A compound acidifier for improving the feed intake of lactating sows and a preparation method thereof

Abstract

The present application relates to a kind of compound acidifier for improving the feed intake of lactating sow and its preparation method, belong to the technical field of feed additive.The compound acidifier includes wall material and core material, the wall material includes cystine-gamma-polyglutamic acid and arginine-chitosan;The core material includes organic acid, organic acid salt and fermentation broth.The compound acidifier of the present application uses cystine crosslinked gamma-polyglutamic acid and arginine grafted chitosan as wall material, forms microcapsule with intestinal target release function by wrapping organic acid, can effectively improve the utilization efficiency of acidifier and the feed intake of lactating sow.

Description

Technical Field

[0001] This invention belongs to the field of feed additive technology, specifically relating to a compound acidifier for increasing feed intake in lactating sows and its preparation method. Background Technology

[0002] The feed intake of lactating sows directly determines their lactation performance, body condition recovery, and piglet survival rate, making it a core factor affecting the economic benefits of pig farms. In actual farming, sows commonly face insufficient feed intake after farrowing, leading to a chain reaction of problems such as weight loss and decreased milk production. To address this issue, feed acidifiers, as a safe and environmentally friendly additive, are widely used. They indirectly increase feed intake by lowering the pH value of the gastrointestinal tract to inhibit harmful bacteria and promote digestion. Currently, most compound acidifiers on the market are prepared using a simple physical mixing process of organic acids and carriers. While this has some effect, it is limited by traditional technical approaches and fails to break through the extensive "mixing-release" model. It exhibits significant shortcomings in precision, stability, and functionality, making it difficult to meet the needs of modern high-efficiency farming.

[0003] Existing compound acidifiers suffer from the following key problems: First, they have extremely poor targeting. Organic acids are released prematurely in the highly acidic environment of the stomach, and the active ingredients are consumed before reaching the intestines, resulting in insufficient antibacterial concentration in the lower intestinal tract and an inability to achieve precise regulation. Second, they lack stability. Small-molecule organic acids are volatile and highly corrosive, resulting in high loss rates during the high-temperature and high-pressure processes of feed pelleting. Their efficacy declines significantly during long-term storage, and they also corrode processing equipment. Third, they have limited functionality, relying solely on the acidic environment to inhibit pathogens and lacking multiple synergistic mechanisms such as promoting the proliferation of beneficial bacteria and repairing the intestinal barrier, thus limiting their effectiveness in the complex intestinal microecology. These shortcomings severely restrict the actual effectiveness of acidifiers and have become a long-standing technical pain point in the industry. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a compound acidifier for increasing feed intake in lactating sows and its preparation method. The core innovation lies in constructing a microcapsule system with cystine-crosslinked γ-polyglutamic acid and arginine-grafted chitosan as the wall material. The breakthrough is achieved through a triple response mechanism: pH response ensures that the product is not released in the stomach and swells in the intestine; disulfide bond reduction response enables precise release in a specific intestinal environment; and arginine-chitosan exerts a synergistic effect of mucosal adhesion and antibacterial activity.

[0005] The technical solution for achieving the objective of this invention is as follows:

[0006] A compound acidifier for increasing feed intake in lactating sows includes a wall material and a core material; the wall material includes cystine-γ-polyglutamic acid and arginine-chitosan; the mass ratio of cystine-γ-polyglutamic acid to arginine-chitosan in the wall material is 1:(0.8~1.2); the core material includes organic acids, organic acid salts and fermentation broth.

[0007] The fermentation broth includes a compound microbial agent and a fermentation substrate; the compound microbial agent includes Bacillus natto and yeast; the yeast includes one or two of Saccharomyces cerevisiae and Candida utilis; the fermentation substrate, by weight, includes 20-30 parts soybean meal, 1-5 parts wheat bran, 0.5-2 parts magnesium sulfate, 2-5 parts dipotassium hydrogen phosphate, 2-5 parts yeast extract, and 60-70 parts water.

[0008] The method for preparing the fermentation broth includes the following steps:

[0009] Weigh the fermentation substrate according to the ratio, mix them evenly, and sterilize them for later use. Mix Bacillus natto liquid and yeast liquid to make a compound bacterial agent and inoculate it into the fermentation substrate for aerobic fermentation. After fermentation, heat the fermentation liquid to terminate the activity of all microorganisms and enzymes, centrifuge and collect the supernatant, and then filter it aseptically to obtain the fermentation liquid.

[0010] The Bacillus natto liquid and yeast liquid are mixed at a bacterial concentration ratio of (1~3):1; the weight ratio of the compound bacterial agent to the fermentation substrate is (1~8):100.

[0011] A method for preparing a compound acidifier to increase feed intake in lactating sows includes the following steps:

[0012] S1. Preparation of composite wall material solution and core material solution: Cystine-γ-polyglutamic acid and arginine-chitosan are dissolved and prepared into solutions respectively; the two solutions are mixed to obtain composite wall material solution; organic acid, organic acid salt and fermentation broth are weighed, the fermentation broth and organic acid salt are mixed first, and then the fermentation broth and organic acid salt are slowly mixed evenly to obtain core material solution;

[0013] S2. Multiphase emulsification and curing: The core material solution is added dropwise to corn oil containing surfactant. Under ice bath conditions, it is homogenized at high speed to form a primary emulsion. Then, it is added dropwise to the composite wall material solution for continuous emulsification. A crosslinking agent is slowly added dropwise to the secondary emulsion while stirring.

[0014] S3. Purification and collection: Centrifuge and wash the mixture obtained in step S2, disperse the obtained solid in a freeze-drying protectant, freeze-dry and sieve to obtain a composite acidifier.

[0015] The mass ratio of the organic acid, organic acid salt and fermentation broth is (2~4):1:1.

[0016] The crosslinking agent is selected from one or two of sodium tripolyphosphate and sodium citrate; the freeze-drying protectant is selected from one or more of trehalose, mannitol, and maltodextrin.

[0017] Another object of the present invention is to provide the application of the compound acidifier for increasing feed intake in lactating sows prepared by the above-mentioned method for preparing compound acidifier for increasing feed intake in lactating sows.

[0018] A method for increasing feed intake in lactating sows includes the following steps: mixing a compound acidifier and a basal diet evenly to obtain a compound acidifier-fed diet that increases feed intake in lactating sows, and then feeding the compound acidifier-fed diet to the lactating sows.

[0019] The mass ratio of the compound acidifier to the basal diet is (0.5~2):100.

[0020] Beneficial effects

[0021] This invention provides a composite acidifier based on hydrogel microcapsules for improving feed intake in lactating sows and its preparation method. The composite acidifier of this invention utilizes cystine-crosslinked γ-polyglutamic acid and arginine-grafted chitosan as wall materials, encapsulating organic acids to form microcapsules with intestinal-targeted release function. This effectively improves the utilization efficiency of the acidifier and the feed intake of lactating sows, and includes the following beneficial effects:

[0022] 1. Triple intelligent release mechanism for precise intestinal targeting: The microcapsule wall material prepared by this invention has triple intelligent release characteristics of pH response, reduction response and enzyme response. In the acidic environment of the stomach, the microcapsule structure is stable. When it enters the neutral environment of the middle and lower part of the intestine and the glutathione concentration increases, the disulfide bond breaks, the wall material is dissolved and degraded, and the burst release effect of organic acid is realized, which precisely delivers the acidification effect to the main harmful bacteria enrichment area of ​​the intestine, avoiding ineffective consumption in the stomach.

[0023] 2. Excellent encapsulation efficiency and sustained-release properties: Based on the dense polyelectrolyte complex network formed by cystine-γ-polyglutamic acid and arginine-chitosan, it has a high encapsulation efficiency for organic acids, which can effectively slow down the diffusion rate of organic acids in storage and gastric juice, and achieve programmed release through controlled degradation in the intestine, so that the unit dose of acidifier can exert maximum efficacy, and is expected to improve the utilization rate of ordinary acidifiers.

[0024] 3. Synergistic effect of antibacterial and gut microbiota regulation to improve health: This solution not only provides the slow-release acidification effect of organic acids, but also has a synergistic effect with the broad-spectrum antibacterial activity of arginine-chitosan, which multiplies the inhibitory effect on pathogenic bacteria such as Escherichia coli and Salmonella; at the same time, components such as γ-polyglutamic acid can act as prebiotics to promote the proliferation of beneficial bacteria such as lactic acid bacteria, optimize the balance of intestinal microecology, and reduce the intestinal immune burden.

[0025] 4. Strengthening the mucosal barrier and promoting nutrient absorption: On the one hand, arginine-modified chitosan has excellent mucosal adhesion, which can prolong the action time and promote the absorption of nutrients; on the other hand, a healthy intestinal environment can improve the nutrient digestion and absorption rate, thereby stimulating the sow's appetite to meet the needs of lactation and body condition recovery.

[0026] 5. Naturally biodegradable, ensuring product safety: The wall materials and modifiers selected in this invention are all of natural origin, with good biocompatibility and no toxic side effects. The metabolic products in the body are water and carbon dioxide, with no residual risk, which meets the requirements of green and healthy breeding.

[0027] 6. Introducing fermented flavor substances can improve the palatability and appetite of compound feed for sows, thereby improving the digestion and absorption of feed, increasing feed intake, promoting lactation, and improving the survival rate of piglets.

[0028] In summary, this invention constructs intelligent targeted hydrogel microcapsules using natural composite wall materials, integrating multiple core advantages to precisely address the postpartum intestinal health and feed intake pain points of lactating sows. It not only enhances the efficacy of acidifiers and nutrient absorption but also optimizes the intestinal microecology, ensures breeding safety, and is suitable for large-scale production. Attached Figure Description

[0029] Figure 1 Infrared spectra of chitosan and arginine-chitosan.

[0030] Figure 2 Infrared spectra of γ-polyglutamic acid and cystine-γ-polyglutamic acid. Detailed Implementation

[0031] 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.

[0032] Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0033] The raw materials and equipment used in the examples and comparative examples are described below, where eq represents molar equivalent:

[0034] Chitosan: molecular weight 50 kDa, degree of deacetylation 85%, purchased from Shanghai E. En Chemical Technology Co., Ltd.

[0035] γ-Polyglutamic acid: molecular weight 50,000~100,000, purchased from Shanghai E. En Chemical Technology Co., Ltd.

[0036] Yeast: Brewer's yeast, commercially available.

[0037] Arginine-chitosan: Homemade, preparation method as follows:

[0038] A 0.1 mol / L MES buffer solution with pH 6 was prepared as the solvent. 0.3 eq of arginine was added, followed by the addition of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (1.2 times the molar amount of arginine) and N-hydroxysuccinimide (1.2 times the molar amount of arginine) under stirring. The carboxyl groups were activated for half an hour in the dark. In another container, 1.0 eq of chitosan (based on the molar amount of amino groups) was dissolved in a 1% acetic acid aqueous solution to prepare a 1% homogeneous solution. The activated arginine solution was slowly added dropwise to the chitosan solution under stirring. The pH was adjusted and maintained at 5.5 with 0.1 mol / L sodium hydroxide solution. The reaction was carried out at room temperature in the dark for 6 h. After the reaction was completed, glycine was added and stirred for 15 min. The reaction solution was then dialyzed against deionized water for 48 h using a dialysis bag with a molecular weight cutoff of 10 kDa. The deionized water was replaced every 12 h. After dialysis, the solution was freeze-dried under vacuum to obtain arginine-chitosan.

[0039] Cystine-γ-polyglutamic acid: prepared in-house, the preparation method is as follows:

[0040] 0.1 eq of cystine was dissolved in 0.1 mol / L HEPES buffer at pH 8. 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide (1.2 times the molar amount of cystine) were added, and the mixture was reacted at 25°C for 30 min. Subsequently, 1.1 eq of glycine ethyl ester hydrochloride was added to the reaction system, and the pH was adjusted to 8 with 0.1 mol / L sodium hydroxide solution. The reaction was continued for another 30 min, converting the activated carboxyl group to a "cystine-glycine ethyl ester" dipeptide structure via aminolysis. The reaction solution was transferred to a dialysis bag with a molecular weight cutoff of 1 kDa and dialyzed against deionized water for 6 h to remove small molecule byproducts, yielding a purified blocked cystine solution. This achieved carboxyl group blocking while ensuring the amino group of cystine remained free. In another container, 1.0 eq of γ-polyglutamic acid (based on the molar number of carboxyl groups) was dissolved in 0.1 mol / L pH 8 buffer. 6.0 MES buffer was used to activate γ-polyglutamic acid solution at 25 °C for 30 min with 1.0 eq 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 1.0 eq N-hydroxysuccinimide. Finally, the blocked cystine solution was added dropwise to the activated γ-polyglutamic acid solution. The activated γ-polyglutamic acid solution was cooled to 0 °C in an ice bath. Under vigorous stirring, the blocked cystine solution was slowly added dropwise for more than 1 h. After the addition was completed, the reaction was continued at 0 °C for 2 h, and then transferred to room temperature for 4 h. Glycine was added to quench the reaction. The reaction solution was purified by dialysis and freeze-dried to obtain cystine-γ-polyglutamic acid.

[0041] Fermentation broth 1: Self-made, preparation method as follows:

[0042] Weigh out 25 parts soybean meal, 3 parts wheat bran, 1.5 parts magnesium sulfate, 3 parts dipotassium hydrogen phosphate, and 3.5 parts yeast extract according to the specified ratio. Mix them thoroughly with 65 parts water. Adjust the pH of the mixture to 7.5 with 1 mol / L sodium hydroxide solution. Autoclave at 121℃ for 25 min and cool to below 35℃ for later use. Mix the revived and expanded Bacillus natto culture with the activated yeast culture at a live cell ratio of 2:1, ensuring that the total live cell count after mixing is ≥1.0 × 10⁻⁶. 8 A compound bacterial agent was prepared at CFU / mL. Under aseptic conditions, the compound bacterial agent was added to the sterilized fermentation substrate at 5% of the total mass of the fermentation substrate and stirred evenly. Aerobic fermentation was carried out at 35°C for 50 h, during which time stirring at 200 rpm and aeration at 0.8 vvm were maintained to maintain dissolved oxygen. When the pH value remained stable for at least 2 h, the fermentation broth was heated to 80°C and maintained for 25 min to terminate all microbial and enzyme activities. Then, the fermentation broth was centrifuged at 8000 × g for 15 min at 4°C, and the supernatant was collected and aseptically filtered through a 0.45 μm filter membrane to obtain fermentation broth 1.

[0043] Fermentation broth 2: Self-made. The preparation method is the same as that of fermentation broth 1, except that the ratio of fermentation substrate is modified to 20 parts soybean meal, 1 part wheat bran, 0.5 parts magnesium sulfate, 2 parts dipotassium hydrogen phosphate, 2 parts yeast extract, and 60 parts water. All other conditions remain unchanged to obtain fermentation broth 2.

[0044] Fermentation liquid 3: Self-made. The preparation method is the same as that of fermentation liquid 1, except that the ratio of fermentation substrate is modified to 30 parts soybean meal, 5 parts wheat bran, 2 parts magnesium sulfate, 5 parts dipotassium hydrogen phosphate, 5 parts yeast extract, and 70 parts water. All other conditions remain unchanged to obtain fermentation liquid 3.

[0045] Simulated gastric fluid: self-made, preparation method as follows:

[0046] Take 16.4 mL of 0.1 mol / L hydrochloric acid solution, add 800 mL of distilled water and 10 g of pepsin, and dilute to 1000 mL with water for later use.

[0047] Simulated artificial intestinal fluid: self-made, preparation method is as follows:

[0048] Take 6.8g of potassium dihydrogen phosphate, add 500mL of distilled water and stir until completely dissolved. Adjust the pH of the solution to 6.8 with 0.4% sodium hydroxide solution and sterilize at 121℃ for 20 min. Take 10g of pancreatic juice and dissolve it in sterile water. Mix the two solutions evenly and dilute with sterile water to 1000mL.

[0049] The basal diet was formulated according to the NRC (1998) pig feeding standards. The composition and nutrient levels of the basal diet are shown in Table 1.

[0050] Table 1. Composition and nutrient levels of basal diet (air-dried basal diet)

[0051]

[0052] The premix provides 2000 IU of vitamin A, 200 IU of vitamin D, 45 IU of vitamin E, 0.5 mg of vitamin K, 1 mg of vitamin B1, 3.85 mg of vitamin B6, 15 mg of vitamin B12, 12 mg of pantothenic acid, 10.25 mg of niacin, 1.35 mg of folic acid, 0.21 mg of biotin, 20 mg of manganese, 100 mg of iron, 20 mg of copper, 0.14 mg of iodine, and 0.15 mg of selenium per kilogram of feed.

[0053] Example

[0054] Example 1

[0055] Composite acidifier 1: Self-made, preparation method is as follows:

[0056] S1. Preparation of Composite Wall Material Solution 1 and Core Material Solution 1: Weigh 5 g of cystine-γ-polyglutamic acid and prepare a 1% homogeneous solution with 0.1 mol / L PBS buffer at pH 6.5, stirring until fully dissolved; weigh 5 g of arginine-chitosan and dissolve it in 1% acetic acid aqueous solution to prepare a 1% homogeneous solution, stirring until fully dissolved, and adjust the pH to 5.5 with 0.1 mol / L sodium hydroxide solution; mix the above two solutions at a volume ratio of 1:1 to obtain Composite Wall Material Solution 1 with a total polymer concentration of 1%, adjust the pH to 5.5, and store in the dark; weigh formic acid, ammonium formate, and fermentation broth 1 at a mass ratio of 3:1:1, and in an ice bath and fume hood, first mix the fermentation broth with ammonium formate, then slowly add formic acid while stirring, and mix evenly to obtain Core Material Solution 1;

[0057] S2. Multiphase emulsification and curing: The core material solution 1 is slowly added dropwise to corn oil containing 3% Span-80. Under ice bath conditions, it is homogenized at 13000 rpm for 5 min to form a primary emulsion. The above primary emulsion is slowly added dropwise to the composite wall material solution 1 while stirring at 800 rpm. After the addition is complete, the stirring speed is increased to 1500 rpm and emulsification is continued for 10 min. Then, while stirring at 800 rpm, an equal volume of 0.5% sodium tripolyphosphate aqueous solution is slowly added dropwise to the composite emulsion for no less than 20 min. Then, stirring is continued for crosslinking for 2 h.

[0058] S3. Purification and Collection: The reaction solution was dispensed and centrifuged at 1500 rpm for 3 minutes in a fume hood. The supernatant was discarded, and the microspheres were washed twice with petroleum ether to remove residual corn oil, then once with anhydrous ethanol, and then twice with deionized water. The mixture was centrifuged twice, and then washed twice with deionized water. The washed microspheres were redispersed in a 5% trehalose aqueous solution at twice the volume of the microspheres. The suspension was dispensed into lyophilized bottles and pre-frozen at -80℃ for 6 h. Then, the microspheres were dried in a freeze dryer at -50℃ and a vacuum degree <10 Pa for 24 h until they were completely dry. The dried powder was passed through a 200-mesh standard sieve, and the sieve residue was collected to obtain composite acidifier 1. It was stored in a dark, sealed, and moisture-proof environment.

[0059] Example 2

[0060] Composite acidifier 2: self-made. The preparation method is the same as that of composite acidifier 1, except that fermentation broth 1 in step S1 is replaced with fermentation broth 2, while other conditions remain unchanged, thus obtaining composite acidifier 2.

[0061] Example 3

[0062] Composite acidifier 3: self-made. The preparation method is the same as that of composite acidifier 1, except that fermentation liquid 1 in step S1 is replaced with fermentation liquid 3, while other conditions remain unchanged, to obtain composite acidifier 3.

[0063] Example 4

[0064] Composite acidifier 4: self-made. The preparation method is the same as that of composite acidifier 1, except that the mass ratio of formic acid, ammonium formate and fermentation broth 1 in step S1 is replaced with 2:1:1, while other conditions remain unchanged, thus obtaining composite acidifier 4.

[0065] Example 5

[0066] Composite acidifier 5: self-made. The preparation method is the same as that of composite acidifier 1, except that the mass ratio of formic acid, ammonium formate and fermentation broth 1 in step S1 is replaced with 4:1:1, while other conditions remain unchanged, thus obtaining composite acidifier 5.

[0067] Comparative Example 1

[0068] Composite acidifier 6: self-made. The preparation method is the same as that of composite acidifier 1, except that cystine-γ-polyglutamic acid is replaced with γ-polyglutamic acid, while other conditions remain unchanged, to obtain composite acidifier 6.

[0069] Comparative Example 2

[0070] Composite acidifier 7: self-made. The preparation method is the same as that of composite acidifier 1, except that arginine-chitosan is replaced with chitosan, while other conditions remain unchanged, to obtain composite acidifier 7.

[0071] Comparative Example 3

[0072] Compound acidifier 8: Commercially available, purchased from Weifang Zhongtian Feed Technology Co., Ltd.

[0073] Application examples

[0074] Application Example 1

[0075] Compound acidifier feed 1: self-made, the preparation method is to mix compound acidifier 1 with the basic feed at a weight ratio of 1:100 to make compound acidifier feed 1.

[0076] Application Example 2

[0077] Compound acidifier diet 2: self-made. The preparation method is the same as that of compound acidifier diet 1. The difference is that compound acidifier 1 is mixed with the basic diet at a weight ratio of 1:200, while other conditions remain unchanged, to obtain compound acidifier diet 2.

[0078] Application Example 3

[0079] Compound acidifier diet 3: self-made. The preparation method is the same as that of compound acidifier diet 1. The difference is that compound acidifier 1 is mixed with the basic diet at a weight ratio of 1:50, while other conditions remain unchanged, to obtain compound acidifier diet 3.

[0080] Application Example 4

[0081] Compound acidifier diet 4: self-made. The preparation method is the same as that of compound acidifier diet 1, except that compound acidifier 1 is replaced with compound acidifier 2, while other conditions remain unchanged, to obtain compound acidifier diet 4.

[0082] Application Example 5

[0083] Compound acidifier diet 5: self-made. The preparation method is the same as that of compound acidifier diet 1, except that compound acidifier 1 is replaced with compound acidifier 3, while other conditions remain unchanged, to obtain compound acidifier diet 5.

[0084] Application Example 6

[0085] Compound acidifier diet 6: self-made. The preparation method is the same as that of compound acidifier diet 1, except that compound acidifier 1 is replaced with compound acidifier 4, while other conditions remain unchanged, to obtain compound acidifier diet 6.

[0086] Application Example 7

[0087] Compound acidifier diet 7: self-made. The preparation method is the same as that of compound acidifier diet 1, except that compound acidifier 1 is replaced with compound acidifier 5, while other conditions remain unchanged, to obtain compound acidifier diet 7.

[0088] Comparative Application Example 1

[0089] Compound acidifier diet 8: self-made. The preparation method is the same as that of compound acidifier diet 1, except that compound acidifier 1 is replaced with compound acidifier 6, while other conditions remain unchanged, to obtain compound acidifier diet 8.

[0090] Comparative Application Example 2

[0091] Compound acidifier diet 9: self-made. The preparation method is the same as that of compound acidifier diet 1, except that compound acidifier 1 is replaced with compound acidifier 7, while other conditions remain unchanged, to obtain compound acidifier diet 9.

[0092] Comparative Application Example 3

[0093] Compound acidifier diet 10: self-made. The preparation method is the same as that of compound acidifier diet 1, except that compound acidifier 1 is replaced with compound acidifier 8, and all other conditions remain unchanged, to obtain compound acidifier diet 10.

[0094] The following are the test methods for performance parameters involved in this invention:

[0095] 1. Fourier transform infrared spectroscopy (FT-IR): Tested using a Thermo Nicolet IS10 Fourier transform infrared spectrometer; Figure 1 This is the infrared spectrum of chitosan and arginine-chitosan; arginine-chitosan is at 1650 cm⁻¹. -1 and 1590 cm -1 The presence of characteristic peaks of amide I and amide II bands, and the newly generated absorption peaks masking the characteristic amino peaks of the original chitosan, indicates the successful preparation of arginine-chitosan; Figure 2 The infrared spectra of γ-polyglutamic acid and cystine-γ-polyglutamic acid are shown. The significant enhancement of the characteristic peaks of amide I and amide II indicates the successful synthesis of the -CONH- crosslinking bond, proving the successful synthesis of cystine-γ-polyglutamic acid.

[0096] 2. Stability Test of Composite Acidifier: The composite acidifiers of Examples 1-5 and Comparative Examples 1-2 were tested using simulated gastric and intestinal fluids. The test method was carried out according to the General Chapter 0931, Method II (Paddle Method) of the 2020 edition of the Chinese Pharmacopoeia. 0.1 g of each composite acidifier from Examples 1-5 and Comparative Examples 1-2 was placed in a dissolution vessel containing 200 mL of simulated gastric fluid at 37°C and continuously shaken at 100 rpm for 2 h. Immediately afterwards, 1 mL of the solution was taken and filtered through a 0.22 μm organic filter membrane. After removing hydrochloric acid by nitrogen blowing, the filtrate was reconstituted with methanol. The content of formic acid, a representative core material, was determined by high-performance liquid chromatography (HPLC). The gastric fluid retention rate was calculated using the formula: retention rate (%) = (Ct / C0) × 100, where Ct is the concentration measured after 2 h of gastric fluid treatment, and C0 is the original content of formic acid. Subsequently, all the composite acidifiers treated with gastric fluid were transferred to a 200 mL immersion vessel. The sample was placed in an artificial intestinal fluid at a constant temperature of 37℃ and oscillated at 100 rpm. 2 mL samples were automatically taken at time points of 5, 15, 30, 60, and 120 min, and an equal volume of fresh artificial intestinal fluid was added simultaneously. After filtration through a 0.22 μm filter membrane, the formic acid content was directly analyzed by high-performance liquid chromatography. The cumulative release rate (%) was calculated using the formula: (cumulative release amount / total feed amount) × 100. The results are shown in Table 2 below.

[0097] 3. Growth performance index test of lactating sows: This test was conducted at a breeding farm. A total of 50 healthy sows with 3-5 parities and close expected farrowing dates were selected and randomly divided into 10 groups. The sows in each group were transferred to the farrowing house three days before their expected farrowing date. The farrowing house was a raised bed with a slatted floor. The pen was well ventilated and kept clean and dry. Conventional feeding and management were adopted. The day of farrowing was recorded as day 0 of the experiment. No feed was given. After farrowing, the sows were fed the corresponding feed according to their groups. For the first 5 days after farrowing, restricted feeding was adopted. On the first day, the sows were fed 1.9 kg / day, and the amount was increased by 0.5 kg / day thereafter. On the 6th day, free access to feed and water began.

[0098] (1) Production performance of lactating sows: The birth weight of piglets was weighed immediately after farrowing and the average birth weight of piglets was calculated. On the morning of the 21st day of the experiment, the weight of each litter of piglets was weighed at 08:00 and the average weaning weight and average daily weight gain of piglets on the 21st day were calculated. The experimental results are shown in Table 3 below.

[0099] (2) Feed intake of lactating sows: The weight change of each experimental sow was recorded and recorded every day. The average daily feed intake of each sow was calculated. Average daily feed intake (kg) = total feed intake of the group / (number of experimental days × number of experimental pigs in the group). The experimental results are shown in Table 3 below.

[0100] Table 2. Stability test of composite acidifiers in Examples 1-5 and Comparative Examples 1-2

[0101]

[0102] Table 3. Experimental results on growth performance of lactating sows

[0103]

[0104] Table 2 shows that the retention rates of the examples in simulated gastric fluid were all higher than those of the comparative examples, indicating that the synergistic effect of the wall materials cystine-γ-polyglutamic acid and arginine-chitosan can effectively resist gastric acid, achieving low leakage in the stomach, which is consistent with the pH response mechanism. In simulated intestinal fluid, the release rates of Examples 1-3 were higher, indicating that the wall materials can dissolve rapidly in the neutral environment of the intestine, which is consistent with the reduction response mechanism. Comparative Examples 1 and 2 show that the lack of disulfide crosslinking or the lack of arginine modification will lead to poor stability in gastric fluid and weakened responsiveness in intestinal fluid.

[0105] Table 3 shows that the growth performance test results of sows in Application Examples 1-7 were all better than those in Comparative Examples 1-3, proving that the composite acidifier of the present invention effectively improved the utilization efficiency of the acidifier through an intelligent targeted release mechanism and improved the feed intake of lactating sows. Meanwhile, Application Examples 1 and 3 showed the highest average weaning weight and average daily weight gain of piglets at 21 days, with similar values, indicating that the increased feed intake of lactating sows translated into improved milk production and milk quality, promoting piglet growth. Furthermore, there was no significant difference in the average birth weight of piglets among the groups, eliminating the interference of initial conditions and making the experimental results more comparable.

[0106] The test results of Comparative Application Examples 1 and 2 were worse than those of Application Example 1, demonstrating that cystine-γ-polyglutamic acid and arginine-chitosan, as composite wall materials, are two indispensable core elements for achieving the beneficial effects of this invention; the absence of either one would lead to a decline in product performance. Meanwhile, the results of Comparative Application Examples 1-2 were superior to those of Comparative Application Example 3, proving that the intelligent microcapsule technology used in this invention improves the performance of traditional acidifiers, solving problems such as poor targeting, insufficient stability, single function, loss of active ingredients in the stomach, and inability to efficiently act on the intestines.

[0107] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A compound acidifier for increasing feed intake in lactating sows, characterized in that, The product includes a wall material and a core material; the wall material comprises cystine-γ-polyglutamic acid and arginine-chitosan; the mass ratio of cystine-γ-polyglutamic acid to arginine-chitosan in the wall material is 1:(0.8~1.2); the core material comprises organic acids, organic acid salts, and fermentation broth; the preparation method of the cystine-γ-polyglutamic acid includes the following steps: dissolving cystine in HEPES buffer, adding 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide, reacting, then adding glycine ethyl ester hydrochloride, adjusting the pH and continuing the reaction, dialyzing to obtain a purified carboxyl-blocked cystine solution; in another container, dissolving γ-polyglutamic acid in MES buffer, using 1-ethyl-(3-dimethylaminopropyl)carbodiimide... The γ-polyglutamic acid solution was activated by activating carbodiimide hydrochloride and N-hydroxysuccinimide, and then cooled in an ice bath. Under vigorous stirring, a carboxyl-blocked cystine solution was slowly added dropwise to the activated γ-polyglutamic acid solution to carry out the reaction. Glycine was added to quench the reaction. The reaction solution was purified by dialysis and freeze-dried to obtain cystine-γ-polyglutamic acid. The fermentation broth includes a compound microbial agent and a fermentation substrate. The compound microbial agent includes Bacillus natto and yeast. The yeast includes one or both of Saccharomyces cerevisiae and Candida utilis. The fermentation substrate, by weight, includes 20-30 parts soybean meal, 1-5 parts wheat bran, 0.5-2 parts magnesium sulfate, 2-5 parts dipotassium hydrogen phosphate, 2-5 parts yeast extract, and 60-70 parts water.

2. The compound acidifier for increasing feed intake in lactating sows as described in claim 1, characterized in that, The organic acid includes one or more of formic acid, fumaric acid, lactic acid, malic acid, and benzoic acid; the organic acid salt includes one or more of ammonium formate, calcium formate, and calcium propionate.

3. The compound acidifier for increasing feed intake in lactating sows as described in claim 1, characterized in that, The method for preparing the fermentation broth includes the following steps: Weigh the fermentation substrate according to the ratio, mix them evenly, and sterilize them for later use. Mix Bacillus natto liquid and yeast liquid to make a compound bacterial agent and inoculate it into the fermentation substrate for aerobic fermentation. After fermentation, heat the fermentation liquid to terminate the activity of all microorganisms and enzymes, centrifuge and collect the supernatant, and then filter it aseptically to obtain the fermentation liquid.

4. The compound acidifier for increasing feed intake in lactating sows as described in claim 3, characterized in that, The Bacillus natto liquid and yeast liquid are mixed at a concentration ratio of (1~3):1; the weight ratio of the compound bacterial agent to the fermentation substrate is (1~8):100; the aerobic fermentation method is to stir and aerate at 30~37℃ for 48~72 h.

5. A method for preparing a compound acidifier for increasing feed intake in lactating sows as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Preparation of composite wall material solution and core material solution: Cystine-γ-polyglutamic acid and arginine-chitosan are dissolved and prepared into solutions respectively; the two solutions are mixed to obtain composite wall material solution; organic acid, organic acid salt and fermentation broth are weighed, the fermentation broth and organic acid salt are mixed first, and then the fermentation broth and organic acid salt are slowly mixed evenly to obtain core material solution; S2. Multiphase emulsification and curing: The core material solution is added dropwise to corn oil containing surfactant. Under ice bath conditions, it is homogenized at high speed to form a primary emulsion. Then, it is added dropwise to the composite wall material solution for continuous emulsification. A crosslinking agent is slowly added dropwise to the secondary emulsion while stirring. S3. Purification and collection: Centrifuge and wash the mixture obtained in step S2, disperse the obtained solid in a freeze-drying protectant, freeze-dry and sieve to obtain a composite acidifier.

6. The method for preparing a compound acidifier to increase feed intake in lactating sows as described in claim 5, characterized in that, The mass ratio of the organic acid, organic acid salt and fermentation broth is (2~4):1:

1.

7. The method for preparing a compound acidifier to increase feed intake in lactating sows as described in claim 5, characterized in that, The crosslinking agent is selected from one or two of sodium tripolyphosphate and sodium citrate; the freeze-drying protectant is selected from one or more of trehalose, mannitol, and maltodextrin.

8. The application of the compound acidifier for increasing feed intake in lactating sows prepared by the method of preparing the compound acidifier for increasing feed intake in lactating sows according to any one of claims 1 to 4 or any one of claims 5 to 7 in increasing feed intake in lactating sows.

9. A method for increasing feed intake in lactating sows, characterized in that, Includes the following steps: The compound acidifier for increasing feed intake in lactating sows prepared by any one of the methods described in claims 1 to 4 or any one of the methods described in claims 5 to 7 is mixed evenly with the basal diet to obtain a compound acidifier-fed diet for increasing feed intake in lactating sows. The compound acidifier-fed diet is then fed to lactating sows.

10. The method for increasing feed intake in lactating sows as described in claim 9, characterized in that, The mass ratio of the compound acidifier to the basal diet is (0.5~2):100.

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