NO155723B - PROCEDURE AND CONSERVATIVE FOR THE CONSERVATION OF STRONGLY WATER-FREE ANIMAL SUBSTANCES, SPECIAL FISH ENSILATION. - Google Patents

Description

The present invention relates to a method for the preservation of highly aqueous animal precursors, in particular fish silage, for use in fur animal fodder, by adding one or more organic acids, possibly one or more inorganic acids and an antioxidant, and the peculiarity of the method according to the invention is that 0-5% by weight acetic acid, 0-2% by weight formic acid, 0.01-0.20% by weight polyhexamethylene biguanide, 0 - 0.10% by weight 8-hydroxyquinoline or a salt or complex thereof, 0 -2.5% by weight of phosphoric acid and 0.003-0.030% by weight of antioxidant, although at least 0.2% by weight of formic acid or 0.5% by weight of acetic acid is added, as well as, if no formic acid is present, at least 0.025% by weight 8-Hydroxyquinoline or salt or complex thereof.

The invention also relates to a preservative for use in the aforementioned method and which contains one or more organic acids, possibly one or more inorganic acids and an antioxidant, and the distinctive feature of the preservative according to the invention is that it consists of 0-5 parts by weight Acetic acid, 0-2 parts by weight formic acid, 0.01 - 0.2 parts by weight polyhexamethylene biguanide, 0 - 0.1 parts by weight 8-hydroxyquinoline or a salt or complex thereof, 0 -

2.5 parts by weight of phosphoric acid and 0.003 - 0.03 parts by weight of antioxidant, with at least 0.2 parts by weight of formic acid or 0.5 parts by weight of acetic acid, and, if no formic acid is included, at least 0.025 parts by weight of 8-hydroxyquinoline or a salt or complex hence.

These features of the invention appear from the patent claims.

The present invention can be used for

strongly water-containing precursors such as slaughterhouse waste, special

such as poultry slaughterhouse waste, fish waste and especially fish silage, for use in fur animal feed, especially mink feed, where

where one or more organic acids, possibly one or more inorganic acids and one or more antioxidants are used as preservatives.

It is well known that the upfront costs make up a very significant proportion of the overall operating expenses in fur breeding and ongoing efforts are being made to obtain a sufficiently healthy feed at a relatively reasonable price and with a high degree of security of supply.

In 1981, approx. 230,000 tonnes of finished mink meat, which in round numbers was composed of 100,000 fish waste, 40,000 industrial fish (half sulfuric acid preserved fish silage and half acetic acid preserved and chilled or frozen industrial fish), 16,000 tonnes poultry waste, 25,000 tonnes barley, 10,000 tonnes vitamin and protein mixtures, 5,000 tonnes technical grease and approx. 10,000 tonnes of water.

As can be seen, very significant amounts of fish raw materials are included in the mink feed and a significant problem in this regard is that while fish are caught in all seasons,

however approx. 7 5% in the months of May to October, the large amounts of mold should first be used in increasing quantities from July to December/January, as the mink puppies in this period grow strongly until the beginning of the coat around

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November.

For this reason, it is necessary to store fish raw materials

for long periods, which can either happen by freezing, which becomes very expensive due to the large energy consumption (currently approx. NOK 300/tonne for freezing and approx. NOK 15/tonne/week for frozen storage), or by a -clay which, depending on the preservatives chosen, can be made significantly cheaper (NOK 80-100/tonne when using sulfuric acid).

In practice, the most commonly used preservative for fish silage is sulfuric acid, but practical experience and experiments have shown that sulfuric acid-preserved silage, if you want to be sure of avoiding food strikes in the mink puppies, can only be included in the finished mink feed with up to 15-20%.

A method for preserving fish silage, which made it possible to incorporate larger amounts of fish silage into the mink feed, would therefore have major economic and energy-saving effects.

In the 427th report from the Statens Husdyrbrugsforsøg, Copenhagen 1975 (P.M Jensen and G. Jørgensen: Production and application of fish silage, especially for mink) a detailed review of the literature on the subject and considerable experimental work has been carried out. It has thus been stated, among other things, that there are in principle three different methods for preserving fish and fish waste: 1) Acid preservation, where a low pH is decisive for the product's durability. 2) Sodium bisulphite or other conservation, where anaerobic conditions are achieved. 3) Carbohydrate fermentation, where with the help of present or added microorganisms, acids with sufficient preservative effect are formed from the carbohydrates, which must likewise be added to the fish mass.

Of these methods, sodium bisulphite preservation has been shown to lead to a breakdown of thiamine (vitamin B^), while carbohydrate fermentation has not gained significant popularity, because it has proven very difficult to control the fermentation

in the desired direction. |

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The investigations carried out in the report have therefore concentrated on preservation with sulfuric acid, hydrochloric acid and formic acid as the main components. Experiments have been carried out in the presence and absence of antioxidants to counter the rancidity of the fat fraction of the silage, as well as where acetic acid, formic acid, sorbic acid, citric acid, hexamethylenetetramine and sodium benzoate were investigated as auxiliary preservatives.

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The investigations showed that both sulfuric acid (2.5%), hydrochloric acid (5.5%) and formic acid (2-2.2%) over an experimental period of 3 months showed satisfactory preservation against bacteria and fungi, and that the presence of antioxidase A preservative was needed to protect the fat from rancidity. However, the growth trials showed that

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Formic acid-preserved silages are not good in the amounts used (2.0-2.2% formic acid calculated on the silage) which was added to the base in amounts of 24.5% of the finished

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for. The experiments showed that the untested sulfuric acid and hydrochloric acid silages gave satisfactory growth,

but it is recommended to lower the amount of silage to 15-20%

off the feed if you want to avoid hunger strikes. However, the growth trials were of such a short duration (2 weeks) that the results achieved must be taken with a certain reservation.

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It later turned out that the information regarding the sulfuric acid preservation was too optimistic and in Notice No. 139 of 13 October 1976 from the National Animal Husbandry Experiment it is recommended to use 3% sulfuric acid, 0.6% acetic acid, 0.01 % citric acid and 0.015% ethoxyquin (antioxidant).

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It has, however, shown that even "preserved mink fodder with this mixture in the aforementioned 15-20% has in a number of cases led to hunger strikes or has caused

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a disturbance of the animal's acid-base balance with a fatal acidosis as a result. Investigations seem to show that a critical lower limit is pH 5.5 in the finished feed, which depends on the feed's other components and limits the usable amount of fish silage.

Similar observations have been made by Austreng et al. "Acid preservation of forfish", Norsk Fiskeopprett 1979, no.

1, pages 4-7, which has examined the preservation ability of different amounts of sulfuric acid and formic acid as well as mixtures of sulfuric acid and formic acid or acetic acid, to which in all cases 0.067% antioxidant (BHT) and 0.2% sorbic acid had been added, with a view to utilization of fish silage for fish feed or fur animal feed. The conclusion was that there are no insurmountable problems with storing acid-preserved forfish for up to 1 year when suitable amounts of acid and mixtures are used. In general, 25% sulfuric acid, 2.0% sulfuric acid + 1.0% acetic acid, 1.5% formic acid and 1.5% sulfuric acid + 0.5% formic acid were the weakest mixtures that persisted throughout the experiment. However, the authors state that it is difficult to decide from these results which acid addition is preferable, and that it is also a question of what the fish that will consume the feed want and can tolerate. This of course also applies to fur animals, and it is said here that using more than 10-15% acid-preserved forfish can cause difficulties.

For the sake of completeness, it should be mentioned that short-term preservation of finished fur for mink with organic acids has also been used, K. Frøysedal, Norsk Pelsdyrblad no. 51, 1973, pages 309-313 has thus demonstrated that formic acid in concentrations of over 0.2% of finished food has a negative effect on appetite and thus growth. 0.2% formic acid + 0.2% acetic acid gives a better result, while acetic acid is tolerated in amounts of up to 1%. These amounts are sufficient to preserve the finished food for 2-3 days. However, the examined finish is not based

on fish silage.

In summary, it can be said that at the present time there is no satisfactory combination of preservatives, which both enables a suitable long-term conservation of highly water-containing animal precursors, as illustrated above with fish silage, and enables the incorporation of the precursors in fur animal fodder in larger quantities than 10-15% without risk to the animals.

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The purpose of the present invention is to satisfy these purposes or, more precisely, to provide a preservation method and a preservative for highly aqueous animal feedstuffs, in particular fish silage, based on a combination of preservatives which

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a) ensures a satisfactory storage stability over a long period of time at the ambient temperature, which requires a reasonably broad-spectrum biocide or bio-static effect of the included preservatives towards microorganisms,

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b) enables the use of the precursor in question in quantities of up to 40% or more of the total precursor mixture, which in turn assumes that

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ba) the prepared premix exhibits a taste satisfactory to the fur animals and non-toxicity,

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bb) premixes give the animals satisfactory growth,

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bc) the mixture does not adversely affect the quality of the animal's fur.

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In the development of the invention, it has been chosen to take as a point of departure the tried-and-tested acid preservation in the near-

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be of an antioxidant, based on the hypothesis that the recognized disadvantages of acid preservation could perhaps be remedied by a closer definition of the nature and amount of the acid or acid mixture included as well as the selection of one or more additional preservatives that could reinforce or supplement the acid provided by brought a preservative effect, whereby the acids could be reduced to "excipients".

That this hypothesis could be confirmed could not be expected in advance, as the previously carried out experiments with widely used preservatives such as sodium bisulphite, citric acid, hexamethylenetetramine, sodium benzoate and sorbic acid as a supplement to acid preservation had not proved too encouraging.

In order to establish suitable combinations of organic acids, inorganic acids and microbiocides, indicative taste and pre-absorption experiments were carried out with varying amounts of each of the acids acetic acid, formic acid, propionic acid, phosphoric acid and sulfuric acid in a standard mink feed and reached on the basis of measurements of acid uptake, acid content in forage and fertilisation/urine and the calculated amount of acid excreted from this in relation to the acid uptake up to the following indicative maximum acid content before reduction of forage uptake.

Among approx. 200 commercially available microbiocides

was it on the basis of<y> toxicological data and effect-

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spectra selected approx. 40 microbiocides or groups of structurally or functionally related microbiocides. A number of the biocides had previously been thoroughly tested, cf. above-mentioned literature sources, while the others had not previously been mentioned in connection with mink fodder.

These were then reduced to approx. 20, which was subjected to a detailed analysis for preservative effect alone or in mixture with organic and/or inorganic acids. On the basis of these investigations, 6 agents were subjected to indicative taste tests. After continued conservation trials on a larger scale, the range of biocides that could be used was limited to

"Chinosol" which is s-hydroxyquinoline sulfate, as well as the corresponding acetate, propionate and complexes thereof with zinc and copper,

"Vantocil IB" which is a 20% aqueous solution of polyhexamethylene biguanide hydrochloride, as well as

Sodium bisulphite.

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With a view to an indicative sorting of these three biocides for the formulation of mixtures for subsequent taste tests, microorganisms/g in 1 kg of chopped small herring were examined immediately after the addition of the following four mixtures on the basis of 0.5% formic acid, 1.5% acetic acid and 75 ppm BHA and after a 2 1/2 week grace period:

With the above-mentioned three biocides in a mixture with different acids and antioxidants, a series of taste tests were carried out which did not distinguish any of the three candidates, but in terms of taste spoke in favor of sodium bisulphite.

It was therefore decided to subject all three biocides to growth trials in a mixture with different acids and at the same time investigate the preservative effect on the very large quantities of silage that were necessary for the growth trials. On the basis of the initial trials with chopped small herring, it was decided to place the main emphasis on "Vantocil".

Although there is great concern with application

of sodium bisulphite due to its thiamine-degrading effect, the additional sodium supply and the difficult handling of the substance, it was however hoped that at least the preservative effect would be sufficient, which however did not prove to be the case, at least not in the mixture used was 1.4% phosphoric acid, 1.5% acetic acid, 1.0% sodium bisulfite and 0.02% ethoxyquin. Also for this reason, sodium bisulphite therefore had to be rejected as a biocide.

8-Hydroxyquinoline was examined in the form of the copper complex, which, however, in an amount of 0.05% in mixture with 1.4% phosphoric acid, 1.0% formic acid and 0.02% ethoxyquin gave an insufficient preservative effect. As it did not meet the expectations for the increase, as man

expected on the basis of copper's growth-promoting effect on pigs, it was also based on the subsequent production trials.

Alongside the growth trials, micro-organism count determinations were made in the 12 fish silages and the one poultry silage that were used. The results appear in the following table.

It can be seen from the bacterial count determinations, which were carried out respectively under practical conditions (outdoor temperature at the test sites) and after storage at 25°C, that a number of the examined mixtures, especially mixture 1, 2, 10, 12 and 12a, show a particularly good shelf life. Growth trials carried out by the National Livestock Experiment showed that the investigated silages were biologically suitable as an addition to minkfsr.

Experiments have also been carried out with the durability of finished mink feed mixed with varying amounts of fish silage. Below is the result for silage preserved with mixture 2.

It can be seen that silage preserved in accordance with the invention also results in an improved durability of the finished pre-mix. In practice, a shelf life of 2 days will be sufficient.

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Later, production trials with groups of 25 mink and subsequent killing<1> and examination of the fur quality gave the following results (relative fur quality compared to control = 100) j

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The experiments showed no effect on skin size and only a small effect on the animals' weight.

On the basis of the extensive investigations, it had to be con-

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it is concluded that the only one of the numerous theoretically applicable biocides, which used as the only microbiocide in combination with organic acids and an antioxidant fulfilled the purpose of the invention "Vantocil IB", which

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is a cationic biocide sold by ICI based on polyhexamethylene biguanide hydrochloride. That this very product, which is a well-suited spectrum disinfectant i

should be particularly suitable, was surprising due to the fact that it is stated by the dealer to be poorly compatible with proteins and is proposed to be limited to non-ionic and cationic systems.

The agent has so far been used in particular for rinsing beer glasses, short-term preservation of hides and for use in swimming pool meadows.

Another biocide which can be used in the invention to supplement "Vantocil" is 8-hydroxyquinoline or salts, such as sulphate, acetate, propionate or complexes thereof, especially with copper or zinc.

The preferred organic acid, if only a single acid is used, is formic acid. Due to the previous observations regarding mink rejection of food with too high a formic acid content, however, depending on the required preservation time, it would also be preferable to add acetic acid, which to some extent masks the taste of formic acid.

The use of acetic acid is also beneficial because the acid exhibits a fungicidal effect and further contributes to pH adjustment. Alternatively, an inorganic acid can be added, where phosphoric acid is preferred for physiological reasons, while sulfuric acid or hydrochloric acid can also be used.

In addition to the silage's composition, the concrete choice of acid will also depend on the quantities in which it is to be included in the finished premix, as the disadvantages of formic acid naturally increase with increasing advantage. As far as the amounts used are concerned, it can be said more generally that 0.2% by weight of formic acid represents the practical lower limit for biocidal action, while amounts above 2% are not tolerated by mink. Acetic acid is usable in amounts of 0.5-5%.

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For Vantocil, 100 ppm, calculated as polyhexamethylene biguanide, is the practical lower limit, and you will rarely go over 2000 ppm. A preferred amount is 200-400 ppm.

If 8-hydroxyquinoline or a derivative thereof added is desired, 250-1000 ppm will be suitable. This compound will generally be necessary if formic acid is not used in the preservation.

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As mentioned, in order to avoid rancidity of the fat fraction, it is also necessary that, in the invention, an antioxidant is also used in an amount of 30-300 ppm calculated on the precursor.

Common antioxidants can be used for this, such as ethoxyquin, BHT (tert.butylhydroxytoluene), BHA (tert.butylhydroxyanisole) or TBHQ (tert.butylhydroquinoline). However, the invention is not limited to the use of these antioxidants.

The quantities used depend on the composition of the precursor and the antioxidant used, but 150-300 ppm will usually be sufficient.

The invention has been explained above in particular in relation to the preservation of fish silage and poultry pulp for use in mink feed. However, the invention also finds application in connection with other water-containing animal precursors, such as slaughterhouse waste and blood, and in connection with food for other fur-bearing animal species, such as fox, marten, chincilla, otter, beaver, etc. and other domestic animal species, as the expert based on knowledge of the animals' dietary habits, the nature and composition of the precursors, etc., by means of experiments according to the above guidelines, the most suitable preservative mixtures can be determined.

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Claims (2)

1. Method for the preservation of highly aqueous animal precursors, especially fish silage, for use in fur animal feed, by adding one or more organic acids, possibly one or more inorganic acids and an oxidizing agent, characterized by the addition of 0-5% by weight acetic acid, 0-2% by weight formic acid, 0.01 - 0.20% by weight polyhexamethylene biguanide, 0 - 0.10% by weight 8-hydroxyquinoline or a salt or complex thereof, 0-2.5% by weight of phosphoric acid and 0.003-0.030% by weight of antioxidant, although at least 0.2% by weight of formic acid or 0.5% by weight of acetic acid is added, and if no formic acid is present, at least 0.025% by weight of 8-hydroxyquinoline or salt or complex thereof. 2. Preservative for use in the method as specified in claim 1 and containing one or more organic acids, possibly one or more inorganic acids and an antioxidant, characterized in that it consists of 0 - 5 parts by weight acetic acid, 0-2 parts by weight formic acid, 0.01 - 0.2 parts by weight polyhexamethylene biguanide, 0-0.1 parts by weight 8-hydroxyquinoline or a salt or complex thereof, 0 - 2.5 parts by weight phosphoric acid and 0.003 - 0.03 parts by weight of antioxidant, with at least 0.2 parts by weight of formic acid or 0.5 parts by weight of acetic acid and, if no formic acid is included, at least 0.025 parts by weight of 8-hydroxyquinoline or a salt or complex thereof.