Sorghum straw fermented feed and preparation method thereof

Abstract

The invention relates to the technical field of forage grass fermentation, in particular to sorghum straw fermented feed and a preparation method thereof.The preparation method comprises the steps of sorghum straw pretreatment, fluffy substance preparation, compound zymophyte liquid preparation, fermentation auxiliary nutrition emulsion preparation, compound zymophyte-containing bran preparation and mixed fermentation, and the fermented feed is obtained. Through a synergistic system of a specific strain, a fluffy carrier, a nutrition emulsion and a bran carrier, triple breakthrough of degradation efficiency, nutrition quality and storage stability is achieved, the anti-nutritional factors of the prepared sorghum straw fermented feed are degraded more thoroughly, the degradation rate of crude fibers is increased to 35% or above, the crude protein content is larger than or equal to 21.0%, and the content of wheat bran is larger than or equal to 21.0%. The mildew rate is reduced to 5% or below, and finally the fermented feed with stable quality and balanced nutrition is obtained. The method is stable in process, can be implemented on a large scale, and is suitable for ruminant feed production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of crop straw resource utilization and anaerobic fermentation feed preparation, and specifically relates to a fermented feed of sorghum straw and a preparation method thereof. BACKGROUND

[0002] Traditional treatment of sorghum straw is mainly incineration, which not only wastes biomass resources such as cellulose and hemicellulose, but also produces pollutants such as sulfur dioxide and nitrogen oxides, aggravating air pollution. Converting it into fermented feed is a key way to realize resource utilization, which can not only alleviate the shortage of protein feed, but also reduce breeding costs, in line with the concept of circular agriculture development.

[0003] In the prior art, the preparation of sorghum straw fermented feed has been studied. For example, patent CN108576123A discloses a method for fermenting sorghum straw with single lactic acid bacteria, but it uses ordinary lactobacillus plantarum, which has weak degradation ability for tannin in sorghum straw with a content of 2-3%, resulting in a crude fiber degradation rate of less than 20% and poor palatability of the feed; patent CN110236541A uses compound bacteria fermentation, but does not set a special fluffy carrier, and the porosity of the material after compaction is less than 20%, the residual oxygen is high, the spoilage bacteria breed, resulting in a feed moldy rate of more than 15%, and the key parameters such as fermentation temperature and compaction degree are not disclosed, so the process has poor repeatability; patent CN113969243A adds a nutritional aid, but it is named "bacteriophage emulsion", which is not consistent with the function of "carbon source supplement", and the nutritional improvement effect is not quantified, and the crude protein content is only increased to 16-18%, which cannot meet the nutritional needs of ruminants.

[0004] Further analysis shows that the core bottleneck of the prior art is concentrated in three points: first, the strain lacks specificity, ordinary lactic acid bacteria cannot efficiently degrade lignin-polymer complex in sorghum straw, and the fiber digestion rate is limited; second, the oxygen control of the fermentation system is insufficient, and there is a lack of carrier design considering "oxygen removal + air permeability", resulting in poor fermentation stability; third, the nutritional transformation is not sufficient, and the synergistic mechanism of "strain degradation + nutrient supplement" has not been formed, resulting in low feed quality.

[0005] In addition, the practice of silage in hot and humid areas shows that when the temperature is greater than 30℃ and the compaction degree is less than 650Kg / m 3 , the proliferation speed of spoilage bacteria significantly increases, and the existing technology does not optimize the parameters, resulting in short shelf life of the feed (less than 3 months), large transportation loss, and difficulty in large-scale application. SUMMARY

[0006] In view of the above defects in the prior art, the present application aims to provide a fermented feed of sorghum straw and a preparation method thereof, and the core is to construct a synergistic system of "strain-specific degradation-fluffy carrier oxygen control-nutrient carbon supplement".

[0007] The technical purpose of the present application is achieved by a preparation method of fermented feed of sorghum straw, comprising the following steps:

[0008] S1, pretreatment of sorghum straw: the sorghum straw is crushed, and the large material with a length of 3-5 cm and the small material with a length of 2-3 cm are mixed at a mass ratio of 3:1, and the water content is adjusted to 50-60%;

[0009] S2, preparation of fluffy material: the bean dregs and cassava dregs are mixed at a mass ratio of 1:3, and after expansion treatment and cooling, the fluffy material with a porosity of 40-50% is obtained;

[0010] S3, preparation of composite fermentation bacteria liquid: the Lactobacillus plantarum CAV-M6 with the preservation number of CGMCC No.17614 and the Lactobacillus plantarum CAU-a214 with the preservation number of CGMCC No.13609 are respectively cultured to the logarithmic phase, and then mixed at a volume ratio of Lactobacillus plantarum CAV-M6:Lactobacillus plantarum CAU-a214=2:1, and the total number of colonies is adjusted to 5x10 9 -1x10 10 CFU / mL, to obtain the composite fermentation bacteria liquid;

[0011] The Lactobacillus plantarum CAV-M6 with the preservation number of CGMCC No.17614 is preserved in the China General Microbiological Culture Collection Center, and the preservation date is April 22, 2019, and the preservation address is No.3, Beichen West Road, Chaoyang District, Beijing;

[0012] The Lactobacillus plantarum CAU-a214 with the preservation number of CGMCC No.13609 is preserved in the China General Microbiological Culture Collection Center, and the preservation date is January 13, 2017, and the preservation address is No.3, Beichen West Road, Chaoyang District, Beijing;

[0013] S4, preparation of fermentation auxiliary nutrient emulsion: starch 8-10 parts, water 15-20 parts, emulsifier 1-2 parts, and vegetable oil 68-76 parts are mixed and emulsified to obtain the fermentation auxiliary nutrient emulsion;

[0014] S5, preparation of bran containing composite fermentation bacteria: 90-98 parts of feed-grade bran and 2-10 parts of the composite fermentation bacteria liquid prepared in S3 are mixed, and then put into a horizontal stirrer to stir at 120 r / min for 10 min to ensure that the bacteria liquid is evenly attached to the surface of the bran;

[0015] S6, mixed fermentation: the fermentation auxiliary nutrient emulsion of S4 and the fluffy material of S2 are mixed in a mass ratio of 1:6 to obtain a filling material, then 80-90 parts of the pretreated sorghum straw of S1, 3-5 parts of the bran containing the compound fermentation bacteria of S5, 2-5 parts of the compound fermentation bacteria liquid of S3 and 5-10 parts of the filling material are mixed and compacted to 700-800 Kg / m 3 , and then closed fermentation is carried out at 25-30 DEG C for 20-48 h to obtain the fermented feed.

[0016] Further, the length of the crushed sorghum straw of S1 is 4 cm for large material and 2.5 cm for small material, and the water content is adjusted to 55%.

[0017] Further, the parameters of the puffing treatment of S2 are 130 DEG C, 1.0 MPa and 180 r / min, and the porosity of the fluffy material after puffing is 45-50%.

[0018] Further, the Lactobacillus plantarum of S3 is cultured in MRS medium at 30 DEG C for 24-36 h, and the logarithmic growth phase is reached when the OD 600 value is 0.6-0.8.

[0019] Further, the emulsifier of S4 is sucrose ester, the emulsification temperature is 35-40 DEG C, the stirring speed is 50 r / min, and the emulsification time is 30-40 min, and the system is in a uniform emulsion state without stratification.

[0020] Further, the specific surface area of the bran of step S5 is 1.0-1.2 m 2 / g, and the porosity is 35-38%.

[0021] Further, in S6, the fermentation time is 20-30 h when the amount of single batch of material is less than 1000 kg, and the fermentation time is 30-48 h when the amount of single batch of material is greater than or equal to 1000 kg.

[0022] Further, the adsorption amount of the compound fermentation bacteria liquid on the surface of the bran is 0.7-0.8 mL / g.

[0023] Further, in the compound fermentation bacteria liquid of S3, the tannin-degrading enzyme activity of Lactobacillus plantarum CAV-M6 is greater than or equal to 4.5 μmol / min.mL.

[0024] The application also provides a sorghum straw fermented feed prepared by the above method, wherein the crude protein content is greater than or equal to 21.0%, the total sugar content is greater than or equal to 9.6%, the crude fiber degradation rate is greater than or equal to 35%, the pH value is 4.2-4.8, the tannin residual amount is less than or equal to 0.8%, the moldy rate is less than or equal to 1%, and the feed contains the metabolic product of Lactobacillus plantarum CAV-M6.

[0025] The application has the following beneficial effects:

[0026] 1. This invention utilizes two specific *Lactobacillus plantarum* strains, CAV-M6 and CAU-a214, whose synergistic tannin degradation capacity is more than 40% higher than that of ordinary strains. Secondly, the fluffy material achieves a dual function of "oxygen control + air permeability," reducing the fermentation mold rate to below 5%. Thirdly, the fermentation-aiding nutrient emulsion synergistically enhances the crude protein content, increasing it from 15% to 40% compared to existing technologies. Compared to existing sorghum straw fermentation feed preparation technologies, this invention achieves a triple breakthrough in "degradation efficiency, nutritional quality, and storage stability" through a synergistic system of "specific strains - fluffing carrier - nutrient emulsion - bran carrier." In particular, CAV-M6, as a high-tannin-producing *Lactobacillus plantarum* strain (CGMCC No. 17614), has enzymatic characteristics highly compatible with the fermentation process of this invention. Specific parameters and technical significance are as follows:

[0027] (1) Core indicators of tanninase activity: Under the conditions of pH 5.0 and 30℃ (with propyl gallate as substrate), the tanninase activity reaches 4.85 μmol / (min˙mL), which is 3 times that of common tannin-producing lactic acid bacteria (such as STS-6 strain, 1.6U / mL), providing an enzymatic basis for rapid tannin degradation; the optimal pH for its enzymatic reaction is 5.0, which precisely matches the pH (4.5-5.5) of the material in the middle stage of silage fermentation, thus avoiding enzyme inactivation during fermentation; the optimal temperature is 30℃, which completely covers the process temperature control range of 25-30℃ of this invention, ensuring that high enzyme activity can be maintained in different seasons.

[0028] (2) Temperature stability: The growth temperature range of the strain is 5-50℃, and the OD at 45℃ is... 620 The activity level (nm) remains at 1.8 (compared to 2.1 in the 37℃ control group), making it suitable for production in northern winters (10-15℃) and summers (35-40℃). The tanninase activity retention rate is >90% within the 30-40℃ range, and it retains 72% activity after 1 hour of treatment at 50℃ (superior to the commonly used industrial Aspergillus nabumi tanninase). It can withstand localized temperature increases in the center of the material during large-scale fermentation (such as the 10m in Example 5). 3 The temperature at the center of the pit material reaches 38°C to avoid a sudden drop in enzyme activity that could lead to degradation stagnation.

[0029] (3) pH stability: The strain can grow normally at pH 3.0, and OD at pH 4.0 620 The tannin activity reaches 1.9 (close to 90% of the neutral environment), making it suitable for acidic environments where the pH drops below 4.0 in the later stages of silage. The tannin enzyme activity retention rate is >85% in the pH range of 4.0-6.5, especially in the pH range of 4.5-5.0 (the critical degradation period of silage), where the enzyme activity does not decrease significantly, thus solving the industry pain point of activity decay of ordinary tannin enzymes in acidic silage environments.

[0030] The above-mentioned enzymatic characteristics indicate that CAV-M6 is not an ordinary Lactobacillus plantarum. Its core features of high enzyme activity, wide temperature range, and acid resistance are the key technical support for the "24h rapid fermentation + large-scale stable degradation" of this invention, rather than relying on simple optimization of process parameters.

[0031] 2. The sorghum straw fermented feed prepared by the method of this invention exhibits more thorough degradation of anti-nutritional factors and significantly improved fiber utilization: The *Lactobacillus plantarum* CAV-M6 and CAU-a214 used in this invention synergistically possess highly active tannin-degrading enzymes, which can specifically break the ester and ether bonds of tannins in sorghum straw. The tannin degradation rate is more than 40% higher than that of ordinary *Lactobacillus plantarum* (CGMCC No. 1.1293). Combined with the porous structure (40-50%) of the fluffy material, it provides a uniform metabolic space for the strain, avoiding local enzyme activity inhibition, and keeping the crude fiber degradation rate stable at more than 35%, which is 40% higher than that of traditional fermentation processes (≤25%). This solves the industry pain point of "difficult-to-degrade straw fiber and low animal digestibility".

[0032] 3. The sorghum straw fermented feed prepared by the method of this invention has high nutrient conversion efficiency and superior feed quality: the starch and vegetable oil in the fermentation auxiliary nutrient emulsion provide a continuous carbon source for the compound bacteria, avoiding carbon source competition between lactic acid bacteria and Bacillus, and promoting protein synthesis metabolism; the porous structure of the bran carrier reduces the coefficient of variation of bacterial distribution from 35% to 8%, ensuring uniform nutrient conversion. The bran meets the requirements of this invention (specific surface area 1.0-1.2 m²). 2 Wheat bran (with a porosity of 35-38%) can be obtained through conventional screening methods: select wheat bran with a particle size of 20-40 mesh (remove coarse residue with a diameter >0.85mm through a 20-mesh sieve and remove fine powder with a diameter <0.425mm through a 40-mesh sieve), and dry it with hot air at 50℃ to a moisture content of 12-14%. No special processing equipment is required to meet the characteristic requirements. The final product has a crude protein content ≥21.0%, which is 40% higher than the 15% disclosed in existing technologies, and a total sugar content ≥9.6%, far exceeding the 6-8% of conventional silage.

[0033] 4. The method of this invention provides precise control over the anaerobic environment and significantly enhances storage stability: The skeletal structure of the fluffy material and the pore filling of the nutrient emulsion form a "gradient oxygen control" system, reducing the residual oxygen content in the fermentation system to below 0.3% (compared to 0.8-1.2% in traditional processes); the rapid acid production by the compound bacteria stabilizes the pH at 4.2-4.8, inhibiting the growth of mold and other spoilage bacteria, reducing the feed mold rate from 5-10% in existing technologies to 0%, and ensuring no mold growth even after 6 months of storage at 25℃, thus solving the problem of "fermented feed being prone to spoilage and having a short storage period".

[0034] 5. The method and process of this invention have strong adaptability and lower industrialization costs: all raw materials are conventional feed-grade materials (cassava residue, tofu residue, bran, etc.), and the procurement cost is reduced by 30% compared with the process of adding exogenous enzyme preparations; the equipment for puffing, stirring and other processes are general equipment for the breeding industry, which do not require customization, and the fermentation cycle is only 20-48 hours (20-30 hours for small-scale fermentation and 30-48 hours for large-scale fermentation), which is more than 80% shorter than the traditional silage of 15-20 days, significantly improving production efficiency.

[0035] 6. The synergistic effect of the method of this invention is prominent, and the comprehensive benefits are better than single improvements: using CAV-M6 strain alone can only improve the tannin degradation rate, and adding fluffing material alone can only reduce the mold rate by 50%. However, this invention, through the combination of CAV-M6 and CAU-a214, and in conjunction with the corresponding processes, realizes the chain optimization of "tannin degradation - fiber conversion - nutrient synthesis - oxygen control and preservation", which improves the comprehensive quality score of feed (according to GB / T 29304-2012 standard) by 2.3 levels compared with the existing technology, and has both technological advancement and economic practicality.

[0036] 7. This invention, through screening specific degrading strains, optimizing the fluffy carrier formula, and clarifying key process parameters, constructs a synergistic system of "strain degradation - carrier oxygen control - nutrient carbon supplementation" to achieve three major goals: first, to increase the crude fiber degradation rate to over 35%; second, to achieve a crude protein content ≥21.0%; and third, to reduce the mold rate to below 5%. Ultimately, it yields stable, nutritionally balanced fermented feed, promoting the industrialization of sorghum straw resource utilization. This invention effectively solves the core contradictions of existing technologies, such as "incomplete degradation of anti-nutritional factors, low nutrient conversion efficiency, short storage period, and high difficulty in industrialization." The prepared feed has good palatability and high digestibility, and can be widely used in ruminant animal farming. Attached Figure Description

[0037] Figure 1 This is a comparison chart showing the total sugar content and crude protein content of the fermented sorghum straw feed prepared in Examples 1-4 and Comparative Examples 1-6 of the present invention. Detailed Implementation

[0038] In the following examples, all raw materials are feed grade, and the process equipment (expander, mixer, fermentation bag) is conventional equipment used in the aquaculture industry.

[0039] Raw material specifications:

[0040] Sorghum straw: The variety is "Jinnuo No. 3". It was processed within 3 days after harvest. The initial moisture content was 65%, crude fiber content was 32.5%, crude protein content was 8.2%, and tannin content was 2.3% (to ensure that the raw materials of all examples are consistent with those of the comparative examples, to eliminate the interference of raw material differences on the results, and the raw materials used in the examples are from the same batch as those used in comparative examples 1-6).

[0041] The bacterial strains, Lactobacillus plantarum CAV-M6 (CGMCC No. 17614) and Lactobacillus plantarum CAU-a214 (CGMCC No. 13609), were deposited at the China General Microbiological Culture Collection Center on April 22, 2019 and January 13, 2017, respectively, at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing. Both are freeze-dried bacterial powders and will be used after activation.

[0042] Auxiliary materials: tofu residue (protein content 18%, moisture content 82%), cassava residue (starch content 65%, moisture content 80%), and wheat bran (crude fiber content 10%, moisture content 12%). The specific surface area, porosity, and bacterial liquid adsorption capacity were determined as follows: The specific surface area was determined by the BET low-temperature nitrogen adsorption method (referring to GB / T 19587-2017 "Determination of Specific Surface Area of ​​Solid Substances by Gas Adsorption BET Method"). The porosity was determined by the mercury intrusion porosimetry method (referring to GB / T21650.1-2008 "Determination of Pore Size Distribution and Porosity of Solid Materials by Mercury Intrusion Porosimetry and Gas Adsorption Method Part 1: Mercury Intrusion Porosimetry"). The static adsorption equilibrium method was used (at room temperature of 25℃, wheat bran and compound fermentation bacterial liquid were mixed at a mass ratio of 1:5, shaken for 30 minutes, filtered, and the adsorption capacity was calculated as (initial bacterial liquid mass - filtrate bacterial liquid mass / wheat bran mass).

[0043] Soybean oil / rapeseed oil / peanut oil (all feed grade, acid value ≤3mg KOH / g), sucrose esters (feed grade, HLB value 11);

[0044] Equipment Model:

[0045] Chopper: 9Z-2.5 type (adjustable particle size, error ±0.1cm);

[0046] Extruder: SLG-65 twin-screw extruder (die temperature, pressure, and speed can be precisely controlled);

[0047] Mixer: HJJ-50 horizontal mixer (speed adjustable from 50-200 r / min);

[0048] Fermentation equipment: 50L silage fermentation bags (PE material, airtightness ≥0.1MPa, to ensure an anaerobic environment).

[0049] The preparation process of fermented sorghum straw feed of the present invention:

[0050] S1. Sorghum straw pretreatment:

[0051] Select fresh sorghum stalks free of mold, remove withered leaves and impurities, and shred them into two sizes using a chaff cutter—large pieces with a length of 3-5cm and small pieces with a length of 2-3cm, and mix them at a mass ratio of 3:1; spray deionized water into the mixture to adjust the moisture content to 50-60%.

[0052] S2. Preparation of fluffy material: Mix tofu residue and cassava residue at a mass ratio of 1:3 (cassava residue provides a rigid skeleton structure, while tofu residue enhances adsorption; the mass ratio of 1:3 balances fluffiness and cost), and dry to a moisture content of 10-13%; feed into a twin-screw extruder and extrude at a die temperature of 120-140℃, a pressure of 0.8-1.2MPa, and a screw speed of 150-200r / min. The selection of the puffing parameters is based on the following: a die temperature of 120-140℃ ensures that the cellulose in the cassava residue is moderately softened (avoiding insufficient puffing at temperatures below 120℃, resulting in a porosity of <35%, or carbonization of the raw material at temperatures above 140℃, producing harmful substances); a pressure of 0.8-1.2MPa and a rotation speed of 150-200r / min allow the protein network structure of the tofu residue to form uniform pores, ultimately stabilizing the porosity of the fluffy material at 40-50%, meeting the dual requirements of "oxygen removal + microbial metabolic space"; after cooling, a fluffy material with a porosity of 40-50% is obtained, which fills the gaps between the straw and balances the requirements of "oxygen removal" and "microbial metabolic space".

[0053] S3. Preparation of the compound fermentation broth: The conventional method of "mixing after single-cell culture" was adopted: *Lactobacillus plantarum* CAV-M6 (CGMCC No. 17614) and *Lactobacillus plantarum* CAU-a214 (CGMCC No. 13609) were inoculated separately into MRS medium and incubated statically at 30℃ for 24-36 hours until the logarithmic growth phase. Then, the two broths, both in the logarithmic growth phase, were mixed at a volume ratio of *Lactobacillus plantarum* CAV-M6: *Lactobacillus plantarum* CAU-a214 = 2:1, and the total bacterial count was adjusted to 5 × 10⁻⁶ with sterile physiological saline. 9 -1×10 10 CFU / mL.

[0054] Among them, *Lactobacillus plantarum* CAV-M6 has a tannin-degrading enzyme activity ≥4.5 μmol / min˙mL, which can specifically degrade anti-nutritional factors in sorghum straw. The initial tannin content of sorghum straw is 2.3%; after fermentation for 24 hours using the combined fermentation of *Lactobacillus plantarum* CAV-M6 and CAU-a214 in the process of this invention, the tannin residue is reduced to 0.6%, and the tannin degradation rate reaches 73.9% (degradation rate = (initial content - residual content / initial content × 100%). To verify specificity, compared with common *Lactobacillus plantarum* (strain number: CGMCCNo.1.1293, a commonly used strain in the industry), under the same fermentation conditions (28℃, 24h, same bacterial count), its tannin residue is 1.5%, and the degradation rate is only 34.8%. In summary, the tannin degradation efficiency of CAV-M6 is 112.3% higher than that of common strains (increase rate = (CAV-M6 degradation rate - common strain degradation rate) / common strain degradation rate × 100%).

[0055] S4. Preparation of Fermentation-Assisted Nutrient Emulsion: By weight, take 8-10 parts starch, 15-20 parts deionized water, 1-2 parts emulsifier (sucrose ester), and 68-76 parts vegetable oil. First, mix the starch and water and heat to 60℃ to gelatinize. After cooling to 35-40℃, add the sucrose ester and vegetable oil, and stir at 50 r / min for 30-40 min until emulsified uniformly. The core function of this emulsion is to provide a carbon source for microorganisms and fill micropores, further optimizing the anaerobic environment.

[0056] S5. Preparation of bran containing compound fermentation bacteria: Take 90-98 parts of feed-grade bran and mix it with 2-10 parts of the compound fermentation bacteria liquid prepared in S3. Put it into a horizontal mixer and stir at 120r / min for 10min to ensure that the bacteria liquid is evenly attached to the surface of the bran.

[0057] S6. Mixed Fermentation: First, mix the fermentation aid nutrient emulsion of S4 with the loosening material of S2 at a mass ratio of 1:6 to obtain the filler. Then, by weight, take 80-90 parts of sorghum straw obtained from the pretreatment of S1, 3-5 parts of wheat bran containing compound fermentation bacteria from S5, 2-5 parts of compound fermentation liquid from S3, and 5-10 parts of filler, mix them evenly, and compact them to 700-800 kg / m³. 3 The fermented feed is obtained by sealing and fermenting at 25-30℃ for 20-48 hours.

[0058] The fermentation time setting in this invention is based on a synergistic matching of "material scale - temperature control accuracy - metabolic efficiency":

[0059] Small-scale fermentation (<1000kg, such as fermentation bags, small silage pits): high material mixing uniformity (coefficient of variation <8%), temperature control accuracy ±1℃, and the entire process of "tannin degradation - lactic acid accumulation - fiber conversion" can be completed in 20-30h. At this time, the crude protein content is ≥21.0% and the crude fiber degradation rate is ≥35%.

[0060] Large-scale fermentation (≥1000kg, such as large silage pits and continuous fermentation equipment): Because the temperature difference between the center and the surface of the material can reach 3-5℃ (28℃ on the surface, and the center needs 6 hours to rise to 26℃), and the residual oxygen content increases to 0.5-0.8%, it needs to be extended to 30-48 hours. At the same time, the temperature should be controlled at 26-30℃ (1-2℃ higher for smaller scales) to compensate for the efficiency loss caused by the delay in mass transfer.

[0061] Pilot test (10m) 3 Silage pit (material capacity 8000kg): Compaction degree 750kg / m³ 3 The temperature was 28℃ and the fermentation time was 36h. The test results showed that the crude protein was 21.1%, the total sugar was 9.5%, the crude fiber degradation rate was 35.2%, and the pH was 4.6, all of which met the product index requirements of this invention. Moreover, the coefficient of variation between batches was <3%, which proved the adaptability of the parameters for large-scale production.

[0062] If the fermentation time exceeds 48 hours, some starch will be excessively broken down (total sugar drops below 9.0%), and the lactic acid bacteria will enter their decline phase, increasing the risk of contamination by other microorganisms (mold rate > 1%). Therefore, the upper limit is set at 48 hours. During fermentation, there is no need to turn the pile; the porous structure of the loose material allows for "microenvironment ventilation," preventing excessively high local temperatures (> 35℃) that could lead to the growth of other microorganisms.

[0063] Example 1

[0064] S1. Sorghum straw pretreatment:

[0065] Select fresh sorghum stalks free from mold, remove withered leaves and impurities, and shred them into two specifications using a chaff cutter: large pieces with a length of 4cm and a stalk diameter of <0.05cm, and small pieces with a length of 2-3cm and a stalk diameter of <0.05cm, and mix them at a mass ratio of 3:1; spray deionized water into the mixture to adjust the moisture content to 55%;

[0066] S2. Preparation of fluffy material: Mix tofu residue and cassava residue at a mass ratio of 1:3, put them into a hot air dryer, and dry them at 60℃ until the moisture content is 11% (the drying temperature avoids carbonization of the raw materials and conforms to the conventional drying of plant residues); send them into a twin-screw extruder, and extrude them at a die temperature of 130℃, a pressure of 1.0MPa, and a screw speed of 180r / min to obtain a fluffy material with a porosity of 48%.

[0067] S3. Preparation of the compound fermentation broth: *Lactobacillus plantarum* CAV-M6 (CGMCC No. 17614) and *Lactobacillus plantarum* CAU-a214 (CGMCC No. 13609) were inoculated separately into MRS medium and incubated statically at 30℃ for 30 h until the logarithmic growth phase. Then, the two broths, both in the logarithmic growth phase, were mixed at a volume ratio of 2:1 (*Lactobacillus plantarum* CAV-M6: *Lactobacillus plantarum* CAU-a214), and the total bacterial count was adjusted to 8.5 × 10⁻⁶ with sterile physiological saline. 9 CFU / mL.

[0068] S4. Preparation of fermentation-aided nutrient emulsion: By weight, take 9 parts starch, 17 parts deionized water, 1.5 parts emulsifier (sucrose ester), and 72.5 parts vegetable oil; first, mix starch and water in a 60℃ water bath and stir for 15 minutes until gelatinization (gelatinization degree > 90%). After cooling to 37℃, add sucrose ester and vegetable oil, and stir at 50 r / min for 35 minutes until emulsification is uniform. The system is then homogeneous and turbid (no layering, centrifugal stability ≥ 95%), thus obtaining the fermentation-aided nutrient emulsion.

[0069] S5. Preparation of wheat bran containing compound fermentation bacteria: Mix 92 parts of wheat bran (feed grade) with 8 parts of compound fermentation bacteria liquid, and place in a horizontal mixer to stir at 120 r / min for 10 min, ensuring that the bacterial liquid is evenly adhered to the surface of the wheat bran. The wheat bran used is 20-40 mesh feed grade wheat bran with a specific surface area of ​​1.2 m². 2 / g, porosity 37%, bacterial adsorption capacity 0.8mL / g, bacterial species distribution variation coefficient 8%.

[0070] S6. Mixed Fermentation: First, mix the fermentation aid nutrient emulsion of S4 with the fluffing material of S2 at a mass ratio of 1:6 to obtain the filler. Then, by weight, take 85 parts of sorghum straw obtained from the pretreatment of S1, 4 parts of wheat bran containing compound fermentation bacteria of S5, 3 parts of compound fermentation liquid of S3, and 8 parts of filler and put them into a horizontal mixer. Mix at 100 r / min for 6 minutes until uniformly mixed. Pack the mixture into 50L silage fermentation bags and compact them in layers to 750 kg / m³. 3 After sealing, place it in a constant temperature environment of 28℃ for 24 hours to ferment, and you will get fermented sorghum straw feed.

[0071] The test results of the fermented sorghum straw feed in this embodiment are as follows: total sugar 9.75%, crude protein 21.74%, crude fiber degradation rate 38.2%, pH 4.5, and ammonia nitrogen 82.3 mg / 100g.

[0072] Example 2

[0073] S1, Same as Example 1;

[0074] S2. Preparation of fluffy material: The difference from Example 1 is that tofu residue and cassava residue are mixed at a mass ratio of 1:3, dried to 10% moisture content, and puffed at 120℃, 0.8MPa, and 150r / min to obtain a fluffy material with a porosity of 40%.

[0075] S3. Preparation of compound fermentation broth: The difference from Example 1 is that the total bacterial count is adjusted to 8.0 × 10⁻⁶ using sterile physiological saline. 9 CFU / mL;

[0076] S4. Preparation of fermentation-assisted nutrient emulsion: The difference from Example 1 is that 8% starch, 10% water, 6% sucrose ester, and 76% rapeseed oil are stirred at 35°C for 40 minutes.

[0077] S5. Preparation of bran containing compound fermentation bacteria: The difference from Example 1 is that 90 parts of bran + 10 parts of compound fermentation bacteria liquid;

[0078] S6. Mixed Fermentation: The difference from Example 1 is that 90 parts of sorghum straw obtained from S1 pretreatment, 3 parts of wheat bran containing compound fermentation bacteria from S5, 2 parts of compound fermentation liquid from S3, and 5 parts of filler are placed in a horizontal mixer and stirred at 100 r / min for 6 minutes until uniformly mixed; the mixture is then packed into 50L silage fermentation bags and compacted in layers to 700 kg / m³. 3 After sealing, place it in a constant temperature environment of 25℃ for 20 hours to ferment, and you will get fermented sorghum straw feed.

[0079] The test results of the fermented sorghum straw feed in this embodiment are as follows: total sugar 9.62%, crude protein 21.37%, crude fiber degradation rate 35.1%, pH 4.8, and ammonia nitrogen 85.7 mg / 100g.

[0080] Example 3

[0081] S1, Same as Example 1;

[0082] S2. Preparation of fluffy material: The difference from Example 1 is that the material is dried to 13% moisture content and puffed at 140°C, 1.2 MPa, and 200 r / min to obtain a fluffy material with a porosity of 50%.

[0083] S3. Preparation of compound fermentation broth: The difference from Example 1 is that the total bacterial count is adjusted to 9.0 × 10⁻⁶ using sterile physiological saline. 9 CFU / mL;

[0084] S4. Preparation of fermentation-assisted nutrient emulsion: The difference from Example 1 is that 10% starch, 15% water, 10% sucrose ester, and 65% peanut oil are stirred at 40°C for 60 minutes.

[0085] S5. Preparation of bran containing compound fermentation bacteria: The difference from Example 1 is that 95 parts of bran + 5 parts of compound fermentation bacteria liquid;

[0086] S6. Mixed Fermentation: The difference from Example 1 is that 85 parts of sorghum straw obtained from S1 pretreatment, 5 parts of wheat bran containing compound fermentation bacteria from S5, 3 parts of compound fermentation liquid from S3, and 7 parts of filler are placed in a horizontal mixer and stirred at 100 r / min for 6 minutes until uniformly mixed; the mixture is then packed into 50L silage fermentation bags and compacted in layers to 800 kg / m³. 3 After sealing, place it in a constant temperature environment of 30℃ for 30 hours to ferment, and you will get fermented sorghum straw feed.

[0087] The test results of the fermented sorghum straw feed in this embodiment are as follows: total sugar 9.94%, crude protein 21.98%, crude fiber degradation rate 39.5%, pH 4.3, and ammonia nitrogen 81.9 mg / 100g.

[0088] Example 4

[0089] S1, Same as Example 1;

[0090] S2. Preparation of fluffy material: The difference from Example 1 is that the material is dried to 12% moisture content and puffed at 135°C, 1.1 MPa, and 170 r / min to obtain a fluffy material with a porosity of 45%.

[0091] S3. Preparation of compound fermentation broth: The difference from Example 1 is that the total bacterial count is adjusted to 8.2 × 10⁻⁶ using sterile physiological saline. 9 CFU / mL;

[0092] S4. Preparation of fermentation-assisted nutrient emulsion: The difference from Example 1 is that 9.5% starch, 12% water, 8% sucrose ester, and 70.5% soybean oil + rapeseed oil (mixed in a 1:1 ratio) are stirred at 38°C for 45 minutes.

[0093] S5. Preparation of bran containing compound fermentation bacteria: The difference from Example 1 is that 91 parts of bran + 9 parts of compound fermentation bacteria liquid;

[0094] S6. Mixed Fermentation: The difference from Example 1 is that 82 parts of sorghum straw obtained from S1 pretreatment, 5 parts of wheat bran containing compound fermentation bacteria from S5, 3 parts of compound fermentation liquid from S3, and 10 parts of filler are placed in a horizontal mixer and stirred at 100 r / min for 6 minutes until uniformly mixed; the mixture is then packed into 50L silage fermentation bags and compacted in layers to 780 kg / m³. 3 After sealing, place it in a constant temperature environment of 29℃ for 26 hours to ferment, and you will get fermented sorghum straw feed.

[0095] The test results of the fermented sorghum straw feed in this embodiment are as follows: total sugar 9.68%, crude protein 21.51%, crude fiber degradation rate 37.8%, pH 4.4, and ammonia nitrogen 83.5 mg / 100g.

[0096] Example 5

[0097] S1, Same as Example 1;

[0098] S2. Preparation of fluffy material: Same as in Example 1;

[0099] S3. Preparation of compound fermentation liquid: Same as in Example 1;

[0100] S4. Preparation of fermentation-assisted nutrient emulsion: Same as in Example 1;

[0101] S5. Preparation of wheat bran containing compound fermentation bacteria:

[0102] S6. Mixed Fermentation: The difference from Example 1 is that 80 parts of sorghum straw obtained from S1 pretreatment, 5 parts of wheat bran containing compound fermentation bacteria from S5, 5 parts of compound fermentation liquid from S3, and 10 parts of filler are placed in a horizontal mixer and stirred at 100 r / min for 6 minutes until uniformly mixed; the mixture is then loaded into a 10m... 3 Silage pits (equipped with temperature monitoring probes), compacted in layers to 750 kg / m³ 3 After sealing, the mixture is fermented at a constant temperature of 28℃ for 36 hours to obtain fermented sorghum straw feed. The test results of the fermented sorghum straw feed in this embodiment are as follows: total sugar 9.65%, crude protein 21.1%, crude fiber degradation rate 35.2%, pH 4.6, and mold rate 0%, which meet the product index requirements of this invention. Furthermore, the difference in crude protein across different regions of the material (surface / middle / center) is only 0.3%, proving that uniformity can still be maintained even after extended fermentation time in large-scale production.

[0103] Comparative Example 1: Verifying the effect of not adding fermentation auxiliary nutrient emulsion when preparing fermented sorghum straw feed:

[0104] The preparation method of fermented sorghum straw feed is the same as in Example 1, except that there is no fermentation auxiliary nutrient emulsion preparation step, and fluffy material is used as filler.

[0105] The test results of the fermented sorghum straw feed prepared in Comparative Example 1 were as follows: total sugar 8.24%, crude protein 18.36%, crude fiber degradation rate 26.5%, pH 5.1, and ammonia nitrogen 98.7 mg / 100g. Compared with Example 1, the total sugar decreased by 15.5% (9.75%-8.24%), the crude protein decreased by 15.5% (21.74%-18.36%), and the crude fiber degradation rate decreased by 30.6% (38.2%-26.5%). This proves that without emulsifier, the carbon source is insufficient, the oxygen residue is increased (the measured oxygen residue is 0.8%, while it is 0.3% in Example 1), and the nutrient conversion efficiency is significantly reduced, verifying the dual role of emulsifier in "carbon supplementation + oxygen control".

[0106] Comparative Example 2: The fluffy material was replaced with dried residue (to verify the effect of puffing treatment):

[0107] The differences between the preparation method and Example 1 are as follows: (1) "Dried residue" is used instead of fluffy material: Tofu residue and cassava residue are mixed at a mass ratio of 1:3 and dried at 60°C to 11% moisture (without puffing treatment) to obtain dried residue (porosity of 12%, which is in contrast to the 48% of fluffy material in Example 1), ensuring that the only difference is "whether it is puffed", and the variable is unique; (2) Filler preparation: Fermentation auxiliary nutrient emulsion and dried residue are mixed at a mass ratio of 1:6. Other steps and parameters (such as bacterial concentration, compaction degree, fermentation temperature) are completely consistent with Example 1.

[0108] The test results of the fermented sorghum straw feed prepared in Comparative Example 2 were as follows: total sugar 7.92%, crude protein 19.44%, crude fiber degradation rate 28.3%, pH 4.9, and ammonia nitrogen 92.1 mg / 100g. Compared with Example 1, the crude fiber degradation rate decreased by 25.9% (38.2%-28.3%). Due to insufficient porosity of the dried residue, the coefficient of variation of microbial distribution increased to 22% (8% in Example 1), indicating insufficient local fermentation. This verifies the key role of puffing treatment in "preserving metabolic space + uniform oxygen control".

[0109] Comparative Example 3: Emulsion without fermentation aid + fluffing material replaced with dried residue (to verify the synergistic effect of emulsion and fluffing material):

[0110] The differences between the preparation method and Example 1 are as follows: (1) No fermentation auxiliary nutrient emulsion preparation step is used, and the dried residue (porosity 12%) of Comparative Example 2 is used to replace the fluffy material in Example 1; (2) During mixed fermentation, fluffy material is used as filler, and other parameters (compaction degree 750Kg / m) are maintained. 3 The fermentation temperature (28℃) and time (24h) were the same as in Example 1.

[0111] The test results of the fermented sorghum straw feed prepared in Comparative Example 3 were as follows: total sugar 6.94%, crude protein 16.62%, crude fiber degradation rate 22.4%, pH 5.3, and ammonia nitrogen 105.2 mg / 100g. Compared with Example 1, the crude protein decreased by 23.6%, the crude fiber degradation rate decreased by 41.4%, and the mold rate increased to 2% (0% in Example 1). The decrease was greater than the sum of the individual decreases of Comparative Example 1 (without emulsion) and Comparative Example 2 (without extrusion), proving that there is a synergistic effect between the "carbon supplementation" of the emulsion and the "oxygen control" of the fluffy material.

[0112] Comparative Example 4: Wheat bran containing compound fermentation bacteria was replaced with compound fermentation broth (to verify the role of wheat bran as a carrier):

[0113] The difference between the preparation method and Example 1 is that there is no step of preparing bran containing compound fermentation bacteria, and compound fermentation bacteria liquid is added directly, with a total of 7 parts of compound fermentation bacteria liquid added.

[0114] Test results of fermented sorghum straw feed prepared in Comparative Example 4: Total sugar 6.01%, crude protein 14.37%, crude fiber degradation rate 18.7%, pH 5.5, ammonia nitrogen 112.4 mg / 100g; Compared with Example 1, crude protein decreased by 34.0%, and due to the absence of bran carrier, the coefficient of variation of microbial distribution increased to 35% (8% in Example 1), indicating excessively high microbial density at the bottom layer (1.5 × 10⁻⁶). 10 CFU / mL leads to nutrient competition, resulting in excessively low bacterial count in the upper layer (1×10⁻⁶). 9 The presence of CFU / mL caused fermentation to stop, verifying the core role of bran in "uniformly adsorbing microorganisms".

[0115] Comparative Example 5: No fermentation auxiliary nutrient emulsion + dried residue as a substitute for fluffing material + bacterial solution as a substitute for bran carrier (validating the synergistic effect of the entire system):

[0116] The differences between the preparation method and Example 1 are as follows: (1) There is no fermentation auxiliary nutrient emulsion preparation step, and the dried residue of Comparative Example 2 is used to replace the fluffy material; (2) There is no bran preparation step containing compound fermentation bacteria, and compound fermentation liquid is added directly, with a total of 7 parts of compound fermentation liquid added.

[0117] The test results of the fermented sorghum straw feed prepared in Comparative Example 5 were as follows: total sugar 6.33%, crude protein 15.79%, crude fiber degradation rate 20.1%, pH 5.4, and ammonia nitrogen 108.6 mg / 100g. Compared with Example 1, the crude fiber degradation rate decreased by 47.4%, and the mold rate increased to 6%, proving that the technical effect is greatly reduced when the whole system of "emulsion + fluffing substance + bran carrier" is missing, further highlighting the necessity of the synergistic system of the present invention.

[0118] Comparative Example 6: Lactobacillus plantarum CAV-M6 was replaced with common Lactobacillus plantarum (to verify the specificity of the CAV-M6 strain):

[0119] The difference between the preparation method and Example 1 is as follows: (1) In the compound fermentation liquid, common Lactobacillus plantarum (strain number: CGMCC No.1.1293, a commonly used strain in the industry) was used to replace Lactobacillus plantarum CAV-M6 with preservation number CGMCC No.17614; the culture conditions remained unchanged (MRS medium, static culture at 30℃ for 30h to the logarithmic growth phase, OD 600 (Value 0.6-0.8), the bacterial concentration was still adjusted to 8.5×10. 9 CFU / mL (ensure the bacterial count is consistent with Example 1, only the strain is replaced, and the variable is unique); (2) other steps and parameters are completely consistent with Example 1 (including the preparation of fluffy material, emulsion, bran carrier and fermentation parameters).

[0120] The test results of the fermented sorghum straw feed prepared in Comparative Example 6 were as follows: total sugar 7.85%, crude protein 19.21%, crude fiber degradation rate 27.6%, pH 4.9, ammonia nitrogen 94.3 mg / 100g, and tannin residue 1.5%. Compared with Example 1, the crude protein decreased by 11.6% (21.74%-19.21%), and the tannin degradation rate decreased from 73.9% to 34.8%, proving that the highly active tannin enzyme of CAV-M6 can specifically degrade anti-nutritional factors, and ordinary strains cannot achieve the same effect.

[0121] Quality comparison test of Examples 6, 1-5 and Comparative Examples 1-6:

[0122] 6.1 Test subjects:

[0123] Fermented sorghum straw feed prepared in Examples 1-5 and Comparative Examples 1-6.

[0124] 6.2 Test Indicators and Testing Basis:

[0125] Table 1 Test Indicators and Testing Basis

[0126]

[0127] 6.3 Sample processing specifications:

[0128] (1) Sampling method: Samples are taken from the upper, middle and lower layers of the fermentation bag / silage pit. Three points are randomly selected from each layer, and 50g of sample is taken from each point. (2) Sample mixing: Nine samples (3 layers × 3 points) of the same group are combined, reduced to 200g by quartering, crushed and passed through a 40-mesh sieve (0.425mm aperture) for later use. (3) Parallel determination: Each index is measured in parallel 3 times, and the average value is taken as the final result (relative standard deviation RSD < 5%, which meets the reliability requirements of trace analysis data). (4) Standard verification: Standard recovery rate test is carried out simultaneously during the detection process (such as crude protein spike recovery rate of 95%-105% and ammonia nitrogen spike recovery rate of 90%-110%) to ensure the accuracy of the detection method.

[0129] The experimental results are shown in Table 2:

[0130] Table 2. Quality comparison between Examples 1-5 and Comparative Examples 1-6

[0131]

[0132] Results analysis:

[0133] (1) Verification of the effects of Examples 1-5: According to the data in the experimental results table, the total sugar content of Examples 1-4 is ≥9.62% and the crude protein content is ≥21.37%, while the total sugar content of Example 5 (large-scale pilot test) is 9.50% and the crude protein content is 21.10%. All examples meet the product indicators of "total sugar content ≥9.6%, crude protein content ≥21.0%, crude fiber degradation rate ≥35.1%, pH value 4.2-4.8, ammonia nitrogen ≤86.2mg / 100g, and mold rate 0%". The variance analysis of SPSS26.0 software (P<0.05) shows that all indicators of each group of Examples 1-5 are significantly better than those of Comparative Examples 1-6, proving that the technical solution of the present invention can stably improve feed quality and fully match the technical effect defined in the claims.

[0134] (2) Effect of fermentation-assisted nutrient emulsion (Example 1 vs Comparative Example 1): Since Comparative Example 1 does not contain fermentation-assisted nutrient emulsion, the degradation rates of total sugar, crude protein, and crude fiber decreased by 15.5% (9.75%-8.24%), 15.5% (21.74%-18.36%), and 30.6% (38.2%-26.5%) compared with Example 1, respectively, while ammonia nitrogen increased by 19.9% ​​(82.3mg / 100g→98.7mg / 100g). The core reason is that the starch and vegetable oil in the emulsion provide a continuous carbon source for the compound bacteria, advancing the logarithmic growth phase of the compound bacteria by 6 hours (from 12 hours to 6 hours). At the same time, the emulsion can fill the tiny pores of the fluffy material, reducing the residual oxygen content of the system from 0.8% in Comparative Example 1 to 0.3% in Example 1, effectively inhibiting the growth of aerobic putrefactive bacteria such as Bacillus, and reducing the ammonia nitrogen produced by protein decomposition. This is in line with the general knowledge of microbial metabolism that "sufficient carbon source promotes acid production and inhibits protein decomposition".

[0135] (3) The effect of the loosening material (Example 1 vs. Comparative Example 2): In Comparative Example 2, the loosening material (porosity 48%) in Example 1 was replaced with dried residue (porosity 12%). The crude fiber degradation rate decreased by 25.9% (38.2% - 28.3%) compared to Example 1. The key issue is that the insufficient porosity of the dried residue cannot provide a uniform metabolic space for the microorganisms, resulting in excessively high local microbial concentrations (up to 1.2 × 10⁻⁶). 10 CFU / mL) leads to nutrient competition and excessively low local concentrations (only 1×10). 9 The insufficient fermentation (CFU / mL) caused by the low porosity makes it difficult for metabolites (such as lactic acid) to diffuse, and the local pH value drops to 3.8, which inhibits the activity of the microorganisms, thus confirming the core principle of forage fermentation that "pore structure directly affects the microenvironment of microorganisms".

[0136] (4) The role of bran carrier (Example 1 vs. Comparative Example 4): Comparative Example 4 used a compound fermentation broth to directly replace the bran containing bacteria, resulting in a 34.0% decrease in crude protein content compared to Example 1 (21.74% - 14.37%). The core advantage lies in the fact that the bran used in Example 1 (specific surface area 1.2 m²)... 2 The bacterial bran prepared by adsorbing bacterial solution (g, porosity 37%) reduced the coefficient of variation of bacterial distribution to 8%, while the coefficient of variation of bacterial distribution in Comparative Example 4 was as high as 35%. This shows that bacterial bran ensures uniform adhesion of bacteria to the material surface; while directly adding bacterial solution easily leads to excessively high bacterial count at the bottom layer (1.5 × 10⁻⁶ g / g, porosity 37%) due to gravity settling. 10 CFU / mL), upper layer too low (1×10⁻⁶) 9 (CFU / mL), significantly reducing fermentation efficiency, which aligns with the principle of "carriers improving the uniformity of microbial distribution" in microbial applications.

[0137] (5) Synergistic effect verification (Example 1 vs Comparative Example 3): Comparative Example 3 lacked both fermentation auxiliary nutrient emulsion and fluffing material. The crude fiber degradation rate decreased by 41.4% (38.2%-22.4%) compared with Example 1. This decrease was less than the theoretical superposition value (56.5%) of Comparative Example 1 (lacking emulsion, decrease of 30.6%) and Comparative Example 2 (lacking fluffing material, decrease of 25.9%). This proves that there is a synergistic effect between emulsion and fluffing material: emulsion can fill the micropores of fluffing material to achieve "precise oxygen control", while fluffing material provides diffusion channels for carbon sources in emulsion. The combination of the two increases the tannin-degrading enzyme activity of the compound bacteria from 4.5 μmol / (min˙mL) to 5.7 μmol / (min˙mL), further enhancing the degradation efficiency.

[0138] (6) Specificity of CAV-M6 strain (Example 1 vs. Comparative Example 6): Comparative Example 6 used *Lactobacillus plantarum* (CGMCC No. 1.1293) instead of CAV-M6, and the tannin degradation rate decreased by 27.7% compared to Example 1—in Example 1, the tannin content of sorghum straw decreased from the initial 2.3% to 0.6% (degradation rate 73.9%), while in Comparative Example 6 it only decreased to 1.5% (degradation rate 34.8%). The core reason is that CAV-M6 can secrete specific tannin enzymes (amino acid sequence difference rate of 18% compared with ordinary strains), and its enzyme activity reaches 4.85 μmol / (min˙mL), which is 3 times that of ordinary strains. It can efficiently break the ester and ether bonds of tannins, reduce the inhibition of tannins on the activity of the strain, and demonstrate the microbiological advantage of "specific strains improving the degradation rate of anti-nutritional factors".

[0139] Example 7, Stability and Repeatability Verification:

[0140] 7.1 Stability Test:

[0141] The fermented feed prepared in Example 1 was sealed and stored for 6 months in a constant temperature and humidity environment of 25°C and 60% relative humidity. The quality was tested monthly according to current valid standards. The results showed:

[0142] After 6 months of storage, the total sugar content was 8.92%, the crude protein content was 20.15%, the pH value was 4.7, the mold rate was 0%, and the total mold count was ≤5×10⁻⁶. 3 The CFU / g values ​​all meet the "Grade 1 Silage" standard in the "NY / T4469-2025 Comprehensive Evaluation Index Method for Whole Plant Maize Silage Quality", proving that the feed of this invention has excellent storage stability and solves the pain point of "short storage period (<3 months)" in the existing technology.

[0143] 7.2 Repeatability verification:

[0144] Using the process parameters of Example 1, the experiment was repeated with three different batches of sorghum straw (the same variety "Jinnuo No. 3", harvested 7 days apart). The fluctuations in the test results of the three replicates are as follows:

[0145] Total sugar: 9.75% ± 0.12% (fluctuation ≤ 0.2%);

[0146] Crude protein: 21.74% ± 0.06% (fluctuation ≤ 0.3%);

[0147] Crude fiber degradation rate: 38.2% ± 0.5% (fluctuation ≤ 1.3%);

[0148] All core indicators fluctuated within the allowable range for trace analysis, proving that the process of this invention has excellent stability and can meet the batch consistency requirements of large-scale production.

[0149] As can be seen from the above embodiments and comparative examples, this invention, through a synergistic system of "specific strain combination (highly active tannin degradation + bacterial bran carrier (uniform bacterial distribution) + fluffy material (oxygen control and breathability) + fermentation auxiliary nutrient emulsion (carbon supplementation and oxygen control)", specifically addresses the problems of "low crude fiber degradation rate (≤20%), insufficient crude protein content (16-18%), short storage period, and poor large-scale stability" in existing technologies. This results in a stable crude fiber degradation rate of ≥35%, a 40% improvement over traditional processes; a crude protein content of ≥21.0%, a 40% improvement over existing technologies; and no mold growth after 6 months of storage at 25℃, reducing the mold rate from 5-10% in existing technologies to 0%. The final sorghum straw fermented feed has stable quality and balanced nutrition, and the process is compatible with conventional equipment in the livestock industry, allowing for widespread large-scale application in ruminant farming.

Claims

1. A method for preparing fermented sorghum straw feed, characterized in that, Includes the following steps: S1. Sorghum straw pretreatment: Crush sorghum straw and mix it with larger pieces (3-5cm in length) and smaller pieces (2-3cm in length) at a mass ratio of 3:1, and adjust the moisture content to 50-60%. S2. Preparation of fluffy material: Mix tofu residue and cassava residue at a mass ratio of 1:3, puff them up and then cool them to obtain a fluffy material with a porosity of 40-50%. S3. Preparation of the compound fermentation broth: Lactobacillus plantarum CAV-M6 (CGMCC No. 17614) and Lactobacillus plantarum CAU-a214 (CGMCC No. 13609) were cultured to the logarithmic growth phase, respectively. Then, they were mixed at a volume ratio of 2:1 (Lactobacillus plantarum CAV-M6:Lactobacillus plantarum CAU-a214), and the total bacterial count was adjusted to 5 × 10⁻⁶. 9 -1×10 10 CFU / mL, to obtain a compound fermentation broth; S4. Preparation of fermentation-aided nutrient emulsion: Mix and emulsify 8-10 parts of starch, 15-20 parts of water, 1-2 parts of emulsifier, and 68-76 parts of vegetable oil to obtain fermentation-aided nutrient emulsion. S5. Preparation of bran containing compound fermentation bacteria: Take 90-98 parts of feed-grade bran and mix it with 2-10 parts of the compound fermentation bacteria liquid prepared in S3. Put it into a horizontal mixer and stir at 120r / min for 10min to ensure that the bacteria liquid is evenly attached to the surface of the bran. S6. Mixed Fermentation: First, mix the fermentation aid nutrient emulsion of S4 with the loosening material of S2 at a mass ratio of 1:6 to obtain the filler. Then, by weight, take 80-90 parts of sorghum straw obtained from the pretreatment of S1, 3-5 parts of wheat bran containing compound fermentation bacteria from S5, 2-5 parts of compound fermentation liquid from S3, and 5-10 parts of filler, mix them evenly, and compact them to 700-800 kg / m³. 3 The fermented feed is obtained by sealing and fermenting at 25-30℃ for 20-48 hours.

2. The preparation method according to claim 1, characterized in that, The sorghum stalks of S1 are crushed to a length of 4cm for large pieces and 2.5cm for small pieces, with the moisture content adjusted to 55%.

3. The preparation method according to claim 1, characterized in that, The parameters for the expansion treatment of S2 are 130℃, 1.0MPa, and 180r / min, and the porosity of the expanded fluffy material is 45-50%.

4. The preparation method according to claim 1, characterized in that, The *Lactobacillus plantarum* strain S3 was cultured on MRS medium at 30°C for 24-36 hours until OD reached. 600 The logarithmic growth period has a value of 0.6-0.

8.

5. The preparation method according to claim 1, characterized in that, The emulsifier of S4 is sucrose ester, the emulsification temperature is 35-40℃, the stirring speed is 50r / min, the emulsification time is 30-40min, and the emulsified system is uniform and turbid without layering.

6. The preparation method according to claim 1, characterized in that, The specific surface area of ​​the bran in step S5 is 1.0-1.2 m². 2 / g, porosity 35-38%.

7. The preparation method according to claim 1, characterized in that, The adsorption capacity of the compound fermentation liquid on the surface of wheat bran is 0.7-0.8 mL / g.

8. The preparation method according to claim 1, characterized in that, In S6, if the amount of material in a single batch is less than 1000 kg, the fermentation time is 20-30 h; if the amount of material in a single batch is greater than or equal to 1000 kg, the fermentation time is 30-48 h.

9. The preparation method according to claim 1, characterized in that, In the S3 compound fermentation broth, the tannin-degrading enzyme activity of Lactobacillus plantarum CAV-M6 is ≥4.5 μmol / min˙mL.

10. A fermented sorghum straw feed, characterized in that, The feed is prepared by any one of claims 1-9, and the feed has a crude protein content ≥21.0%, a total sugar content ≥9.6%, a crude fiber degradation rate ≥35%, a pH value of 4.2-4.8, a tannin residue ≤0.8%, a mold rate ≤1%, and contains Lactobacillus plantarum CAV-M6 metabolites.

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