Feed additive for sows in lactation period and preparation method of feed additive

Abstract

The invention discloses a lactating sow feed additive and a preparation method thereof, and relates to the technical field of lactating sow feed. The preparation method comprises the following steps: mixing vitamin E and a rosemary extract in proportion, emulsifying to prepare an emulsion, compounding with a polylysine solution, curing with calcium chloride, and centrifugally drying to prepare an inner core; then mixing acid protease with sorbitol to prepare a stable solution, compounding the stable solution with the inner core, and drying to obtain a composite core; and finally, preparing a coating solution from cellulose acetate succinate and glycerol, and carrying out bottom spraying type spray coating to prepare the double-layer microcapsule. The process parameters are scientific and reasonable, the auxiliary material adaptability is good, the double-layer wall material design is adopted, accurate release of acid protease in the stomach funguses and slow release of vitamin E and rosemary extract in the pylorus can be achieved, the core material utilization rate is increased, the process is easy to scale, and the production performance of lactating sows can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of lactating sow feed technology, specifically to a lactating sow feed additive and its preparation method. Background Technology

[0002] In the lactation sow farming industry, lactation stress easily leads to insufficient secretion of endogenous pepsin and fragile gastrointestinal mucosa in lactating sows, resulting in digestive and absorptive disorders and diarrhea, which seriously affects the reproductive performance of lactating sows. To address this issue, the feed industry widely uses functional components such as acidic protease, vitamin E, and rosemary extract as feed additives. Among them, acidic protease can supplement the insufficient digestive enzymes of lactating sows and improve feed protein utilization, while vitamin E and rosemary extract can synergistically exert antioxidant and gastrointestinal mucosal protective effects. Meanwhile, microencapsulation technology has become the mainstream preparation method for functional feed additives because it can protect the activity of the core material and control the release rate. However, the rationality of its preparation process and the scientific design of the wall material directly determine the effectiveness of the core material's function. The industry urgently needs a precise release microcapsule preparation technology adapted to the physiological environment of the lactating sow's stomach.

[0003] Existing microencapsulated feed additive preparation technologies suffer from the following drawbacks: First, the core material release lacks targeting. Most existing microcapsules have a single-layer structure or inappropriate wall material selection, failing to adapt to the pH gradient of the weakly acidic cardia, strongly acidic fundus, and weakly acidic pylorus in the stomach of lactating sows. This leads to premature release and inactivation of acidic proteases in non-active areas (the weakly acidic cardia region), and excessively rapid release of vitamin E and rosemary extract, failing to achieve long-term mucosal protection, resulting in low core material utilization efficiency. Second, the preparation process is unreasonable. The process parameters such as excipient ratio, emulsification, and coating lack scientific ranges, and the compatibility between excipients and core and wall materials is insufficient, easily leading to uneven emulsification and activity loss of the core material, poor wall material curing effect, and uneven coating. Third, the feasibility of large-scale process is low. Some processes require specially customized equipment or have a narrow parameter fluctuation range, making it difficult to adapt to the needs of industrial production. At the same time, the synergy between the core material and wall material is poor, making it impossible to achieve precise release of different core materials in different zones, and failing to meet the dual requirements of efficient protein hydrolysis and gastrointestinal protection. Summary of the Invention

[0004] The purpose of this invention is to provide a feed additive for lactating sows and its preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A feed additive for lactating sows, the feed additive comprising vitamin E, rosemary extract and acidic protease; The preparation steps are as follows: the feed additive is prepared using vitamin E, rosemary extract and acidic protease as functional core materials; firstly, vitamin E and rosemary extract are emulsified, then an inner core is prepared using vitamin E and rosemary extract emulsion as the core and polylysine as the wall material, and then the inner core is combined with acidic protease through electrostatic adsorption to obtain a composite core; finally, a double-layer microcapsule is prepared using the composite core as the core and cellulose acetate succinate as the wall material by spray coating.

[0006] As an optimization, the mass ratio of vitamin E, rosemary extract and acidic protease is 30:8:7.

[0007] As an optimization, the acidic protease is Aspergillus niger aspartic acidic protease.

[0008] A method for preparing a feed additive for lactating sows, applicable to any of the above-described feed additives for lactating sows, wherein the feed additive for lactating sows comprises the following preparation steps: S1. Add polylysine to deionized water at 10-15 times its weight, and stir for 15-20 minutes at 35-45°C. After stirring, allow to cool to 25-30°C. Then, add vitamin E and rosemary extract emulsion at 3.2-3.8 times its weight, and stir for 30-40 minutes at 25-35°C. After stirring, add calcium chloride solution at 1% by mass at 1-1.2 times its weight, and stir for 30-40 minutes at 25-35°C. Then, centrifuge at 8000 r / min for 10 minutes, remove the supernatant, filter, and vacuum dry the filtered product at 25-35°C for 2-3 hours. After drying, sieve to obtain the inner core. S2. Add the prepared inner core to an acidic protease stabilizing solution with a mass of 12-15 times that of the inner core, and stir at 35-40℃ for 15-20 min. Then let it stand and cool to 25-30℃, stir for 1-1.5 h, then centrifuge at 6000 r / min for 8-10 min, remove the supernatant, filter and separate, and vacuum dry the filtered product at 25-35℃ for 1-2 h to obtain the composite core. S3. Weigh the cellulose acetate succinate coating solution and the composite core at a mass ratio of 4~5:1. Then add the composite core to the coating machine barrel, turn on the hot air bottom blowing, set the inlet air temperature to 45~50℃, the outlet air temperature to 30~35℃, and the bottom blowing air volume to 0.8~1m³ / h, so that the composite core is in a fluidized state in the barrel, and preheat for 10~15min. Then pump the cellulose acetate succinate coating solution into the atomizer at a flow rate of 1.5~2mL / min, set the atomization pressure to 0.3~0.4MPa. After all the cellulose acetate succinate coating solution has been pumped in, continue fluidized drying for 30~40min. After drying, cool to 25~35℃ to obtain double-layer microcapsules.

[0009] As an optimization, the vitamin E and rosemary extract emulsion in S1 includes the following preparation steps: vitamin E and rosemary extract are mixed at a mass ratio of 8:7, then 0.125 to 0.15 times the mass of vitamin E is added to Tween 80, and the mixture is stirred evenly at a temperature of 25 to 35°C. Then, 6 to 7 times the mass of vitamin E is added dropwise to deionized water. After the addition is complete, the mixture is emulsified at high speed for 20 to 30 minutes to prepare the vitamin E and rosemary extract emulsion, which is then refrigerated at 4°C for later use.

[0010] As an optimization, the acidic protease stabilizer in S2 includes the following preparation steps: acidic protease and sorbitol are mixed at a mass ratio of 15:1. After mixing, 3.5 to 4.5 times the mass of the acidic protease in deionized water is added. Then, the mixture is stirred for 10 to 15 minutes at a temperature of 25 to 30°C. After stirring, the pH is adjusted to 3 to 4 with 1 mol / L hydrochloric acid solution to prepare the acidic protease stabilizer, which is then refrigerated at 4°C for later use.

[0011] As an optimization, the cellulose acetate succinate coating solution in S3 includes the following preparation steps: cellulose acetate succinate and glycerol are mixed at a mass ratio of 15:1. After mixing, 4.5 to 5 times the mass of cellulose acetate succinate in ethanol solution is added. Then, the mixture is stirred for 30 to 40 minutes at a temperature of 25 to 35°C. The pH is then adjusted to 4 to 4.5 using 1 mol / L hydrochloric acid solution, and the mixture is allowed to stand for 30 to 40 minutes to remove bubbles, thus preparing the cellulose acetate succinate coating solution.

[0012] As an optimization, the material in step S1 is dried and then passed through a 200-mesh sieve.

[0013] A lactating sow feed, by weight, comprises: 380-400 parts wheat, 200-220 parts corn flour, 100-110 parts whey powder, 140-150 parts soybean meal, 62-65 parts soybean oil, 47-50 parts fish meal, 5-6 parts limestone powder, 10-12 parts dicalcium phosphate, 3-5 parts salt, 5-7 parts lysine hydrochloride, 1.5-2.5 parts methionine, 1.5-2.5 parts threonine, 7-10 parts premix, and 2-3 parts feed additives, wherein the feed additives include the lactating sow feed additives described above.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are: This technical solution, from emulsion preparation and inner core molding to composite core preparation and outer coating molding, is adapted to the process fluctuation requirements of industrial production. At the same time, the selection of excipients is highly targeted. Tween 80 efficiently emulsifies fat-soluble vitamin E and rosemary extract, sorbitol can stabilize the bioactivity of acidic proteases, calcium chloride can solidify the polylysine wall material, and glycerol can improve the film-forming properties of cellulose acetate succinate coating solution. Moreover, all excipients have good compatibility with the wall material and core material, have no harmful components, and meet the safety requirements of feed additives. The bilayer microcapsules prepared by this technical solution have a precise zoned release function thanks to the synergistic design of the bilayer wall material. As a feed additive, they are adapted to the physiological digestive characteristics of the stomach of lactating sows, and the core material function can be performed efficiently. The microcapsules form an inner core with polylysine as the wall material and vitamin E and rosemary extract emulsion as the core. A composite core is then obtained by electrostatic adsorption of a complex acidic protease. Finally, cellulose acetate succinate serves as the outer protective wall material. The characteristics of this double-layer wall material are highly matched to the pH gradient of the lactating sow's stomach. Cellulose acetate succinate forms an effective barrier in the weakly acidic zone of the pylorus, preventing premature and excessive release of acidic protease and vitamin E. In the strongly acidic zone of the gastric fundus, the wall material dissolves, allowing for precise and rapid release of the complex acidic protease. This efficiently hydrolyzes large protein molecules in the feed, compensating for the insufficient endogenous pepsin in lactating sows. Meanwhile, the inner polylysine wall material allows for the slow release of vitamin E and rosemary extract in the weakly acidic zone of the pylorus, providing long-lasting antioxidant effects, protecting the gastrointestinal mucosa of lactating sows, and alleviating lactation stress. This zoned release function effectively prevents the core material from being released and inactivated in non-active areas, significantly improving the utilization efficiency of the core material and achieving the dual effects of efficient protein hydrolysis and gastrointestinal mucosal protection. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1 S1. Mix vitamin E and rosemary extract at a mass ratio of 8:7. Then add 0.125 times the mass of vitamin E in Tween 80 and stir until homogeneous at 25°C. Next, add 6 times the mass of vitamin E in deionized water dropwise. After the addition is complete, emulsify at high speed for 20 minutes to prepare a vitamin E and rosemary extract emulsion, and refrigerate at 4°C for later use. Add polylysine to 10 times the mass of polylysine in deionized water and stir at 35°C for 15 minutes. After stirring, allow to cool to a stand temperature. At 25°C, vitamin E and rosemary extract emulsion with a mass ratio of 3.2 times that of polylysine were added dropwise, and the mixture was stirred for 30 min at 25°C. After stirring, a 1% calcium chloride solution with a mass ratio of 1 times that of polylysine was added dropwise, and the mixture was stirred for 30 min at 25°C. Then, the mixture was centrifuged at 8000 r / min for 10 min, the supernatant was removed, and the mixture was filtered. The filtered product was then vacuum dried at 25°C for 2 h. After drying, the product was passed through a 200-mesh sieve to obtain the inner core. S2. Acidic protease and sorbitol were mixed at a mass ratio of 15:1. After mixing, 3.5 times the mass of deionized water was added to the mixture. The mixture was then stirred at 25°C for 10 min. After stirring, the pH was adjusted to 3 with 1 mol / L hydrochloric acid solution to prepare an acidic protease stable solution, which was then refrigerated at 4°C for later use. The prepared inner core was added to 12 times the mass of the inner core in the acidic protease stable solution and stirred at 35°C for 15 min. The mixture was then allowed to stand and cool to 25°C and stirred for 1 h. After that, it was centrifuged at 6000 r / min for 8 min. After removing the supernatant, the mixture was filtered and the filtered product was vacuum dried at 25°C for 1 h to obtain the composite core. S3. Mix cellulose acetate succinate and glycerol at a mass ratio of 15:1. After mixing, add 4.5 times the mass of cellulose acetate succinate in ethanol solution. Then, stir at 25℃ for 30 min. Adjust the pH to 4 with 1 mol / L hydrochloric acid solution and let stand for 30 min to remove bubbles, thus preparing the cellulose acetate succinate coating solution. Weigh the cellulose acetate succinate coating solution and composite core at a mass ratio of 4:1, and then add them to the coating machine barrel. Add the composite core, turn on the hot air bottom blowing, set the inlet air temperature to 45℃, the outlet air temperature to 30℃, and the bottom blowing air volume to 0.8m³ / h, so that the composite core is in a fluidized state in the barrel, and preheat for 10min; then pump the cellulose acetate succinate coating solution into the atomizer at a flow rate of 1.5mL / min, set the atomization pressure to 0.3MPa, after all the cellulose acetate succinate coating solution has been pumped in, continue fluidization drying for 30min, and cool to 25℃ after drying to obtain double-layer microcapsules.

[0017] Example 2 S1. Mix vitamin E and rosemary extract at a mass ratio of 8:7. Then add 0.1375 times the mass of vitamin E in Tween 80 and stir until homogeneous at 30°C. Next, add 6.5 times the mass of vitamin E in deionized water dropwise. After the addition is complete, emulsify at high speed for 25 minutes to prepare a vitamin E and rosemary extract emulsion, and refrigerate at 4°C for later use. Add polylysine to 12.5 times the mass of polylysine in deionized water and stir at 40°C for 17.5 minutes. After stirring is complete, allow to stand and cool. The mixture was heated to 27.5℃, and then vitamin E and rosemary extract emulsion with a mass ratio of 3.5 times that of polylysine were added dropwise. The mixture was stirred at 30℃ for 35 min. After stirring, calcium chloride solution with a mass fraction of 1% and a mass ratio of 1.1 times that of polylysine were added dropwise. The mixture was stirred at 30℃ for 35 min. Then, the mixture was centrifuged at 8000 r / min for 10 min. After removing the supernatant, the mixture was filtered and separated. The filtered product was vacuum dried at 30℃ for 2.5 h. After drying, the product was passed through a 200-mesh sieve to obtain the inner core. S2. Acidic protease and sorbitol were mixed at a mass ratio of 15:1. After mixing, deionized water with a mass of 4 times that of the acidic protease was added. The mixture was then stirred at 27.5℃ for 12.5 min. After stirring, the pH was adjusted to 3.5 with 1 mol / L hydrochloric acid solution to prepare an acidic protease stable solution, which was then refrigerated at 4℃ for later use. The prepared inner core was added to the acidic protease stable solution with a mass of 13.5 times that of the inner core and stirred at 37.5℃ for 17.5 min. After cooling to 27.5℃, the mixture was stirred for 1.25 h. Then, it was centrifuged at 6000 r / min for 9 min. After removing the supernatant, the mixture was filtered and the filtered product was vacuum dried at 30℃ for 1.5 h to obtain the composite core. S3. Mix cellulose acetate succinate and glycerol at a mass ratio of 15:1. After mixing, add 4.75 times the mass of cellulose acetate succinate in ethanol solution. Then, stir for 35 minutes at 30°C. Adjust the pH to 4.25 with 1 mol / L hydrochloric acid solution and let stand for 35 minutes to remove bubbles, thus preparing the cellulose acetate succinate coating solution. Weigh the cellulose acetate succinate coating solution and composite core at a mass ratio of 4.5:1, and then add them to the coating machine barrel. The composite core was introduced, and hot air bottom blowing was turned on. The inlet air temperature was set to 47.5℃, the outlet air temperature to 32.5℃, and the bottom blowing air volume to 0.9m³ / h, so that the composite core was in a fluidized state in the barrel and preheated for 12.5min. Then, the cellulose acetate succinate coating solution was pumped into the atomizer at a flow rate of 1.75mL / min and the atomization pressure was set to 0.35MPa. After all the cellulose acetate succinate coating solution was pumped in, fluidized drying continued for 35min. After drying, the solution was cooled to 30℃ to obtain double-layer microcapsules.

[0018] Example 3 S1. Mix vitamin E and rosemary extract at a mass ratio of 8:7. Then add 0.15 times the mass of vitamin E in Tween 80 and stir evenly at 35°C. Next, add 7 times the mass of vitamin E in deionized water. After the addition is complete, emulsify at high speed for 30 minutes to prepare a vitamin E and rosemary extract emulsion, and refrigerate at 4°C for later use. Add polylysine to 15 times the mass of polylysine in deionized water and stir at 45°C for 20 minutes. After stirring, let it stand and cool to 3°C. At 0℃, vitamin E and rosemary extract emulsion with a mass ratio of 3.8 times that of polylysine were added dropwise, and the mixture was stirred at 35℃ for 40 min. After stirring, calcium chloride solution with a mass fraction of 1% and a mass ratio of 1.2 times that of polylysine were added dropwise, and the mixture was stirred at 35℃ for 40 min. Then, the mixture was centrifuged at 8000 r / min for 10 min, the supernatant was removed, and the mixture was filtered. The filtered product was then vacuum dried at 35℃ for 3 h. After drying, the product was passed through a 200-mesh sieve to obtain the inner core. S2. Acidic protease and sorbitol were mixed at a mass ratio of 15:1. After mixing, 4.5 times the mass of deionized water was added to the mixture. The mixture was then stirred at 30°C for 15 min. After stirring, the pH was adjusted to 4 with 1 mol / L hydrochloric acid solution to prepare an acidic protease stable solution, which was then refrigerated at 4°C for later use. The prepared inner core was added to 15 times the mass of the inner core in the acidic protease stable solution, and stirred at 40°C for 20 min. After standing and cooling to 30°C, the mixture was stirred for 1.5 h. Then, it was centrifuged at 6000 r / min for 10 min. After removing the supernatant, the mixture was filtered and the filtered product was vacuum dried at 35°C for 2 h to obtain the composite core. S3. Mix cellulose acetate succinate and glycerol at a mass ratio of 15:1. After mixing, add 5 times the mass of ethanol solution of cellulose acetate succinate. Then, stir at 35℃ for 40 min. Adjust the pH to 4.5 with 1 mol / L hydrochloric acid solution and let stand for 40 min to remove bubbles, thus preparing the cellulose acetate succinate coating solution. Weigh the cellulose acetate succinate coating solution and composite core at a mass ratio of 5:1, and then add them to the coating machine material. The composite core was added to the cylinder, and hot air bottom blowing was turned on. The inlet air temperature was set to 50℃, the outlet air temperature to 35℃, and the bottom blowing air volume to 1m³ / h, so that the composite core was in a fluidized state in the cylinder and preheated for 15min. Then, the cellulose acetate succinate coating solution was pumped into the atomizer at a flow rate of 2mL / min and the atomization pressure was set to 0.4MPa. After all the cellulose acetate succinate coating solution was pumped in, fluidized drying continued for 40min. After drying was completed, the solution was cooled to 35℃ to obtain double-layer microcapsules.

[0019] Comparative Example 4 The only difference from Example 2 is that steps S2 and S3 are omitted; Comparative Example 5 The only difference from Example 2 is that step S3 is omitted.

[0020] Partition release performance test The bilayer microcapsules prepared in the above examples and comparative examples were used for experiments. Each group was repeated in triplicate. The stirring speed was 100 r / min to simulate the gastric peristalsis of lactating sows. An in vitro stepwise release simulation experiment was conducted. 0.5 g of sample was added to 50 mL of preheated gastric cardia simulated gastric juice at pH 5.8-6.0 and shaken for 1 h. Fresh gastric juice was added after sampling. The pH was then adjusted to 1.5-3.0, and pepsin was added to prepare gastric fundus simulated gastric juice. After shaking for 3 h, samples were taken and the juice was added. Finally, the pH was adjusted to 4.0-4.5, and calcium chloride and an appropriate amount of pepsin were added to prepare pyloric simulated gastric juice. Samples were taken after shaking for 4 h. After the experiment, the residual core material was detected by centrifugation. All samples were centrifuged at 4 °C and 10000 r / min for 10 min, and the supernatant was filtered through a 0.22 μm filter membrane for later use.

[0021] Acidic protease release assay: The release solution was diluted and reacted with casein substrate. The reaction was terminated with trichloroacetic acid. The supernatant was collected by centrifugation and the absorbance was measured at 275 nm. The enzyme activity was calculated using a standard curve. The cumulative release rate was then calculated based on the ratio of the total enzyme activity to the total enzyme activity in the microcapsules. Vitamin E was detected by high performance liquid chromatography. The VE in the release solution was extracted with anhydrous ethanol, separated by a C18 column, and detected at 292 nm with methanol:water = 98:2 as the mobile phase. The cumulative release rate was calculated after quantification by external standard method.

[0022] Table 1 Performance Test Results The data from Examples 1-3 are similar and all meet the criteria for qualified release of partitions; Comparative Example 4: The S2 step was not performed, and no acidic protease was added, so the acidic protease was not detected. It relied solely on polylysine wall material. There was no sustained-release control of vitamin E in the gastric fundus. The release rate was high in the cardia stage, rapid in the gastric fundus stage, and almost complete in the pyloric stage. There was no regional targeting. Comparative Example 5 contained a complex acidic protease but lacked an outer cellulose acetate succinate protective wall material. The acidic protease adhered to the surface of the complex core only through electrostatic adsorption of polylysine, without the blocking effect of cellulose acetate succinate. It was released in large quantities in the weakly acidic zone of the cardia, with a release rate of 60.5%. The remaining protease in the strongly acidic zone of the fundus was released rapidly, with a cumulative release rate of 98.3%, and was almost completely released in the pyloric stage. Vitamin E lacked the protection of the outer cellulose acetate succinate, and its release rate was significantly accelerated, with a release rate of 20.2% in the cardia stage and a cumulative release rate of 70.8% in the fundus stage. It could not achieve the requirement of small release in the fundus and slow release in the pylorus.

[0023] The release rate of rosemary extract showed a consistent trend and similar data to that of vitamin E. It was not listed separately in the table, but was measured simultaneously during the test, and the results matched the VE release rate of the corresponding group.

[0024] Animal husbandry effect test: The animal feeding effect of Example 2 as a feed additive is illustrated using lactating sows as an example. Lactating sows were selected and divided into 4 groups of 20-30 sows each. The lactating sow feed formula consisted of: 400 parts wheat, 200 parts corn flour, 100 parts whey powder, 150 parts soybean meal, 62 parts soybean oil, 50 parts fish meal, 6 parts limestone powder, 10 parts dicalcium phosphate, 3 parts salt, 5 parts lysine hydrochloride, 1.5 parts methionine, 2.5 parts threonine, and 10 parts premix.

[0025] The first group served as the control group, and was fed the above-mentioned lactating sow feed for 35 days.

[0026] The second group was experimental group 1, in which 2 portions of the feed additive obtained in Example 2 were added to the feed of lactating sows and fed for 35 days.

[0027] The third group was experimental group 2, in which two portions of the feed additive obtained from comparative example 4 were added to the feed of lactating sows and fed for 35 days.

[0028] The fourth group, experimental group 3, added two portions of the feed additive obtained in comparison ratio 5 to the feed of lactating sows for 35 days. The experimental results are shown in Table 2.

[0029] Table 2. Effects of feed additives on weaned and lactating sows during trial. Feeding trial results showed no significant difference in daily feed intake among the groups. However, experimental group 1 (Example 2) had the best daily weight gain and feed conversion ratio, with a daily weight gain of 439 g / d and a feed conversion ratio of 0.61 g / g, significantly higher than the control group and experimental groups 2 and 3. This is because Example 2 has precise zoned release characteristics, allowing the compound acidic protease to be released efficiently in the strongly acidic zone of the gastric fundus, greatly improving the efficiency of feed protein hydrolysis. Vitamin E can be slowly released in the weakly acidic zone of the pylorus and provide long-term protection for the gastric mucosa. Comparative example 4 did not add acidic protease, which could not compensate for the lack of endogenous pepsin in lactating sows, resulting in low protein digestion efficiency. Comparative example 5, due to the lack of an outer cellulose acetate succinate barrier, experienced a large release and inactivation of protease at the cardia, and the excessively rapid release of vitamin E limited the function of the core material. Therefore, the growth performance indicators of both were inferior to those of experimental group 1.

[0030] The diarrhea rate in all additive groups was lower than that in the control group. The diarrhea rate in experimental groups 1 and 3 was 7%, while that in experimental group 2 was 8%. Diarrhea in weaned and lactating sows is mainly caused by intestinal fermentation of undigested protein and damage to the gastrointestinal mucosa. Experimental group 1 reduced intestinal fermentation through efficient hydrolysis by protease, while the slow release of vitamin E provided long-term mucosal protection, effectively reducing the diarrhea rate under the dual effects. Although the core material release in experimental group 3 was disordered, it still had the hydrolytic effect of complex acidic protease and the mucosal protective effect of vitamin E, so the diarrhea rate was lower. Experimental group 2, lacking acidic protease, had a slightly higher diarrhea rate than experimental group 1 due to the slight fermentation of a small amount of undigested protein entering the intestine, but the vitamin E it contained still played a mucosal protective role, resulting in a lower diarrhea rate than the control group.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A feed additive for lactating sows, characterized in that, The feed additives include vitamin E, rosemary extract, and acidic protease; The preparation steps are as follows: the feed additive is prepared using vitamin E, rosemary extract and acidic protease as functional core materials; firstly, vitamin E and rosemary extract are emulsified, then an inner core is prepared using vitamin E and rosemary extract emulsion as the core and polylysine as the wall material, and then the inner core is combined with acidic protease through electrostatic adsorption to obtain a composite core; finally, a double-layer microcapsule is prepared using the composite core as the core and cellulose acetate succinate as the wall material by spray coating.

2. The feed additive for lactating sows according to claim 1, characterized in that, The mass ratio of vitamin E, rosemary extract, and acidic protease is 30:8:

7.

3. The feed additive for lactating sows according to claim 1, characterized in that, The acidic protease used is Aspergillus niger aspartic acidic protease.

4. A method for preparing a feed additive for lactating sows, applied to the feed additive for lactating sows described in any one of claims 1 to 3, characterized in that, The feed additive for lactating sows includes the following preparation steps: S1. Add polylysine to deionized water at 10-15 times its weight, and stir for 15-20 minutes at 35-45°C. After stirring, allow to cool to 25-30°C. Then, add vitamin E and rosemary extract emulsion at 3.2-3.8 times its weight, and stir for 30-40 minutes at 25-35°C. After stirring, add calcium chloride solution at 1% by mass at 1-1.2 times its weight, and stir for 30-40 minutes at 25-35°C. Then, centrifuge at 8000 r / min for 10 minutes, remove the supernatant, filter, and vacuum dry the filtered product at 25-35°C for 2-3 hours. After drying, sieve to obtain the inner core. S2. Add the prepared inner core to an acidic protease stabilizing solution with a mass of 12-15 times that of the inner core, and stir at 35-40℃ for 15-20 min. Then let it stand and cool to 25-30℃, stir for 1-1.5 h, then centrifuge at 6000 r / min for 8-10 min, remove the supernatant, filter and separate, and vacuum dry the filtered product at 25-35℃ for 1-2 h to obtain the composite core. S3. Weigh the cellulose acetate succinate coating solution and the composite core at a mass ratio of 4~5:

1. Then add the composite core to the coating machine barrel, turn on the hot air bottom blowing, set the inlet air temperature to 45~50℃, the outlet air temperature to 30~35℃, and the bottom blowing air volume to 0.8~1m³ / h, so that the composite core is in a fluidized state in the barrel, and preheat for 10~15min. Then pump the cellulose acetate succinate coating solution into the atomizer at a flow rate of 1.5~2mL / min, set the atomization pressure to 0.3~0.4MPa. After all the cellulose acetate succinate coating solution has been pumped in, continue fluidized drying for 30~40min. After drying, cool to 25~35℃ to obtain double-layer microcapsules.

5. The method for preparing the feed additive for lactating sows according to claim 4, characterized in that, The vitamin E and rosemary extract emulsion in S1 includes the following preparation steps: vitamin E and rosemary extract are mixed at a mass ratio of 8:7, then 0.125 to 0.15 times the mass of vitamin E is added to Tween 80, and the mixture is stirred evenly at a temperature of 25 to 35°C. Then, 6 to 7 times the mass of vitamin E is added dropwise to deionized water. After the addition is complete, the mixture is emulsified at high speed for 20 to 30 minutes to prepare the vitamin E and rosemary extract emulsion, which is then refrigerated at 4°C for later use.

6. The method for preparing the feed additive for lactating sows according to claim 4, characterized in that, The acidic protease stabilizer in S2 includes the following preparation steps: acidic protease and sorbitol are mixed at a mass ratio of 15:

1. After mixing, 3.5 to 4.5 times the mass of the acidic protease in deionized water is added. Then, the mixture is stirred for 10 to 15 minutes at a temperature of 25 to 30°C. After stirring, the pH is adjusted to 3 to 4 with 1 mol / L hydrochloric acid solution to prepare the acidic protease stabilizer. The stabilizer is then stored at 4°C for later use.

7. The method for preparing the feed additive for lactating sows according to claim 4, characterized in that, The cellulose acetate succinate coating solution in S3 includes the following preparation steps: cellulose acetate succinate and glycerol are mixed at a mass ratio of 15:

1. After mixing, 4.5 to 5 times the mass of cellulose acetate succinate in ethanol solution is added. Then, the mixture is stirred for 30 to 40 minutes at a temperature of 25 to 35°C. The pH is then adjusted to 4 to 4.5 using 1 mol / L hydrochloric acid solution, and the mixture is allowed to stand for 30 to 40 minutes to remove bubbles, thus preparing the cellulose acetate succinate coating solution.

8. The method for preparing the feed additive for lactating sows according to claim 4, characterized in that, After drying in step S1, the sample is passed through a 200-mesh sieve.

9. A feed for lactating sows, comprising, by weight parts: The feed additive comprises 380-400 parts wheat, 200-220 parts corn flour, 100-110 parts whey powder, 140-150 parts soybean meal, 62-65 parts soybean oil, 47-50 parts fish meal, 5-6 parts limestone powder, 10-12 parts dicalcium phosphate, 3-5 parts salt, 5-7 parts lysine hydrochloride, 1.5-2.5 parts methionine, 1.5-2.5 parts threonine, 7-10 parts premix, and 2-3 parts feed additives. The feed additives include the lactating sow feed additives as described in claims 1-3.

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