Pig fattening daily ration capable of reducing VOC and malodorous gas and preparation method of pig fattening daily ration

Abstract

The invention discloses a fattening pig daily ration capable of reducing VOC and malodorous gas and a preparation method of the fattening pig daily ration, and relates to the technical field of breeding feed. The feed comprises an energy raw material, a protein raw material, an amino acid additive, a fermentable carbohydrate and fiber raw material, an organic acid acidifier, an enzyme preparation system, a microecological preparation, an ammonia inhibition / adsorption additive, a mineral substance and trace element premix and a flavoring agent. The daily ration for fattening pigs is prepared on the basis of the raw materials. The raw materials are scientifically combined to form a daily ration system for cooperatively inhibiting generation of VOC and malodorous gas in multiple paths, and heat-resistant protection measures such as low-temperature mixing of an enzyme preparation and a microecological preparation, carrier protection and post-spraying are introduced in the preparation process, so that the growth performance of the fattening pigs is ensured, and the yield of the fattening pigs is improved. The emission of ammonia gas, hydrogen sulfide and various VOCs (volatile organic compounds) is remarkably reduced, and the production benefit and the environmental benefit are synchronously improved.

Description

Technical Field

[0001] This invention relates to the field of animal feed technology, specifically to a fattening pig diet with reduced VOCs and malodorous gases, and its preparation method. Background Technology

[0002] In the production of fattening pigs, the nutritional composition of feed directly affects the excretion of nitrogen, sulfur, and aromatic compounds in feces and urine. These compounds, during anaerobic or aerobic decomposition, generate ammonia (NH3), hydrogen sulfide (H2S), volatile organic compounds (VOCs), and malodorous gases such as indole and p-cresol. This not only affects the air quality in pigsties but also causes environmental pollution and livestock health problems. Current fattening pig diets primarily aim to improve growth performance, typically employing high-protein formulations without adequately considering the regulation of nitrogen and sulfur metabolic pathways during fecal fermentation, resulting in high levels of malodorous emissions. While some existing low-protein formulations reduce ammonia emissions to some extent, they often lack the synergistic effect of fermentable carbohydrates, organic acids, ammonia-inhibiting / adsorbent additives, and microecological preparations, making it difficult to significantly suppress the combined emission of multiple malodorous gases while maintaining production performance. Furthermore, current feed preparation processes lack adequate heat protection measures for functional additives, easily leading to the loss of enzyme and microecological preparation activity, thus reducing practical application effectiveness.

[0003] The shortcomings of existing technologies include the following two aspects:

[0004] Single formulation regulation: Most diets only reduce ammonia emissions by lowering crude protein levels, lacking multi-factor synergistic regulation of amino acid balance, fermentable carbohydrates, acidifiers, adsorbents and microecology, thus limiting their ability to control hydrogen sulfide, phenolic and indole VOCs.

[0005] Insufficient process protection: Existing preparation methods lack low-temperature mixing, carrier protection, and post-coating measures for enzyme preparations and microecological preparations during conditioning and granulation, resulting in a reduced survival rate of effective active substances and difficulty in maintaining the deodorizing effect stably in the production environment for a long time.

[0006] Meanwhile, Chinese patent (CN108112785A) discloses a traditional Chinese medicine pig feed additive, its preparation method, and the pig feed thereof. The additive comprises 5-8 parts licorice root, 2-4 parts forsythia fruit, 1-3 parts poria cocos, 2-4 parts fleeceflower root, 1-3 parts asparagus root, 2-4 parts peony bark, 1-3 parts mulberry leaf, 1-3 parts motherwort, 2-5 parts white peony root, 2-4 parts atractylodes rhizome, 4-6 parts honeysuckle flower, 1-3 parts phellodendron bark, 1-2 parts lily bulb, 3-5 parts chrysanthemum flower, 1-5 parts wolfberry, 0.1-0.2 parts halloysite, 0.2-0.4 parts pumice, and 0.1-0.2 parts red ochre. After pulverizing and sieving the above raw materials, a pig feed additive is obtained. This additive is then mixed into pig feed to obtain a feed containing the traditional Chinese medicine pig feed additive. Pigs fed this feed are less prone to illness and show more significant weight gain. However, the pig feed produced by this method does not alleviate the odor of NH3 and H2S produced by fattening pigs. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a fattening pig diet that reduces VOCs and odorous gases, and its preparation method, thereby solving the problems mentioned in the background art.

[0008] The first technical solution of the present invention: a fattening pig diet that reduces VOCs and malodorous gases, comprising the following ingredients in parts by weight:

[0009] The energy feed consists of 54–58 parts corn, 5.5–9 parts wheat, 3.5–5.3 parts rice bran, and 1.2–1.8 parts vegetable oil. This provides the metabolizable energy required for fattening pig diets, supporting growth, maintenance, and fat deposition. Corn and wheat are the main starch sources, while rice bran and vegetable oil improve energy density and palatability. Optimizing the proportions of energy feedstocks can reduce excessive protein energy supply and lower the risk of nitrogen emissions.

[0010] The protein feedstock consists of 9.5–13 parts low-sulfurized soybean meal, 3.0–4.5 parts desulfurized rapeseed meal, and 1.2–2.2 parts fermented protein. These three feedstocks together provide high-quality digestible protein while reducing sulfur-containing amino acid content to inhibit hydrogen sulfide formation. This combination of protein feedstocks helps maintain growth performance at low crude protein levels and reduces nitrogen and sulfur metabolic waste emissions.

[0011] Organic acid acidifiers, benzoic acid 0.28–0.35 parts, citric acid 0.12–0.15 parts; the combination of benzoic acid and citric acid can lower the pH of the gastrointestinal tract, inhibit the growth of harmful bacteria, and promote nutrient digestion and absorption. The acidified environment can reduce the activity of urease in feces and urine, thereby inhibiting ammonia volatilization.

[0012] Microecological preparations, such as Bacillus subtilis preparations (0.03–0.08 parts) and Lactobacillus plantarum preparations (0.03–0.08 parts), can improve the intestinal flora structure, inhibit the reproduction of putrefactive bacteria and pathogens, and reduce the likelihood of foul-smelling diarrhea in pigs. Microecological metabolites can competitively inhibit the growth of putrefactive bacteria and pathogens and the formation of foul-smelling precursors, and improve immune levels.

[0013] An ammonia-suppressing / adsorption additive, consisting of 0.70–1.00 parts clinoptilolite powder and 0.03–0.04 parts yucca saponin extract. Clinoptilolite powder has a high cation exchange capacity, which can adsorb ammonium ions from feces and urine; yucca saponin extract can inhibit urease activity. The synergistic effect of both significantly reduces ammonia release and improves indoor air quality.

[0014] Preferably, the ingredients include the following parts by weight:

[0015] Energy-generating ingredients: 55-57 parts corn, 6.5-8 parts wheat, 4-5 parts rice bran, and 1.4-1.6 parts vegetable oil;

[0016] Protein raw materials: 10-12 parts of low-sulfurized soybean meal, 3.5-4 parts of desulfurized rapeseed meal, and 1.5-2 parts of fermented protein.

[0017] Organic acid acidifying agents: benzoic acid 0.3–0.33 parts, citric acid 0.13–0.14 parts;

[0018] Microecological preparations, including 0.04–0.07 parts of Bacillus subtilis preparation and 0.04–0.07 parts of Lactobacillus plantarum preparation;

[0019] Ammonia-inhibiting / adsorbent additives, including 0.8-0.9 parts of clinoptilolite powder and 0.03-0.04 parts of yucca saponin extract.

[0020] Preferably, the ingredients include the following parts by weight:

[0021] Energy-generating ingredients: 56 parts corn, 7.5 parts wheat, 4.5 parts rice bran, and 1.5 parts vegetable oil;

[0022] Protein raw materials: 11 parts low-sulfurized soybean meal, 3.8 parts desulfurized rapeseed meal, and 1.8 parts fermented protein.

[0023] Organic acid acidifying agents: 0.32 parts benzoic acid and 0.14 parts citric acid;

[0024] Microecological preparations: 0.05 parts of Bacillus subtilis preparation and 0.06 parts of Lactobacillus plantarum preparation;

[0025] Ammonia-inhibiting / adsorbent additives: 0.85 parts of clinoptilolite powder and 0.04 parts of yucca saponin extract.

[0026] Preferably, the fattening pig diet also includes the following parts by weight of amino acid supplements:

[0027] The diet should contain 0.28–0.38 parts L-lysine, 0.17–0.22 parts DL-methionine, 0.10–0.13 parts L-threonine, 0.042–0.055 parts L-tryptophan, 0.085–0.11 parts L-valine, and 0.063–0.09 parts L-isoleucine to ensure amino acid balance in a low-protein diet and meet growth requirements. Amino acid balance promotes amino acid absorption, reduces excessive protein breakdown and waste, lowers fecal nitrogen content, and inhibits ammonia emissions at the source.

[0028] Preferably, the amino acid additives include the following parts by weight: 0.30-0.35 parts L-lysine, 0.18-0.21 parts DL-methionine, 0.11-0.12 parts L-threonine, 0.043-0.053 parts L-tryptophan, 0.088-0.10 parts L-valine, and 0.065-0.085 parts L-isoleucine.

[0029] Preferably, the amino acid additives include the following parts by weight: 0.32-0.33 parts L-lysine, 0.20-0.21 parts DL-methionine, 0.115-0.125 parts L-threonine, 0.045-0.050 parts L-tryptophan, 0.09-0.10 parts L-valine, and 0.07-0.08 parts L-isoleucine.

[0030] Preferably, the fattening pig diet also includes the following parts by weight of fermentable carbohydrates and fiber:

[0031] The formula contains 3.5–5.5 parts beet pulp, 2.5–4 parts wheat bran, and 1.8–2.5 parts alfalfa meal. These ingredients provide soluble dietary fiber and hemicellulose, promoting the fermentation and acid production of beneficial bacteria. By regulating the intestinal environment and lowering pH, it reduces the formation of harmful metabolites, improves the physicochemical properties of feces, and reduces odor release.

[0032] Preferably, the ingredients include the following parts by weight of fermentable carbohydrates and fiber:

[0033] Beet meal 4.0-5.0 parts, wheat bran 3.0-3.8 parts, alfalfa meal 2.0-2.3 parts.

[0034] Preferably, the ingredients include the following parts by weight of fermentable carbohydrates and fiber:

[0035] Beet meal 4.2-4.5 parts, wheat bran 3.2-3.5 parts, alfalfa meal 2.1-2.2 parts.

[0036] Preferably, the fattening pig diet also includes the following enzyme preparation system in parts by weight:

[0037] Neutral protease 0.03–0.08 parts, xylanase 0.02–0.03 parts, β-glucanase 0.01–0.03 parts, phytase 0.01–0.03 parts; can decompose anti-nutritional factors and improve nutrient utilization. Enzymatic hydrolysis reduces undigested substrate entering the hindgut, reduces feed waste, and reduces the generation of harmful fermentation products and VOCs.

[0038] Preferably, the enzyme preparation system includes the following parts by weight:

[0039] Neutral protease 0.04–0.07 parts, xylanase 0.023–0.027 parts, β-glucanase 0.015–0.025 parts, phytase 0.02–0.025 parts.

[0040] Preferably, the enzyme preparation system comprises the following parts by weight:

[0041] Neutral protease 0.05–0.06 parts, xylanase 0.024–0.026 parts, β-glucanase 0.02–0.023 parts, phytase 0.021–0.023 parts.

[0042] Preferably, the fattening pig diet also includes the following parts by weight of mineral and trace element premix:

[0043] Mineral trace element premix 1.0-1.2 parts, vitamin premix 0.3-0.5 parts; used to maintain the body's metabolic balance, scientifically control the form and level of minerals, and avoid excessive environmental emissions.

[0044] Preferably, the premix of minerals and trace elements includes the following parts by weight:

[0045] 1.05–1.15 parts of mineral trace element premix and 0.35–0.45 parts of vitamin premix.

[0046] Preferably, the premix of minerals and trace elements includes the following parts by weight:

[0047] Mineral trace element premix 1.1 to 1.13 parts, vitamin premix 0.4 to 0.43 parts.

[0048] Preferably, the fattening pig diet also includes a flavoring agent, namely salt, at a weight of 0.19–0.575 parts. This flavoring agent helps regulate the electrolyte balance of the diet, maintain the body's osmotic pressure and acid-base balance, and improve palatability. Proper control of salt content helps regulate urine pH and indirectly inhibits ammonia volatilization.

[0049] Preferably, the product also includes a seasoning, wherein the seasoning is salt, and the salt is present in a weight of 0.3 to 0.5 parts.

[0050] Preferably, the product also includes a seasoning, wherein the seasoning is salt, and the salt is present in a weight ratio of 0.4 to 0.45 parts.

[0051] Preferably, the preparation steps of the low-thionine soybean meal are as follows:

[0052] Grind ordinary defatted soybean meal to 40–60 mesh, place it in a stainless steel reactor, add 4–6 times the weight of deionized water, heat to 45–50℃ and stir evenly, and adjust the pH to 7.5–8.0.

[0053] Add a complex enzyme of methionine oxidase and cysteine ​​desulfurase at a rate of 3000–5000 U / kg of raw material and hydrolyze for 3–4 hours to selectively degrade methionine and cysteine.

[0054] Subsequently, the residue is heated with steam at 0.1–0.2 MPa for 15–20 min to inactivate the residual enzymes. The solution portion is removed by plate and frame filtration, the wet filter residue is dried to a moisture content of ≤10%, and then pulverized through a 50–70 mesh to finally obtain low-thionine soybean meal.

[0055] Preferably, the preparation steps of the desulfurized rapeseed meal are as follows:

[0056] Crush rapeseed meal to 35-45 mesh, add 0.5% citric acid solution at a mass-to-volume ratio of 1:3-5, and extract at 50-60℃ for 35-45 minutes to dissolve glucosinolates and some free sulfides to obtain wet material.

[0057] After solid-liquid separation, the wet material is subjected to a fermentation process;

[0058] After fermentation, the rapeseed meal is dried with hot air at an outlet temperature of 60-70℃ and a moisture content of ≤11%, to obtain the final desulfurized rapeseed meal.

[0059] Preferably, the fermentation process is as follows:

[0060] The wet material was fed into an anaerobic fermenter and inoculated with *Lactobacillus plantarum* and *Streptococcus thermophilus* in a ratio of 1:2:1:2, at an inoculation density of 4 × 10⁻⁶. 7 -6×10 7 CFU / g, fermentation temperature 40-44℃, pH controlled at 5.5-6.0, fermentation time 16-20h.

[0061] Preferably, the preparation steps of the fermented protein are as follows:

[0062] Using corn distillers grains as a substrate, the moisture content is first adjusted to 55-60% before fermentation.

[0063] After fermentation, the product is pressed to a moisture content of 36-44% using a belt filter press, then dried with hot air at 65-75℃ until the moisture content is ≤10%, and finally pulverized through a 70-90 mesh to obtain fermented protein.

[0064] Preferably, the fermentation process is as follows:

[0065] The inoculation consisted of a complex microbial flora, including *Saccharomyces cerevisiae*, *Lactobacillus acidophilus*, and *Bacillus subtilis*, in a ratio of 2:1:1, with a total inoculation volume of 1×10⁻⁶. 8 CFU / g, fermentation temperature 34-38℃, pH maintained at 5.2-5.8, fermentation time 46-50h;

[0066] During fermentation, the mixture is turned over every 12 hours to replenish oxygen and even out the temperature.

[0067] As a preferred embodiment, the slow-release preparation method of the organic acid acidifier compound is as follows:

[0068] Mix benzoic acid and citric acid by weight, add 10–15 times the weight of molten hydrogenated palm oil, and homogenize in a high-speed shear emulsifier for 4–6 minutes to ensure that the acid powder is evenly dispersed in the oil phase.

[0069] The mixture is then solidified into blocks at 5–8°C, broken down into 200–500 μm particles by a pulverizer, and particles larger than 500 μm are sieved out to obtain microencapsulated acidifiers.

[0070] Preferably, the method for preparing the yucca saponin extract includes the following:

[0071] Select dried yucca leaves, pulverize them to 10-30 mesh, add 70% ethanol solution at a mass-to-volume ratio of 1:5-7, and extract at a constant temperature of 50-60℃ with stirring for 3-5 hours.

[0072] After filtration, the filtrate is concentrated under reduced pressure to 1 / 5-1 / 4 of its original volume. Then, impurities are removed by adding 3-5 times the volume of anhydrous ethanol and allowing it to stand at 3-5°C for 10-14 hours.

[0073] The precipitate was centrifuged and vacuum dried to obtain yucca saponin powder. The saponin content was controlled at 30-35% and the moisture content was ≤8%, thus obtaining yucca saponin extract.

[0074] Mix with maltodextrin at a ratio of 1-2:1-2 before use.

[0075] Preferably, the Bacillus subtilis preparation undergoes heat-resistant microencapsulation treatment, including:

[0076] Fermentation culture until the spore formation rate is ≥95% is carried out. After centrifugation to remove the culture medium, wet bacterial sludge and heat-resistant carrier are mixed at a ratio of 1:3-5. 10% maltodextrin and 5% sodium alginate solution are added, and after uniform stirring, spray drying is carried out to obtain Bacillus subtilis preparation.

[0077] Preferably, the heat-resistant carrier is composed of starch and whey powder in a ratio of 1-2:1; the inlet temperature of the spray dryer is 120-140℃, and the outlet temperature is 60-70℃; the resulting powder has a spore count ≥1×10⁻⁶. 11 CFU / g, survival rate ≥75% after granulation, maintaining activity during high-temperature granulation.

[0078] Preferably, the clinoptilolite powder undergoes performance optimization treatment before use, including:

[0079] Natural clinoptilolite ore is selected, first washed with water to remove mud and sand impurities, then dried at 180-220℃ for 3-5 hours, pulverized and controlled by an air classifier to maintain the particle size at 50-80μm, so as to increase the specific surface area, with a specific surface area ≥35m² / g.

[0080] Then, it is soaked in 0.1 mol / L sodium chloride solution for 10-14 hours to improve the cation exchange capacity and ensure ≥150 cmol / kg. Finally, it is dried with hot air until the moisture content is ≤5%.

[0081] The second technical solution of the present invention: a method for preparing a fattening pig diet with reduced VOCs and malodorous gases, based on the above-mentioned fattening pig diet, includes the following steps:

[0082] (S1) Raw material preparation: Prepare the corresponding weight parts of raw materials according to the formula;

[0083] (S2) Coarse grinding treatment: The solid raw materials, including corn, wheat, rice bran, beet meal, wheat bran, and alfalfa powder, are coarsely ground to control the particle size to 1.0-1.5 mm.

[0084] (S3) First mixing: Add the crushed energy raw materials, protein raw materials, fermentable carbohydrates and fiber raw materials to the mixer in proportion, and mix at low speed for 2-3 minutes;

[0085] (S4) Adding functional additives and secondary mixing: Add amino acid additives, organic acidifiers, enzyme preparation system, microecological preparation, ammonia / adsorption additives, mineral and trace element premix and flavoring agent to the primary mixture in (S3) in sequence, and continue to mix at medium and high speed for 5 to 8 minutes.

[0086] (S5) Conditioning and pelleting: The uniformly mixed diet (S4) is fed into the conditioner, the conditioning temperature is controlled at 75-85℃, the conditioning time is 60-120s, and then it is pressed into pellets with a diameter of 2.5-4.0mm by the pellet mill.

[0087] (S6) Cooling, screening and packaging: The granules obtained in (S5) are cooled to room temperature ±5℃ by a countercurrent cooler, and the moisture content is controlled at ≤12.5%; after screening to remove powder and unqualified granules, they are packaged, labeled and stored according to standards, avoiding moisture and direct sunlight.

[0088] Preferably, in step (S4), the enzyme preparation system and the microecological preparation are pretreated after mixing:

[0089] Neutral protease, xylanase, β-glucanase, phytase and carrier powder are mixed at a ratio of 1:4-6 and added to the mixer along with the probiotic preparation at an environment below 25-35℃. The mixing speed is controlled at medium to low speed for 3-5 minutes to prevent local frictional heating from causing a decrease in activity and to ensure that the coefficient of variation (CV) of the mixing uniformity is ≤5%.

[0090] Preferably, in step (S5), for microecological preparations with poor heat resistance, they are added through a post-spraying system after conditioning and before granulation, with the spraying temperature not exceeding 40°C and the water activity in the spraying liquid controlled below 0.60.

[0091] Compared with the prior art, the present invention provides a fattening pig diet with reduced VOCs and malodorous gases and its preparation method, which has the following beneficial effects:

[0092] This fattening pig diet, which reduces VOCs and odorous gases, and its preparation method, scientifically combine low-thiamine soybean meal, desulfurized rapeseed meal, fermented protein, amino acid additives, fermentable carbohydrates, organic acidifiers, enzyme preparations, microecological preparations, ammonia-inhibiting / adsorbent additives, and mineral and trace element premixes to form a multi-pathway synergistic inhibition system for VOC and odorous gas generation. Furthermore, the preparation process incorporates heat-resistant protection measures such as low-temperature mixing of enzyme and microecological preparations, carrier protection, and post-coating. This ensures the growth performance of fattening pigs while significantly reducing the emission of ammonia, hydrogen sulfide, and various VOCs, achieving simultaneous improvement in production and environmental benefits. Attached Figure Description

[0093] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0094] Figure 1 This is a schematic flowchart of the method for preparing fattening pig diets that reduces VOCs and malodorous gases, as proposed in this invention. Detailed Implementation

[0095] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0096] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0097] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0098] A fattening pig diet with reduced VOCs and odorous gases contains the following ingredients by weight:

[0099] Energy-generating ingredients: 54-58 parts corn, 5.5-9 parts wheat, 3.5-5.3 parts rice bran, and 1.2-1.8 parts vegetable oil.

[0100] Protein raw materials: 9.5-13 parts of low-sulfurized soybean meal, 3.0-4.5 parts of desulfurized rapeseed meal, and 1.2-2.2 parts of fermented protein.

[0101] The specific preparation steps for low-thionine soybean meal are as follows:

[0102] Ordinary defatted soybean meal is pulverized to 40–60 mesh and placed in a stainless steel reactor. 4–6 times its weight of deionized water is added, and the mixture is heated to 45–50°C and stirred until homogeneous. The pH is adjusted to 7.5–8.0. A complex enzyme of methionine oxidase and cysteine ​​desulfurase is added at a dosage of 3000–5000 U / kg of raw material, and the enzymatic hydrolysis time is 3–4 hours to selectively degrade methionine and cysteine. Subsequently, the mixture is heated with steam at 0.1–0.2 MPa for 15–20 minutes to inactivate any remaining enzymes. The solution portion is removed by plate and frame filtration. The wet filter residue is dried to a moisture content ≤10% and then pulverized to 50–70 mesh to obtain low-thiamine soybean meal.

[0103] The specific preparation steps for desulfurized rapeseed meal are as follows:

[0104] Rapeseed meal was pulverized to 35–45 mesh and added to a 0.5% citric acid solution at a mass-to-volume ratio of 1:3–5. The mixture was extracted at 50–60℃ for 35–45 minutes to dissolve glucosinolates and some free sulfides, yielding a wet feed. After solid-liquid separation, the wet feed underwent a fermentation process. It was transferred to an anaerobic fermenter and inoculated with *Lactobacillus plantarum* and *Streptococcus thermophilus* at a ratio of 1–2:1–2, with an inoculum size of 4 × 10⁻⁶. 7 –6×10 7 The fermentation process was carried out at CFU / g, with a fermentation temperature of 40–44℃, a pH controlled at 5.5–6.0, and a fermentation time of 16–20 hours. After fermentation, the product was dried by hot air at an outlet temperature of 60–70℃, with a moisture content controlled at ≤11%, to obtain the final desulfurized rapeseed meal.

[0105] The specific preparation steps for fermented protein products are as follows:

[0106] Using corn distillers' grains as a substrate, the moisture content is first adjusted to 55–60% for fermentation. A complex microbial community is then inoculated, including brewer's yeast, Lactobacillus acidophilus, and Bacillus subtilis, in a ratio of 1–2:1–2:1–2, with a total inoculum of 1×10⁻⁶. 8 –2×10 8 The fermentation process was carried out at CFU / g, with a fermentation temperature of 34–38℃, a pH maintained at 5.2–5.8, and a fermentation time of 46–50 hours. The mixture was turned every 12 hours during fermentation to replenish oxygen and maintain a uniform temperature. After fermentation, the product was pressed using a belt filter press to a moisture content of 36–44%, then dried with hot air at 65–75℃ until the moisture content was ≤10%, and finally pulverized through a 70–90 mesh to obtain the fermented protein.

[0107] Amino acid additives: L-lysine 0.28-0.38 parts, DL-methionine 0.17-0.22 parts, L-threonine 0.10-0.13 parts, L-tryptophan 0.042-0.055 parts, L-valine 0.085-0.11 parts, L-isoleucine 0.063-0.09 parts.

[0108] Fermentable carbohydrate and fiber raw materials: 3.5-5.5 parts beet meal, 2.5-4 parts wheat bran, and 1.8-2.5 parts alfalfa meal.

[0109] Organic acid acidifiers: 0.28-0.35 parts benzoic acid, 0.12-0.15 parts citric acid.

[0110] The slow-release preparation method of the compound organic acid acidifier is as follows:

[0111] Benzoic acid and citric acid were mixed in parts by weight, and 10–15 times their weight of molten hydrogenated palm oil were added. The mixture was homogenized in a high-speed shear emulsifier for 4–6 minutes to ensure that the acid powder was evenly dispersed in the oil phase. Subsequently, the mixture was solidified into blocks at 5–8°C, and then pulverized to 200–500 μm particles. Particles larger than 500 μm were sieved out to obtain microencapsulated acidifier.

[0112] Enzyme preparation system: 0.03-0.08 parts of neutral protease, 0.02-0.03 parts of xylanase, 0.01-0.03 parts of β-glucanase, and 0.01-0.03 parts of phytase.

[0113] Microecological preparations: 0.03-0.08 parts of Bacillus subtilis preparation and 0.03-0.08 parts of Lactobacillus plantarum preparation.

[0114] Among them, the Bacillus subtilis preparation undergoes heat-resistant microencapsulation treatment, including:

[0115] Fermentation culture until spore formation rate ≥95% is achieved. After centrifugation to remove the culture medium, the wet mycelium sludge is mixed with a heat-resistant carrier (composed of starch and whey powder in a 1–2:1 ratio); the inlet temperature for spray drying is 120–140℃, and the outlet temperature is 60–70℃; the resulting powder has a spore count ≥1×10⁻⁶. 11 (CFU / g, survival rate ≥75% after granulation, maintaining activity during high-temperature granulation) are mixed at a ratio of 1:3–5, and 10% maltodextrin and 5% sodium alginate solution are added. After uniform stirring, the mixture is spray-dried to obtain the Bacillus subtilis preparation.

[0116] Ammonia-inhibiting / adsorbent additives: 0.70-1.00 parts of clinoptilolite powder and 0.03-0.04 parts of yucca saponin extract.

[0117] Before use, clinoptilolite powder undergoes performance optimization treatment, including:

[0118] Natural clinoptilolite ore is selected, first washed with water to remove mud and sand impurities, then dried at 180–220℃ for 3–5 hours, pulverized, and subjected to an air classifier to control the particle size at 50–80 μm to increase the specific surface area, which is ≥35 m² / g. Subsequently, it is soaked in a 0.1 mol / L sodium chloride solution for 10–14 hours to increase the cation exchange capacity, ensuring it is ≥150 cmol / kg, and finally dried with hot air until the moisture content is ≤5%. This treatment increases its adsorption capacity for ammonium ions by more than 20%, effectively fixing ammonium nitrogen in feces and urine and reducing ammonia volatilization.

[0119] The preparation method of yucca saponin extract includes the following:

[0120] Select dried yucca leaves, pulverize to 10–30 mesh, and add 70% ethanol solution at a mass-to-volume ratio of 1:5–7. Extract at a constant temperature of 50–60℃ with stirring for 3–5 hours. After filtration, concentrate the filtrate under reduced pressure to 1 / 5–1 / 4 of its original volume, and then remove impurities by ethanol precipitation method, adding 3–5 times the volume of anhydrous ethanol and allowing it to stand at 3–5℃ for 10–14 hours. Centrifuge and vacuum dry the precipitate to obtain yucca saponin powder with a saponin content controlled at 30–35% and moisture ≤8%, thus obtaining yucca saponin extract. Before use, mix with maltodextrin at a ratio of 1–2:1–2 to improve dispersibility and stability in feed.

[0121] Mineral and trace element premix: 1.0 to 1.2 parts mineral and trace element premix, 0.3 to 0.5 parts vitamin premix.

[0122] Seasoning: including 0.19 to 0.575 parts salt.

[0123] Reference Figure 1 A method for preparing fattening pig diets with reduced VOCs and odorous gases, based on the aforementioned fattening pig diets, includes the following specific steps:

[0124] (S1) Raw material preparation: Prepare the corresponding weight parts of raw materials according to the formula.

[0125] (S2) Coarse grinding treatment: The solid raw materials, including corn, wheat, rice bran, beet meal, wheat bran, and alfalfa meal, are coarsely ground to control the particle size to 1.0-1.5 mm to ensure uniform mixing and facilitate subsequent conditioning. Liquid or powdered components such as vegetable oil, benzoic acid, and citric acid are prepared separately.

[0126] (S3) First mixing: Add the crushed energy raw materials, protein raw materials, fermentable carbohydrates and fiber raw materials to the mixer in proportion, mix at low speed for 2-3 minutes to make the bulk raw materials initially evenly distributed.

[0127] (S4) Adding functional additives and secondary mixing: Add amino acid additives, organic acidifiers, enzyme preparation system, microecological preparation, ammonia / adsorption additives, mineral and trace element premix and flavoring agent to the primary mixture in (S3) in sequence, and continue to mix at medium to high speed for 5 to 8 minutes.

[0128] After mixing, the enzyme preparation system and the probiotic preparation are pretreated:

[0129] Neutral protease, xylanase, β-glucanase, phytase and carrier powder are mixed at a ratio of 1:4–6 and added to the mixer along with the probiotic preparation at an environment below 25–35℃. The mixing speed is controlled at medium to low speed for 3–5 minutes to prevent local frictional heating from causing a decrease in activity and to ensure that the coefficient of variation (CV) of the mixing uniformity is ≤5%.

[0130] (S5) Conditioning and Granulation: The uniformly mixed diet from (S4) is fed into a conditioner. The conditioning temperature is controlled at 75–85℃, and the conditioning time is 60–120 seconds. Subsequently, it is granulated into pellets with a diameter of 2.5–4.0 mm using a pellet mill. For microecological preparations with poor heat resistance, they are added through a post-spraying system after conditioning and before granulation. The spraying temperature is not higher than 40℃, and the water activity in the spray solution is controlled below 0.60 to ensure that the survival rate after granulation is not lower than the design requirements.

[0131] (S6) Cooling, sieving and packaging: The granules obtained by (S6) are cooled to room temperature ±5℃ by a countercurrent cooler, and the moisture content is controlled at ≤12.5%; after sieving to remove powder and unqualified granules, they are packaged, labeled and stored according to standards, avoiding moisture and direct sunlight.

[0132] Example 1:

[0133] Prepare fattening pig diets using the following ingredients:

[0134] Corn 54 parts, wheat 5.5 parts, rice bran 3.5 parts, vegetable oil 1.2 parts, low-sulfurine soybean meal 9.5 parts, desulfurized rapeseed meal 3.0 parts, fermented protein 1.2 parts, L-lysine 0.28 parts, DL-methionine 0.17 parts, L-threonine 0.10 parts, L-tryptophan 0.042 parts, L-valine 0.085 parts, L-isoleucine 0.063 parts, beet meal 3.5 parts, wheat bran 2.5 parts, alfalfa 1.8 parts powder, 0.28 parts benzoic acid, 0.12 parts citric acid, 0.03 parts neutral protease, 0.02 parts xylanase, 0.01 parts β-glucanase, 0.01 parts phytase, 0.03 parts Bacillus subtilis preparation, 0.03 parts Lactobacillus plantarum preparation, 0.70 parts clinoptilolite powder, 0.03 parts yucca saponin extract, 1.0 part mineral trace element premix, 0.3 parts vitamin premix, and 0.19 parts salt.

[0135] The preparation steps for the low-thionine soybean meal are as follows:

[0136] Grind ordinary defatted soybean meal to 40 mesh, place it in a stainless steel reactor, add 4 times the mass of deionized water, heat to 45℃ and stir evenly, and adjust the pH to 7.5.

[0137] A complex enzyme of methionine oxidase and cysteine ​​desulfurase was added at a rate of 3000 U / kg of raw material, and the enzymatic hydrolysis time was 3 hours to selectively degrade methionine and cysteine.

[0138] Subsequently, the residual enzymes were inactivated by steam heating at 0.1 MPa for 15 minutes. The solution portion was removed by plate and frame filtration, the wet filter residue was dried to a moisture content of ≤10%, and then pulverized through a 50-mesh sieve to finally obtain low-thionine soybean meal.

[0139] The preparation steps of the desulfurized rapeseed meal are as follows:

[0140] Rapeseed meal was crushed to 35 mesh and then added to a 0.5% citric acid solution at a mass-to-volume ratio of 1:3. The mixture was then extracted at 50°C for 35 minutes to dissolve glucosinolates and some free sulfides, resulting in a wet material.

[0141] After solid-liquid separation, the wet material is fermented; after fermentation, it is dried with hot air at an outlet temperature of 60℃ and the moisture content is controlled at ≤11% to obtain the final desulfurized rapeseed meal.

[0142] The fermentation process is as follows:

[0143] The wet material was fed into an anaerobic fermenter and inoculated with *Lactobacillus plantarum* and *Streptococcus thermophilus* in a 1:1 ratio, at an inoculation density of 4 × 10⁻⁶. 7 CFU / g, fermentation temperature 40℃, pH controlled at 5.5, fermentation time 16h.

[0144] The preparation steps of the fermented protein are as follows:

[0145] Using corn distillers grains as a substrate, the moisture content is first adjusted to 55% and fermentation is carried out. After fermentation, the mixture is pressed to a moisture content of 36% using a belt filter press, then dried with hot air at 65℃ to a moisture content of ≤10%, and pulverized through a 70-mesh sieve to obtain fermented protein.

[0146] The fermentation process is as follows:

[0147] The inoculation consisted of a complex microbial flora, including *Saccharomyces cerevisiae*, *Lactobacillus acidophilus*, and *Bacillus subtilis*, in a ratio of 1:1:1, with a total inoculation volume of 1×10⁻⁶. 8 CFU / g, fermentation temperature 34℃, pH maintained at 5.2, fermentation time 46h;

[0148] During fermentation, the mixture is turned over every 12 hours to replenish oxygen and even out the temperature.

[0149] The slow-release preparation method of the organic acid acidifier compound is as follows:

[0150] Mix benzoic acid and citric acid according to the weight ratio, add 10 times the weight of molten hydrogenated palm oil, and homogenize in a high-speed shear emulsifier for 4 minutes to evenly disperse the acid powder in the oil phase.

[0151] The mixture was then cooled to 5°C and solidified into a block. It was then crushed into 200μm particles using a pulverizer, and particles larger than 500μm were sieved out to obtain a microencapsulated acidifier.

[0152] The preparation method of the yucca saponin extract is as follows:

[0153] Select dried yucca leaves and pulverize them to 10 mesh. Add 70% ethanol solution at a mass-to-volume ratio of 1:5 and extract at 50℃ with stirring for 3 hours. After filtration, concentrate the filtrate under reduced pressure to 1 / 5 of the original volume. Then, remove impurities by adding 3 times the volume of anhydrous ethanol and letting it stand at 3℃ for 10 hours.

[0154] The precipitate was centrifuged and vacuum dried to obtain yucca saponin powder with a saponin content controlled at 30% and moisture content ≤8%, thus obtaining yucca saponin extract; it was then mixed with maltodextrin at a ratio of 1:1 before use.

[0155] The Bacillus subtilis preparation undergoes heat-resistant microencapsulation treatment.

[0156] Fermentation culture until the spore formation rate is ≥95% is carried out. After centrifugation to remove the culture medium, wet bacterial sludge and heat-resistant carrier are mixed at a ratio of 1:3. 10% maltodextrin and 5% sodium alginate solution are added, and after uniform stirring, spray drying is carried out to obtain Bacillus subtilis preparation.

[0157] The heat-resistant carrier is composed of starch and whey powder in a 1:1 ratio; the inlet temperature of the spray dryer is 120℃, and the outlet temperature is 60℃; the resulting powder has a spore count ≥1×10⁻⁶. 11 CFU / g, survival rate after granulation ≥75%.

[0158] The clinoptilolite powder undergoes performance optimization treatment before use.

[0159] Natural clinoptilolite ore is selected, first washed with water to remove mud and sand impurities, then dried at 180℃ for 3 hours, pulverized and controlled to a particle size of 50μm by an air classifier to increase the specific surface area, with a specific surface area ≥35m² / g.

[0160] It was then soaked in 0.1 mol / L sodium chloride solution for 10 hours to improve the cation exchange capacity and ensure ≥150 cmol / kg, and finally dried with hot air until the moisture content was ≤5%.

[0161] The preparation of fattening pig diets includes the following steps:

[0162] (S1) Raw material preparation: Prepare the corresponding weight parts of raw materials according to the formula;

[0163] (S2) Coarse grinding treatment: The solid raw materials, including corn, wheat, rice bran, beet meal, wheat bran, and alfalfa powder, are coarsely ground to control the particle size to 1.0 mm.

[0164] (S3) Mix once: Add the crushed energy raw materials, protein raw materials, fermentable carbohydrates and fiber raw materials to the mixer in proportion and mix at low speed for 2 minutes;

[0165] (S4) Adding functional additives and secondary mixing: In the primary mixture of (S3), add amino acid additives, organic acidifiers, enzyme preparation system, microecological preparation, ammonia / adsorption additives, mineral and trace element premix and flavoring agent in sequence, and continue to mix at medium and high speed for 5 minutes.

[0166] After mixing, the enzyme preparation system and the microecological preparation were pretreated. Neutral protease, xylanase, β-glucanase, phytase and carrier powder were mixed at a ratio of 1:4 and added to the mixer together with the microecological preparation at an environment below 25℃. The mixing speed was controlled at medium to low speed for 3 minutes to prevent local frictional heating that could lead to a decrease in activity, and to ensure that the coefficient of variation of the mixing uniformity was ≤5%.

[0167] (S5) Conditioning and granulation: The uniformly mixed diet from (S4) is fed into the conditioner. The conditioning temperature is controlled at 75℃ and the conditioning time is 60s. Then, it is pressed into granules with a diameter of 2.5mm by the granulator. For microecological preparations with poor heat resistance, they are added through the post-spraying system after conditioning and before granulation. The spraying temperature is not higher than 40℃ and the water activity in the spraying liquid is controlled below 0.60.

[0168] (S6) Cooling, screening and packaging: The granules obtained in (S5) are cooled to room temperature -5°C by a countercurrent cooler, and the moisture content is controlled at ≤12.5%; after screening to remove powder and unqualified granules, they are packaged, labeled and stored according to standards.

[0169] Example 2:

[0170] Prepare fattening pig diets using the following ingredients:

[0171] Corn 56 parts, wheat 7.25 parts, rice bran 4.4 parts, vegetable oil 1.5 parts, low-sulfurine soybean meal 11.25 parts, desulfurized rapeseed meal 3.75 parts, fermented protein 1.7 parts, L-lysine 0.33 parts, DL-methionine 0.195 parts, L-threonine 0.115 parts, L-tryptophan 0.049 parts, L-valine 0.098 parts, L-isoleucine 0.077 parts, beet meal 4.5 parts, wheat bran 3.25 parts, alfalfa meal 2.15 parts, benzoic acid 0.315 parts, citric acid 0.135 parts, neutral protease 0.055 parts, xylanase 0.025 parts, β-glucanase 0.02 parts, phytase 0.02 parts, Bacillus subtilis preparation 0.055 parts, Lactobacillus plantarum preparation 0.055 parts, clinoptilolite powder 0.85 parts, yucca saponin extract 0.035 parts, mineral trace element premix 1.1 parts, vitamin premix 0.4 parts, salt 0.38 parts.

[0172] The preparation steps for the low-thionine soybean meal are as follows:

[0173] Grind ordinary defatted soybean meal to 50 mesh, place it in a stainless steel reactor, add 5 times the mass of deionized water, heat to 47°C and stir evenly, and adjust the pH to 7.8.

[0174] A complex enzyme of methionine oxidase and cysteine ​​desulfurase was added at a rate of 4000 U / kg of raw material, and the enzymatic hydrolysis time was 3.5 h to selectively degrade methionine and cysteine.

[0175] Subsequently, the residual enzymes were inactivated by steam heating at 0.15 MPa for 17 minutes. The solution portion was removed by plate and frame filtration, the wet filter residue was dried to a moisture content of ≤10%, and then pulverized through a 60-mesh sieve to finally obtain low-thionine soybean meal.

[0176] The preparation steps of the desulfurized rapeseed meal are as follows:

[0177] Rapeseed meal was crushed to 40 mesh and then added to a 0.5% citric acid solution at a mass-to-volume ratio of 1:4. The mixture was then extracted at 55°C for 40 minutes to dissolve glucosinolates and some free sulfides, resulting in a wet material.

[0178] After solid-liquid separation, the wet material is subjected to a fermentation process;

[0179] After fermentation, the rapeseed meal is dried with hot air at an outlet temperature of 65℃ and a moisture content of ≤11% to obtain the final desulfurized rapeseed meal.

[0180] The fermentation process is as follows:

[0181] The wet material was fed into an anaerobic fermenter and inoculated with *Lactobacillus plantarum* and *Streptococcus thermophilus* in a ratio of 1:1.5, at an inoculation density of 5 × 10⁻⁶. 7CFU / g, fermentation temperature 42℃, pH controlled at 5.7, fermentation time 18h.

[0182] The preparation steps of the fermented protein are as follows:

[0183] Using corn distillers grains as a substrate, the moisture content is first adjusted to 57% before fermentation.

[0184] After fermentation, the product is pressed to a moisture content of 40% using a belt filter press, then dried with hot air at 70℃ until the moisture content is ≤10%, and finally pulverized through an 80-mesh sieve to obtain fermented protein.

[0185] The fermentation process is as follows:

[0186] A complex microbial flora, including Saccharomyces cerevisiae, Lactobacillus acidophilus, and Bacillus subtilis, was inoculated in a ratio of 1:1.5:2, with a total inoculation amount of 1.5 × 10⁻⁶. 8 CFU / g, fermentation temperature 36℃, pH maintained at 5.5, fermentation time 48h;

[0187] During fermentation, the mixture is turned over every 12 hours to replenish oxygen and even out the temperature.

[0188] The slow-release preparation method of the organic acid acidifier compound is as follows:

[0189] Mix benzoic acid and citric acid according to the weight ratio, add 12 times the weight of molten hydrogenated palm oil, and homogenize in a high-speed shear emulsifier for 5 minutes to evenly disperse the acid powder in the oil phase.

[0190] The mixture was then cooled to 6°C and solidified into a block. It was then crushed into 300μm particles using a pulverizer, and particles larger than 500μm were sieved out to obtain a microencapsulated acidifier.

[0191] The preparation method of the yucca saponin extract is as follows:

[0192] Select dried yucca leaves and pulverize them to 20 mesh. Add 70% ethanol solution at a mass-to-volume ratio of 1:6 and extract at 55℃ with stirring for 4 hours. After filtration, concentrate the filtrate under reduced pressure to 1 / 4 of the original volume. Then, remove impurities by adding 4 times the volume of anhydrous ethanol and letting it stand at 4℃ for 12 hours.

[0193] The precipitate was centrifuged and vacuum dried to obtain yucca saponin powder with a saponin content controlled at 33% and moisture content ≤8%, thus obtaining yucca saponin extract; before use, it was mixed with maltodextrin at a ratio of 1:1.5.

[0194] The Bacillus subtilis preparation undergoes heat-resistant microencapsulation treatment.

[0195] Fermentation culture was carried out until the spore formation rate was ≥95%. After centrifugation to remove the culture medium, the wet bacterial sludge was mixed with a heat-resistant carrier at a ratio of 1:4. A 10% maltodextrin and a 5% sodium alginate solution were added, and the mixture was stirred evenly and then spray-dried to obtain the Bacillus subtilis preparation. The heat-resistant carrier was composed of starch and whey powder in a ratio of 1:1.5. The inlet temperature of the spray dryer was 130℃, and the outlet temperature was 65℃. The resulting powder had a spore count ≥1×10⁻⁶. 11 CFU / g, survival rate after granulation ≥75%.

[0196] The clinoptilolite powder undergoes performance optimization treatment before use.

[0197] Natural clinoptilolite ore is selected, first washed with water to remove mud and sand impurities, then dried at 200℃ for 4 hours, pulverized and controlled to a particle size of 65μm by an air classifier to increase the specific surface area, with a specific surface area ≥35m² / g.

[0198] The sample was then soaked in a 0.1 mol / L sodium chloride solution for 12 hours to improve the cation exchange capacity and ensure it was ≥150 cmol / kg. Finally, it was dried with hot air until the moisture content was ≤5%.

[0199] The preparation of fattening pig diets includes the following steps:

[0200] (S1) Raw material preparation: Prepare the corresponding weight parts of raw materials according to the formula;

[0201] (S2) Coarse grinding treatment: The solid raw materials, including corn, wheat, rice bran, beet meal, wheat bran, and alfalfa powder, are coarsely ground to control the particle size to 1.25 mm.

[0202] (S3) Mix once: Add the crushed energy raw materials, protein raw materials, fermentable carbohydrates and fiber raw materials to the mixer in proportion and mix at low speed for 2.5 minutes;

[0203] (S4) Adding functional additives and secondary mixing: In the primary mixture of (S3), add amino acid additives, organic acidifiers, enzyme preparation system, microecological preparation, ammonia / adsorption additives, mineral and trace element premix and flavoring agent in sequence, and continue to mix at medium and high speed for 6.5 min.

[0204] After mixing, the enzyme preparation system and the microecological preparation were pretreated. Neutral protease, xylanase, β-glucanase, phytase and carrier powder were mixed at a ratio of 1:5 and added to the mixer along with the microecological preparation at 30℃. The mixing speed was controlled at medium to low speed for 4 minutes to prevent local frictional heating that could lead to a decrease in activity, and to ensure that the coefficient of variation of the mixing uniformity was ≤5%.

[0205] (S5) Conditioning and granulation: The uniformly mixed diet from (S4) is fed into the conditioner. The conditioning temperature is controlled at 80℃ and the conditioning time is 90s. Then, it is pressed into granules with a diameter of 3.2mm by the granulator. For microecological preparations with poor heat resistance, they are added through the post-spraying system after conditioning and before granulation. The spraying temperature is not higher than 40℃ and the water activity in the spraying liquid is controlled below 0.60.

[0206] (S6) Cooling, screening and packaging: The granules obtained in (S5) are cooled to room temperature by a counter-current cooler, and the moisture content is controlled at ≤12.5%; after screening to remove powder and unqualified granules, they are packaged, labeled and stored according to standards.

[0207] Example 3:

[0208] Prepare fattening pig diets using the following ingredients:

[0209] The ingredients are: corn (58 parts), wheat (9 parts), rice bran (5.3 parts), vegetable oil (1.8 parts), low-sulfurine soybean meal (13 parts), desulfurized rapeseed meal (4.5 parts), fermented protein (2.2 parts), L-lysine (0.38 parts), DL-methionine (0.22 parts), L-threonine (0.13 parts), L-tryptophan (0.055 parts), L-valine (0.11 parts), L-isoleucine (0.09 parts), beet meal (5.5 parts), wheat bran (4 parts), and alfalfa meal (2.5 parts). 0.35 parts benzoic acid, 0.15 parts citric acid, 0.08 parts neutral protease, 0.03 parts xylanase, 0.03 parts β-glucanase, 0.03 parts phytase, 0.08 parts Bacillus subtilis preparation, 0.08 parts Lactobacillus plantarum preparation, 1.00 parts clinoptilolite powder, 0.04 parts yucca saponin extract, 1.2 parts mineral trace element premix, 0.5 parts vitamin premix, and 0.575 parts salt.

[0210] The preparation steps for the low-thionine soybean meal are as follows:

[0211] Grind ordinary defatted soybean meal into 60 mesh, place it in a stainless steel reactor, add 6 times the mass of deionized water, heat to 50℃ and stir evenly, and adjust the pH to 8.0.

[0212] A complex enzyme of methionine oxidase and cysteine ​​desulfurase was added at a rate of 5000 U / kg of raw material, and the enzymatic hydrolysis time was 4 hours to selectively degrade methionine and cysteine.

[0213] Subsequently, the residual enzymes were inactivated by steam heating at 0.2 MPa for 20 minutes. The solution portion was removed by plate and frame filtration, the wet filter residue was dried to a moisture content of ≤10%, and then pulverized through a 70-mesh sieve to finally obtain low-thionine soybean meal.

[0214] The preparation steps of the desulfurized rapeseed meal are as follows:

[0215] Rapeseed meal was crushed to 45 mesh and 0.5% citric acid solution was added at a mass-to-volume ratio of 1:5. The mixture was then extracted at 60℃ for 45 minutes to dissolve glucosinolates and some free sulfides, resulting in wet material.

[0216] After solid-liquid separation, the wet material is subjected to a fermentation process;

[0217] After fermentation, the rapeseed meal is dried with hot air at an outlet temperature of 70℃ and a moisture content of ≤11% to obtain the final desulfurized rapeseed meal.

[0218] The fermentation process is as follows:

[0219] The wet material was fed into an anaerobic fermenter and inoculated with *Lactobacillus plantarum* and *Streptococcus thermophilus* in a 2:1 ratio, at an inoculation density of 6 × 10⁶. 7 CFU / g, fermentation temperature 44℃, pH controlled at 6.0, fermentation time 20h.

[0220] The preparation steps of the fermented protein are as follows:

[0221] Using corn distillers grains as a substrate, the moisture content is first adjusted to 60% before fermentation.

[0222] After fermentation, the product is pressed to a moisture content of 44% using a belt filter press, then dried with hot air at 75℃ until the moisture content is ≤10%, and finally pulverized through a 90-mesh sieve to obtain fermented protein.

[0223] The fermentation process is as follows:

[0224] The inoculation consisted of a complex microbial flora, including *Saccharomyces cerevisiae*, *Lactobacillus acidophilus*, and *Bacillus subtilis*, in a ratio of 2:1.5:1, with a total inoculation volume of 2 × 10⁻⁶. 8 CFU / g, fermentation temperature 38℃, pH maintained at 5.8, fermentation time 50h;

[0225] During fermentation, the mixture is turned over every 12 hours to replenish oxygen and even out the temperature.

[0226] The slow-release preparation method of the organic acid acidifier compound is as follows:

[0227] Mix benzoic acid and citric acid according to the weight ratio, add 15 times the weight of molten hydrogenated palm oil, and homogenize in a high-speed shear emulsifier for 6 minutes to evenly disperse the acid powder in the oil phase.

[0228] The mixture was then cooled and solidified into a block at 8°C, and then crushed into 500μm particles using a pulverizer. Particles larger than 500μm were sieved out to obtain the microencapsulated acidifier.

[0229] The preparation method of the yucca saponin extract is as follows:

[0230] Select dried yucca leaves, pulverize them to 30 mesh, add 70% ethanol solution at a mass-to-volume ratio of 1:7, and extract at 60℃ with stirring for 5 hours.

[0231] After filtration, the filtrate was concentrated under reduced pressure to 1 / 4 of its original volume, and then impurities were removed by adding 5 times the volume of anhydrous ethanol and letting it stand at 5°C for 14 hours.

[0232] The precipitate was centrifuged and vacuum dried to obtain yucca saponin powder with a saponin content controlled at 35% and moisture content ≤8%, thus obtaining yucca saponin extract; it was then mixed with maltodextrin at a ratio of 2:1 before use.

[0233] The Bacillus subtilis preparation undergoes heat-resistant microencapsulation treatment.

[0234] Fermentation culture until the spore formation rate is ≥95% is carried out. After centrifugation to remove the culture medium, wet bacterial sludge and heat-resistant carrier are mixed at a ratio of 1:5. 10% maltodextrin and 5% sodium alginate solution are added, and after uniform stirring, spray drying is carried out to obtain Bacillus subtilis preparation.

[0235] The heat-resistant carrier is composed of starch and whey powder in a 1:2 ratio; the inlet temperature of the spray dryer is 140℃, and the outlet temperature is 70℃; the resulting powder has a spore count ≥1×10⁻⁶. 11 CFU / g, survival rate after granulation ≥75%.

[0236] The clinoptilolite powder undergoes performance optimization treatment before use.

[0237] Natural clinoptilolite ore is selected, first washed with water to remove mud and sand impurities, then dried at 220℃ for 5 hours, pulverized and controlled to a particle size of 80μm by an air classifier to increase the specific surface area, with a specific surface area ≥35m² / g.

[0238] The sample was then soaked in a 0.1 mol / L sodium chloride solution for 14 hours to improve the cation exchange capacity and ensure it was ≥150 cmol / kg. Finally, it was dried with hot air until the moisture content was ≤5%.

[0239] The preparation of fattening pig diets includes the following steps:

[0240] (S1) Raw material preparation: Prepare the corresponding weight parts of raw materials according to the formula;

[0241] (S2) Coarse grinding treatment: The solid raw materials, including corn, wheat, rice bran, beet meal, wheat bran, and alfalfa powder, are coarsely ground to control the particle size to 1.5 mm.

[0242] (S3) Mix once: Add the crushed energy raw materials, protein raw materials, fermentable carbohydrates and fiber raw materials to the mixer in proportion and mix at low speed for 3 minutes.

[0243] (S4) Adding functional additives and secondary mixing: In the primary mixture of (S3), add amino acid additives, organic acidifiers, enzyme preparation system, microecological preparations, ammonia / adsorption additives, mineral and trace element premix and flavoring agent in sequence, and continue to mix at medium and high speed for 8 minutes.

[0244] After mixing, the enzyme preparation system and the microecological preparation were pretreated. Neutral protease, xylanase, β-glucanase, phytase and carrier powder were mixed at a ratio of 1:6 and added to the mixer together with the microecological preparation at an environment below 35℃. The mixing speed was controlled at medium to low speed for 5 minutes to prevent local frictional heating that could lead to a decrease in activity, and to ensure that the coefficient of variation of the mixing uniformity was ≤5%.

[0245] (S5) Conditioning and granulation: The uniformly mixed diet from (S4) is fed into the conditioner. The conditioning temperature is controlled at 85℃ and the conditioning time is 120s. Then, it is pressed into granules with a diameter of 4.0mm by the granulator. For microecological preparations with poor heat resistance, they are added through the post-spraying system after conditioning and before granulation. The spraying temperature is not higher than 40℃ and the water activity in the spraying liquid is controlled below 0.60.

[0246] (S6) Cooling, screening and packaging: The granules obtained in (S5) are cooled to room temperature +5°C by a countercurrent cooler, and the moisture content is controlled at ≤12.5%; after screening to remove powder and unqualified granules, they are packaged, labeled and stored according to standards.

[0247] Comparative Example 1 (conventional control diet, with organic acidifiers, enzyme preparations, probiotics, and ammonia-inhibiting / adsorbent additives removed): A fattening pig diet was prepared using the following ingredients:

[0248] Corn 59.0 parts, wheat 8.0 parts, rice bran 5.0 parts, vegetable oil 1.5 parts, low-sulfurine soybean meal 17.5 parts, desulfurized rapeseed meal 3.0 parts, L-lysine 0.10 parts, DL-methionine 0.05 parts, L-threonine 0.06 parts, L-tryptophan 0.02 parts, L-valine 0.05 parts, L-isoleucine 0.04 parts, beet meal 2.0 parts, wheat bran 1.0 part, alfalfa meal 0.5 parts, mineral trace element premix 1.2 parts, vitamin premix 0.5 parts, salt 0.48 parts.

[0249] The preparation steps for the low-thionine soybean meal are as follows:

[0250] Grind ordinary defatted soybean meal to 50 mesh, place it in a stainless steel reactor, add 5 times the mass of deionized water, heat to 47°C and stir evenly, and adjust the pH to 7.8.

[0251] A complex enzyme of methionine oxidase and cysteine ​​desulfurase was added at a rate of 4000 U / kg of raw material, and the enzymatic hydrolysis time was 3.5 h to selectively degrade methionine and cysteine.

[0252] Subsequently, the residual enzymes were inactivated by steam heating at 0.15 MPa for 17 minutes. The solution portion was removed by plate and frame filtration, the wet filter residue was dried to a moisture content of ≤10%, and then pulverized through a 60-mesh sieve to finally obtain low-thionine soybean meal.

[0253] The preparation steps of the desulfurized rapeseed meal are as follows:

[0254] Rapeseed meal was crushed to 40 mesh and then added to a 0.5% citric acid solution at a mass-to-volume ratio of 1:4. The mixture was then extracted at 55°C for 40 minutes to dissolve glucosinolates and some free sulfides, resulting in a wet material.

[0255] After solid-liquid separation, the wet material is subjected to a fermentation process;

[0256] After fermentation, the rapeseed meal is dried with hot air at an outlet temperature of 65℃ and a moisture content of ≤11% to obtain the final desulfurized rapeseed meal.

[0257] The fermentation process is as follows:

[0258] The wet material was fed into an anaerobic fermenter and inoculated with *Lactobacillus plantarum* and *Streptococcus thermophilus* in a ratio of 1:1.5, at an inoculation density of 5 × 10⁻⁶. 7 CFU / g, fermentation temperature 42℃, pH controlled at 5.7, fermentation time 18h.

[0259] The preparation of fattening pig diets includes the following steps:

[0260] (S1) Raw material preparation: Weigh out 59.0 parts of corn, 8.0 parts of wheat, 5.0 parts of rice bran, 1.5 parts of vegetable oil, 17.5 parts of low-sulfurine soybean meal, 3.0 parts of desulfurized rapeseed meal, 0.10 parts of L-lysine, 0.05 parts of DL-methionine, 0.06 parts of L-threonine, 0.02 parts of L-tryptophan, 0.05 parts of L-valine, 0.04 parts of L-isoleucine, 2.0 parts of beet meal, 1.0 part of wheat bran, 0.5 parts of alfalfa meal, 1.2 parts of mineral trace element premix, 0.5 parts of vitamin premix, and 0.48 parts of salt according to the formula of Comparative Example 1.

[0261] (S2) Coarse crushing process: crush solid raw materials including corn, wheat, rice bran, beet meal, wheat bran, and alfalfa powder to a particle size of about 1.25 mm.

[0262] (S3) Mix once: Add the crushed energy raw materials, protein raw materials, fermentable carbohydrates and fiber raw materials into the mixer and mix at low speed for 2.5 minutes.

[0263] (S4) Add functional additives and mix again. Add amino acid additives, mineral and trace element premix and flavoring agent to the mixture in (S3) in sequence, and continue to mix at medium and high speed for 6.5 min.

[0264] (S5) Conditioning and granulation: The mixture of (S4) is fed into a conditioner, the conditioning temperature is controlled at 80℃, the conditioning time is 90s, and the mixture is granulated into granules with a diameter of 3.2mm by a granulator.

[0265] (S6) Cooling, screening and packaging: The granular material is cooled to room temperature by a counter-current cooler, and the moisture content is controlled at ≤12.5%. After screening out powder and unqualified granules, it is packaged and stored.

[0266] Comparative Example 2 (containing organic acid acidifiers and enzyme preparations, but excluding probiotics and ammonia / adsorption additives) was prepared using the following raw materials for fattening pig diets:

[0267] Corn 57.0 parts, wheat 7.5 parts, rice bran 4.8 parts, vegetable oil 1.5 parts, low-sulfurized soybean meal 13.0 parts, desulfurized rapeseed meal 4.5 parts, L-lysine 0.28 parts, DL-methionine 0.17 parts, L-threonine 0.10 parts, L-tryptophan 0.042 parts, L-valine 0.085 parts, L-isoleucine 0.063 parts, beet meal 3.8 parts, wheat bran 2.75 parts, alfalfa meal 1.8 parts, benzoic acid 0.32 parts, citric acid 0.15 parts, neutral protease 0.05 parts, xylanase 0.02 parts, β-glucanase 0.01 parts, phytase 0.01 parts, mineral trace element premix 1.2 parts, vitamin premix 0.5 parts, salt 0.35 parts.

[0268] The preparation steps for the low-thionine soybean meal are as follows:

[0269] Grind ordinary defatted soybean meal to 50 mesh, place it in a stainless steel reactor, add 5 times the mass of deionized water, heat to 47°C and stir evenly, and adjust the pH to 7.8.

[0270] A complex enzyme of methionine oxidase and cysteine ​​desulfurase was added at a rate of 4000 U / kg of raw material, and the enzymatic hydrolysis time was 3.5 h to selectively degrade methionine and cysteine.

[0271] Subsequently, the residual enzymes were inactivated by steam heating at 0.15 MPa for 17 minutes. The solution portion was removed by plate and frame filtration, the wet filter residue was dried to a moisture content of ≤10%, and then pulverized through a 60-mesh sieve to finally obtain low-thionine soybean meal.

[0272] The preparation steps of the desulfurized rapeseed meal are as follows:

[0273] Rapeseed meal was crushed to 40 mesh and then added to a 0.5% citric acid solution at a mass-to-volume ratio of 1:4. The mixture was then extracted at 55°C for 40 minutes to dissolve glucosinolates and some free sulfides, resulting in a wet material.

[0274] After solid-liquid separation, the wet material is subjected to a fermentation process;

[0275] After fermentation, the rapeseed meal is dried with hot air at an outlet temperature of 65℃ and a moisture content of ≤11% to obtain the final desulfurized rapeseed meal.

[0276] The fermentation process is as follows:

[0277] The wet material was fed into an anaerobic fermenter and inoculated with *Lactobacillus plantarum* and *Streptococcus thermophilus* in a ratio of 1:1.5, at an inoculation density of 5 × 10⁻⁶. 7 CFU / g, fermentation temperature 42℃, pH controlled at 5.7, fermentation time 18h.

[0278] The slow-release preparation method of the organic acid acidifier compound is as follows:

[0279] Mix benzoic acid and citric acid according to the weight ratio, add 12 times the weight of molten hydrogenated palm oil, and homogenize in a high-speed shear emulsifier for 5 minutes to evenly disperse the acid powder in the oil phase.

[0280] The mixture was then cooled to 6°C and solidified into a block. It was then crushed into 300μm particles using a pulverizer, and particles larger than 500μm were sieved out to obtain a microencapsulated acidifier.

[0281] The preparation of fattening pig diets includes the following steps:

[0282] (S1) Raw material preparation: Weigh out the following ingredients according to the formula of Comparative Example 2: 57.0 parts corn, 7.5 parts wheat, 4.8 parts rice bran, 1.5 parts vegetable oil, 13.0 parts low-sulfurized soybean meal, 4.5 parts desulfurized rapeseed meal, 0.28 parts L-lysine, 0.17 parts DL-methionine, 0.10 parts L-threonine, 0.042 parts L-tryptophan, 0.085 parts L-valine, 0.063 parts L-isoleucine, 3.8 parts beet meal, 2.75 parts wheat bran, 1.8 parts alfalfa meal, 0.32 parts benzoic acid, 0.15 parts citric acid, 0.05 parts neutral protease, 0.02 parts xylanase, 0.01 parts β-glucanase, 0.01 parts phytase, 1.2 parts mineral trace element premix, 0.5 parts vitamin premix, and 0.35 parts salt.

[0283] (S2) Coarse crushing process: crush solid raw materials including corn, wheat, rice bran, beet meal, wheat bran, and alfalfa powder to a particle size of about 1.25 mm.

[0284] (S3) Mix once: Add the crushed energy raw materials, protein raw materials, fermentable carbohydrates and fiber raw materials into the mixer and mix at low speed for 2.5 minutes.

[0285] (S4) Adding functional additives and secondary mixing: Add amino acid additives, organic acidifiers, enzyme preparation system, mineral and trace element premix and flavoring agent to the mixture in sequence in (S3), and continue to mix at medium and high speed for 6.5 min.

[0286] (S5) Conditioning and granulation: The mixture of (S4) is fed into a conditioner, the conditioning temperature is controlled at 80℃, the conditioning time is 90s, and the mixture is granulated into granules with a diameter of 3.2mm by a granulator.

[0287] (S6) Cooling, screening and packaging: The granular material is cooled to room temperature by a counter-current cooler, and the moisture content is controlled at ≤12.5%. After screening out powder and unqualified granules, it is packaged and stored.

[0288] Based on the above embodiments and comparative examples, as shown in Table 1, multiple odor reduction and gas production tests were conducted to detect the odor generated during a 21-day feeding cycle after feeding different fattening pig diets.

[0289] Table 1

[0290] experimental group <![CDATA[NH3 (ppm)]]> <![CDATA[H2S (ppm)]]> TVOC (µg / m³) p-Cresol (mg / m³) Indole (mg / m³) Odor concentration (OU) fecal pH TAN (g / kg) ADG (g / d) F / G Comparative Example 1 30 5.0 600 1.5 0.8 2500 8.8 6.0 900 2.7 Comparative Example 2 24 4.0 520 1.2 0.65 2100 8.4 5.5 920 2.6 Example 1 14 2.0 300 0.6 0.3 1200 7.2 3.8 950 2.5 Example 2 12 1.8 260 0.5 0.25 1000 7.0 3.5 960 2.48 Example 3 11 1.6 240 0.45 0.22 900 6.9 3.3 940 2.52

[0291] Based on the data obtained in Table 1, as shown in Table 2, data analysis was performed on Examples 1-3 and Comparative Example 2, with Comparative Example 1 as the benchmark, and the reduction ratio (%) of each experimental group relative to each data in Comparative Example 1 was given.

[0292] Table 2

[0293] experimental group <![CDATA[NH3↓]]> <![CDATA[H2S↓]]> TVOC↓ p-Cresol↓ Indole↓ Odor concentration ↓ TAN↓ Comparative Example 2 20.0 20.0 13.3 20.0 18.8 16.0 8.3 Example 1 53.3 60.0 50.0 60.0 62.5 52.0 36.7 Example 2 60.0 64.0 56.7 66.7 68.8 60.0 41.7 Example 3 63.3 68.0 60.0 70.0 72.5 64.0 45.0

[0294] During the 21-day feeding cycle, compared to Comparative Example 1:

[0295] In Example 1, the average emission concentrations of ammonia (NH3) and hydrogen sulfide (H2S) decreased by approximately 53% and 60%, respectively; total volatile organic compounds (TVOC) decreased by approximately 50%; p-cresol and indole concentrations decreased by approximately 60% and 63%, respectively; odor concentration decreased by approximately 52%; and total ammonia nitrogen (TAN) in feces and urine decreased by approximately 37%, while maintaining a high average daily gain (ADG) and a low feed conversion ratio (F / G).

[0296] Example 2 showed better emission reduction effects than Example 1. The reductions in NH3 and H2S were both over 60%, TVOC was reduced by about 57%, p-cresol and indole were reduced by 67% and 69% respectively, odor concentration was reduced by about 60%, TAN was reduced by about 42%, and ADG was slightly higher than in Example 1.

[0297] Example 3 showed the best overall emission reduction effect, with an average reduction of approximately 63% and 68% in NH3 and H2S, respectively, a 60% reduction in TVOC, a 70% and 72% reduction in p-cresol and indole, a 64% reduction in odor concentration, and a 45% reduction in TAN. It achieved the most significant environmental emission reduction effect while maintaining production performance.

[0298] Compared with Comparative Example 2, the three examples showed significant advantages in suppressing NH3, H2S, TVOC, and gases containing phenols and indole. This indicates that the synergistic application of organic acid acidifiers, enzyme preparation systems, microecological preparations, and ammonia-suppressing / adsorption additives is the key to achieving comprehensive control of multiple types of odorous gases.

[0299] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A fattening pig diet that reduces VOCs and malodorous gases, characterized in that: Contains the following ingredients by weight, Energy-generating ingredients: 54-58 parts corn, 5.5-9 parts wheat, 3.5-5.3 parts rice bran, and 1.2-1.8 parts vegetable oil; Protein raw materials: 9.5-13 parts of low-sulfurized soybean meal, 3.0-4.5 parts of desulfurized rapeseed meal, and 1.2-2.2 parts of fermented protein. Organic acid acidifying agents: benzoic acid 0.28–0.35 parts, citric acid 0.12–0.15 parts; Microecological preparations, including 0.03–0.08 parts of Bacillus subtilis preparation and 0.03–0.08 parts of Lactobacillus plantarum preparation; Ammonia-inhibiting / adsorbent additives, including 0.70-1.00 parts of clinoptilolite powder and 0.03-0.04 parts of yucca saponin extract.

2. The fattening pig diet with reduced VOCs and malodorous gases according to claim 1, characterized in that: It also includes the following enzyme preparation system by weight, Neutral protease 0.03–0.08 parts, xylanase 0.02–0.03 parts, β-glucanase 0.01–0.03 parts, phytase 0.01–0.03 parts.

3. The fattening pig diet with reduced VOCs and malodorous gases according to claim 1, characterized in that: The preparation steps for the low-thionine soybean meal are as follows: Grind ordinary defatted soybean meal to 40–60 mesh, place it in a stainless steel reactor, add 4–6 times the weight of deionized water, heat to 45–50℃ and stir evenly, and adjust the pH to 7.5–8.

0. Add a complex enzyme of methionine oxidase and cysteine ​​desulfurase at a rate of 3000–5000 U / kg of raw material and hydrolyze for 3–4 hours to selectively degrade methionine and cysteine. Subsequently, the residue is heated with steam at 0.1–0.2 MPa for 15–20 min to inactivate the residual enzymes. The solution portion is removed by plate and frame filtration, the wet filter residue is dried to a moisture content of ≤10%, and then pulverized through a 50–70 mesh to finally obtain low-thionine soybean meal.

4. The fattening pig diet with reduced VOCs and malodorous gases according to claim 1, characterized in that: The preparation steps of the desulfurized rapeseed meal are as follows: Crush rapeseed meal to 35-45 mesh, add 0.5% citric acid solution at a mass-to-volume ratio of 1:3-5, and extract at 50-60℃ for 35-45 minutes to dissolve glucosinolates and some free sulfides to obtain wet material. After solid-liquid separation, the wet material is subjected to a fermentation process; After fermentation, the rapeseed meal is dried by hot air at an outlet temperature of 60-70℃ and a moisture content of ≤11% to obtain the final desulfurized rapeseed meal.

5. The fattening pig diet with reduced VOCs and malodorous gases according to claim 1, characterized in that: The preparation steps of the fermented protein are as follows: Using corn distillers grains as a substrate, the moisture content is first adjusted to 55-60% before fermentation. After fermentation, the product is pressed to a moisture content of 36-44% using a belt filter press, then dried with hot air at 65-75℃ until the moisture content is ≤10%, and finally pulverized through a 70-90 mesh to obtain fermented protein.

6. The fattening pig diet with reduced VOCs and malodorous gases according to claim 1, characterized in that: The slow-release preparation method of the organic acid acidifier compound is as follows: Mix benzoic acid and citric acid by weight, add 10–15 times the weight of molten hydrogenated palm oil, and homogenize in a high-speed shear emulsifier for 4–6 minutes to ensure that the acid powder is evenly dispersed in the oil phase. The mixture is then solidified into blocks at 5–8°C, broken down into 200–500 μm particles by a pulverizer, and particles larger than 500 μm are sieved out to obtain microencapsulated acidifiers.

7. The fattening pig diet with reduced VOCs and malodorous gases according to claim 1, characterized in that: The preparation method of the yucca saponin extract is as follows: Select dried yucca leaves, pulverize them to 10-30 mesh, add 70% ethanol solution at a mass-to-volume ratio of 1:5-7, and extract at a constant temperature of 50-60℃ with stirring for 3-5 hours. After filtration, the filtrate is concentrated under reduced pressure to 1 / 5-1 / 4 of its original volume. Then, impurities are removed by adding 3-5 times the volume of anhydrous ethanol and allowing it to stand at 3-5°C for 10-14 hours. The precipitate was centrifuged and vacuum dried to obtain yucca saponin powder. The saponin content was controlled at 30-35% and the moisture content was ≤8%, thus obtaining yucca saponin extract. Mix with maltodextrin at a ratio of 1-2:1-2 before use.

8. A method for preparing a fattening pig diet with reduced VOCs and malodorous gases, prepared based on the fattening pig diet according to any one of claims 1-7, characterized in that: Includes the following steps, (S1) Raw material preparation: Prepare the corresponding weight parts of raw materials according to the formula; (S2) Coarse grinding treatment: The solid raw materials, including corn, wheat, rice bran, beet meal, wheat bran, and alfalfa powder, are coarsely ground to control the particle size to 1.0-1.5 mm. (S3) Mix once: Add the crushed energy raw materials, protein raw materials, fermentable carbohydrates and fiber raw materials to the mixer in proportion and mix at low speed for 2 to 3 minutes. (S4) Adding functional additives and secondary mixing: In the primary mixture of (S3), add amino acid additives, organic acidifiers, enzyme preparation system, microecological preparation, ammonia / adsorption additives, mineral and trace element premix and flavoring agent in sequence, and continue to mix at medium and high speed for 5 to 8 minutes. (S5) Conditioning and pelleting: The uniformly mixed diet (S4) is fed into the conditioner, the conditioning temperature is controlled at 75-85℃, the conditioning time is 60-120s, and then it is pressed into pellets with a diameter of 2.5-4.0mm by the pellet mill. (S6) Cooling, screening and packaging: The granules obtained in (S5) are cooled to room temperature ±5℃ by a countercurrent cooler, and the moisture content is controlled at ≤12.5%. After screening to remove powder and unqualified granules, they are packaged, labeled and stored according to standards to avoid moisture and direct sunlight.

9. The method for preparing a fattening pig diet with reduced VOCs and malodorous gases according to claim 8, characterized in that: In step (S4), the enzyme preparation system and the microecological preparation are pretreated after mixing. Neutral protease, xylanase, β-glucanase, phytase and carrier powder are mixed at a ratio of 1:4-6 and added to the mixer along with the probiotic preparation at an environment below 25-35℃. The mixing speed is controlled at medium to low speed for 3-5 minutes to prevent local frictional heating from causing a decrease in activity and to ensure that the coefficient of variation of the mixing uniformity is ≤5%.

10. The method for preparing a fattening pig diet with reduced VOCs and malodorous gases according to claim 8, characterized in that: In step (S5), for microecological preparations with poor heat resistance, they are added through a post-spraying system after conditioning and before granulation. The spraying temperature is not higher than 40°C, and the water activity in the spraying liquid is controlled below 0.60.

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