Feed additive for aquaculture as well as preparation method and application of feed additive

Abstract

The invention belongs to the technical field of aquaculture, and particularly relates to a feed additive for aquaculture as well as a preparation method and application of the feed additive. The preparation method of the feed additive comprises the following steps: (1) weighing the raw material medicines, adding water for soaking, boiling with strong fire, then decocting with slow fire, and collecting first filtrate and first filter residues; (2) adding water into the first filter residue, boiling with strong fire, decocting with slow fire, collecting a second filtrate, and concentrating to obtain a traditional Chinese medicine composition extracting solution; (3) adding yeast powder, peptone, dipotassium phosphate, inositol galactoside and 1, 3-diphosphoglyceric acid into the traditional Chinese medicine composition extracting solution to obtain a fermentation culture medium; and (4) inoculating the lactobacillus fermentum liquid and the bacillus subtilis liquid into the fermentation culture medium for fermentation to obtain a fermentation mixture, and performing centrifugation and freeze drying to obtain the lactobacillus fermentum and bacillus subtilis compound feed. The feed additive for aquaculture is added into feed, so that the growth and development capability of animals can be effectively promoted, the immunocompetence of the animals is improved, and the feed additive has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of aquaculture, and in particular relates to a feed additive for aquaculture, a preparation method thereof and an application thereof. Background Art

[0002] In the early days of aquaculture, fish were stocked at low densities, creating a relatively friendly environment for growth and a low incidence of disease and mass mortality. However, with the continuous improvement of aquaculture standards and the rapid expansion of aquaculture density and scale, the aquaculture environment has deteriorated and aquatic animal diseases have become more frequent. This not only increases aquaculture costs but also poses severe challenges to the sustainable and green development of aquaculture. Therefore, the development of non-toxic, harmless, and residue-free feed additives with multiple bioactive properties has become a critical need in the industry.

[0003] Feed additives are substances added to feed in small or trace amounts to enhance animal growth performance, improve feed utilization, strengthen immunity, and prevent disease. With the rapid development of the aquaculture industry, research on feed additives has received increasing attention. Since chemical drugs and antibiotics are often used as additives in feed, they can not only cause bacterial resistance but also pollute the environment. Furthermore, drug residues in animals can pose a threat to human health. Therefore, there is increasing interest in developing new, healthy, and green feed additives that can improve the quality of aquatic animals.

[0004] In recent years, probiotics, a class of active microorganisms that benefit their hosts, have gained popularity in aquaculture due to their diverse benefits. Research has shown that probiotics can enhance the immunity of aquatic animals, improve aquaculture water quality, increase feed utilization, and promote growth, offering broad application prospects as feed additives.

[0005] Based on the above objectives, the present invention provides a feed additive for aquaculture and its preparation method and application, aiming to solve the problems existing in the technology and meet the industry's pursuit of green and efficient feed additives. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the primary purpose of the present invention is to provide a method for preparing a feed additive for aquaculture.

[0007] A second object of the present invention is to provide a feed additive for aquaculture.

[0008] The third object of the present invention is to provide use of a feed additive for aquaculture in preparing feed.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] In order to achieve the above object, the technical solution adopted by the present invention is:

[0011] A method for preparing a feed additive for aquaculture, comprising the following steps:

[0012] (1) Weighing the raw materials of Astragalus, Sophora flavescens, Isatis indigotica, and Licorice, crushing and sieving, soaking in water, boiling over high heat, then decocting over low heat, filtering and centrifuging after stopping the heat, and collecting the first filtrate and the first filter residue;

[0013] (2) adding water to the first filter residue obtained in step (1), boiling over high heat, then decocting over low heat, filtering and centrifuging after stopping the heat, collecting the second filtrate, combining the first filtrate and the second filtrate, and concentrating to obtain a Chinese medicine composition extract;

[0014] (3) adding yeast powder, peptone, dipotassium hydrogen phosphate, galactinol, and 1,3-diphosphoglyceric acid to the extract of the traditional Chinese medicine composition obtained in step (2), and sterilizing to obtain a fermentation medium;

[0015] (4) inoculating the fermentation medium of step (3) with the fermentation bacteria liquid and the Bacillus subtilis bacteria liquid to obtain a fermentation mixture, and freeze-drying the mixture.

[0016] Preferably, in step (3), the mass of the yeast powder is 0.3-0.5% of the mass of the Chinese medicine composition extract, the mass of the peptone is 0.5-1.5% of the mass of the Chinese medicine composition extract, the mass of the dipotassium hydrogen phosphate is 0.5-2.5% of the mass of the Chinese medicine composition extract, the mass of the inositol galactosidase is 0.5-1.0% of the mass of the Chinese medicine composition extract, and the mass of the 1,3-diphosphoglyceric acid is 0.1-0.3% of the mass of the Chinese medicine composition extract.

[0017] Preferably, the weight proportions of the raw materials in step (1) are: 20-30 parts of Astragalus, 25-35 parts of Sophora flavescens, 10-15 parts of Isatis indigotica, and 3-8 parts of Licorice; the amount of water added in step (1) is 4-8 times the total weight of the raw materials, the soaking time in water is 2-4 hours, and the simmering time is 40-60 minutes.

[0018] Preferably, the amount of water added in step (2) is 4-8 times the weight of the first filter residue, the soaking time in water is 2-4 hours, the simmering time is 40-60 minutes, and the density of the concentrated solution after concentration is 1.1-1.3 g / mL.

[0019] Preferably, the specific steps of preparing the fermented Lactobacillus liquid in step (4) are: inoculating the fermented Lactobacillus into MRS liquid culture medium at a rate of 4-5 v / v% and culturing for 24-48 hours; the specific steps of preparing the Bacillus subtilis liquid are: inoculating the Bacillus subtilis into LB liquid culture medium at a rate of 4-5 v / v% and culturing for 12-22 hours; the effective viable counts of the fermented Lactobacillus liquid and the Bacillus subtilis liquid are both 3-5×10 8 CFU / mL.

[0020] Preferably, in step (4), the fermentation Lactobacillus liquid, the Bacillus subtilis liquid and the fermentation medium are inoculated at a volume ratio of 5:(5-8):100; the fermentation temperature is 35-40° C.; and the fermentation time is 2-4 days.

[0021] A feed additive for aquaculture is prepared according to the above-mentioned method for preparing the feed additive for aquaculture.

[0022] According to the above-mentioned application of the feed additive for aquaculture in preparing feed.

[0023] Preferably, the feed comprises a basic feed and a feed additive; based on the total weight of the basic feed, the amount of the feed additive is 2-4% of the weight of the basic feed.

[0024] Compared with the prior art, the beneficial effects of the present invention are mainly:

[0025] The feed additive for aquaculture of the present invention is developed from a fermentation medium through probiotic fermentation. By adding inositol galactoside and 1,3-diphosphoglyceric acid to the fermentation medium, the effective viable count of Bacillus subtilis and Lactobacillus fermentum in the fermentation mixture is increased. The probiotics and the Chinese medicine composition synergize with each other to enhance the efficacy of the Chinese medicine composition and promote the growth and development of animals. The test results show that adding the feed additive for aquaculture to feed can effectively promote the growth and development ability of animals, increase the content of T-SOD in animal serum, and reduce the content of MDA in animal serum, thereby enhancing the body's immune capacity. The feed additive for aquaculture is green and non-toxic, meets food safety requirements, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the content of T-SOD in crucian carp serum;

[0027] Figure 2 is the MDA content in crucian carp serum. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be further described below in conjunction with specific embodiments. However, it should be understood by those skilled in the art that the following examples are only intended to illustrate the present invention and should not be construed as limiting the present invention. Specific conditions not specified in the examples are to be followed according to conventional conditions or the conditions recommended by the manufacturer. All reagents or instruments used, unless otherwise specified, are conventional products obtained from commercial channels.

[0029] The fermented lactobacillus used in the present invention is fermented lactobacillus SYSU-ZG3 with the accession number of CGMCC No. 21381;

[0030] The Bacillus subtilis used in the present invention is Bacillus subtilis JLCC513, and its preservation number is CGMCC No.20625.

[0031] Example 1

[0032] A method for preparing a feed additive for aquaculture, comprising the following steps:

[0033] (1) Weigh 25 parts of Astragalus, 30 parts of Sophora flavescens, 12 parts of Isatis indigotica, and 5 parts of Glycyrrhiza uralensis, crush and sieve, and soak in water for 3 hours. The amount of water added is 6 times the total weight of each raw material. Boil over high heat and then simmer over low heat for 50 minutes. After stopping the heat, filter and centrifuge to collect the first filtrate and the first filter residue.

[0034] (2) adding water to the first filter residue obtained in step (1) and soaking the mixture for 3 hours, wherein the amount of water added is 6 times the total weight of the first filter residue, boiling the mixture over high heat and then decocting the mixture over low heat for 50 minutes, filtering and centrifuging the mixture after stopping the heat, collecting the second filtrate, combining the first filtrate and the second filtrate; concentrating the filtrate to a density of 1.2 g / mL to obtain a Chinese medicine composition extract;

[0035] (3) adding 0.4% by mass of yeast powder, 1.0% by mass of peptone, 1.5% by mass of dipotassium hydrogen phosphate, 0.7% by mass of galactinol, and 0.2% by mass of 1,3-diphosphoglyceric acid to the extract of the traditional Chinese medicine composition obtained in step (2), and sterilizing to obtain a fermentation medium;

[0036] (4) Lactobacillus fermentum was inoculated into MRS liquid culture medium at a rate of 5 v / v% and cultured for 36 hours to obtain a Lactobacillus fermentum culture solution; Bacillus subtilis was inoculated into LB liquid culture medium at a rate of 5 v / v% and cultured for 17 hours to obtain a Bacillus subtilis culture solution. The effective viable counts of the Lactobacillus fermentum and Bacillus subtilis culture solutions were both 4×10 8 CFU / mL.

[0037] (5) inoculating the fermentation Lactobacillus liquid and the Bacillus subtilis liquid obtained in step (4) with the fermentation medium obtained in step (3) at a volume ratio of 5:7:100, fermenting and culturing at 37° C. for 3 days to obtain a fermentation mixture, and freeze-drying the mixture.

[0038] The present invention also provides a feed additive for aquaculture prepared by the above preparation method.

[0039] Example 2

[0040] A method for preparing a feed additive for aquaculture, comprising the following steps:

[0041] (1) Weigh 20 parts of Astragalus, 25 parts of Sophora flavescens, 10 parts of Isatis indigotica, and 3 parts of Glycyrrhiza uralensis, crush and sieve, and soak in water for 2 hours. The amount of water added is 4 times the total weight of each raw material. Boil over high heat and then simmer over low heat for 40 minutes. After stopping the heat, filter and centrifuge to collect the first filtrate and the first filter residue.

[0042] (2) adding water to the first filter residue obtained in step (1) and soaking the mixture for 2 hours, wherein the amount of water added is 4 times the total weight of the first filter residue, boiling the mixture over high heat and then decocting the mixture over low heat for 40 minutes, filtering and centrifuging the mixture after stopping the heat, collecting the second filtrate, combining the first filtrate and the second filtrate; concentrating the filtrate to a density of 1.1 g / mL to obtain a Chinese medicine composition extract;

[0043] (3) adding 0.3% by mass of yeast powder, 0.5% by mass of peptone, 0.5% by mass of dipotassium hydrogen phosphate, 0.5% by mass of galactinol, and 0.1% by mass of 1,3-diphosphoglyceric acid to the extract of the traditional Chinese medicine composition obtained in step (2), and sterilizing to obtain a fermentation medium;

[0044] (4) Lactobacillus fermentum was inoculated into MRS liquid culture medium at a rate of 4 v / v% and cultured for 24 h to obtain a Lactobacillus fermentum culture solution; Bacillus subtilis was inoculated into LB liquid culture medium at a rate of 4 v / v% and cultured for 12 h to obtain a Bacillus subtilis culture solution. The effective viable counts of the Lactobacillus fermentum and Bacillus subtilis culture solutions were both 3×10 8 CFU / mL.

[0045] (5) inoculating the fermentation Lactobacillus liquid and the Bacillus subtilis liquid obtained in step (4) with the fermentation medium obtained in step (3) at a volume ratio of 5:5:100, fermenting and culturing at 35° C. for 2 days to obtain a fermentation mixture, and freeze-drying the mixture.

[0046] The present invention also provides a feed additive for aquaculture prepared by the above preparation method.

[0047] Example 3

[0048] A method for preparing a feed additive for aquaculture, comprising the following steps:

[0049] (1) Weigh 30 parts of Astragalus, 35 parts of Sophora flavescens, 15 parts of Isatis indigotica, and 8 parts of Glycyrrhiza uralensis, crush and sieve, and soak in water for 4 hours. The amount of water added is 8 times the total weight of each raw material. Boil over high heat and then simmer over low heat for 60 minutes. After stopping the heat, filter and centrifuge to collect the first filtrate and the first filter residue.

[0050] (2) adding water to the first filter residue obtained in step (1) and soaking the mixture for 4 hours, wherein the amount of water added is 8 times the total weight of the first filter residue, boiling the mixture over high heat and then decocting the mixture over low heat for 60 minutes, filtering and centrifuging the mixture after stopping the heat, collecting the second filtrate, combining the first filtrate and the second filtrate; concentrating the filtrate to a density of 1.3 g / mL to obtain a Chinese medicine composition extract;

[0051] (3) adding 0.5% by mass of yeast powder, 1.5% by mass of peptone, 2.5% by mass of dipotassium hydrogen phosphate, 1.0% by mass of galactinol, and 0.1-0.3% by mass of 1,3-diphosphoglyceric acid to the extract of the traditional Chinese medicine composition obtained in step (2), and sterilizing to obtain a fermentation medium;

[0052] (4) Lactobacillus fermentum was inoculated into MRS liquid culture medium at a rate of 5 v / v% and cultured for 48 h to obtain a Lactobacillus fermentum culture solution; Bacillus subtilis was inoculated into LB liquid culture medium at a rate of 5 v / v% and cultured for 22 h to obtain a Bacillus subtilis culture solution. The effective viable counts of the Lactobacillus fermentum and the Bacillus subtilis culture solution were both 5×10 8 CFU / mL.

[0053] (5) inoculating the fermentation Lactobacillus liquid and the Bacillus subtilis liquid obtained in step (4) with the fermentation medium obtained in step (3) in a volume ratio of 5:8:100, fermenting and culturing at 40° C. for 4 days to obtain a fermentation mixture, and freeze-drying the mixture.

[0054] The present invention also provides a feed additive for aquaculture prepared by the above preparation method.

[0055] Comparative Example 1

[0056] The difference between Comparative Example 1 and Example 1 is that inositol galactoside in the fermentation medium prepared in step (3) is replaced by inositol, and the rest is the same as Example 1.

[0057] Comparative Example 2

[0058] The difference between Comparative Example 2 and Example 1 is that 1,3-diphosphoglyceric acid is omitted from the fermentation medium components prepared in step (3), and the rest are the same as in Example 1.

[0059] Comparative Example 3

[0060] The difference between Comparative Example 3 and Example 1 is that inositol galactoside is omitted from the fermentation medium components prepared in step (3), and the rest are the same as in Example 1.

[0061] Test Example 1

[0062] Effects of different fermentation media on viable cell counts

[0063] The dilution plate method was used to determine the effect of different fermentation media on the number of viable bacteria. The specific steps are as follows: After centrifuging the fermentation mixture prepared in Example 1-3 and step (5) of Comparative Example 1-3, the precipitate was gradiently diluted with sterile physiological saline, and the dilution was spread on an MRS plate. Three parallel plates were made for each dilution, and the plates were cultured at 37°C for 48 hours. The plates with colony counts of 30-300 CFU were selected for counting and the total number of viable bacteria was calculated. The number of viable bacteria was calculated using the following formula: Total number of viable bacteria (CFU / mL) = [average number of colonies × dilution factor] / coating volume (mL). The results are shown in Table 1, which are the results of the determination of the total number of viable bacteria in the fermentation broth.

[0064] Table 1 Determination of total viable bacteria in fermentation broth

[0065]

[0066] As can be seen from Table 1, compared with the comparative examples 1-3, the total number of viable bacteria in the feed additives for aquaculture prepared in Examples 1-3 of the present invention is higher. This indicates that galactoinositol and 1,3-diphosphoglyceric acid are important components in the fermentation medium and play a key role in microbial fermentation, significantly increasing the total number of viable bacteria of Lactobacillus fermentum and Bacillus subtilis in the fermentation mixture. Among them, the total number of viable bacteria in the fermentation mixture prepared in Example 1 was the highest, at 8.74×10 9 CFU / mL. This indicates that galactinol and 1,3-diphosphoglycerate synergistically activate the primary metabolism of microorganisms by providing efficient carbon sources, energy carriers, and key metabolic intermediates, thereby significantly promoting the proliferation of Lactobacillus fermentum and Bacillus subtilis.

[0067] Test Example 2

[0068] Effects of different feed additives on the growth performance of crucian carp:

[0069] The following is an effect test of the feed additive for aquaculture obtained from Examples 1-3 and Comparative Examples 1-3:

[0070] (1) Seventy crucian carps weighing approximately 6 g were randomly divided into a control group, Example 1 group, Example 2 group, Example 3 group, Comparative Example 1 group, Comparative Example 2 group, and Comparative Example 3 group, with 10 fish in each group. The experimental crucian carps were in good health. Example 1 group: 3% of the weight of the basic feed was added to the basic feed of the feed additive prepared in Example 1; Control group: No feed additive for aquaculture was added to the basic feed during the feeding process, and the other contents of the feeding feed were the same as those of Example 1 group; The remaining groups added 3% of the weight of the basic feed of the corresponding group of feed additives for aquaculture to the basic feed. Each group was fed 3 times a day until full, and the feeding was continued for 30 days; the basic feed formula of crucian carp, in terms of mass percentage, included the following raw materials: 50% corn, 10% bran, 30% soybean meal, 5% fish meal, 2% shrimp shell powder, 1% vitamin premix, 1% calcium carbonate, and 1% salt. Weigh the fish, record the average initial weight (g / tail), the average final weight (g / tail), and calculate the weight gain rate (%). The results are shown in Table 1.

[0071] Table 1 Effects of different feed additives on the growth performance of crucian carp

[0072] Group Average starting weight (g / tail) Average final weight (g / tail) Weight gain rate (%) control group 6.02±0.04 18.89±0.06 213.79 Example 1 6.13±0.05 23.90±0.04 289.89 Example 2 6.09±0.03 23.73±0.07 289.66 Example 3 6.17±0.04 23.81±0.08 285.90 Comparative Example 1 5.98±0.04 22.21±0.06 271.40 Comparative Example 2 6.07±0.06 21.81±0.05 259.31 Comparative Example 3 5.96±0.02 20.87±0.06 250.17

[0073] The results are shown in Table 1, which shows the effects of feeding different feed additives for aquaculture on the growth performance of crucian carp. As can be seen from Table 1, compared with the comparative examples 1-3, the feed additives for aquaculture prepared in Examples 1-3 can significantly improve the weight gain rate of crucian carp. This shows that the feed additives for aquaculture prepared in Examples 1-3 can effectively promote the growth and development ability of crucian carp, improve the absorption and utilization rate of nutrients, and are of great significance to improving the economic value of fish.

[0074] (2) Continue to raise the fish for 60 days. Select 3 live fish from each group and fast for 1 day. Then collect blood samples from the tail vein with a 1mL heparin syringe. The blood samples are centrifuged at 4000rpm for 10 minutes at 4℃. The supernatant is collected and stored in the refrigerator for analysis of serum-related biochemical indicators. The content of T-SOD (total superoxide dismutase) and MDA (malondialdehyde) in the serum of crucian carp is analyzed using a kit. The results are as follows: Figure 1 、 Figure 2 shown.

[0075] The results are as follows Figure 1 、 Figure 2The following table shows the levels of T-SOD (total superoxide dismutase) and MDA (malondialdehyde) in the serum of crucian carp in different groups. T-SOD is a key enzyme in the body that scavenges superoxide free radicals. It can reduce oxidative damage, maintain the normal activity and proliferation of immune cells, and thus improve immunity. MDA is the main end product of lipid peroxidation, and its content directly reflects the degree of oxidative damage in the body. Figure 1 、 Figure 2 It can be seen that compared with the comparative examples 1-3, the feed additives for aquaculture prepared in the examples 1-3 of the present invention can significantly increase the content of T-SOD in the serum of crucian carp and reduce the content of MDA in the serum of crucian carp, thereby improving the body's immune capacity. This shows that the crucian carp in the examples 1-3 groups can maintain growth and development while also having high immune performance.

[0076] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the same. The basic principles and main features of the present invention have been described above using specific implementation schemes. Modifications or substitutions may be made based on the present invention, but such modifications or substitutions do not detract from the essence of the corresponding technical solutions from the scope of protection claimed by the present invention.

Claims

1. A method for preparing a feed additive for aquaculture, characterized in that: The specific steps are as follows: (1) Weighing the raw materials of Astragalus, Sophora flavescens, Isatis indigotica, and Licorice, crushing and sieving, soaking in water, boiling over high heat, then decocting over low heat, filtering and centrifuging after stopping the heat, and collecting the first filtrate and the first filter residue; (2) adding water to the first filter residue obtained in step (1), boiling over high heat, then decocting over low heat, filtering and centrifuging after stopping the heat, collecting the second filtrate, combining the first filtrate and the second filtrate, and concentrating to obtain a Chinese medicine composition extract; (3) adding yeast powder, peptone, dipotassium hydrogen phosphate, galactinol, and 1,3-diphosphoglyceric acid to the extract of the traditional Chinese medicine composition obtained in step (2), and sterilizing the extract to obtain a fermentation medium; (4) inoculating the fermentation medium of step (3) with the fermentation bacteria liquid and the Bacillus subtilis bacteria liquid to obtain a fermentation mixture, and freeze-drying the mixture.

2. The method for preparing a feed additive for aquaculture according to claim 1, characterized in that: In the step (3), the mass of the yeast powder is 0.3-0.5% of the mass of the Chinese medicine composition extract, the mass of the peptone is 0.5-1.5% of the mass of the Chinese medicine composition extract, the mass of the dipotassium hydrogen phosphate is 0.5-2.5% of the mass of the Chinese medicine composition extract, the mass of the inositol galactoside is 0.5-1.0% of the mass of the Chinese medicine composition extract, and the mass of the 1,3-diphosphoglyceric acid is 0.1-0.3% of the mass of the Chinese medicine composition extract.

3. The method for preparing a feed additive for aquaculture according to claim 1, characterized in that: The weight proportions of the raw materials in step (1) are: 20-30 parts of Astragalus, 25-35 parts of Sophora flavescens, 10-15 parts of Isatis indigotica, and 3-8 parts of Licorice; the amount of water added in step (1) is 4-8 times the total weight of the raw materials, the soaking time in water is 2-4 hours, and the simmering time is 40-60 minutes.

4. The method for preparing a feed additive for aquaculture according to claim 1, characterized in that: In the step (2), the amount of water added is 4-8 times the weight of the first filter residue, the soaking time is 2-4 hours, the simmering time is 40-60 minutes, and the density of the concentrated solution after concentration is 1.1-1.3 g / mL.

5. The method for preparing a feed additive for aquaculture according to claim 1, characterized in that: The specific steps of preparing the fermented Lactobacillus liquid in step (4) are as follows: inoculating the fermented Lactobacillus into MRS liquid culture medium at a rate of 4-5 v / v% and culturing for 24-48 hours; the specific steps of preparing the Bacillus subtilis liquid are as follows: inoculating the Bacillus subtilis into LB liquid culture medium at a rate of 4-5 v / v% and culturing for 12-22 hours; the effective viable counts of the fermented Lactobacillus liquid and the Bacillus subtilis liquid are both 3-5×10 8 CFU / mL.

6. The method for preparing a feed additive for aquaculture according to claim 1, characterized in that: In the step (4), the fermentation lactobacillus liquid, the Bacillus subtilis liquid and the fermentation medium are inoculated at a volume ratio of 5:(5-8):100; the fermentation temperature is 35-40° C.; and the fermentation time is 2-4 days.

7. A feed additive for aquaculture, characterized in that: The feed additive for aquaculture is prepared according to the preparation method of the feed additive for aquaculture according to any one of claims 1 to 6.

8. Use of the feed additive for aquaculture according to claim 7 in preparing feed.

9. Use of the feed additive for aquaculture according to claim 8 in preparing feed, characterized in that: The feed comprises a basic feed and a feed additive; based on the total weight of the basic feed, the amount of the feed additive is 2-4% of the weight of the basic feed.

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