GB/T 22919.11-2024Aquatic feed - Part 11: Formula feed for loach (English PDF)

1 Scope

The document defines the terms and definitions for formula feed for loach, gives the product classification, lays down the technical requirements, the inspection rules and the labelling, packaging, transport, storage and shelf life, and describes the matching sampling and test methods.

It applies to the production and use of formula feed for loach.

3 Terms and definitions

The terms and definitions of GB/T 10647 apply, together with the following.

3.1 Loach: the collective name for fish of the class Osteichthyes, order Cypriniformes, family Cobitidae, genus Misgurnus and genus Paramisgurnus. The note adds that the kinds commonly farmed are Misgurnus anguillicaudatus and Paramisgurnus dabryanus, the latter including the Taiwan loach.

4 Product classification

Products are divided by the growth stage of the loach into fry feed, fingerling feed and grow-out feed.

Table 1 gives the classification, pairing each of the three product classes with the feeding stage expressed as the body weight of the fish being fed, in grams per fish: below 2.5 g for fry feed, from 2.5 g up to but not including 10 g for fingerling feed, and 10 g and above for grow-out feed.

5 Technical requirements

5.1 Appearance and condition. The product is a powder, a crumble, or pellets even in size, uniform in colour and regular in shape. It is free of mould, caking, off-odour and insect infestation.

5.2 Processing quality. Table 2 sets the requirements, in percent, for four product forms: powdered feed, crumbled feed, pelleted feed and extruded pelleted feed. The four items are mixing uniformity expressed as the coefficient of variation CV, powder content, water stability expressed as the loss rate, and moisture. In the extraction several rows of the table carry fewer cells than there are product columns, because cells are merged across forms, so the values cannot be assigned to the product forms with certainty and are not reproduced here.

5.3 Physical and chemical requirements. Table 3 sets the requirements for the three product classes, fry feed, fingerling feed and grow-out feed. The items are crude protein, crude fat, crude fibre, crude ash, total phosphorus, lysine, the ratio of lysine to crude protein, all in percent, and malondialdehyde calculated on the crude fat contained in the feed, in mg/kg. Crude protein is bounded above and below by a range for each of the three classes; the other rows carry fewer cells than there are class columns because cells are merged, so those values are not assigned to classes here.

5.4 Hygiene requirements follow GB 13078.

6 Sampling

Sampling is carried out according to GB/T 14699.1.

7 Test methods

7.1 Appearance and condition: a suitable amount of sample is placed in a clean dry white porcelain tray and assessed by the senses under normal lighting, in a well ventilated place free of off-odours.

7.2 Mixing uniformity as the coefficient of variation: GB/T 5918.

7.3 Powder content: Annex A of NY/T 4128-2022.

7.4 Water stability as the loss rate: Annex C of NY/T 4128-2022, with a soaking time of 5 min for pelleted feed and 20 min for extruded feed.

7.5 Moisture: GB/T 6435 or GB/T 18868, GB/T 6435 being the arbitration method.

7.6 Crude protein: GB/T 6432 or GB/T 18868, GB/T 6432 being the arbitration method.

7.7 Crude fat: GB/T 6433 or GB/T 18868, GB/T 6433 being the arbitration method.

7.8 Crude fibre: GB/T 6434 or GB/T 18868, GB/T 6434 being the arbitration method.

7.9 Crude ash: GB/T 6438.

7.10 Total phosphorus: GB/T 6437.

7.11 Lysine: GB/T 18246.

7.12 Ratio of lysine to crude protein: Annex C of SC/T 1074-2022.

7.13 Malondialdehyde calculated on the crude fat contained in the feed: Annex A of the document.

7.14 Hygiene items: GB 13078.

8 Inspection rules

8.1 Lot: products of one specification made from the same raw materials, to the same production formula, by the same process and under the same production conditions, produced continuously or in one shift, form one lot; a lot does not exceed 120 t.

8.2 Delivery inspection covers appearance and condition, moisture and crude protein.

8.3 Type inspection covers all the items of Clause 5. Under normal production it is carried out at least once every six months. It is also carried out when the product goes into production after being finalized; when the process, the formula or the source of a main raw material changes materially in a way that may affect quality; when production resumes after a stoppage of three months or more; when a delivery inspection result differs materially from the last type inspection result; and when the feed administration authority calls for it.

8.4.1 Where every item inspected passes, the lot passes.

8.4.2 Where any item fails, a doubled sample is drawn afresh from the same lot for re-inspection; if any item still fails, the lot fails. Microbiological items are not re-inspected.

8.4.3 Limit values are judged by the rounded value comparison method of GB/T 8170.

8.4.4 Permitted errors in judging results for moisture, the physical and chemical items and the hygiene items follow GB/T 18823, except for items GB/T 18823 does not cover.

8.4.5 Permitted errors in judging results for powder content and water stability follow Annexes A and C of NY/T 4128-2022, and for malondialdehyde Annex A of the document.

9 Labelling, packaging, transport, storage and shelf life

9.1 Labelling follows GB 10648.

9.2 Packaging materials are clean and hygienic, non-toxic and free of contamination, and resist damp, leakage and tearing.

9.3 Transport vehicles are clean and hygienic; the feed is not loaded or carried together with toxic or harmful goods, and is protected from sun, rain and damage in transit.

9.4 The product is stored in a ventilated dry place, protected from rodents and insects, and not stored together with toxic or harmful goods.

9.5 For unopened packages kept under the packaging, transport and storage conditions above, the shelf life is the one declared on the label.

A Annex A (normative) Determination of malondialdehyde

A.1 Principle: the crude fat in the test portion is extracted with petroleum ether, the malondialdehyde in that crude fat is then extracted with trichloroacetic acid solution, it reacts with thiobarbituric acid to form a pink complex, and the complex is measured by high performance liquid chromatography and quantified against an external standard.

A.2 Reagents. Unless otherwise stated the reagents are analytical grade. Water is grade one to GB/T 6682. Petroleum ether has a boiling range of 30 °C to 60 °C. Acetonitrile is chromatographic grade. Anhydrous sodium sulfate is used. Potassium dihydrogen phosphate solution at 50 mmol/L is made by weighing 6.804 g to 0.001 g, dissolving in water and making up to 1 000 mL. Thiobarbituric acid solution at 0.02 mol/L is made by weighing 0.288 g to 0.001 g into a beaker, adding a suitable amount of water, heating to dissolve, cooling and making up to 100 mL. The mixed trichloroacetic acid solution is made by weighing 75.0 g of trichloroacetic acid and 1.0 g of disodium EDTA to 0.01 g, dissolving in water and diluting to 1 000 mL. The malondialdehyde standard stock solution at 100 micrograms per millilitre is made by weighing 0.315 g to 0.0001 g of 1,1,3,3-tetraethoxypropane, CAS 122-31-6, of purity not below 97 percent, dissolving in water and diluting to 1 000 mL; it is kept at 2 °C to 8 °C and is valid for three months. The intermediate standard solution at 1 microgram per millilitre is made by taking 1 mL of the stock solution and diluting to 100 mL with the mixed trichloroacetic acid solution; it is kept at 2 °C to 8 °C and is valid for two weeks. The standard series is made by taking 0 mL, 1.0 mL, 2.0 mL, 4.0 mL, 8.0 mL and 10.0 mL of the intermediate solution into 50 mL volumetric flasks and making up with the mixed trichloroacetic acid solution, giving mass concentrations of 0, 0.02, 0.04, 0.08, 0.16 and 0.20 micrograms per millilitre; it is made up fresh before use. Quantitative filter paper of the rapid type and a 0.45 micrometre aqueous membrane filter are also used. In the printed text the paragraph making the standard series cites the stock solution reference number rather than the intermediate solution it names in words.

A.3 Apparatus: a high performance liquid chromatograph fitted with a fluorescence detector; an analytical balance accurate to 0.01 g, 0.001 g and 0.0001 g; a reciprocating shaker running at not less than 180 strokes per minute and able to hold 25 °C +/- 1 °C; a thermostatic water bath able to hold 90 °C +/- 1 °C; a refrigerated centrifuge, described in the printed text as having a centrifugal force of not less than 12 000 revolutions per minute; a rotary evaporator; and a vortex mixer.

A.4 Sample: at least 200 g is prepared according to GB/T 20195, ground so that all of it passes a 0.425 mm analytical sieve, mixed well, put into a ground-neck bottle and analysed at once.

A.5.1 Extraction of the crude fat. Two portions are run in parallel. 100 g of the test portion is weighed and wrapped in ten filter paper packets, not tied with degreased cotton thread, and placed in a 500 mL stoppered conical flask; 300 mL of petroleum ether is added to soak the packets, 10 g of anhydrous sodium sulfate is added, nitrogen is passed for 30 s and the flask is stoppered at once. It is shaken on the reciprocating shaker at 25 °C and 180 strokes per minute for 1 h, left to stand 2 min to 3 min, and the extract is transferred to a pear-shaped or round-bottomed flask; the packets are washed once more with 100 mL of petroleum ether, the extracts are combined and rotary evaporated at 35 °C until no more petroleum ether comes off, the residue being the crude fat.

A.5.2 Extraction of the malondialdehyde from the crude fat. Immediately after A.5.1, 1 g of the crude fat is weighed to 0.001 g into a 250 mL stoppered conical flask, exactly 50 mL of the mixed trichloroacetic acid solution is added, the flask is shaken at 25 °C and 180 strokes per minute for 30 min, about 20 mL of the extract is taken into a 50 mL centrifuge tube and centrifuged at 4 °C to 6 °C and 5 000 revolutions per minute for 5 min, and the supernatant is kept.

A.5.3 Derivatization. 5 mL each of the supernatant and of the standard series is pipetted into 25.0 mL colorimetric tubes, 5.0 mL of the thiobarbituric acid solution is added, the tubes are vortexed for 1 min, held in a 90 °C water bath for 20 min, taken out and cooled quickly in an ice water bath, transferred to centrifuge tubes and centrifuged at 4 °C to 6 °C and 12 000 revolutions per minute for 5 min, and 1 mL of the supernatant is passed through the membrane filter, the filtrate being kept.

A.5.4.1 Reference chromatographic conditions: a C18 column 250 mm long, 4.6 mm internal diameter, 5 micrometre particle size, or one of equivalent performance; a mobile phase of acetonitrile and potassium dihydrogen phosphate solution in the volume ratio 18 to 82; a flow rate of 1.0 mL/min; an excitation wavelength of 525 nm; an emission wavelength of 560 nm; an injection volume of 10 microlitres; and a column temperature of 30 °C. In the printed text the mobile phase cites the reference number of the anhydrous sodium sulfate rather than that of the potassium dihydrogen phosphate solution it names in words.

A.5.4.2 The derivatized standard series and the derivatized test solution are run under the best conditions the instrument allows. Figure A.1 shows the liquid chromatogram of the thiobarbituric acid complex of the malondialdehyde standard solution.

A.5.4.3 Identification is by retention time: the retention time of the peak of the malondialdehyde thiobarbituric acid complex in the test solution agrees with that in a standard solution of comparable concentration, within a relative deviation of +/- 2.5 percent.

A.5.4.4 Quantification: a calibration curve is drawn with malondialdehyde concentration on the abscissa and peak area on the ordinate, and its correlation coefficient is not below 0.995. The concentration in the test solution falls inside the linear range of the curve; if it does not, the extract is diluted with the mixed trichloroacetic acid solution, derivatized and measured again. For single point calibration, the concentration of the analyte in the test solution differs from that of the standard solution by not more than 30 percent.

A.6 Calculation. The malondialdehyde content, calculated on the crude fat contained in the test portion, is expressed as the mass fraction in mg/kg. Multi-point calibration uses formula (A.1) and single point calibration formula (A.2). The quantities entering the formulae are the mass concentration of malondialdehyde in the test solution read from the calibration curve in micrograms per millilitre, or in formula (A.2) the peak areas of the complex in the test and in the standard solution together with the mass concentration of the standard solution; the total volume of the extract in millilitres; the dilution factor used where the linear range was exceeded; and the mass of crude fat weighed out in grams. The result is the arithmetic mean of the parallel determinations, kept to three significant figures.

A.7 Precision: the absolute difference between two independent results obtained under repeatability conditions does not exceed 10 percent of their arithmetic mean.

A.8 Figure A.1 shows the liquid chromatogram of the thiobarbituric acid complex of the malondialdehyde standard solution at 0.20 micrograms per millilitre.