A kind of eucommia leaf fermented extract and its preparation method and application

Abstract

The invention discloses a kind of eucommia leaf fermentation extract and its preparation method and application, and belongs to the technical field of microorganisms and feed additives. With eucommia leaf and wheat bran as substrates, by configuring a specific black aspergillus niger-trichoderma harzianum-saccharomyces cerevisiae complex bacterial liquid as a fermentation agent, a closed fermentation is carried out to make black aspergillus, trichoderma harzianum, and saccharomyces cerevisiae ferment to produce a large amount of cellulase, protease, lipase, amylase and glucosidase, etc., and then by pumping and circulating treatment, the cellulose, protein, starch, beta-glycan and other macromolecular substances in eucommia leaf are further enzymolyzed into protein oligopeptides, monosaccharides, and soluble oligosaccharides that are beneficial to livestock and poultry absorption. The eucommia leaf fermentation extract prepared by the present invention is used as a feed additive for beef cattle feeding, improves the daily weight gain and feed intake of beef cattle, and significantly reduces the feed-to-meat ratio, saves feed consumption, improves the protein content in meat, reduces the fat content, reduces energy, and improves meat quality.

Description

Technical Field

[0001] The invention relates to the technical field of microorganisms and feed additives, and more particularly to a eucommia leaf fermentation extract and a preparation method and application thereof. Background Art

[0002] Antibiotics have been used as feed additives for more than 50 years around the world. Although adding antibiotics to feed can inhibit the growth and reproduction of intestinal pathogens, it can not only prevent the occurrence of diseases, but also promote animal growth rate and feed conversion rate. However, antibiotics in feed can lead to the emergence of drug-resistant strains, which is harmful to the health of humans and animals. The drug resistance of some pathogens has led to almost no drug options for the treatment of diseases caused by the pathogens. It is reported that the rapid spread of drug resistance causes about 23,000 Americans to die each year. In order to avoid the emergence of drug-resistant strains as much as possible, countries around the world not only strictly regulate the use of antibiotics in clinical treatment of humans and animals, but also restrict or prohibit the addition of antibiotics in animal husbandry production, especially in feed.

[0003] Nowadays, people have found that Chinese herbal feed additives not only contain a variety of natural nutrients, such as vitamins, minerals and other trace elements, but also contain special antibacterial substances. While preventing and treating diseases, they can promote animal growth and enhance immunity. They are very important alternatives for antibiotic-free feed additives. For example, Eucommia ulmoides leaves contain various nutrients such as crude protein, crude fat, vitamins and amino acids, especially chlorogenic acid, aucubin, geniposide and flavonoids, which have antibacterial, anti-inflammatory, antiviral, antioxidant and white blood cell elevating functions, and have no toxic side effects. They are ideal functional feeds, which have significant effects on improving the immunity of livestock, poultry and fish, reducing the use of antibiotics, and improving the quality of meat and eggs.

[0004] However, the existing technology has insufficiently developed and utilized Eucommia leaves. For example, improper selection of fermentation agents or unreasonable extraction processes lead to low raw material utilization and low content of beneficial ingredients. Therefore, developing suitable fermentation agents and optimizing fermentation processes are of great significance to the fermentation production of Eucommia leaves. Summary of the invention

[0005] In view of the above problems, the present invention provides a eucommia leaf fermentation extract and a preparation method and application thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for preparing a eucommia leaf fermentation extract comprises the following steps:

[0008] (1) mixing the eucommia leaf powder and wheat bran in a mass ratio of 100:1.0-1.2, adding water (50-60% by mass of the eucommia leaf powder) and a composite bacterial solution of Aspergillus niger-Trichoderma harzianum-Saccharomyces cerevisiae (5-6% by mass of the eucommia leaf powder) in sequence, mixing and fermenting in a closed manner for 5-6 days;

[0009] (2) adding 5 times the mass of water of Eucommia leaf powder to the material after fermentation in step (1), pumping and circulating for 4-6 hours, reflux extraction twice, and combining the two filtrates;

[0010] (3) using a reverse osmosis membrane to concentrate the combined filtrate obtained in step (2) and collect the retentate;

[0011] (4) performing low-temperature vacuum concentration and spray drying on the retentate collected in step (3), collecting the dried solid product, crushing it, and sieving it to obtain the fermentation extract of Eucommia fallen leaves.

[0012] Preferably, in the composite bacterial solution of step (1), the number of viable bacteria of Aspergillus niger is 200 cfu / g, the number of viable bacteria of Trichoderma harzianum is 400 cfu / g, and the number of viable bacteria of Saccharomyces cerevisiae is 200 cfu / g.

[0013] Preferably, the conditions for the closed fermentation in step (1) are: compacting and covering in the fermentation tank, fermenting at a temperature of 25-35° C., and ventilating once a day for 30 minutes each time.

[0014] Fermentation of Aspergillus niger, Trichoderma harzianum, and Saccharomyces cerevisiae can produce a large amount of cellulase, protease, lipase, amylase, glucosidase, etc.

[0015] Preferably, the flow rate of the pump circulation in step (2) is 100 kg / min, the pump power is 1500 kW, and the processing temperature is 35-45°C.

[0016] The pumping circulation treatment can allow the cellulase, protease, lipase, amylase and glucosidase produced by the above fermentation to continue to contact with the reaction materials for further reaction.

[0017] Cellulase hydrolyzes the cellulose on the cell wall of Eucommia ulmoides fallen leaves, making it easy for the effective ingredients in the cells to be leached out of the cells; protease hydrolyzes a large amount of protein in Eucommia ulmoides fallen leaves and hydrolyzes it into protein oligopeptides, so that the protein that is not conducive to the absorption of livestock and poultry is converted into protein oligopeptides that are conducive to the absorption of livestock and poultry, and the efficacy of protein oligopeptides is fully exerted; amylase hydrolyzes a large amount of starch and β-glycan in Eucommia ulmoides fallen leaves and converts them into monosaccharides and soluble oligosaccharides, converting the starch that is not conducive to the absorption of livestock and poultry into monosaccharides that can be absorbed by livestock and poultry and soluble oligosaccharides with health benefits.

[0018] Preferably, the specific operation of reflux extraction twice in step (2) is: add 3 times the mass of water of Eucommia leaf powder to the material after pump circulation treatment in step (2), reflux extraction at 50-60°C for 3 hours, filter through 200 mesh, and collect the filtrate; continue to add 6 times the mass of water to the remaining residue, reflux extraction at 50-60°C for 2 hours, filter through 200 mesh, and collect the filtrate.

[0019] Preferably, the molecular weight cut-off of the reverse osmosis membrane in step (3) is 100Da, and the concentration pressure is 400-800psi.

[0020] Preferably, the conditions for low-temperature vacuum concentration in step (4) are: 45-55°C, -0.098MPa, and the concentration multiple is 1.20 times.

[0021] Preferably, the inlet air temperature of the spray drying in step (4) is 180-190°C, the outlet air temperature is 90-96°C, and the drying time is 5-10s.

[0022] Preferably, the size of the sieving in step (4) is 80 mesh.

[0023] Another object of the present invention is to provide the use of the eucommia leaf fermentation extract prepared by the above method in feed additives.

[0024] Another object of the present invention is to provide a feed additive comprising the above-mentioned eucommia leaf fermented extract.

[0025] It can be known from the above technical scheme that the present invention discloses a kind of eucommia leaf fermentation extract and its preparation method and application. Using eucommia leaf and wheat bran as substrates, by configuring a specific composite bacterial liquid as a fermentation agent, closed fermentation is carried out to make Aspergillus niger, Trichoderma harzianum, and Saccharomyces cerevisiae ferment to produce a large amount of cellulase, protease, lipase, amylase and glucosidase, etc., and then by pumping and circulating treatment, the cellulose, protein, starch, β-glycan and other macromolecular substances in eucommia leaf are further enzymolyzed into protein oligopeptides, monosaccharides, and soluble oligosaccharides that are beneficial to livestock and poultry absorption. The eucommia leaf fermentation extract prepared by the present invention is used as a feed additive in beef cattle feeding, which improves the daily weight gain and feed intake of beef cattle, significantly reduces the feed-to-meat ratio, saves feed consumption, increases the protein content in meat, reduces fat content, reduces energy, and improves meat quality. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The reagents involved in the embodiments of the present invention are all purchased from commercial channels, and the methods not mentioned are conventional experimental methods and will not be described in detail here.

[0028] The following is an example description:

[0029] Aspergillus niger was purchased from Beijing Huayueyang Biotechnology Co., Ltd., product number: Beijing Huayueyang Biological NRR00430;

[0030] Trichoderma harzianum was purchased from Shandong Changtai Biotechnology Co., Ltd., Trichoderma harzianum T-22 strain;

[0031] Saccharomyces cerevisiae was purchased from Weifang Yihao Biotechnology Co., Ltd.

[0032] The Aspergillus niger, Trichoderma harzianum and Saccharomyces cerevisiae were activated and cultured in accordance with the instructions, and then prepared into bacterial suspensions with a viable count of 800 cfu / g for use.

[0033] Aspergillus niger - Trichoderma harzianum - Saccharomyces cerevisiae composite bacterial liquid: The bacterial suspensions of Aspergillus niger, Trichoderma harzianum and Saccharomyces cerevisiae (the number of live bacteria is 800 cfu / g) are mixed at a volume ratio of 1:2:1, the number of live bacteria of Aspergillus niger and Saccharomyces cerevisiae in the composite bacteria is 200 cfu / g, and the number of live bacteria of Trichoderma harzianum is 400 cfu / g.

[0034] Reverse osmosis membrane (model XKT-100) was purchased from Chengdu Hecheng Filtration Technology Co., Ltd. 。

[0035] Example 1

[0036] A eucommia leaf fermented extract is prepared by the following steps:

[0037] (1) After the dried Eucommia ulmoides leaves were crushed through a 10-mesh sieve, 500 kg of Eucommia ulmoides leaf powder was weighed and put into a mixer together with 5 kg of bran, and then 300 kg of water was added to continue stirring and mixing, and then 25 kg of a mixed bacterial liquid of Aspergillus niger-Trichoderma harzianum-Saccharomyces cerevisiae was added. After stirring, the mixture was transferred to an environmentally friendly fermentation tank, lightly compacted and covered until there were no large gaps between the mixtures, and fermented and cultured at 30° C. for 6 days (during which the fermentation tank was regularly ventilated once a day for 30 minutes each time).

[0038] (2) The material after fermentation in step (1) is transported to an enzymatic hydrolysis extraction tank, 2500 kg of water is added, and enzymatic hydrolysis is carried out at 40° C. for 5 h through a pump circulation system (flow rate 100 kg / min, pump power 1500 kW); 1500 kg of water is continued to be added, and circulating hot reflux extraction is carried out at 55° C. for 3 h, and coarse filtering is carried out through a double filter with a mesh size of 200, and the filtrate is collected; water is continued to be added to the residue at a mass ratio of residue: water = 1:6, and circulating hot reflux extraction is carried out at 55° C. for 2 h, and coarse filtering is carried out through a double filter with a mesh size of 200, and the filtrate is collected, and the filtrates obtained by the two coarse filterings are combined.

[0039] (3) The combined filtrate obtained in step (2) is filtered using a reverse osmosis membrane (molecular weight cut-off 100 Da, concentration pressure 400-800 psi), and the retentate is placed in a low-temperature vacuum concentrator.

[0040] (4) The parameters of the vacuum concentrator were adjusted to 45°C and -0.098 MPa. After concentrating to a specific gravity of 1.20, the mixture was spray dried (inlet air temperature 180°C, outlet air temperature 90°C) for 10 seconds and crushed to 80 mesh to obtain the eucommia leaf fermentation extract.

[0041] Example 2

[0042] A eucommia leaf fermented extract is prepared by the following steps:

[0043] (1) After the dried Eucommia ulmoides leaves were crushed through a 10-mesh sieve, 1000 kg of Eucommia ulmoides leaf powder was weighed and put into a mixer together with 12 kg of bran and stirred evenly, 500 kg of water was added and continued to be stirred and mixed, and 60 kg of a mixed bacterial liquid of Aspergillus niger-Trichoderma harzianum-Saccharomyces cerevisiae was added. After stirring evenly, the mixture was transferred to an environmentally friendly fermentation tank, compacted and covered until there were no large gaps between the mixtures, and fermented and cultured at 35° C. for 5 days (during which the fermentation tank was regularly ventilated once a day for 30 minutes each time).

[0044] (2) The material after fermentation in step (1) is transported to an enzymatic hydrolysis extraction tank, 5000 kg of water is added, and enzymatic hydrolysis is carried out at 35° C. for 6 hours through a pump circulation system (flow rate 100 kg / min, pump power 1500 kW); 3000 kg of water is continued to be added, and circulating hot reflux extraction is carried out at 50° C. for 3 hours, and coarse filtering is carried out through a double filter with a mesh size of 200, and the filtrate is collected; water is continued to be added to the residue at a mass ratio of residue: water = 1:6, and circulating hot reflux extraction is carried out at 50° C. for 2 hours, and coarse filtering is carried out through a double filter with a mesh size of 200, and the filtrate is collected, and the filtrates obtained by the two coarse filterings are combined.

[0045] (3) The combined filtrate obtained in step (3) is filtered using a reverse osmosis membrane (molecular weight cut-off 100 Da, concentration pressure 400-800 psi), and the retentate is placed in a low-temperature vacuum concentrator.

[0046] (4) The parameters of the vacuum concentrator were adjusted to 55°C and -0.098 MPa. After concentrating to a specific gravity of 1.20, the mixture was spray dried (inlet air temperature 185°C, outlet air temperature 96°C) for 5 seconds and crushed through 80 mesh to obtain the eucommia leaf fermentation extract.

[0047] Example 3

[0048] A eucommia leaf fermented extract is prepared by the following steps:

[0049] (1) After the dried Eucommia ulmoides leaves were crushed through a 10-mesh sieve, 5000 kg of Eucommia ulmoides leaf powder was weighed and put into a mixer together with 50 kg of bran and stirred evenly, 3000 kg of water was added and continued to be stirred and mixed, and 250 kg of a mixed bacterial liquid of Aspergillus niger-Trichoderma harzianum-Saccharomyces cerevisiae was added. After stirring evenly, the mixture was transferred to an environmentally friendly fermentation tank, compacted and covered until there were no large gaps between the mixtures, and fermented and cultured at 25° C. for 6 days (during which the fermentation tank was regularly ventilated once a day for 30 minutes each time).

[0050] (2) The material after fermentation in step (1) is transported to an enzymatic hydrolysis extraction tank, 25,000 kg of water is added, and enzymatic hydrolysis is carried out at 45° C. for 4 hours through a pump circulation system (flow rate 100 kg / min, pump power 1500 kW); 15,000 kg of water is continued to be added, and circulating hot reflux extraction is carried out at 55° C. for 3 hours, and coarse filtering is carried out through a double filter with a mesh size of 200, and the filtrate is collected; water is continued to be added to the residue at a mass ratio of residue: water = 1:6, and circulating hot reflux extraction is carried out at 55° C. for 2 hours, and coarse filtering is carried out through a double filter with a mesh size of 200, and the filtrate is collected, and the filtrates obtained by the two coarse filterings are combined.

[0051] (3) The combined filtrate obtained in step (3) is filtered using a reverse osmosis membrane (molecular weight cut-off 100 Da, concentration pressure 400-800 psi), and the retentate is placed in a low-temperature vacuum concentrator.

[0052] (4) The parameters of the vacuum concentrator were adjusted to 50°C and -0.098 MPa. After concentrating to a specific gravity of 1.20, the mixture was spray dried (inlet air temperature 190°C, outlet air temperature 96°C) for 5 seconds and crushed through 80 mesh to obtain the eucommia leaf fermentation extract.

[0053] Comparative Example 1

[0054] On the basis of Example 1, the fermentation agent was replaced by Aspergillus niger with the same bacterial concentration from the Aspergillus niger-Trichoderma harzianum-Saccharomyces cerevisiae composite bacterial liquid, the closed fermentation temperature was 30°C, and the conditions of other steps remained unchanged to obtain a single Aspergillus niger fermentation extract.

[0055] Comparative Example 2

[0056] On the basis of Example 1, the fermentation agent was replaced by Trichoderma harzianum of the same bacterial concentration from the Aspergillus niger-Trichoderma harzianum-Saccharomyces cerevisiae composite bacterial liquid, the closed fermentation temperature was 30°C, and the conditions of other steps remained unchanged to obtain a single Trichoderma harzianum fermentation extract.

[0057] Comparative Example 3

[0058] On the basis of Example 1, the fermentation agent was replaced by Saccharomyces cerevisiae with the same bacterial concentration from the Aspergillus niger-Trichoderma harzianum-Saccharomyces cerevisiae composite bacterial liquid, the closed fermentation temperature was 30°C, and the conditions of other steps remained unchanged to obtain a single yeast fermentation extract.

[0059] Example 4 Performance Test of Eucommia Leaf Fermentation Extract

[0060] (1) Changes in the effective components and nutritional components of Eucommia ulmoides leaves fermented with different fermentation agents

[0061] The fermentation extract prepared in Example 1 and the single Aspergillus niger, Trichoderma harzianum and yeast fermentation extracts obtained in Comparative Examples 1-3 were tested for effective ingredients and nutritional components such as aucubin, chlorogenic acid, polysaccharides, crude protein, small molecule protein peptides, crude fat, crude ash, calcium, total phosphorus and crude fiber. The results are shown in Table 1.

[0062] Table 1 Changes in nutritional components of Eucommia ulmoides leaves after fermentation with different starters (g / 100g)

[0063]

[0064]

[0065] As can be seen from Table 1: compared with the dry leaves of Eucommia ulmoides, the contents of aucubin, chlorogenic acid, polysaccharides, crude protein, small molecule protein peptides, crude fat and crude fiber in the fermentation of composite bacteria, single Aspergillus niger, single Trichoderma harzianum and single yeast showed the same change trend, and the difference was significant (P<0.05). The contents of aucubin in the fermentation of composite bacteria, single Aspergillus niger, single Trichoderma harzianum and single yeast increased by 24.90%, 8.16%, 3.68% and 6.53%, respectively. The chlorogenic acid content of compound bacteria fermentation, single Aspergillus niger, single Trichoderma harzianum, and single yeast fermentation increased by 20.31%, 7.81%, 1.95%, and 2.34%, respectively; the polysaccharide content of compound bacteria fermentation, single Aspergillus niger, single Trichoderma harzianum, and single yeast fermentation increased by 20.47%, 8.02%, 1.88%, and 2.35%, respectively; the crude protein content of compound bacteria fermentation, single Aspergillus niger, single Trichoderma harzianum, and single yeast fermentation increased by 27.94%, 10.11%, 6.00%, and 8.74%, respectively; The contents of small molecule protein peptides in Trichoderma and single yeast fermentation increased by 598.09%, 519.85%, 462.98% and 492.37%, respectively; the crude fiber contents in compound bacteria fermentation, single Aspergillus niger, single Trichoderma harzianum and single yeast fermentation decreased by 10.41%, 7.91%, 2.65% and 5.58%, respectively; the crude fat contents in compound bacteria fermentation, single Aspergillus niger, single Trichoderma harzianum and single yeast fermentation increased by 29.78%, 14.89%, 5.06% and 10.11%, respectively; Compared with the dry leaves of Eucommia ulmoides, the changes in crude ash, total calcium and total phosphorus contents of composite bacteria fermentation, single Aspergillus niger, single Trichoderma harzianum and single yeast fermentation were not significantly different. The crude ash contents of composite bacteria fermentation, single Aspergillus niger, single Trichoderma harzianum and single yeast fermentation decreased by 1.82%, 0.98%, 0.14% and 0.42% respectively, while the total calcium contents of composite bacteria fermentation and single yeast fermentation remained unchanged. The total phosphorus contents of composite bacteria fermentation, single Aspergillus niger, single Trichoderma harzianum and single yeast fermentation increased by 6.35%, 3.17%, 1.59% and 1.59% respectively.

[0066] It can be seen that the extract obtained by fermenting Eucommia ulmoides leaves with the composite bacterial solution is better than the extract obtained by fermenting with single Aspergillus niger, Trichoderma harzianum and yeast. Therefore, only the fermented extract prepared by fermenting Eucommia ulmoides leaves with the composite bacterial solution in Example 1 and the dried fallen leaves of Eucommia ulmoides were used for the beef cattle feeding experiment.

[0067] (2) Beef cattle feeding experiment

[0068] The test beef cattle were selected completely randomly. 12 healthy and disease-free Tongren Sinan cattle in the growth period (10-12 months old) with consistent weight, body condition, fatness and coat color were selected and randomly divided into 3 groups (including 2 experimental groups and 1 blank group), 4 cattle in each group, and each group of cattle was located in different cowsheds. At the beginning of the experiment, the participating beef cattle were numbered, registered and weighed on an empty stomach for initial weight. The experimental period was 90 days.

[0069] The blank group was fed with a basic diet, the experimental group 1 was fed with a basic diet + 5% dried Eucommia leaves, and the experimental group 2 was fed with a basic diet + 5% composite bacteria fermented Eucommia leaves (prepared in Example 1).

[0070] Feeding management: The participating cattle were fed twice a day at 7:00 and 5:00. The cattle in the experimental group and the cattle in the blank group were fed according to the above feed ratio. At the end of the experiment, the cattle were weighed after fasting for 14 hours to compare the weight gain of the cattle. The results are shown in Table 2.

[0071] Table 2 Statistical table of growth performance of beef cattle after the feeding experiment in each group

[0072]

[0073] As can be seen from Table 2, there are no significant differences in the growth performance of beef cattle such as feed intake, daily weight gain, and feed-to-meat ratio between experimental groups 1-2. However, it can be seen that the feed intake and daily weight gain of beef cattle fed with the groups fed with the Eucommia ulmoides dried leaves and the Eucommia ulmoides leaf composite bacteria fermentation extract showed an upward trend, indicating that the addition of Eucommia ulmoides leaf composite bacteria fermentation extract and the addition of Eucommia ulmoides dried leaves can increase the feed intake and daily weight gain of beef cattle, and the addition of Eucommia ulmoides leaf composite bacteria fermentation extract to feed beef cattle is better than the addition of Eucommia ulmoides dried leaves; the feed-to-meat ratio of beef cattle fed with Eucommia ulmoides leaf composite bacteria fermentation extract and Eucommia ulmoides dried leaves showed a downward trend, and the addition of Eucommia ulmoides leaf composite bacteria fermentation extract was better than the addition of Eucommia ulmoides dried leaves, indicating that the feed consumed by beef cattle fed with Eucommia ulmoides leaf composite bacteria fermentation extract to increase 1kg is lower.

[0074] The longissimus dorsi muscle of the experimental group of beef cattle fed for 3 months was collected as samples for determination of energy, protein and fat content. The results are shown in Table 3.

[0075] Table 3 Statistical table of nutritional components of beef meat after the feeding experiment in each group

[0076]

[0077] As can be seen from Table 3, compared with the beef cattle fed with Eucommia ulmoides leaves (experimental group 1), the energy content of each 100g meat sample of the beef cattle fed with Eucommia ulmoides leaves composite fermentation extract in the basic feed (experimental group 2) was reduced by 21.31%, and the difference was extremely significant (P<0.01). The protein content of each 100g meat sample increased by 5.11%, and the difference was significant (P<0.05). The fat content of each 100g meat sample was reduced by 3.69%, and the difference was not significant.

[0078] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0079] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a fermented extract of Eucommia ulmoides leaves, characterized in that: The following steps are involved: (1) mixing the eucommia leaf powder and wheat bran in a mass ratio of 100:1.0-1.2, adding water (50-60% by mass of the eucommia leaf powder) and a composite bacterial solution of Aspergillus niger-Trichoderma harzianum-Saccharomyces cerevisiae (5-6% by mass of the eucommia leaf powder) in sequence, mixing and fermenting in a closed manner for 5-6 days; (2) adding 5 times the mass of water of Eucommia leaf powder to the material after fermentation in step (1), pumping and circulating for 4-6 hours, reflux extraction twice, and combining the two filtrates; (3) using a reverse osmosis membrane to concentrate the combined filtrate obtained in step (2) and collect the retentate; (4) performing low-temperature vacuum concentration and spray drying on the retentate collected in step (3), collecting the dried solid product, crushing it, and sieving it to obtain the eucommia leaf fermentation extract.

2. A method for preparing a fermented extract of Eucommia ulmoides leaves, characterized in that: In the composite bacterial solution of step (1), the number of viable bacteria of Aspergillus niger is 200 cfu / g, the number of viable bacteria of Trichoderma harzianum is 400 cfu / g, and the number of viable bacteria of Saccharomyces cerevisiae is 200 cfu / g.

3. The method for preparing a eucommia leaf fermented extract according to claim 1, characterized in that: The conditions of the closed fermentation in step (1) are: compacting and covering in the fermentation tank, fermenting at a temperature of 25-35° C., and ventilating once a day for 30 minutes each time.

4. The method for preparing a eucommia leaf fermented extract according to claim 1, characterized in that: The flow rate of the pump circulation in step (2) is 100kg / min, the pump power is 1500kw, and the processing temperature is 35-45°C.

5. The method for preparing a eucommia leaf fermented extract according to claim 1, characterized in that: The specific operation of reflux extraction twice in step (2) is: add 3 times the mass of water of Eucommia leaf powder to the material after pump circulation treatment in step (2), reflux extraction at 50-60° C. for 3 hours, filter through 200 mesh, and collect the filtrate; continue to add 6 times the mass of water to the remaining residue, reflux extraction at 50-60° C. for 2 hours, filter through 200 mesh, and collect the filtrate.

6. The method for preparing a eucommia leaf fermented extract according to claim 1, characterized in that: The molecular weight cut-off of the reverse osmosis membrane in step (3) is 100Da, and the concentration pressure is 400-800psi.

7. The method for preparing a eucommia leaf fermented extract according to claim 1, characterized in that: The conditions of the low-temperature vacuum concentration in step (4) are: 45-55°C, -0.098MPa, and the concentration multiple is 1.20 times.

8. The method for preparing a eucommia leaf fermented extract according to claim 1, characterized in that: The inlet air temperature of the spray drying in step (4) is 180-190°C, and the outlet air temperature is 90-96°C; Drying time 5-10s.

9. Use of the eucommia leaf fermented extract prepared according to any one of claims 1 to 8 in feed additives.

10. A feed additive, characterized in that: The invention comprises the eucommia leaf fermented extract according to any one of claims 1 to 8.

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