Enzyme and bacteria synergistic fermentation process for improving quality and application effect of palm cake and application thereof

Abstract

The application discloses a process for improving the quality of palm kernel meal feed by enzyme and bacteria synergistic fermentation, and belongs to the field of feed biotechnology.The process is characterized by the following steps: crushing and screening palm kernel meal, mixing the palm kernel meal with 20% bran and 4% ammonium sulfate as dry matter to obtain a basic substrate;compounding bacillus subtilis, aspergillus niger and saccharomyces cerevisiae at a ratio of 1:1:1 of viable bacterial number, adding 0.67% mannanase and 0.3% xylanase to prepare a bacteria-enzyme mixed solution, inoculating the bacteria-enzyme mixed solution at a 10% inoculation amount, adjusting the moisture content to 50% and the pH to 6.4, and then sealing and storing the bacteria-enzyme mixed solution for use after 4 days of fermentation at 33.5 DEG C; and the bacteria-enzyme mixed solution can be stored for a long time.The process can efficiently degrade crude fiber and anti-nutritional factors, improve the protein content and the digestibility, is stable and easy to mass-produce, can replace part of corn and soybean meal in the daily ration of ruminants, and realizes high-value utilization of palm kernel meal.

Description

Technical Field

[0001] This invention belongs to the field of feed biotechnology and unconventional feed resource development technology, specifically involving an enzyme-microbe synergistic fermentation process and its application to improve the quality and application effect of palm meal. Background Technology

[0002] With the large-scale development of my country's livestock industry, the shortage of protein feed resources has become increasingly prominent. Palm meal (PKC) is a major byproduct of oil palm fruit extraction, with a global annual production exceeding 10 million tons and my country's annual imports exceeding 1 million tons. Its price is only 30%-50% of soybean meal, and it contains 14%-20% crude protein, abundant minerals and fatty acids, possessing extremely high potential for feed development. However, palm meal itself has a high crude fiber content, with neutral detergent fiber (NDF) reaching 60%-80%, acid detergent fiber (ADF) reaching 40%-60%, and acid detergent lignin (ADL) exceeding 15%. It is also rich in non-starch polysaccharides (NSPs) and anti-nutritional factors such as mannan, which are difficult for animals to digest, limiting its addition to diets. Furthermore, palm meal is low in essential amino acids such as lysine and methionine, making direct feeding insufficient to meet the nutritional needs of livestock and poultry. Currently, the utilization rate of palm meal resources in my country is insufficient, with most being directly discarded or used for low-value purposes, resulting in serious resource waste and increased environmental burden.

[0003] Microbial solid-state fermentation is a core technology for enhancing the feed value of palm meal. It utilizes enzymes produced by microbial metabolism to degrade crude fiber and anti-nutritional factors, while simultaneously synthesizing microbial protein from inorganic nitrogen, thereby increasing crude protein content and feed digestibility. However, existing fermentation technologies have significant shortcomings: First, they often use commercially available strains without selecting suitable strains from the palm meal substrate, resulting in poor adaptability of the strains to the substrate and low cellulose degradation efficiency. Second, they often focus on single or dual-strain fermentation, failing to fully leverage the synergistic fermentation effects among Bacillus, Aspergillus, and yeast, leading to unstable fermentation results. Third, there is a lack of comprehensive system optimization of the entire process, including strain cultivation conditions, compounding ratios, additives, fermentation parameters, and enzyme-microbe synergistic systems, resulting in inconsistent quality of fermented palm meal and hindering its industrial-scale application.

[0004] To address the shortcomings of the existing technologies, this invention isolates and screens highly active cellulose-degrading Bacillus subtilis from palm meal raw materials, optimizes its culture conditions and compounding ratio with Aspergillus niger and Saccharomyces cerevisiae, and optimizes the entire process of fermentation auxiliary materials, core process parameters, and exogenous enzyme synergistic system to construct a highly efficient enzyme-bacterial synergistic fermentation process, which significantly improves the nutritional quality of palm meal. The application effect has been verified through beef cattle feeding trials, providing a complete technical solution for the industrial-scale development of palm meal for feed.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of weak fiber degradation, unstable fermentation effect, and low product utilization rate in existing palm meal processing technology, and to provide an enzyme-microbe co-fermentation process to improve the quality and application effect of palm meal. At the same time, it provides the application of fermented palm meal prepared by this process in ruminant feed, realize the high-value utilization of palm meal, and alleviate the shortage of protein feed resources.

[0007] To address the aforementioned technical problems, this invention provides an enzyme-microbial co-fermentation process for improving the quality and application effects of palm meal, specifically comprising the following steps: Raw material pretreatment and substrate preparation: Palm meal is thoroughly pulverized using a high-speed pulverizer and passed through a 40-mesh standard sieve to increase the specific surface area of ​​the material, which is conducive to the contact between the inoculum and enzyme molecules. Based on the dry matter mass of palm meal, 20% wheat bran is precisely added to supplement the carbon source and loosen the structure, and 4% ammonium sulfate is added to supplement the inorganic nitrogen source. The mixture is stirred evenly throughout the process to obtain the basic fermentation substrate. 2) Preparation of compound bacterial solution: Bacillus subtilis, Aspergillus niger, and Saccharomyces cerevisiae, suitable for palm meal substrates, were selected and cultured separately to obtain logarithmic growth phase seed solutions. The three seed solutions were mixed in a 1:1:1 ratio to form a compound bacterial solution with a total viable count ≥1×10⁻⁶. 9 CFU / mL; Bacillus subtilis is a strain isolated from palm meal with high cellulose degradation activity, which is good at degrading cellulose. Aspergillus niger enhances the secretion of hemicellulase system, and Saccharomyces cerevisiae can enrich cell protein and optimize fermentation flavor. The three strains complement each other synergistically. 3) Preparation of the bacterial-enzyme mixture: An exogenous enzyme preparation is added to the compound bacterial solution. Based on the dry matter of palm meal, 0.67% high-activity mannanase and 0.3% xylanase are added. The exogenous enzymes pre-decompose mannan and xylan anti-nutritional factors, forming a synergistic effect with the enzymes produced by the bacterial strain. The mixture is stirred evenly and set aside. The mannanase activity is 6 × 10⁻⁶. 5 U / g, xylanase activity is 1×10 5 U / g; 4) Inoculation and conditioning: Spray the prepared bacterial enzyme mixture evenly onto the fermentation substrate at an inoculation rate of 10% of the material mass; simultaneously add sterile water to adjust the initial moisture content of the entire fermentation system to 50%, and use dilute hydrochloric acid or sodium hydroxide to precisely adjust the initial pH to 6.4; thoroughly stir and mix to ensure that the material is loose, without lumps or agglomerates, so as to achieve uniform contact between the bacterial enzyme and the substrate throughout the entire process; 5) Sealed constant temperature fermentation: The well-stirred fermentation material is quantitatively packaged into food-grade one-way exhaust fermentation bags at a rate of 0.5 kg / bag; after manually purging the free air inside the bag, it is sealed, and the seal is strictly checked to prevent air leakage and bacterial contamination; the sealed fermentation bags are placed in a constant temperature environment of 33.5℃ and allowed to ferment in a closed environment for at least 4 days to obtain the finished product, which can be stored for a long time; during the fermentation period, there is no need to turn the material or add oxygen, and the waste gas such as carbon dioxide produced by the metabolism of the bacteria can be discharged autonomously through the one-way exhaust valve to prevent the invasion of external bacteria.

[0008] In this invention, all percentages unless otherwise specified are based on the mass percentage of palm meal dry matter.

[0009] Furthermore, Bacillus subtilis was cultured in LB liquid medium with an inoculum size of 2%, at a temperature of 37°C, a shaking speed of 180 r / min, and a culture time of 12 h; Aspergillus niger was cultured in PDA liquid medium with an inoculum size of 2%, at a temperature of 30°C, a shaking speed of 180 r / min, and a culture time of 24 h; and Saccharomyces cerevisiae was cultured in YPD liquid medium with an inoculum size of 2%, at a temperature of 30°C, a shaking speed of 180 r / min, and a culture time of 18 h. All cultures were cultured to the logarithmic growth phase for later use.

[0010] This invention also provides the application of fermented palm meal prepared by the above process in ruminant feed. The fermented palm meal is added to beef cattle diets at a ratio of 20%, which can replace an equal proportion of corn and soybean meal. This improves the growth performance and feed efficiency of beef cattle. Feeding trials have verified that at this addition ratio, the average daily weight gain of beef cattle increases by 10%-15%, feed conversion rate increases by 8%-12%, and feed costs are reduced, resulting in significant economic benefits.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. Significant synergistic effect of enzymes and bacteria: A three-strain compound system of Bacillus subtilis, Aspergillus niger and Saccharomyces cerevisiae was constructed. Combined with exogenous mannanase and xylanase complex enzymes, the synergistic effect of "enzyme production by strains + exogenous enzyme supplementation" was achieved, which greatly improved the degradation efficiency of crude fiber and non-starch polysaccharides. The degradation rate was 20%-30% higher than that of existing technologies.

[0012] 2. Optimization of the entire process: The entire process of strain culture conditions, compound ratio, auxiliary material addition, fermentation parameters, and enzyme-strain synergistic system is optimized, resulting in stable fermentation effect, strong reproducibility, and suitability for industrial production.

[0013] 3. Significant improvement in product quality: After fermentation, the crude fiber content of palm meal is reduced by more than 30%, the crude protein content is increased by 25%-30%, the content of essential amino acids is significantly increased, the content of anti-nutritional factors is reduced to a safe level, and the feed digestibility is increased by 15%-20%.

[0014] 4. Clear application effects: Through feeding trials on beef cattle, fermented palm meal can replace 20% of corn and soybean meal, significantly improving the growth performance and feed efficiency of beef cattle, reducing feed costs, realizing the high-value utilization of palm meal, alleviating the shortage of protein feed resources, and having significant economic, social and environmental benefits. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0016] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0017] Optimal process implementation of enzyme-microbial co-fermentation of palm meal The culture conditions for Bacillus subtilis, Aspergillus niger, and Saccharomyces cerevisiae were optimized. The optimal culture conditions for each strain were determined using the ratio of viable cells to enzyme activity after culture as the evaluation index. The optimal culture conditions for Bacillus subtilis are: LB liquid medium, initial pH 7.0, inoculum size 2%, culture temperature 37℃, shaker speed 180 r / min, and culture time 12 h. Under these conditions, the viable bacterial count can reach 1.1 × 10⁻⁶. 9 CFU / mL. The optimal culture conditions for Aspergillus niger H1 are: PDA liquid medium, initial pH 5.5, inoculum size 2%, culture temperature 30℃, shaker speed 180 r / min, culture time 24 h, under these conditions the viable count ≥1.0×10⁻⁶. 9 The strain exhibited CFU / mL cellulase activity up to 20.48 U / mL, indicating it was in the logarithmic growth phase. The optimal culture conditions for *Saccharomyces cerevisiae* were: YPD liquid medium, initial pH 6.0, inoculum size 2%, culture temperature 30℃, shaker speed 180 r / min, and culture time 18 h. Under these conditions, the viable cell count reached 2.2 × 10⁻⁶. 9 CFU / mL.

[0018] Determination of the ratio of the three strains of bacteria The total inoculum amount of the fixed compound bacterial solution was 10%. Based on the number of viable bacteria, the ratio of the three strains was set as a factor, and each factor was set with 3 levels. The factor level table of the orthogonal experiment is shown in Table 1. There were a total of 9 treatment groups, and each treatment was set with 3 replicates. Fermentation conditions: initial moisture 45%, room temperature fermentation for 4 days. After fermentation, the crude protein (CP) and neutral detergent fiber (NDF) content were detected, and the CP enhancement rate and NDF degradation rate were calculated.

[0019] Table 1 Results of orthogonal experiment on strain mixing ratio

[0020] The overall score is calculated as follows: CP enhancement rate + NDF degradation rate. The effect of the three strains on fermentation efficiency was: *Aspergillus niger* (H) > *Bacillus subtilis* (Z) > *Saccharomyces cerevisiae* (N). The optimal combination was A2B2C1, i.e., *Bacillus subtilis*: *Aspergillus niger*: *Saccharomyces cerevisiae* = 1:1:1. A verification experiment was conducted on the optimal combination. Under this ratio, after 4 days of fermentation, the CP content of palm meal increased from 16.14% to 19.16%, an increase of 18.71%; the NDF content decreased from 78.06% to 64.38%, a degradation rate of 17.52%, significantly better than other ratios. Therefore, this ratio was determined to be the optimal blending ratio of the three strains.

[0021] Optimization of the amount of exogenous excipients added during fermentation Two factors were set up: the amount of wheat bran added (factor A: 10%, 15%, 20%) and the amount of ammonium sulfate added (factor B: 3%, 4%, 5%). Each factor had 3 levels, resulting in a total of 9 treatment groups, with 3 replicates for each treatment. The basic fermentation conditions were: 10% inoculum of compound bacteria (Z:H:N=1:1:1), 50% initial moisture, natural pH, and fermentation at room temperature for 4 days. After fermentation, the contents of CP and NDF were measured.

[0022] Table 2. Results of the orthogonal experiment on the amount of excipients added

[0023] The addition of both wheat bran and ammonium sulfate significantly improved the fermentation effect, with wheat bran having a greater impact than ammonium sulfate. There was no significant difference in the overall score between the 20% wheat bran + 4% ammonium sulfate group and the 20% wheat bran + 5% ammonium sulfate group, but the 4% ammonium sulfate group had a lower cost, a CP improvement rate of 30.24%, and an NDF degradation rate of 28.76%. Taking all factors into consideration, the optimal amount of auxiliary materials added was determined to be: 20% wheat bran and 4% ammonium sulfate.

[0024] Optimization of core process parameters for solid-state fermentation The inoculum size of the compound bacterial culture was 10%, wheat bran 20%, and ammonium sulfate 4%. In each single-factor experiment, only the target parameter was changed, while the other parameters remained constant. Each treatment was repeated three times, with CP content as the core indicator to determine the suitable range for each parameter. Using the post-fermentation CP content as the response value, three core factors were selected: fermentation temperature (A), initial pH (B), and fermentation time (C).

[0025] Table 3. Coding table for response surface methodology factors

[0026] CP content (%) = 25.09 - 0.155A - 0.1987B + 0.7288C - 0.0025AB - 0.2125AC -0.09BC-0.4245A²-0.637B²-0.897C². Analysis of variance was performed on the regression model. Through model optimization, the theoretically optimal process conditions for maximum CP content were obtained as follows: fermentation temperature 33.41℃, initial pH 6.41, and fermentation time 5.45 days. Under these conditions, the theoretical CP content can reach 25.10%. To facilitate actual production operation, the parameters were modified to: fermentation temperature 33.5℃, initial pH 6.4, and fermentation time 5.5 days. Three verification experiments were conducted on the modified conditions. The actual measured CP content of the fermented palm meal was 25.04%, with a relative deviation of only 0.24% from the theoretical prediction, indicating that the model is reliable and the optimized process parameters are stable and feasible.

[0027] Determination of synergistic system of exogenous enzyme preparations Palm meal was pulverized and passed through a 40-mesh sieve, then mixed with wheat bran in a 4:1 ratio. Bacillus subtilis, Aspergillus niger, and Lactobacillus plantarum were cultured separately to the logarithmic growth phase, then mixed in a 1:1:1 ratio of live strains to prepare a compound bacterial solution. After adding mannanase or xylanase, the solution was evenly sprayed onto the fermentation substrate with a moisture content adjusted to 45%. Among single enzyme additions, the 0.67% mannanase group showed the best fiber degradation effect, reducing NDF to 53.10%, ADF to 35.88%, and CP to 22.04%, significantly better than the xylanase-only group. Among compound enzyme additions, the 0.67% mannanase + 0.3% xylanase group showed the best effect, with CP reaching 22.12%, NDF decreasing to 51.24%, ADF decreasing to 37.38%, and TDN increasing by 7.01% compared to the control group. While there was no significant difference compared to the 0.67% mannanase-only group, the mannanase combination showed better fiber degradation and lower cost.

[0028] Taking into account both fermentation effect and production cost, the optimal exogenous enzyme addition scheme was determined to be: based on palm meal dry matter, mannanase 0.67% (6×105 U / g) + xylanase 0.3% (1×105 U / g), and the exogenous enzymes and compound bacterial solution were simultaneously introduced into the fermentation system.

[0029] Complete process flow of enzyme-microbial co-fermentation of palm meal Palm meal raw material was crushed using a high-speed pulverizer and passed through a 40-mesh sieve. On a dry matter basis, it was mixed evenly with 20% wheat bran and 4% ammonium sulfate to obtain the basic fermentation substrate. Bacillus subtilis, Aspergillus niger, and Saccharomyces cerevisiae were prepared by mixing seed cultures of Bacillus subtilis, Aspergillus niger, and Saccharomyces cerevisiae at a live cell ratio of 1:1:1 to prepare a compound bacterial solution. 0.67% mannanase and 0.3% xylanase (on a dry matter basis of palm meal) were added to the compound bacterial solution and stirred evenly for later use. The bacterial-enzyme mixture was evenly sprayed onto the basic fermentation substrate at an inoculation rate of 10%. Simultaneously, sterile water was added to adjust the initial moisture content of the system to 50%, and dilute hydrochloric acid / sodium hydroxide was used to adjust the initial pH of the system to 6.4. The mixture was stirred thoroughly until the material was free of lumps and agglomerates. Distribute the well-mixed fermentation material into one-way venting fermentation bags at 0.5 kg / bag, expelling as much air as possible from the bags. Seal the bags with a sealing machine and check for leaks. Place the sealed fermentation bags in a 33.5℃ constant temperature incubator and allow them to ferment for at least 4 days, preferably 5.5 days. No turning is required during this period. The gas produced during fermentation will be automatically expelled through the one-way venting valve. After fermentation, store the bags in their original packaging. When feeding, open the packaging and mix with other diet ingredients to prepare TMR diets.

[0030] Example 2 Comparison of the nutritional quality of fermented palm meal and its application in feeding fattening beef cattle Comparison of nutritional quality of palm meal before and after fermentation The nutritional indicators of palm meal before and after fermentation using the optimal process in Example 1 were systematically tested. A control group of unfermented palm meal and an optimal combination fermentation group were also set up. The results are shown in Table 6.

[0031] Table 4 Comparison of nutritional indicators of palm meal in different treatment groups (DM basis)

[0032] Compared with unfermented palm meal, the palm meal fermented by the process of this invention has a 61.83% higher CP content, a 34.36% lower NDF content, a 43.30% lower ADF content, a 34.62% lower ADL content, and a 16.38% higher TDN content. All nutritional indicators are significantly better than the unfermented group and the conventional dual-strain fermentation group, greatly improving the feed nutritional value of palm meal.

[0033] Validation of the feeding application of fermented palm meal in beef cattle Experimental Design: Forty-eight healthy Angus fattening bulls of similar weight (504.50±52.45 kg) were randomly divided into four groups of 12 bulls each. The control group (CON) was fed a basal diet; the experimental groups (10% FPKC, 20% FPKC, and 30% FPKC) had 10%, 20%, and 30% of the concentrate in their basal diet replaced by the FPKC prepared in Example 1, respectively. The experiment lasted for 70 days (14 days of pre-feeding period and 56 days of trial period).

[0034] Growth performance was measured by recording initial weight, final weight, and feed intake. The results showed that the average daily gain (ADG) of the 20% FPKC group was significantly higher than that of the control group (P<0.05), and the feed conversion ratio (F / G) was significantly lower (P<0.05).

[0035] Table 5. Effects of fermented palm meal on beef cattle production performance

[0036] Serum markers were measured: Blood was collected on day 56 of the trial period, and serum was separated. The results showed that, compared with the control group, the levels of immunoglobulin A (IgA) and total antioxidant capacity (T-AOC) in the serum of the 20% FPKC and 30% FPKC groups were significantly increased (P<0.05), while the levels of pro-inflammatory cytokine-1β (IL-1β) and malondialdehyde (MDA), a marker of oxidative stress, were significantly decreased (P<0.05).

[0037] Table 6. Effects of fermented palm meal on serum biochemical parameters of beef cattle

[0038] Rumen fermentation parameters were measured: Rumen fluid was collected on day 56 of the trial period. Results showed that the propionic acid content in all FPKC-added groups was significantly higher than that in the control group (P<0.01). The microbial protein (MCP) content in the 20% FPKC group was significantly higher than that in the control group (P<0.05), and the acetic acid / propionic acid ratio was significantly lower (P<0.05).

[0039] Table 7. Effects of fermented palm meal on rumen fermentation parameters in beef cattle.

[0040] In summary, the enzyme-microbial co-fermentation process provided by this invention can significantly improve the nutritional value of palm meal. When the product replaces 20% of the concentrate in the diet of fattening beef cattle, it can effectively promote growth, enhance immunity and antioxidant capacity, and optimize rumen fermentation, showing excellent application effects.

[0041] Example 3 Effects of fermented palm meal on growth performance and digestibility of growing cattle Thirty healthy Simmental crossbred beef cattle of similar weight were randomly divided into two groups of 15 each: a control group and an experimental group. The pre-trial period was 10 days, and the formal trial period was 60 days. Compared with the control group, the experimental group showed a significantly higher average daily weight gain of 15.28% (P < 0.05) and a significantly lower feed conversion ratio of 12.31% (P < 0.05). There was no significant difference in average daily feed intake. This indicates that fermented palm meal can significantly improve the growth performance and feed conversion efficiency of beef cattle (see Table 9).

[0042] Table 8 Effects of fermented palm meal on growth performance of beef cattle

[0043] Apparent digestibility of nutrients: The results are shown in Table 10. The apparent digestibility of dry matter, crude protein, neutral detergent fiber and acid detergent fiber in the experimental group diet were significantly higher than those in the control group (P<0.05), indicating that fermented palm meal significantly degraded crude fiber and improved the digestibility and utilization of dietary nutrients.

[0044] Table 9. Effect of fermented palm meal on apparent nutrient digestibility of TMR in beef cattle (%)

[0045] Serum biochemical indicators: The total protein and albumin content in the serum of beef cattle in the experimental group was significantly higher than that in the control group (P<0.05), while the urea nitrogen content was significantly lower than that in the control group (P<0.05), indicating that fermented palm meal improved the protein metabolism efficiency of beef cattle. There were no significant differences in serum aspartate aminotransferase, alanine aminotransferase, creatinine and other indicators between the two groups, indicating that fermented palm meal had no adverse effects on the liver and kidney function of beef cattle and had good feeding safety.

[0046] Economic benefit analysis: Based on a trial period of 60 days, the weight gain per head of beef cattle in the experimental group was 286.4 yuan higher than that in the control group, while feed costs were reduced by 142.8 yuan, resulting in an average increase of 429.2 yuan in comprehensive economic benefits per head, demonstrating significant economic value.

[0047] This invention significantly enhances the feed value of palm meal through a synergistic enzyme-microbe fermentation process. Feeding trials in beef cattle show that adding 20% ​​of the fermented palm meal of this invention to the diet results in a significant increase in average daily weight gain of over 15% and a decrease in feed conversion ratio of over 11%. Its mechanism of action lies in: optimizing the rumen fermentation pattern, significantly increasing propionic acid concentration and microbial protein synthesis efficiency; improving the apparent digestibility of dietary nutrients, especially fiber components; and simultaneously enhancing the animal's immunity and antioxidant capacity. Compared with existing technologies, this invention not only achieves a high-proportion substitution of palm meal in ruminant diets but also achieves breakthrough progress in growth performance and economic benefits, possessing extremely strong industrial application value.

[0048] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A co-fermentation process for enzymes and bacteria to improve the quality and application effect of palm meal, characterized in that, Includes the following steps: 1) Raw material pretreatment and substrate preparation: Palm meal is crushed and sieved using a high-speed pulverizer; based on the dry matter of palm meal, 20% wheat bran and 4% ammonium sulfate are mixed in and mixed evenly to obtain the basic fermentation substrate; 2) Preparation of compound bacterial solution: Take the seed liquids of Bacillus subtilis, Aspergillus niger, and Saccharomyces cerevisiae, and mix them evenly at a viable cell volume ratio of 1:1:1 to obtain a compound bacterial solution. The total viable cell count of the compound bacterial solution is ≥1×10⁻⁶. 9 CFU / mL; 3) Preparation of bacterial enzyme mixture: Add enzyme preparation to the compound bacterial solution. Based on the dry matter of palm meal, add 0.67% mannanase and 0.3% xylanase, and stir evenly to obtain bacterial enzyme mixture. 4) Inoculation and conditioning: Spray the bacterial enzyme mixture evenly onto the fermentation substrate at an inoculation rate of 10% by weight, add sterile water to adjust the initial moisture content of the system to 50%, and use dilute hydrochloric acid or sodium hydroxide to adjust the initial pH of the system to 6.

4. Stir thoroughly until the material is free of lumps. 5) Sealed constant temperature fermentation: The mixed fermentation material is divided into one-way exhaust fermentation bags and placed at 33.5℃ for static fermentation for at least 4 days to obtain the finished product, which can be stored for a long time.

2. The fermentation process according to claim 1, characterized in that, The Bacillus subtilis strain is isolated from palm meal and has high cellulose degradation activity.

3. The fermentation process according to claim 1, characterized in that, Bacillus subtilis was cultured on LB liquid medium with an inoculum size of 2%, at a temperature of 37°C, a shaking speed of 180 r / min, and a culture time of 12 h. Aspergillus niger was cultured on PDA liquid medium with an inoculum size of 2%, at a temperature of 30°C, a shaking speed of 180 r / min, and a culture time of 24 h. Saccharomyces cerevisiae was cultured on YPD liquid medium with an inoculum size of 2%, at a temperature of 30°C, a shaking speed of 180 r / min, and a culture time of 18 h. All cultures were cultured to the logarithmic growth phase for later use.

4. The fermentation process according to claim 1, characterized in that, The mannanase activity is 6 × 10⁻⁶. 5 U / g, the xylanase activity is 1×10 5 U / g.

5. The application of fermented palm meal prepared according to any one of claims 1-4 in ruminant feed, characterized in that, The fermented palm meal is added to beef cattle diets at a rate of 20%, which can replace an equal proportion of corn and soybean meal.

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