Granular crushed concentrated feed for ruminants and preparation method of granular crushed concentrated feed

Abstract

The invention discloses a particle crushed concentrated feed for ruminants and a preparation method thereof, and belongs to the technical field of feed processing, and the preparation process comprises the following steps: crushing and uniformly mixing the raw materials, feeding the uniformly mixed materials into a granulator, tempering by steam, granulating after tempering, and carrying out vacuum freeze drying on the granules to obtain the particle crushed concentrated feed for ruminants. Carrying out ultrasonic treatment, then feeding the granules into a granule crusher for crushing, and finally carrying out screening treatment through a double-layer vibrating screen to obtain middle-size-fraction granules; through the preparation process, the porosity of the feed can be increased, the palatability of the feed and the nutrient retention rate of the feed can be improved, the digestibility of beef cattle to the feed can be improved, and a vacuum freeze-drying and ultrasonic crushing process, a ring die granulator for granulation and a screening process in a specific particle size range are combined, so that the feed quality is improved. The uniformity of the material granularity can be improved, the granularity difference of particles is eliminated, and the pulverization condition of the feed is reduced, so that the net energy utilization efficiency of the feed is improved.

Description

Technical Field

[0001] This invention relates to the field of feed processing technology, specifically to a process for preparing pelleted concentrate for ruminants. Background Technology

[0002] Currently, ruminant concentrates are mainly powdered concentrates made from premixed feed, soybean meal, cottonseed meal, corn by-products, etc. In the actual formulation process, a mixer is usually used to precisely proportion, cut and mix the various raw materials in the ruminant diet according to a scientific formula. However, after feeding, due to the large differences in the physical properties of traditional powdered concentrates, they are very easy to separate due to vibration and gravity during transportation and feeding. This will cause materials with different densities and particle sizes to gradually separate in the feed trough: heavier minerals and granules will sink to the bottom, while lighter hay and bran will float to the top, resulting in animals in different locations eating completely different diet compositions. The stratification of concentrate feed can have serious consequences for the growth and development of ruminants: for example, some ruminants may consume too much concentrate, leading to metabolic diseases such as rumen acidosis and laminitis, while others may mainly consume roughage, resulting in insufficient energy and protein intake and affecting growth, thus causing an imbalance in the nutritional intake of ruminants; the production performance of ruminants is unstable, and the average daily weight gain cannot reach the genetic potential; because the actual intake of ruminants is completely different from the formula-designed diet, it is impossible to conduct accurate nutritional assessment and management, resulting in management difficulties.

[0003] If the particle size of the concentrate feed for ruminants is insufficient, it will have the following effects on ruminants: (1) Inhibition of ruminant behavior: Ruminants need a certain length of fiber to stimulate the rumen wall and promote rumination and chewing. Powdered feed cannot provide this physical stimulation, resulting in a reduction in saliva secretion. Saliva is a natural rumen buffer. Its reduction will lower the rumen pH value and increase the risk of acidosis; (2) Rumen passage speed is too fast: The material that is too fine stays in the rumen for a short time and does not have enough time to be fully fermented by microorganisms before entering the next digestive tract, resulting in a decrease in feed utilization; (3) Poor palatability: Extremely fine powdered feed is easy to cause nasal irritation, causing animals to be picky eaters and give priority to eating long grass. The components that are too fine and dusty are easy to be left behind, further aggravating the nutritional imbalance; (4) Losses during processing and feeding: Powdered feed is dusty and is easy to be scattered during feeding, causing waste and environmental pollution, and harming the respiratory health of animals.

[0004] In addition, the protein in traditional concentrate feed has an excessively high degradation rate in the rumen. A large amount of high-quality protein is broken down into ammonia by microorganisms in the rumen. If it is not utilized by microorganisms in time to synthesize microbial protein, this ammonia will be absorbed and excreted in urine, resulting in protein waste. Furthermore, rumen nutrition is insufficient for ruminants. In other words, the concentrate feed for ruminants prepared by traditional processes will ultimately lead to the inability of animals to efficiently absorb and utilize nutrients, resulting in a mismatch in rumen degradation rates for ruminants.

[0005] Therefore, there is an urgent need for a preparation process that can eliminate particle size differences in pelleted concentrates for ruminants, improve feed palatability and nutrient retention, and enhance feed digestibility for ruminants. Summary of the Invention

[0006] To address the aforementioned deficiencies in the prior art, this invention provides a method for preparing pelleted concentrate for ruminants. By freeze-drying and ultrasonically treating the pellets after pelleting, the porosity of the feed is increased, improving palatability and nutrient retention. High porosity facilitates the contact and action of digestive enzymes, thereby improving feed digestibility and utilization. Crushing the pellets after vacuum freeze-drying and ultrasonic processing enhances particle size uniformity. Furthermore, combining pelleting with a ring die pellet mill and screening within a specific particle size range further improves particle size uniformity, eliminates particle size differences, and reduces feed pulverization, thus preventing rumen acidosis. The uniform particle size and high porosity of the pellets stimulate rumen motility, promote digestive fluid secretion, improve the rumen microbial fermentation environment, increase microbial protein synthesis and volatile fatty acid production, optimize the acetic acid / propionic acid ratio, and improve the net energy utilization efficiency of the feed.

[0007] To achieve the above technical effects, the following technical solution is adopted: A method for preparing pelleted concentrate for ruminants includes the following steps: Step S1: Weigh the raw materials and crush them, then mix the powdered materials thoroughly. Step S2: The uniformly mixed material is fed into a pellet mill and conditioned by steam, and then pelletized. Step S3: The granules prepared in step S2 are subjected to vacuum freeze-drying and ultrasonic treatment, and then the granules are fed into a granulator for crushing. Step S4: The material crushed in step S3 is screened through a double-layer vibrating screen, where the upper screen has a mesh size of 6 mesh and the lower screen has a mesh size of 12 mesh, and intermediate-sized pellet feed with a mesh size between 6 mesh and 12 mesh is obtained after screening.

[0008] Furthermore, in step S3, the freezing temperature of vacuum freeze drying is -30 to -50°C, the freezing time is 3 to 6 hours, the heating drying temperature is -10 to 15°C, and the drying time is 10 to 24 hours. Furthermore, in step S3, the vacuum degree of vacuum freeze drying reaches 30-50 Pa within 1 hour, and the heating rate is 1-5℃ / min; Furthermore, in step S3, the ultrasonic vibration frequency is 15-30 kHz; the ultrasonic amplitude is 15-30 μm; and the ultrasonic vibration time is 20-30 min. Furthermore, the mixing time in step S1 is 3–15 min; Furthermore, in step S2, the conditioning temperature is 50℃~65℃, and the steam pressure is 0.2~0.5 MPa; Furthermore, the granulation temperature in step S2 is 50℃~65℃. Furthermore, in step S2, a ring die granulator is used for granulation, and the diameter of the membrane pores of the ring die granulator is 3.5-6 mm. Furthermore, in step S4, the oversized particles separated by the upper screen are returned to the crusher for further crushing, while the overly fine powder separated by the lower screen is returned to the pellet mill for re-granulation, resulting in a finished crushed granular material with uniform particle size.

[0009] The present invention also provides a pelleted concentrate for ruminants prepared by the above-described preparation method.

[0010] The beneficial effects of this invention are as follows: This invention discloses a method for preparing pelleted concentrate for ruminants. By freeze-drying and ultrasonically treating the pellets after pelleting, the porosity of the feed can be increased, improving palatability and nutrient retention. The high porosity of the feed facilitates the contact and action of digestive enzymes, promotes digestive fluid secretion, and improves the digestibility of feed for beef cattle. Crushing the pellets after vacuum freeze-drying and ultrasonic processing improves the uniformity of particle size. Furthermore, combining pelleting with a ring die pellet mill and screening within a specific particle size range further enhances the quality of the feed. The uniformity of particle size, elimination of particle size differences, and reduction of feed pulverization result in uniformly mixed pelleted feed with consistent particle size, preventing rumen acidosis. The uniform particle size and high porosity of the pelleted feed can stimulate rumen motility, promote digestive juice secretion, improve the rumen microbial fermentation environment, increase microbial protein synthesis and volatile fatty acid production, optimize the acetic acid / propionic acid ratio, and improve the net energy utilization efficiency of the feed. In other words, the preparation process of this invention can comprehensively improve the growth performance and rumen health of beef cattle, and has significant value for promotion and application. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0012] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0013] Example 1: Step S1: Take wheat, corn alcohol residue, cottonseed meal, soybean meal, sprayed corn husks, and glutamic acid residue. Put the above raw materials into a pulverizer for pulverization. The pulverizer screen has a mesh size of 12 mesh to obtain powder raw materials. Then weigh each powder raw material according to the weight in Table 1 and put it into a horizontal ribbon mixer for mixing. The mixing time is 5 minutes. The horizontal ribbon mixer has a power of 30KW and a speed of 30rpm.

[0014] Table 1. Ingredients for preparing pelleted concentrate for ruminants

[0015] Step S2: The mixed raw materials prepared in step S1 are fed into a ring die granulator. They are conditioned by steam at a temperature of 60°C for 1 minute and a steam pressure of 0.5 MPa. After conditioning, they are fed into the granulation chamber and granulated at 65°C. The membrane pore diameter of the ring die granulator is 3.5 mm. Step S3: The pellets prepared in step S2 are fed into a freeze dryer at a freezing temperature of -40℃ for 4 hours. Then, a low-temperature vacuum is applied, with the preset vacuum level reaching 40 Pa within 1 hour. Once the preset vacuum level is reached, heating is turned on at a heating plate heating rate of 2℃ / min, a drying temperature of 10℃, and a drying time of 20 hours. When the drying temperature reaches 10℃, an ultrasonic vibration device is activated at a frequency of 30kHz, an amplitude of 30μm, and a duration of 30 minutes. After ultrasonic vibration is completed, the ultrasonic vibration is turned off, and sublimation drying continues. After freeze-drying, the pellets are fed into a pellet crusher for crushing to obtain feed pellets with a particle size of approximately 2.5 mm. Step S4: The crushed material is screened through a double-layer vibrating screen, where the upper screen has a mesh size of 6 mesh and the lower screen has a mesh size of 12 mesh. After screening, intermediate-sized feed pellets SS1, which are between 6 mesh and 12 mesh, are obtained.

[0016] Example 2: Step S1: Take wheat, corn alcohol residue, cottonseed meal, soybean meal, sprayed corn husks, and glutamic acid residue. Put the above raw materials into a pulverizer for pulverization. The pulverizer screen has a mesh size of 12 mesh to obtain powder raw materials. Then weigh each powder raw material according to the weight in Table 1 and put it into a horizontal ribbon mixer for mixing. The mixing time is 8 minutes. The horizontal ribbon mixer has a power of 25KW and a speed of 30rpm.

[0017] Step S2: The mixed raw materials prepared in step S1 are fed into a ring die granulator. They are conditioned by steam at a temperature of 60°C for 2 minutes and a steam pressure of 0.4 MPa. After conditioning, they are fed into the granulation chamber and granulated at 65°C. The membrane pore diameter of the ring die granulator is 3.5 mm. Step S3: The pellets prepared in step S2 are fed into a freeze dryer at a freezing temperature of -50℃ for 3 hours. Then, a low-temperature vacuum is applied, with the preset vacuum level reaching 50 Pa within 1 hour. Once the preset vacuum level is reached, heating is turned on at a heating plate heating rate of 3℃ / min, a drying temperature of -10℃, and a drying time of 24 hours. When the drying temperature reaches 10℃, an ultrasonic vibration device is activated at a frequency of 20kHz, an amplitude of 20μm, and a duration of 20 minutes. After ultrasonic vibration is completed, the ultrasonic vibration is turned off, and sublimation drying continues. After freeze-drying, the pellets are fed into a pellet crusher for crushing to obtain feed pellets with a particle size of approximately 2.5 mm. Step S4: The crushed material is screened through a double-layer vibrating screen, where the upper screen has a mesh size of 6 mesh and the lower screen has a mesh size of 12 mesh. After screening, intermediate-sized feed pellets SS2, which are between 6 mesh and 12 mesh, are obtained.

[0018] Comparative Example 1 Step S3 does not involve vacuum freeze-drying or ultrasonic processing; other processes and parameters are the same as in Example 1. The resulting pelleted feed DS1 is prepared using the following specific process: Step S1: Take wheat, corn alcohol residue, cottonseed meal, soybean meal, sprayed corn husks, and glutamic acid residue. Put the above raw materials into a pulverizer for pulverization. The pulverizer screen has a mesh size of 12 mesh to obtain powder raw materials. Then weigh the pulverized raw materials and other preparation materials according to the weight in Table 1 and put them into a horizontal ribbon mixer for mixing. The mixing time is 5 minutes. The power of the horizontal ribbon mixer is 30KW and the speed is 30rpm. Step S2: The mixed raw materials prepared in step S1 are fed into a ring die granulator. They are conditioned by steam at a temperature of 60°C for 1 minute and a steam pressure of 0.5 MPa. After conditioning, they are fed into the granulation chamber and granulated at 65°C. The membrane pore diameter of the ring die granulator is 3.5 mm. Step S3: The pellets prepared in step S2 are fed into a pellet crusher for crushing to obtain feed pellets with a particle size of approximately 2.5 mm. Step S4: The crushed material is screened through a double-layer vibrating screen, where the upper screen has a mesh size of 6 mesh and the lower screen has a mesh size of 12 mesh. After screening, intermediate-sized feed pellets DS1, which are between 6 mesh and 12 mesh, are obtained.

[0019] Comparative Example 2 Step S3 does not involve vacuum freeze-drying; other processes and parameters are the same as in Example 1, yielding pelleted feed DS2. The specific process is as follows: Step S1: Take wheat, corn alcohol residue, cottonseed meal, soybean meal, sprayed corn husks, and glutamic acid residue. Put the above raw materials into a pulverizer for pulverization. The pulverizer screen has a mesh size of 12 mesh to obtain powder raw materials. Then weigh the pulverized raw materials and other preparation materials according to the weight in Table 1 and put them into a horizontal ribbon mixer for mixing. The mixing time is 5 minutes. The power of the horizontal ribbon mixer is 30KW and the speed is 30rpm. Step S2: The mixed raw materials prepared in step S1 are fed into a ring die granulator. They are conditioned by steam at a temperature of 60°C for 1 minute and a steam pressure of 0.5 MPa. After conditioning, they are fed into the granulation chamber and granulated at 65°C. The membrane pore diameter of the ring die granulator is 3.5 mm. Step S3: The pellets prepared in step S2 are fed into an ultrasonic vibration device with an ultrasonic vibration frequency of 30 kHz, an ultrasonic amplitude of 30 μm, and an ultrasonic vibration time of 30 min. After ultrasonication, the pellets are fed into a pellet crusher for crushing to obtain feed pellets with a particle size of approximately 2.5 mm. Step S4: The crushed material is screened through a double-layer vibrating screen, where the upper screen has a mesh size of 6 mesh and the lower screen has a mesh size of 12 mesh. After screening, intermediate-sized feed pellets DS2, which are between 6 mesh and 12 mesh, are obtained.

[0020] Comparative Example 3 Step S3 does not involve ultrasonic processing; other processes and parameters are the same as in Example 1, resulting in pelleted feed DS3. The specific process is as follows: Step S1: Take wheat, corn alcohol residue, cottonseed meal, soybean meal, sprayed corn husks, and glutamic acid residue. Put the above raw materials into a pulverizer for pulverization. The pulverizer screen has a mesh size of 12 mesh to obtain powder raw materials. Then weigh the pulverized raw materials and other preparation materials according to the weight in Table 1 and put them into a horizontal ribbon mixer for mixing. The mixing time is 5 minutes. The power of the horizontal ribbon mixer is 30KW and the speed is 30rpm. Step S2: The mixed raw materials prepared in step S1 are fed into a ring die granulator. They are conditioned by steam at a temperature of 60°C for 1 minute and a steam pressure of 0.5 MPa. After conditioning, they are fed into the granulation chamber and granulated at 65°C. The membrane pore diameter of the ring die granulator is 3.5 mm. Step S3: The pellets prepared in step S2 are fed into a freeze dryer at a freezing temperature of -40℃ for 4 hours. Then, a low-temperature vacuum is applied, with the vacuum level set to reach 40Pa within 1 hour. Once the vacuum level reaches the set value, heating is turned on at a heating plate heating rate of 2℃ / min, a drying temperature of 10℃, and a drying time of 20 hours. After freeze-drying, the pellets are fed into a pellet crusher for crushing to obtain feed pellets with a particle size of approximately 2.5mm. Step S4: The crushed material is screened through a double-layer vibrating screen, where the upper screen has a mesh size of 6 mesh and the lower screen has a mesh size of 12 mesh. After screening, intermediate-sized feed pellets DS3, which are between 6 mesh and 12 mesh, are obtained.

[0021] Comparative Example 4 Step S4 is omitted. Other processes and parameters are the same as in Example 1 to obtain pelleted feed DS4. The specific process is as follows: Step S1: Take wheat, corn alcohol residue, cottonseed meal, soybean meal, sprayed corn husks, and glutamic acid residue. Put the above raw materials into a pulverizer for pulverization. The pulverizer screen has a mesh size of 12 mesh to obtain powder raw materials. Then weigh the pulverized raw materials and other preparation materials according to the weight in Table 1 and put them into a horizontal ribbon mixer for mixing. The mixing time is 5 minutes. The power of the horizontal ribbon mixer is 30KW and the speed is 30rpm. Step S2: The mixed raw materials prepared in step S1 are fed into a ring die granulator. They are conditioned by steam at a temperature of 60°C for 1 minute and a steam pressure of 0.5 MPa. After conditioning, they are fed into the granulation chamber and granulated at 65°C. The membrane pore diameter of the ring die granulator is 3.5 mm. Step S3: The pellets prepared in step S2 are fed into a freeze dryer at a freezing temperature of -40℃ for 4 hours. Then, a low-temperature vacuum is applied, with the preset vacuum level reaching 40 Pa within 1 hour. Once the preset vacuum level is reached, heating is turned on at a heating plate heating rate of 2℃ / min, a drying temperature of 10℃, and a drying time of 20 hours. When the drying temperature reaches 10℃, an ultrasonic vibration device is activated at a frequency of 30kHz, an amplitude of 30μm, and a duration of 30 minutes. After ultrasonic vibration is completed, the ultrasonic vibration is turned off, and sublimation drying continues. After freeze-drying, the pellets are fed into a pellet crusher for crushing to obtain feed pellets DS4 with a particle size of approximately 2.5 mm.

[0022] Comparative Example 5 Without the vacuum freeze-drying, ultrasonication, and crushing processes in step S3, and with other processes and parameters the same as in Example 1, pelleted feed DS5 is obtained. The specific process is as follows: S1: Take wheat, corn alcohol residue, cottonseed meal, soybean meal, sprayed corn husks, and glutamic acid residue. Put the above raw materials into a pulverizer for pulverization. The pulverizer screen has a mesh size of 12 mesh to obtain powder raw materials with particle size. Then, weigh the pulverized raw materials and other preparation materials according to the weight in Table 1 and put them into a horizontal ribbon mixer for mixing. The mixing time is 5 minutes. The power of the horizontal ribbon mixer is 30KW and the speed is 30rpm. Step S2: The mixed raw materials prepared in step S1 are fed into a ring die granulator. They are conditioned by steam at a temperature of 60°C for 1 minute and a steam pressure of 0.5 MPa. After conditioning, they are fed into the granulation chamber and granulated at 65°C. The membrane pore diameter of the ring die granulator is 2.5 mm. S3: The pelleted feed pellets are screened through a double-layer vibrating screen, with the upper screen having a mesh size of 6 mesh and the lower screen having a mesh size of 12 mesh. After screening, intermediate-sized feed pellets DS5, which are between 6 mesh and 12 mesh, are obtained.

[0023] Comparative Example 6 Step S3 does not involve any crushing process; other processes and parameters are the same as in Example 1, yielding pelleted feed DS6. The specific process is as follows: Step S1: Take wheat, corn alcohol residue, cottonseed meal, soybean meal, sprayed corn husks, and glutamic acid residue. Put the above raw materials into a pulverizer for pulverization. The pulverizer screen has a mesh size of 12 mesh to obtain powder raw materials. Then weigh the pulverized raw materials and other preparation materials according to the weight in Table 1 and put them into a horizontal ribbon mixer for mixing. The mixing time is 5 minutes. The power of the horizontal ribbon mixer is 30KW and the speed is 30rpm. Step S2: The mixed raw materials prepared in step S1 are fed into a ring die granulator. They are conditioned by steam at a temperature of 60°C for 1 minute and a steam pressure of 0.5 MPa. After conditioning, they are fed into the granulation chamber and granulated at 65°C. The membrane pore diameter of the ring die granulator is 2.5 mm. Step S3: The granules prepared in step S2 are fed into a freeze dryer at a freezing temperature of -40℃ for 4 hours. Then, a low-temperature vacuum is applied, with the preset vacuum level reaching 40 Pa within 1 hour. Once the preset vacuum level is reached, heating is started at a heating plate heating rate of 2℃ / min, a drying temperature of 10℃, and a drying time of 20 hours. When the drying temperature reaches 10℃, the ultrasonic vibration device is activated at a frequency of 30kHz, an amplitude of 30μm, and a duration of 30 minutes. After ultrasonication is completed, the ultrasonic vibration is turned off, and sublimation drying continues. Step S4: The material prepared in step S3 is screened through a double-layer vibrating screen, wherein the upper screen has a mesh size of 6 mesh and the lower screen has a mesh size of 12 mesh, and intermediate-sized feed pellets DS6 with a mesh size between 6 mesh and 12 mesh are obtained after screening.

[0024] Test case Test treatment Two hundred and forty Simmental crossbred beef cattle, aged 14 months and of similar weight (480±8 kg) and in good condition, were selected and randomly divided into eight groups of 30 cattle each. The experiment lasted for 60 days, including a 15-day pre-feeding period and a 45-day trial period. A total diet was prepared by mixing 30 wt% of the pellet concentrate prepared in Example 1 or Comparative Examples 1-6 with 70 wt% corn. The feeding period was two months, with free access to feed. Group 1 was fed a total diet prepared by mixing 30 wt% of feed pellets SS1 prepared in Example 1 with 70 wt% corn. Group 2 was fed a total diet prepared by mixing 30 wt% of feed pellets SS2 prepared in Example 2 with 70 wt% corn. Examples 3-8 were fed a total diet prepared by mixing 30 wt% of feed pellets prepared in Comparative Examples 1-6 with 70 wt% corn. The specific feeding details for each experimental group are shown in Table 2.

[0025] Table 2 shows the specific total diet feeding details for each experimental group.

[0026] Trial Management The experimental cattle were housed in separate pens with natural ventilation. They were fed at 7:00 AM and 3:00 PM daily, with free access to fodder and clean drinking water. The cattle pens were regularly cleaned and disinfected to maintain hygiene. Before the experiment, the cattle were strictly dewormed and vaccinated according to the immunization schedule, and the feeding and management conditions were basically the same across all groups.

[0027] Test Records Feed intake record: During the trial period, clean the feed trough once a day and record the amount of feed fed and the amount of leftover feed, and calculate the feed intake; Growth performance: On the first and fourth days of the trial period, the experimental cattle were weighed and recorded on an empty stomach before morning feeding. Their average daily weight gain was calculated. Feed was withheld the night before weighing. After weighing, the initial weight was subtracted and divided by the number of days to calculate the average daily weight gain per cow. The average daily weight gain per group was calculated according to the number of cattle in each group.

[0028] The methods for determining feed conversion ratio, rumen pH, microbial protein concentration, ammonia nitrogen, and total volatile fatty acids are as follows: Feed conversion ratio = Average daily feed intake / Average daily weight gain.

[0029] Rumen fluid pH: After filtering rumen fluid through four layers of gauze, the pH value was immediately measured using a PHS-3C pH meter.

[0030] Microbial protein (MCP) concentration: Centrifuge 8 mL of rumen fluid sample at 13200 r / min for 20 min, collect the precipitate, add 2.104 mL of 0.6 mol / L HClO4 solution, incubate at 90-95℃ for 1 h, cool, add 6 mL of 28.5 mol / L NH4H2PO4 solution, incubate at 15 min, cool, centrifuge at 5130 r / min for 10 min, collect 1.6 mL of supernatant, add 6 mL of 0.2 mol / L NH4H2PO4 solution, adjust the pH of the solution to 2-3 with 85% phosphoric acid, collect 3.8 mL of supernatant, add 0.2 mL of 0.4 mol / L AgNO3 solution, incubate at 5℃ in the dark overnight; centrifuge at 5130 r / min for 10 min, collect the precipitate, rinse with 4.5 mL of distilled water at pH=2, centrifuge again, add 5 mL of 0.5 mol / L HCl solution to the precipitate, incubate at 30 min, centrifuge, collect the supernatant, and centrifuge at 260 nm. Colorimetric analysis was performed at nm, using 0.5 mol / L HCl as a reference and yeast RNA as a standard curve. The RNA concentration in the sample was determined based on the optical density value and the standard curve. The calculation formula is: Microbial protein (mg / mL) = RNA concentration (mg / mL) × RNA nitrogen content (17.83%) / RNA nitrogen content in bacterial nitrogen (10%) × dilution factor × 6.25.

[0031] Ammonia nitrogen (NH3-N) concentration: The NH3-N concentration was determined using the phenol-sodium hypochlorite colorimetric method. After centrifuging rumen fluid at 10000 rpm / min for 20 min, 40 μL of the supernatant was collected, 2.5 mL of phenol was added, and the mixture was thoroughly mixed. Then, 2.0 mL of sodium hypochlorite was added, and the mixture was incubated in a water bath at 37℃ for 30 min. The absorbance was measured at a wavelength of 550 nm.

[0032] Volatile fatty acid (VFA) concentrations: The concentrations of acetic acid, propionic acid, and butyric acid in rumen fluid were determined using gas chromatography. Rumen fluid was centrifuged at 5000 g for 15 min. 1 mL of the supernatant was added to 0.2 mL of 25% (w / v) metaphosphoric acid solution, incubated overnight at 4°C, and then centrifuged at 10000 g for 15 min. 0.1 mL of the supernatant was added to 0.9 mL of chromatographic grade methanol, centrifuged at 10000 g for 5 min, filtered through a 0.22 μm filter, and the concentrations of each VFA were determined using gas chromatography. The ratio of acetic acid to propionic acid was calculated.

[0033] The growth performance of Simmental crossbred beef cattle in experimental groups 1-8 is shown in Table 3. Table 3. Growth performance of Simmental crossbred beef cattle in experimental groups 1-8

[0034] The rumen health levels of Simmental crossbred beef cattle in experimental groups 1-8 are shown in Table 4. Table 4. Rumen health levels of beef cattle in experimental groups 1-8

[0035] Tables 3-4 show that the beef cattle in experimental group 1 had the highest daily feed intake, the highest daily weight gain, and the lowest feed conversion ratio, indicating that experimental group 1, using 30wt% of feed pellets SS1 prepared in Example 1 + 70wt% corn as its diet, had the highest feed conversion rate. The rumen pH of the beef cattle in experimental group 1 was the highest, significantly higher than other experimental groups. The ammonia nitrogen concentration varied significantly among the groups (P<0.05), with experimental group 1 having the highest concentration. Experimental group 1 also had the highest microbial protein concentration, significantly higher than experimental groups 3-8. The total volatile fatty acid yield in experimental group 1 was significantly higher than in experimental groups 3-8, and the acetic acid / propionic acid ratio in experimental group 1 was the lowest. Among all test indicators, experimental groups 1-2 showed the best performance, significantly better than experimental groups 3-8 (experimental groups 3-8 used 30wt% of pelleted concentrate feed prepared in Comparative Examples 1-6 + 70wt% corn as their total diet). This demonstrates that the present invention verifies the effectiveness of freeze-drying the pelleted feed after pelleting. Ultrasonic treatment increases feed porosity, palatability, and nutrient retention, leading to higher feed intake in beef cattle. The high porosity facilitates the contact and action of digestive enzymes, improving feed digestibility and utilization. Vacuum freeze-drying followed by ultrasonic crushing of pellets improves particle size uniformity. Combined with ring die pelleting and screening within specific particle size ranges, this further enhances particle size uniformity, eliminates particle size differences, and reduces feed pulverization. The resulting uniformly mixed pellets prevent rumen acidosis. Furthermore, the uniform size and high porosity of the pellets stimulate rumen motility, promote digestive fluid secretion, improve the rumen microbial fermentation environment, increase microbial protein synthesis and volatile fatty acid production, optimize the acetic acid / propionic acid ratio, and improve net energy utilization efficiency. In summary, the pellet concentrate prepared by the preparation process of this invention can comprehensively improve the growth performance and rumen health of beef cattle, and has significant value for promotion and application.

[0036] Therefore, those skilled in the art will recognize that although embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should be understood and recognized as covering all such other variations or modifications.

Claims

1. A method for preparing pelleted concentrate for ruminants, characterized in that, Includes the following steps: Step S1: Weigh the raw materials and crush them, then mix the powdered materials thoroughly. Step S2: The uniformly mixed material is fed into a pellet mill and conditioned by steam, and then pelletized. Step S3: The granules prepared in step S2 are subjected to vacuum freeze-drying and ultrasonic treatment, and then the granules are fed into a granulator for crushing. Step S4: The material crushed in step S3 is screened through a double-layer vibrating screen, where the upper screen has a mesh size of 6 mesh and the lower screen has a mesh size of 12 mesh, and intermediate-sized pellet feed with a mesh size between 6 mesh and 12 mesh is obtained after screening.

2. The method for preparing pelleted concentrate for ruminants as described in claim 1, characterized in that, In step S3, the freezing temperature for vacuum freeze drying is -30 to -50°C, the freezing time is 3 to 6 hours, the heating and drying temperature is -10 to 15°C, and the drying time is 10 to 24 hours.

3. The method for preparing pelleted concentrate for ruminants as described in claim 1, characterized in that, In step S3, the vacuum degree of vacuum freeze drying is 30-50 Pa within 1 hour, and the heating rate is 1-5℃ / min.

4. The method for preparing pelleted concentrate for ruminants as described in claim 1, characterized in that, In step S3, the ultrasonic vibration frequency is 15-30 kHz; the ultrasonic amplitude is 15-30 μm; and the ultrasonic vibration time is 20-30 min.

5. The method for preparing pelleted concentrate for ruminants as described in claim 1, characterized in that, The mixing time in step S1 is 3 to 15 minutes.

6. The method for preparing pelleted concentrate for ruminants as described in claim 1, characterized in that, In step S2, the conditioning temperature is 50℃~65℃ and the steam pressure is 0.2~0.5 MPa.

7. The method for preparing pelleted concentrate for ruminants as described in claim 1, characterized in that, The granulation temperature in step S2 is 50℃~65℃.

8. The method for preparing pelleted concentrate for ruminants as described in claim 1, characterized in that, In step S2, a ring die granulator is used for granulation. The diameter of the membrane pores of the ring die granulator is 3.5-6 mm.

9. The method for preparing pelleted concentrate for ruminants as described in claim 1, characterized in that, In step S4, the oversized particles separated by the upper screen are returned to the crusher for further crushing, while the overly fine powder separated by the lower screen is returned to the granulator for regranulation.

10. A pelleted concentrate for ruminants prepared by the preparation method described in claims 1-9.

Images