilute the initial filtrate.

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B. BY DISTILLATION

1. Purpose and Scope

This method makes it possible to determine the content of volatile nitrogenous bases, expressed as ammonia, in fish- meal containing practically no urea. It is applicable only to ammonia contents of less than 0·25%.

2. Principle

The sample is extracted with water and the solution clarified and filtered. The volatile nitrogenous bases are displaced at boiling point by adding magnesium oxide and collected in a specific quantity of sulphuric acid, the excess of which is back-titrated with a solution of sodium hydroxide.
3. Reagents
3.1. 20% (w/v) solution of trichloroacetic acid.
3.2. Magnesium oxide A.R.
3.3. Anti- foaming emulsion (e.g. silicone).
3.4. Sulphuric acid 0·1 N.
3.5. Sodium hydroxide solution 0·1 N.
3.6. 0·3% (w/v) solution of methyl red in 95%—96% (v/v) ethanol.
4. Apparatus
4.1. Mixer (tumbler): approximately 35 to 40 r.p.m.
4.2. Distilling apparatus of the Kjeldahl type.
5. Procedure
Weigh 10 g of the sample to the nearest 1 mg and place with 100 ml of water in a 200 ml graduated flask. Mix in the tumbler for 30 minutes. Add 50 ml of trichloroacetic acid solution (3.1), make upto volume with water, shake vigorously and filter through a pleated filter.
Take a quantity of clear filtrate appropriate for the presumed content of volatile nitrogenous bases (100 ml is usually suitable). Dilute to 200 ml and add 2 g of magnesium oxide (3.2) and a few drops of anti- foaming emulsion (3.3).The

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solution should be alkaline to litmus paper; otherwise add some magnesium oxide (3.2). Distil about 150 ml of the solution in the Kjeldahl apparatus and collect the distillate in an Erlenmeyer flask containing an accurately measured volume (25 to 50 ml) of sulphuric acid 0·1 N (3.4). While distilling, avoid overheating of the sides. Boil the sulphuric acid solution for two minutes, cool it and back-titrate the excess sulphuric acid with the sodium hydroxide solution
0·1 N (3.5) in the presence of the methyl red indicator (3.6).
Carry out a blank test using the same procedure but without a sample to be analysed.
6. Calculation of results
1 ml of H2SO4 0·1 N corresponds to 1·7 mg of ammonia. Express the result as a percentage of the sample.

Repeatibility

The difference between the results of two parallel determinations carried out on the same sample should not exceed, in relative value, 10% of ammonia.
III. DETERMINATION OF TOTAL PHOSPHORUS
PHOTOMETRIC METHOD

1. Purpose and Scope

This method makes it possible to determine the content of total phosphorus in feedingstuffs. It is particularly appropriate for the analysis of products low in phosphorus. In certain cases (product rich in phosphorus), a gravimetric method may be used.

2. Principle

The sample is mineralised, either by dry combustion (in the case of organic feedingstuffs) or by acid digestion (in the case of mineral compounds and liquid feedingstuffs), and placed in an acid solution. The solution is treated with molybdovanadate reagent. The optical density of the yellow solution thus formed is measured in a spectrophotometer at 430 nm.
3. Reagents
3.1. Calcium carbonate A.R.

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3.2. Hydrochloric acid A.R., d: 1·1 (approx 6 N).
3.3. Nitric acid A.R., d: 1·045.
3.4. Nitric acid A.R., d: 1·38 to 1·42.
3.5. Sulphuric acid A.R., d: 1·84.
3.6.Molybdovanadate reagent: mix 200 ml of ammonium heptamolybdate solution (3.6.1), 200 ml of ammonium monovanadate solution (3.6.2) and 134 ml of nitric acid (3.4) in a 1 litre graduated flask. Make up to volume with water.
3.6.1. Ammonium heptamolybdate solution: dissolve in hot water 100 g of ammonium heptamolybdate A.R. (NH4) 6Mo7O24.4H2O. Add 10 ml of ammonia (d: 0·91) and make up to 1 litre with water.
3.6.2. Ammonium monovanadate solution: 2·35 g of ammonium monovanadate A.R. NH4VO3 dissolve in 400 ml of hot water. Stirring constantly, slowly add 20 ml of dilute nitric acid (7 ml of HNO3 (3.4) +
13 ml of H2O and make upto 1 litre with water.
3.7. Standard solution of 1 mg phosphorus per ml: dissolve 4·387 g of potassium dihydrogen phosphate A.R. KG2PO4 in water. Make up to 1 litre with water.
4. Apparatus
4.1. Silica or porcelain ashing crucibles.
4.2. Electric muffle- furnace with thermostat set at 550 ºC.
4.3. 250 ml Kjeldahl flask.
4.4. Graduated flasks and precision pipettes.
4.5. Spectrophotometer.
4.6. Test tubes about 16 mm in diameter, with stoppers graded to a diameter of
14·5 mm; capacity: 25 to 30 ml.
5. Procedure
5.1. Preparation of the solution

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According to the nature of the sample, prepare a solution as indicated in
5.1.1 or 5.1.2.
5.1.1. Usual procedure
Weigh 1 g or more of the sample to the nearest 1 mg. Place the test sample in a Kjeldahl flask, add 20 ml of sulphuric acid (3.5), shake to impregnate the substancecompletely with acid and to prevent it from sticking to the sides of the flask, heat and keep at boiling point for 10 minutes. Leave to cool slightly, add 2 ml of nitric acid (3.4), heat gently, leave to cool slightly, add a little more nitric acid (3.4) and bring back to boiling point. Repeat this procedure until a colourless solution is obtained. Cool, add a little water, decant the liquid into a
500 ml graduated flask, rinsing the Kjeldahl flask with hot water.
Leave to cool, make upto volume with water, homogenise and filter.
5.1.2. Samples containing organic substances and free from calcium and magnesium dihydrogen phosphates
Weigh about 2·5 g of the sample to the nearest 1 mg in an ashing crucible. Mix the test sample until completely merged with 1 g of calcium carbonate (3.1). Ash in the oven at 550 ºC ± 5 ºC until white or grey ash is obtained (a little charcoal does not matter).
Transfer the ash into a 250 ml beaker. Add 20 ml of water and hydrochloric acid (3.2) until effervescence ceases. Add a further 10 ml of hydrochloric acid (3.2). Place the beaker on a sand bath and evaporate until dry to make the silica insoluble. Redissolve the residue in 10 ml of nitric acid (3.3) and boil on the sand bath for 5 minutes without evaporating until dry. Decant the liquid into a 500 ml graduated flask, rinsing the beaker several times with hot water. Leave to cool, make up to volume with water, homogenise and filter.
5.2. Development of coloration and measurement of optical density
Dilute an aliquot part of the filtrate obtained by 5.1.1 or 5.1.2 to obtain a phosphorus concentration of not more than 40 µg/ml. Place 10 ml of this solution in a test tube (4.6) and add 10 ml of molybdovanadate reagent (3.6). Homogenise and leave to stand for at least 10 minutes at 20 ºC. Measure the optical density in a spectrophotometer at 430 nm against a solution obtained by adding 10 ml of the molybdovanadate reagent (3.6) to 10 ml of water.
5.3. Calibration curve
From the standard solution (3.7) prepare solutions containing respectively
5, 10, 20, 30 and 40 µg of phosphorus per ml. Take 10 ml of each of these

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solutions and add thereto 10 ml of molybdovanadate reagent (3.6). Homogenise and leave to stand for at least 10 minutes at 20 ºC. Measure the optical density as indicated in 5.2. Trace the calibration curve by plotting the optical densities against the corresponding quantities of phosphorus. For concentrations between 0 and 40 µg/ml, the curve will be linear.
6. Calculation of results
Determine the amount of phosphorus in the test sample by using the calibration curve.
Express the result as a percentage of the sample.

Repeatibility

The difference between the results of two parallel determinations carried out on the same sample should not exceed:
3%, in relative value, for phosphorus contents of less than 5%;
0·15%, in absolute value, for phosphorus contents of 5% or more. IV. DETERMINATION OF CRUDE OILS AND FATS

1. Purpose and scope

This method is for the determination of crude oils and fats in feedingstuffs. It does not cover the analysis of oil seeds and oleaginous fruit defined in Council Regulation 136/66/EEC of 22 September 1966.
The use of the two procedures described below depends on the nature and composition of the feedingstuff and the reason for carrying out the analysis.

1.1. Procedure A — Directly extractable crude oils and fats

This method is applicable to feed materials of plant origin, except those included within the scope of Procedure B.

1.2. Procedure B — Total crude oils and fats

This method is applicable to feed materials of animal origin and to all compound feeds. It is to be used for all materials from which the oils and fats cannot be completely extracted without prior hydrolysis (eg glutens, yeast, potato proteins and products subject to processes such as extrusion, flaking and heating).

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1.3. Interpretation of results

In all cases where a higher result is obtained by using Procedure B than by Procedure A, the result obtained by Procedure B shall be accepted as the true value.
2. Principle

2.1. Procedure A

The sample is extracted with light petroleum. The solvent is distilled off and the residue dried and weighed.
2.2. Procedure B
The sample is treated under heating with hydrochloric acid. The mixture is
cooled and filtered. The residue is washed and dried and submitted to the determination according to Procedure A.
3. Reagents
3.1. Light petroleum, boiling range: 40 to 60 ºC. The bromine value must be less than 1 and the residue on evaporation less than 2 mg/100 ml.
3.2. Sodium sulfate, anhydrous.
3.3. Hydrochloric acid, c = 3 mol HCl/l
3.4. Filtration aid, e.g. Kieselguhr, Hyflo-supercel.
4. Apparatus
4.1. Extraction apparatus. If fitted with a siphon (Soxhlet apparatus), the reflux rate should be such as to produce about 10 cycles per hour; if of the non-siphoning type, the reflux rate should be about 10 ml per minute.
4.2. Extraction thimbles, free of matter soluble in light petroleum and having a porosity consistent with the requirements of point 4.1.
4.3. Drying oven, either a vacuum oven set at 75 ºC ± 3 ºC or an air-oven set at 100
ºC ± 3 ºC.
5. Procedure
5.1. Procedure A (see point 8.1)

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Weigh 5 g of the sample to the nearest 1 mg, transfer it to an extraction thimble (4.2) and cover with a fat- free wad of cotton wool. Place the thimble in an extractor (4.1) and extract for six hours with light petroleum (3.1). Collect the light petroleum extract in a dry, weighed flask containing fragments of pumice stone 1.
Distil off the solvent. Dry the residue maintaining the flask for one and a half hours in the drying oven (4.3). Leave to cool in a desiccator and weigh. Dry again for 30 minutes to ensure that the weight of the oils and fats remains constant (loss in weight between two successive weighings must be less than 1 mg).
5.2. Procedure B
Weigh 2,5 g of the sample to the nearest 1 mg (see point 8.2), place in a
400 ml beaker or a 300 ml conical flask and add 100 ml of hydrochloric acid (3.3) and fragments of pumice stone. Cover the beaker with a watch
glass or fit the conical flask with a reflux condenser. Bring the mixture to a gentle boil over a low flame or a hot-plate and keep it there for one hour. Do not allow the product to stick to the sides of the container.
Cool and add a quantity of filtration aid (3.4) sufficient to prevent any loss of oil and fat during filtration. Filter through a moistened, fat-free, double filter paper. Wash the residue in cold water until a neutral filtrate is obtained. Check that the filtrate does not contain any oil or fats. Their presence indicates that the sample must be extracted with light petroleum, using Procedure A, before hydrolysis.
Place the double filter paper containing the residue on a watch glass and dry for one and a half hours in the air oven (4.3) 100 ºC ± 3 ºC.
Place the double filter paper containing the dry residue in an extraction thimble (4.2) and cover with a fat- free wad of cotton wool. Place the thimble in an extractor (4.1) and proceed as indicated in the second and third paragraphs of point 5.1.
6. Expression of result
Express the weight of the residue as a percentage of the sample.
7. Repeatability
The difference between the results of two parallel determinations carried out on the same sample by the same analyst should not exceed:

1 Where the oil or fat has to undergo subsequent quality tests, replace the fragments of pumice stone by glass beads.

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— 0,2 % in absolute value, for contents of crude oils and fats lower than 5 %,

— 4,0 % relative to the highest result for contents of 5 to 10 %,

— 0,4 % in absolute value, for contents above 10 %.
8. Observations
8.1. For products with a high content of oils and fats, which are difficult to crush or unsuitable for drawing a homogeneous reduced test sample, proceed as follows.
Weigh 20 g of the sample to the nearest 1 mg and mix with 10 g or more of anhydrous sodium sulfate (3.2). Extract with light petroleum (3.1) as indicated in point 5.1. Make up the extract obtained to 500 ml with light petroleum (3.1) and mix. Take 50 ml of the solution and place in a small, dry, weighed flask containing fragments of pumice stone 1.
Distil off the solvent, dry and proceed as indicated in the last paragraph of point
5.1.
Eliminate the solvent from the extraction residue left in the thimble, crush the residue to a fineness of 1 mm, return it to the extraction thimble (do not add sodium sulfate) and proceed as indicated in the second and third paragraphs of point 5.1.
Calculate the content of oils and fats as a percentage of the sample by using the following formula:
(10 a + b) × 5 where:
a = mass in grams of the residue after the first extraction (aliquot part of the extract),
b = mass in grams of the residue after the second extraction.
8.2. For products low in oils and fats the test sample may be increased to 5 g.
8.3. Pet foods containing a high content of water may need to be mixed with anhydrous sodium sulfate prior to hydrolysis and extraction as per Procedure B.

1 Where the oil or fat has to undergo subsequent quality tests, replace the fragments of pumice stone by glass beads.

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8.4. In paragraph 5.2 it may be more effective to use hot water in place of cold water to wash the residue after filtration.
8.5. The drying time of 1,5 h may need to be extended for some feedingstuffs.
Excessive drying should be avoided as this can lead to low results. A
microwave oven can also be used.
8.6. Pre-extraction by Procedure A prior to hydrolysis and re-extraction by
Procedure B is recommended if the crude oil/fat content is greater than 15
%. To some extent this depends on the nature of the feedingstuff and the nature of the oil- fat in the feedingstuff.

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