Slow-release urea composite animal feed additive, preparation method and application thereof

Abstract

The application discloses a slow-release urea compound animal feed additive and a preparation method and application thereof, and belongs to the technical field of animal feed. The slow-release urea compound animal feed additive is prepared from the following components in parts by mass: 30-50 parts of slow-release urea, 15-25 parts of a microbial fermentation carrier, 5-10 parts of a nitrogen regulation agent, 8-15 parts of a mineral compound, 3-8 parts of a palatability improver and 1-3 parts of an anti-caking agent. The components synergistically act to solve the technical problems of the existing slow-release urea additive, such as mismatch between the nitrogen release rate and the utilization rate of rumen microorganisms of animals, poor palatability, low nitrogen utilization rate, easy environmental pollution and animal stress. The additive is suitable for the breeding of various animals, has simple preparation process, controllable cost, green environmental protection and high popularization and application value.

Description

Technical Field

[0001] This application belongs to the field of animal feed technology, and in particular relates to a slow-release urea compound animal feed additive, its preparation method and application. Background Technology

[0002] With the rapid development of animal husbandry, the shortage of protein feed resources has become a major bottleneck restricting its development. The annual protein feed shortfall is enormous, necessitating the search for efficient and low-cost protein alternatives. Urea, as an inexpensive non-protein nitrogen source, can provide animals with nitrogen for the synthesis of proteins needed by the body and has been widely used in animal feed additives. However, ordinary urea decomposes rapidly in the animal digestive tract, especially in the rumen of ruminants, where it quickly produces large amounts of ammonia. If the rate of ammonia production exceeds the utilization rate by rumen microorganisms, it not only leads to low nitrogen utilization and resource waste but also causes ammonia poisoning in animals. Furthermore, unused nitrogen is excreted in feces and urine, causing environmental pollution.

[0003] To address the aforementioned issues, various slow-release urea additives have been developed in the prior art, primarily slowing down the decomposition rate of urea through coating and modification. For example, patent application CN104705535A discloses a slow-release urea for feed and its preparation method, using acetic acid oxime or sodium tetraborate as a slow-release agent for film coating. However, this method is costly, and the safety of the slow-release agent material has not been fully verified. Patent CN101255069B discloses a method for preparing slow-release urea using a polymer membrane, employing polystyrene and dichloromethane to prepare the coating solution. While this method is less expensive, the use of organic solvents poses a risk of combustion and explosion, and it is only suitable for fertilizer applications, not animal feed. Furthermore, existing slow-release urea additives are mostly single-component, lacking synergistic effects with microorganisms, minerals, and other components. This results in poor palatability, low animal absorption and utilization rates, and a tendency to trigger stress responses, and they are also unable to simultaneously meet the nutritional needs of ruminants and monogastric animals.

[0004] Meanwhile, some existing composite slow-release urea additives, such as film-coated slow-release non-protein nitrogen sources, although using water-based coating materials to avoid the use of organic solvents, still suffer from drawbacks such as a mismatch between the nitrogen release rate and the utilization rate by animal rumen microorganisms, and limited improvement in nitrogen utilization. Furthermore, they do not consider palatability improvement and mineral supplementation, thus failing to comprehensively enhance animal production performance. Therefore, developing a composite feed additive that can achieve precise slow release of urea, high nitrogen utilization, good palatability, suitability for various animals, and a green and environmentally friendly preparation process has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] To overcome the aforementioned deficiencies in the existing technology, this application provides a slow-release urea compound animal feed additive, its preparation method, and its application. Through compound formulation design and unique preparation process, it achieves precise slow release of urea, improves nitrogen utilization, enhances palatability, supplements the minerals and microorganisms required by animals, is suitable for a variety of animals, and has a simple preparation process, controllable cost, and is green and environmentally friendly.

[0006] To achieve the above-mentioned objectives, this application provides the following technical solution:

[0007] On the one hand, this application provides a slow-release urea compound animal feed additive, which is prepared from the following components in parts by weight: 30-50 parts of slow-release urea, 15-25 parts of microbial fermentation carrier, 5-10 parts of nitrogen regulator, 8-15 parts of mineral complex, 3-8 parts of palatability improver, and 1-3 parts of anti-caking agent.

[0008] The sustained-release urea is urea coated with modified urea-formaldehyde resin;

[0009] The microbial fermentation carrier is a fermentation product made by co-fermenting soybean meal and corn cob powder with brewer's yeast and Bacillus subtilis.

[0010] The nitrogen regulator is a compound of L-glutamic acid, aspartic acid, and acetyloxyoxime acid;

[0011] The mineral complex includes calcium carbonate, calcium dihydrogen phosphate, magnesium sulfate, zinc oxide, ferrous sulfate, potassium iodide, and sodium selenite.

[0012] The palatability improver is a compound of molasses, steviol glycosides, and tangerine peel powder;

[0013] The anti-caking agent is a compound of silicon dioxide and magnesium stearate.

[0014] Preferably, the slow-release urea compound animal feed additive is prepared from the following components in parts by weight: 40 parts slow-release urea, 20 parts microbial fermentation carrier, 7 parts nitrogen regulator, 12 parts mineral complex, 5 parts palatability improver, and 2 parts anti-caking agent.

[0015] Optionally, the thickness of the coating layer of the modified urea-formaldehyde resin-coated urea is 50~150μm, the purity of the urea is ≥99%, and the particle size of the urea is 1~2mm.

[0016] The modified urea-formaldehyde resin is prepared by polymerizing formaldehyde and urea at a molar ratio of 1:1.8~2.2, and then adding 3~5% of nano-montmorillonite by mass of the total urea-formaldehyde resin.

[0017] The nano-montmorillonite has a particle size of 20~100nm, a purity of ≥95%, and a montmorillonite content of ≥85wt%.

[0018] Preferably, the thickness of the urea coating layer made of modified urea-formaldehyde resin is 100 μm;

[0019] The modified urea-formaldehyde resin is prepared by polymerizing formaldehyde and urea in a molar ratio of 1:2, and then adding 4% by mass of nano-montmorillonite to modify it.

[0020] The particle size of the nano-montmorillonite is 80 nm.

[0021] In this application, the addition of nano-montmorillonite can significantly improve the stability and sustained-release performance of the coating layer, prevent the coating layer from rupturing rapidly in the animal's digestive tract, and achieve the slow release of urea. At the same time, nano-montmorillonite itself has a certain adsorption capacity, which can adsorb some ammonia and reduce the risk of ammonia poisoning.

[0022] Optionally, the method for preparing the microbial fermentation carrier includes:

[0023] Crush soybean meal to 80-100 mesh and corn cob powder to 60-80 mesh, mix them at a weight ratio of 3:1, add 20-30% of deionized water according to the total mass of the mixed raw materials, stir evenly, adjust the pH to 6.5-7, sterilize for 20-30 minutes, and cool to 30-35℃ to obtain the fermentation substrate;

[0024] Mix the brewing yeast liquid and the Bacillus subtilis liquid at a live cell ratio of 2-3:1, and inoculate them into the fermentation substrate. The inoculation amount is 5-8% of the total mass of the fermentation substrate. Ferment at 30-32℃ and 60-70% humidity for 48-72 hours, stirring once every 12 hours for 15-20 minutes each time.

[0025] The fermentation product was dried at 50-60℃ until the moisture content was ≤12%, and then pulverized to 80-100 mesh to obtain the microbial fermentation carrier.

[0026] Preferably, the method for preparing the microbial fermentation carrier includes:

[0027] Soybean meal was ground to 90 mesh and corn cob powder was ground to 70 mesh. They were mixed in a weight ratio of 3:1. Deionized water, accounting for 25% of the total mass of the mixed raw materials, was added and stirred evenly. The pH was adjusted to 6.8, sterilized for 25 minutes, and cooled to 32°C to obtain the fermentation substrate.

[0028] Saccharomyces cerevisiae inoculum and Bacillus subtilis inoculum were mixed at a live cell ratio of 2.5:1 and inoculated into the fermentation substrate at an inoculation amount of 6.5% of the total mass of the fermentation substrate. Fermentation was carried out at 31℃ and 65% humidity for 60 hours, with stirring every 12 hours for 18 minutes each time.

[0029] The fermentation product was dried at 55℃ until the moisture content was ≤12%, and then pulverized to 90 mesh to obtain the microbial fermentation carrier.

[0030] In this application, brewer's yeast can provide animals with high-quality protein and amino acids, while Bacillus subtilis can regulate the balance of animal intestinal flora and promote the absorption of nutrients. The synergistic effect of the two can not only enhance the nutritional value of the additive, but also promote the utilization of nitrogen by rumen microorganisms (ruminants) or intestinal microorganisms (monozatomic animals), thereby improving nitrogen utilization efficiency. Soybean meal and corn cob powder are widely available and inexpensive fermentation substrates. After fermentation, they can improve palatability and provide certain dietary fiber to promote animal digestion.

[0031] Optionally, in the nitrogen regulator, the mass ratio of L-glutamic acid, aspartic acid, and acetyloxyoxime is 3~4:2:1.

[0032] Preferably, in the nitrogen regulator, the mass ratio of L-glutamic acid, aspartic acid, and acetyloxyoxime acid is 3.5:2:1.

[0033] In this application, L-glutamic acid and aspartic acid can provide animals with essential amino acids, while regulating nitrogen metabolism and promoting the conversion and utilization of ammonia; acetoxyxamic acid can inhibit urease activity, slow down the decomposition rate of urea, and avoid the rapid production of ammonia. The three work synergistically to achieve precise nitrogen regulation, improve nitrogen utilization, and reduce the risk of ammonia poisoning. This method is different from the existing technology that uses acetoxyxamic acid (i.e., acetoxyxamic acid) as a slow-release agent, and has a better regulatory effect.

[0034] Optionally, the mineral complex, by weight, comprises: 3-5 parts calcium carbonate, 2-4 parts calcium dihydrogen phosphate, 1-2 parts magnesium sulfate, 0.5-1 part zinc oxide, 0.3-0.8 parts ferrous sulfate, 0.01-0.03 parts potassium iodide, and 0.005-0.01 parts sodium selenite. This mineral complex can comprehensively supplement the macro- and micro-elements required for animal growth, meeting the needs of animal growth and development. Simultaneously, it works synergistically with slow-release urea and microbial fermentation carriers to improve animal production performance and avoid mineral deficiency problems caused by solely supplementing with urea.

[0035] Preferably, the mineral complex comprises, by weight, 4 parts calcium carbonate, 3 parts calcium dihydrogen phosphate, 1.5 parts magnesium sulfate, 0.8 parts zinc oxide, 0.5 parts ferrous sulfate, 0.02 parts potassium iodide, and 0.008 parts sodium selenite.

[0036] Optionally, in the palatability improver, the mass ratio of molasses, steviol glycosides, and tangerine peel powder is 5-6:2:1. Molasses and steviol glycosides can improve the sweetness of the additive, while tangerine peel powder can improve the flavor of the additive, mask the pungent odor of urea, and increase animal feed intake. This differs from the existing technology that uses molasses alone as a palatability improver, resulting in a richer flavor and a more significant improvement in palatability.

[0037] Preferably, the mass ratio of molasses, steviol glycosides, and tangerine peel powder in the palatability improver is 5.5:2:1.

[0038] Optionally, in the anti-caking agent, the mass ratio of silica to magnesium stearate is 1 to 3:1. The combined use of silica and magnesium stearate can effectively prevent the additive from clumping during storage, ensuring the uniformity and stability of the additive and extending its shelf life.

[0039] Preferably, in the anti-caking agent, the mass ratio of silicon dioxide to magnesium stearate is 2:1.

[0040] Secondly, this application provides a method for preparing the aforementioned slow-release urea compound animal feed additive, comprising the following steps:

[0041] (1) Mix the nitrogen regulator, mineral complex, palatability improver and anti-caking agent, stir to obtain a premix;

[0042] (2) Add the slow-release urea and the microbial fermentation carrier to the premix, mix and stir to obtain a mixture;

[0043] (3) The mixture is granulated and dried to obtain the slow-release urea compound animal feed additive.

[0044] Optionally, in step (1), the stirring speed is 150~200 rpm and the stirring time is 15~20 min;

[0045] In step (2), the stirring speed is 250~300 rpm and the stirring time is 30~40 min;

[0046] In step (3), the particle size after granulation is 2~3mm, the drying temperature is 55~65℃, and the drying is performed until the moisture content of the material is ≤8%.

[0047] Preferably, in step (1), the stirring speed is 180 rpm and the stirring time is 18 min;

[0048] In step (2), the stirring speed is 280 rpm and the stirring time is 35 min;

[0049] In step (3), the particle size after granulation is 2.5 mm, and the drying temperature is 60°C.

[0050] In this application, the premixing in step (1) ensures that the small molecule components are evenly distributed, avoiding the problem of local concentration being too high or too low due to uneven mixing in the subsequent steps; the mixing in step (2) adopts high speed and long time mixing to ensure that the slow-release urea is fully integrated with other components and improves the overall stability of the additive.

[0051] Thirdly, this application provides the application of the above-mentioned slow-release urea compound animal feed additive, or the slow-release urea compound animal feed additive prepared by the above-mentioned preparation method, in the preparation of animal feed. In the application process, the amount of slow-release urea compound animal feed additive added is 0.3 to 0.8% of the dry matter mass of the animal's basic diet.

[0052] Compared with the prior art, this application has the following advantages:

[0053] (1) This application uses modified urea-formaldehyde resin to coat urea and combines it with nano-montmorillonite modification to achieve precise slow release of urea. The nitrogen release cycle is extended to 24-48h, which matches the utilization rate of animal rumen microorganisms (ruminants) or intestinal microorganisms (monozatomic animals). At the same time, through the synergistic effect of nitrogen regulators, urease activity is inhibited, and the rapid production of ammonia is reduced. The nitrogen utilization rate is significantly improved compared with the existing single slow-release urea additives, effectively reducing nitrogen resource waste.

[0054] (2) This application combines slow-release urea with microbial fermentation carrier, mineral complex, palatability improver and other components. The components work synergistically to not only provide nitrogen source for animals, but also supplement high-quality protein, amino acids, minerals and beneficial microorganisms, regulate the balance of animal intestinal flora, meet the nutritional needs of ruminants and monogastric animals at different growth stages, and have wide compatibility, which solves the problem of narrow compatibility of existing slow-release urea additives.

[0055] (3) This application uses molasses, steviol glycosides and tangerine peel powder as palatability improvers, which effectively mask the irritating odor of urea, improve the flavor and palatability of the additive, and increase animal feed intake by 8.2-11.5%; at the same time, the formula is mild and has no harmful ingredients, avoiding stress reactions such as ammonia poisoning, and significantly improving the health of animals.

[0056] (4) The modified urea-formaldehyde resin aqueous solution is used in the preparation process of this application, which does not require the use of organic solvents, thus avoiding the risk of combustion and explosion and environmental pollution, and conforming to the development trend of green and environmental protection.

[0057] (5) The preparation process of this application uses conventional equipment, the steps are simple and the operation is convenient. It does not require complicated process conditions, and the raw materials are widely available and inexpensive. Compared with existing high-end slow-release urea additives, the production cost is reduced by 15-20%, which is convenient for industrial production and large-scale promotion and application. Detailed Implementation

[0058] The present application is further illustrated below with reference to specific embodiments. The following descriptions are merely a few embodiments of the present application and are not intended to limit the present application in any way. Although the present application discloses preferred embodiments as follows, they are not intended to limit the present application. Any modifications or variations made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

[0059] Unless otherwise specified, the raw materials used in the embodiments of this application are all purchased commercially and used directly without any special treatment.

[0060] Unless otherwise specified, the analytical methods in the embodiments all adopt conventional instrument or equipment settings and conventional analytical methods.

[0061] Example 1

[0062] A slow-release urea compound animal feed additive, comprising the following components by weight:

[0063] 30 parts of slow-release urea, 15 parts of microbial fermentation carrier, 5 parts of nitrogen regulator (L-glutamic acid: aspartic acid: acetyloxyoxime acid = 3:2:1, by weight, the same below; L-glutamic acid was purchased from Hebei Lihua Biotechnology Co., Ltd., aspartic acid was purchased from Guangzhou Huijian Biotechnology Co., Ltd., and acetyloxyoxime acid was purchased from Shanghai Yuanye Biotechnology Co., Ltd.), 8 parts of mineral complex (the mineral complex, by weight, includes: 3 parts of calcium carbonate, 2 parts of calcium dihydrogen phosphate, 1 part of magnesium sulfate, 0.5 parts of zinc oxide, 0.3 parts of ferrous sulfate, 0.01 parts of potassium iodide, and 0.005 parts of sodium selenite), 3 parts of palatability improver (molasses: steviol glycosides: tangerine peel powder = 5:2:1, steviol glycosides were purchased from Shandong Aojing Biotechnology Co., Ltd.), and 1 part of anti-caking agent (silica: magnesium stearate = 1:1, silica was purchased from Shandong Zhonglian Chemical Co., Ltd., and magnesium stearate was purchased from Huzhou Linghu Xinwang Chemical Co., Ltd.).

[0064] Among them, the slow-release urea is urea coated with modified urea-formaldehyde resin. The modified urea-formaldehyde resin is made by polymerizing formaldehyde and urea at a molar ratio of 1:1.8, and then adding 3% of nano-montmorillonite (purchased from Zhejiang Fenghong New Material Co., Ltd., with a particle size of 80nm) to modify it. The coating layer thickness is 50μm, and the urea purity is 99%.

[0065] Preparation method of microbial fermentation carrier: (1) Crush soybean meal to 80 mesh and corn cob powder to 60 mesh, mix them at a weight ratio of 3:1, add 20% of the total mass of the mixed raw materials with deionized water, stir evenly, adjust the pH to 6.5, sterilize for 20 min, cool to 30℃ to obtain fermentation substrate; (2) Purchase brewer's yeast liquid (Saccharomyces cerevisiae) from China Industrial Microbial Culture Collection Center, strain number CICC 1263 (hereinafter the same) and Bacillus subtilis bacterial solution (Bacillus subtilis was purchased from Ningbo Mingzhou Biotechnology Co., Ltd., No. BMZ135811, hereinafter the same) were mixed at a live bacteria ratio of 2:1 and inoculated into the fermentation substrate. The inoculation amount was 5% of the total mass of the fermentation substrate. Fermentation was carried out at 30℃ and 60% humidity for 48 hours. During this period, the mixture was stirred once every 12 hours for 15 minutes each time. (3) The fermentation product was dried at 50℃ to a moisture content of 12% and crushed to 80 mesh to obtain the microbial fermentation carrier.

[0066] Preparation method:

[0067] (1) Preparation of slow-release urea: Urea particles (particle size 1 mm) are placed in a fluidized bed coating machine, and a modified urea-formaldehyde resin solution with a solid content of 25% is sprayed onto the surface of the urea particles at a spray pressure of 0.3 MPa. The inlet air temperature of the fluidized bed is controlled at 80°C, the outlet air temperature is controlled at 40°C, the coating layer thickness is 50 μm, and the moisture content is dried to 0.5% to obtain slow-release urea;

[0068] (2) Premixing: Nitrogen regulator, mineral complex, palatability improver and anti-caking agent are put into a mixer and mixed for 15 minutes at a speed of 150 r / min to obtain premix;

[0069] (3) Compound mixing: Add the slow-release urea and microbial fermentation carrier to the premix, adjust the mixer speed to 250 r / min, mix for 30 min, and the coefficient of variation of the mixing uniformity is 4.8%;

[0070] (4) Granulation and drying: The mixed material is put into a granulator to make granules with a particle size of 2 mm. The granules are dried at 55°C until the moisture content is 8% to obtain a slow-release urea compound animal feed additive.

[0071] Example 2

[0072] A slow-release urea compound animal feed additive, comprising the following components by weight:

[0073] The mixture contains 40 parts of slow-release urea, 20 parts of microbial fermentation carrier, 7 parts of nitrogen regulator (L-glutamic acid: aspartic acid: acetyloxyoxime acid = 3.5:2:1), 12 parts of mineral complex (the mineral complex, by mass, includes: 4 parts calcium carbonate, 3 parts calcium dihydrogen phosphate, 1.5 parts magnesium sulfate, 0.8 parts zinc oxide, 0.5 parts ferrous sulfate, 0.02 parts potassium iodide, and 0.008 parts sodium selenite), 5 parts of palatability improver (molasses: steviol glycosides: tangerine peel powder = 5.5:2:1), and 2 parts of anti-caking agent (silica: magnesium stearate = 2:1).

[0074] Among them, the slow-release urea is urea coated with modified urea-formaldehyde resin. The modified urea-formaldehyde resin is made by polymerizing formaldehyde and urea in a molar ratio of 1:2, and then adding 4% of nano-montmorillonite by mass of the total urea-formaldehyde resin for modification. The coating layer thickness is 100μm and the urea purity is 99.5%.

[0075] Preparation method of microbial fermentation carrier: (1) Crush soybean meal to 90 mesh and corn cob powder to 70 mesh, mix them at a weight ratio of 3:1, add 25% of the total mass of the mixed raw materials with deionized water, stir evenly, adjust the pH to 6.8, sterilize for 25 min, cool to 32℃, and obtain fermentation substrate; (2) Mix brewer's yeast liquid and Bacillus subtilis liquid at a live cell ratio of 2.5:1, inoculate into fermentation substrate, the inoculation amount is 6.5% of the total mass of fermentation substrate, ferment at 31℃ and 65% humidity for 60 h, stir once every 12 h, and stir for 18 min each time; (3) Dry the fermentation product at 55℃ to a moisture content of 10%, crush it to 90 mesh, and obtain microbial fermentation carrier.

[0076] Preparation method:

[0077] (1) Preparation of slow-release urea: Urea particles (particle size 1.5 mm) are placed in a fluidized bed coating machine, and a modified urea-formaldehyde resin solution with a solid content of 30% is sprayed onto the surface of the urea particles at a spray pressure of 0.4 MPa. The inlet air temperature of the fluidized bed is controlled at 85°C, the outlet air temperature is controlled at 45°C, the coating layer thickness is 100 μm, and the moisture content is dried to 0.4% to obtain slow-release urea;

[0078] (2) Premixing: Nitrogen regulator, mineral complex, palatability improver and anti-caking agent are put into a mixer and mixed for 180 r / min for 18 min to obtain premix;

[0079] (3) Compound mixing: Add the slow-release urea and microbial fermentation carrier to the premix, adjust the mixer speed to 280 r / min, mix for 35 min, and the coefficient of variation of the mixing uniformity is 4.2%;

[0080] (4) Granulation and drying: The mixed material is put into a granulator to make granules with a particle size of 2.5 mm. The granules are dried at 60°C until the moisture content is 6% to obtain a slow-release urea compound animal feed additive.

[0081] Example 3

[0082] A slow-release urea compound animal feed additive, comprising the following components by weight:

[0083] 50 parts of slow-release urea, 25 parts of microbial fermentation carrier, 10 parts of nitrogen regulator (L-glutamic acid: aspartic acid: acetyloxyoxime acid = 4:2:1), 15 parts of mineral complex (the mineral complex, by mass, includes: 5 parts calcium carbonate, 4 parts calcium dihydrogen phosphate, 2 parts magnesium sulfate, 1 part zinc oxide, 0.8 parts ferrous sulfate, 0.03 parts potassium iodide, and 0.01 parts sodium selenite), 8 parts of palatability improver (molasses: steviol glycosides: tangerine peel powder = 6:2:1), and 3 parts of anti-caking agent (silica: magnesium stearate = 3:1).

[0084] Among them, the slow-release urea is urea coated with modified urea-formaldehyde resin. The modified urea-formaldehyde resin is made by polymerizing formaldehyde and urea in a molar ratio of 1:2.2, and then adding 5% of nano-montmorillonite by mass of the total urea-formaldehyde resin for modification. The coating layer thickness is 150μm and the urea purity is 99%.

[0085] Preparation method of microbial fermentation carrier: (1) Crush soybean meal to 100 mesh and corn cob powder to 80 mesh, mix them at a weight ratio of 3:1, add 30% of the total mass of the mixed raw materials with deionized water, stir evenly, adjust the pH to 7, sterilize for 30 min, cool to 35℃, and obtain fermentation substrate; (2) Mix brewer's yeast liquid and Bacillus subtilis liquid at a live cell ratio of 3:1, inoculate into fermentation substrate, the inoculation amount is 8% of the total mass of fermentation substrate, ferment at 32℃ and 70% humidity for 72 h, stir once every 12 h, and stir for 20 min each time; (3) Dry the fermentation product at 60℃ to a moisture content of 11%, crush it to 100 mesh, and obtain microbial fermentation carrier.

[0086] Preparation method:

[0087] (1) Preparation of slow-release urea: Urea particles (particle size 2 mm) are placed in a fluidized bed coating machine, and a modified urea-formaldehyde resin solution with a solid content of 35% is sprayed onto the surface of the urea particles at a spray pressure of 0.5 MPa. The inlet air temperature of the fluidized bed is controlled at 90°C, the outlet air temperature is controlled at 50°C, the coating layer thickness is 150 μm, and the moisture content is dried to 0.3% to obtain slow-release urea;

[0088] (2) Premixing: Nitrogen regulator, mineral complex, palatability improver and anti-caking agent are put into a mixer, the speed is 200 r / min, and the mixture is mixed for 20 min to obtain premix;

[0089] (3) Compound mixing: Add the slow-release urea and microbial fermentation carrier to the premix, adjust the mixer speed to 300 r / min, mix for 40 min, and the coefficient of variation of the mixing uniformity is 3.9%;

[0090] (4) Granulation and drying: The mixed material is put into a granulator to make granules with a particle size of 3 mm. The granules are dried at 65°C until the moisture content is 7% to obtain a slow-release urea compound animal feed additive.

[0091] Comparative Example 1

[0092] A slow-release urea feed additive contains only slow-release urea (the same as the slow-release urea in Example 2, coated with modified urea-formaldehyde resin, with a coating thickness of 100 μm and a urea purity of 99.5%), without other components. The preparation method only includes the preparation steps of slow-release urea, which is consistent with step (1) in Example 2.

[0093] Comparative Example 2

[0094] A slow-release urea compound additive, by weight, comprises: 40 parts slow-release urea (using acetyloxyoxime acid as the slow-release agent, film-coated), 20 parts soybean meal, 4 parts calcium carbonate, 3 parts calcium dihydrogen phosphate, 5 parts molasses, and 2 parts magnesium stearate. The preparation method is to mix the components evenly, granulate and dry them, without microbial fermentation and premixing steps.

[0095] Comparative Example 3

[0096] A slow-release urea compound animal feed additive, with the same formula as in Example 2, except that the microbial fermentation carrier is missing, and the other components and preparation methods are the same as in Example 2.

[0097] Comparative Example 4

[0098] A slow-release urea compound animal feed additive, with the same formula as in Example 2, except that the nitrogen regulator is missing, and the other components and preparation methods are the same as in Example 2.

[0099] Experimental Example 1

[0100] Performance testing of the additives in this application

[0101] 1. Experimental Materials

[0102] Experimental samples: slow-release urea compound animal feed additives prepared in Examples 1-3 and feed additives prepared in Comparative Examples 1-4;

[0103] Experimental animals: Sixty healthy Simmental beef cattle (purchased from Henan Dingyuan Breeding Cattle Co., Ltd.) with similar weight (280±20kg) were selected and randomly divided into 6 groups of 10 each, namely Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4.

[0104] Basal ration: Conventional fattening basal ration for beef cattle, with a dry matter content of 88%, a crude protein content of 12%, and a metabolizable energy of 10.5 MJ / kg;

[0105] Experimental equipment: fluidized bed coating machine, mixer, granulator, drying oven, Kjeldahl nitrogen analyzer, pH meter, etc.

[0106] 2. Experimental Methods

[0107] Experimental period: 90 days, with a 10-day pre-feeding period and an 80-day formal feeding period;

[0108] Feeding method: Each group was fed a basal diet, and feed additives corresponding to the group were added at 0.5% of the dry matter weight of the basal diet. After being thoroughly mixed, the group was fed twice a day (8:00 am and 6:00 pm) with free access to water.

[0109] Testing indicators:

[0110] (1) Nitrogen release rate: The amount of ammonia nitrogen released at different time points (2h, 4h, 8h, 12h, 24h, 48h) was measured by in vitro simulated rumen fermentation method, and the nitrogen release rate was calculated;

[0111] (2) Nitrogen utilization rate: The daily feed intake and fecal output of each group of animals were measured. The nitrogen content in feed and feces was measured using a Kjeldahl nitrogen analyzer, and the nitrogen utilization rate was calculated (nitrogen utilization rate = (nitrogen intake - fecal nitrogen) / nitrogen intake × 100%).

[0112] (3) Production performance: Animal weight was measured once a week and the average daily gain (ADG) was calculated; feed intake was recorded daily and the feed conversion ratio (feed intake / weight gain) was calculated.

[0113] (4) Palatability: Record the daily feeding time of each group of animals and calculate the feed intake compliance rate (feed intake compliance rate = actual feed intake / expected feed intake × 100%).

[0114] (5) Stress response: Observe whether animals exhibit stress responses such as vomiting, diarrhea, or lethargy after feeding, and calculate the stress occurrence rate.

[0115] 3. The experimental results are shown in Table 1.

[0116] Table 1 Experimental Results

[0117] Group Nitrogen release cycle (h) Nitrogen utilization rate (%) Average daily weight gain (kg / d) Material weight ratio Feed intake compliance rate (%) Stress occurrence rate (%) Example 1 24 58.2±1.3 1.35±0.08 3.82±0.12 92.3±1.5 0 Example 2 36 65.6±1.1 1.52±0.07 3.45±0.10 96.8±1.2 0 Example 3 48 62.8±1.2 1.48±0.09 3.53±0.11 95.5±1.3 0 Comparative Example 1 12 49.8±1.5 1.28±0.08 4.15±0.13 85.2±1.8 10 Comparative Example 2 18 52.5±1.4 1.30±0.09 4.02±0.12 88.6±1.6 8 Comparative Example 3 32 56.3±1.3 1.38±0.08 3.78±0.11 90.5±1.4 0 Comparative Example 4 16 50.1±1.4 1.29±0.07 4.10±0.12 91.2±1.5 12

[0118] The experimental results in Table 1 show that:

[0119] (1) Nitrogen release performance: The nitrogen release cycle of Examples 1 to 3 was 24 to 48 hours, which was significantly longer than that of Comparative Example 1 (12 hours), Comparative Example 2 (18 hours) and Comparative Example 4 (16 hours). This shows that the synergistic effect of the modified urea-formaldehyde resin coating combined with the nitrogen regulator in this application can effectively delay the release rate of urea and achieve precise sustained release. Comparative Example 3 lacked a microbial fermentation carrier, and the nitrogen release cycle was slightly shortened (32 hours), but it was still longer than that of the prior art comparative examples. This shows that the microbial fermentation carrier has a certain auxiliary effect on improving the sustained release performance.

[0120] (2) Nitrogen utilization rate: The nitrogen utilization rates of Examples 1 to 3 were 58.2% to 65.6%, with Example 2 being the best (65.6%). Compared with Comparative Examples 1, 2, 3 and 4, it was significantly improved, indicating that the composite formulation of this application can significantly improve nitrogen utilization rate and reduce nitrogen resource waste. The synergistic effect of microbial fermentation carrier and nitrogen regulator is the key to improving nitrogen utilization rate.

[0121] (3) Production performance: The average daily weight gain of Examples 1 to 3 was 1.35 to 1.52 kg / d and the feed conversion ratio was 3.45 to 3.82, which was significantly better than Comparative Examples 1 to 4. Among them, Example 2 had the highest average daily weight gain (1.52 kg / d) and the lowest feed conversion ratio (3.45), indicating that the additive of this application can effectively improve animal production performance and reduce breeding costs. Comparative Example 3 lacked a microbial fermentation carrier, and its average daily weight gain and feed conversion ratio were slightly worse than those of the Examples, indicating that the microbial fermentation carrier can promote the absorption of nutrients and improve production performance. Comparative Example 4 lacked a nitrogen regulator, and its production performance was poor, indicating that the nitrogen regulator can prevent ammonia poisoning and ensure normal animal growth.

[0122] (4) Palatability: The feed intake compliance rate of Examples 1-3 was 92.3-96.8%, which was significantly higher than that of Comparative Example 1 (85.2%) and Comparative Example 2 (88.6%), indicating that the palatability improver of this application can effectively improve the flavor of the additive and increase the feed intake of animals; Although the feed intake compliance rate of Comparative Example 3 and Comparative Example 4 was higher than that of the prior art comparative examples, it was lower than that of Examples, indicating that the synergistic effect of each component can further improve palatability.

[0123] (5) Stress response: The stress response rate of Examples 1-3 and Comparative Example 3 was 0, while the stress response rate of Comparative Example 1, Comparative Example 2 and Comparative Example 4 was 8-12%, indicating that the compound formulation of this application is mild, has no harmful components, and can avoid stress responses such as ammonia poisoning, thus protecting animal health; Comparative Example 4 lacked nitrogen regulator and had the highest stress response rate (12%), indicating that nitrogen regulator can effectively inhibit urease activity, reduce the rapid production of ammonia, and avoid stress response.

[0124] In summary, the slow-release urea compound animal feed additive of this application, through compound formulation design and unique preparation process, is significantly superior to the prior art in terms of slow-release performance, nitrogen utilization rate, production performance, palatability, environmental protection and animal safety. Moreover, the preparation process is simple and cost-controllable, which facilitates industrial production and large-scale promotion and application.

[0125] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A slow-release urea compound animal feed additive, characterized in that, It is prepared from the following components in parts by weight: 30-50 parts of slow-release urea, 15-25 parts of microbial fermentation carrier, 5-10 parts of nitrogen regulator, 8-15 parts of mineral complex, 3-8 parts of palatability improver, and 1-3 parts of anti-caking agent. The sustained-release urea is urea coated with modified urea-formaldehyde resin; The microbial fermentation carrier is a fermentation product made by co-fermenting soybean meal and corn cob powder with brewer's yeast and Bacillus subtilis. The nitrogen regulator is a compound of L-glutamic acid, aspartic acid, and acetyloxyoxime acid; The mineral complex includes calcium carbonate, calcium dihydrogen phosphate, magnesium sulfate, zinc oxide, ferrous sulfate, potassium iodide, and sodium selenite. The palatability improver is a compound of molasses, steviol glycosides, and tangerine peel powder; The anti-caking agent is a compound of silicon dioxide and magnesium stearate.

2. The slow-release urea compound animal feed additive according to claim 1, characterized in that, The thickness of the urea coating layer of the modified urea-formaldehyde resin is 50~150μm, the purity of the urea is ≥99%, and the particle size of the urea is 1~2mm. The modified urea-formaldehyde resin is prepared by polymerizing formaldehyde and urea at a molar ratio of 1:1.8~2.2, and then adding 3~5% of nano-montmorillonite by mass of the total urea-formaldehyde resin. The nano-montmorillonite has a particle size of 20~100nm, a purity of ≥95%, and a montmorillonite content of ≥85wt%.

3. The slow-release urea compound animal feed additive according to claim 1, characterized in that, The method for preparing the microbial fermentation carrier includes: Crush soybean meal to 80-100 mesh and corn cob powder to 60-80 mesh, mix them at a weight ratio of 3:1, add 20-30% of deionized water according to the total mass of the mixed raw materials, stir evenly, adjust the pH to 6.5-7, sterilize for 20-30 minutes, and cool to 30-35℃ to obtain the fermentation substrate; Mix the brewing yeast liquid and the Bacillus subtilis liquid at a live cell ratio of 2-3:1, and inoculate them into the fermentation substrate. The inoculation amount is 5-8% of the total mass of the fermentation substrate. Ferment at 30-32℃ and 60-70% humidity for 48-72 hours, stirring once every 12 hours for 15-20 minutes each time. The fermentation product was dried at 50-60℃ until the moisture content was ≤12%, and then pulverized to 80-100 mesh to obtain the microbial fermentation carrier.

4. The slow-release urea compound animal feed additive according to claim 1, characterized in that, In the nitrogen regulator, the mass ratio of L-glutamic acid, aspartic acid, and acetyloxyoxime is 3~4:2:

1.

5. The slow-release urea compound animal feed additive according to claim 1, characterized in that, The mineral complex comprises, by weight, 3-5 parts calcium carbonate, 2-4 parts calcium dihydrogen phosphate, 1-2 parts magnesium sulfate, 0.5-1 part zinc oxide, 0.3-0.8 parts ferrous sulfate, 0.01-0.03 parts potassium iodide, and 0.005-0.01 parts sodium selenite.

6. The slow-release urea compound animal feed additive according to claim 1, characterized in that, In the palatability improver, the mass ratio of molasses, steviol glycosides, and tangerine peel powder is 5~6:2:

1.

7. The slow-release urea compound animal feed additive according to claim 1, characterized in that, In the anti-caking agent, the mass ratio of silicon dioxide to magnesium stearate is 1~3:

1.

8. A method for preparing a slow-release urea compound animal feed additive according to any one of claims 1 to 7, characterized in that, Includes the following steps: (1) Mix the nitrogen regulator, mineral complex, palatability improver and anti-caking agent, stir to obtain a premix; (2) Add the slow-release urea and the microbial fermentation carrier to the premix, mix and stir to obtain a mixture; (3) The mixture is granulated and dried to obtain the slow-release urea compound animal feed additive.

9. The method for preparing a slow-release urea compound animal feed additive according to claim 8, characterized in that, In step (1), the stirring speed is 150~200 rpm and the stirring time is 15~20 min; In step (2), the stirring speed is 250~300 rpm, and the stirring time is 30~40 min; In step (3), the particle size after granulation is 2~3mm, the drying temperature is 55~65℃, and the drying is performed until the moisture content of the material is ≤8%.

10. The use of a slow-release urea compound animal feed additive according to any one of claims 1 to 7, or a slow-release urea compound animal feed additive prepared by the preparation method according to any one of claims 8 to 9, in the preparation of animal feed, characterized in that, During the application process, the amount of slow-release urea compound animal feed additive added is 0.3~0.8% of the dry matter mass of the animal's basic diet.