A feed additive for reducing heavy metal deposition in pigs and a method for preparing the same

Abstract

This invention discloses a feed additive for reducing heavy metal deposition in pigs and its preparation method, relating to the field of feed technology. The feed additive is composed of the following components: 10-20 parts corn starch, 10-20 parts highland barley starch, 5-15 parts compound microorganisms, 4-12 parts whey powder, 4-8 parts microalgae powder, 2-6 parts fish meal, 4-12 parts active additives, and 0.5-5 parts vitamin C. The active additives are prepared by mixing traditional Chinese medicine extracts and modified activated carbon. Through multiple synergistic effects, the feed additive of this invention can significantly reduce the accumulation of heavy metals in target organs of pigs, while avoiding the loss of feed nutrients. It can simultaneously improve the stress resistance and growth efficiency of pigs, reducing meat safety risks from the source and providing key technical support for the green and healthy transformation of animal husbandry.

Description

Technical Field

[0001] This invention relates to the field of feed technology, specifically to a feed additive for reducing heavy metal deposition in pigs and its preparation method. Background Technology

[0002] With increasing cross-contamination between industry and agriculture, heavy metals such as lead (Pb), cadmium (Cd), arsenic (As), and chromium (Cr) migrate into the agricultural chain through soil, water, and air, with livestock farming being one of the main affected sectors. Pigs, as the core economic animal in globally large-scale farming, face particularly high risks of heavy metal exposure. Studies show that pigs have a weak ability to metabolize heavy metals (e.g., cadmium has a half-life of over 10 years in the liver), and common feed ingredients (corn, soybean meal, fishmeal, etc.) may become major pathways for heavy metal input due to contamination during planting or processing. For example, after pigs ingest lead-contaminated corn (content can exceed 5 mg / kg), about 40% accumulates in their bones and kidneys, with some returning to humans through the food chain. This problem not only leads to decreased growth performance in pig herds (e.g., cadmium exposure causes a feed conversion ratio increase of over 15%), but also threatens food safety (lead residues in pig liver can exceed the standard by 8-10 times).

[0003] CN111838415A discloses a green, antibiotic-free, low-heavy-metal emission premix feed additive for piglets and its preparation method. It is composed of artemisia annua powder, peony bark, medicated leaven, roasted hawthorn, roasted malt, purslane, black tiger leaf, tryptophan, phenylalanine, tyrosine, high-purity nano zinc oxide, peony seed oil, and a carrier. The carrier is composed of any one of montmorillonite and maifanite, or a mixture of the two in any proportion.

[0004] Current heavy metal emission reduction technologies mainly rely on single-function materials (such as adsorbents or chelating agents), which have the following shortcomings: Poor targeting: They cannot distinguish between different types of heavy metals (such as cadmium, lead, and arsenic), and often compete with nutrients such as calcium and zinc for adsorption, resulting in waste or nutrient loss; Insufficient stability: The materials are easily degraded in animal stomach acid, leading to secondary release of heavy metals; Single function: They can only adsorb or partially detoxify in the short term, making it difficult to completely block the absorption and deposition of heavy metals throughout the entire process.

[0005] This invention provides a compound feed additive that selectively captures heavy metals through modification while avoiding interference with nutrients. The carrier material gradually decomposes in the intestine, ensuring the stable release and continuous effect of the active ingredients. Combining the triple functions of adsorption, detoxification, and excretion promotion, it inhibits heavy metal deposition throughout the entire process from feed intake to metabolic excretion, balancing high efficiency and safety, and can significantly reduce heavy metal residues in pigs. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a feed additive for reducing heavy metal deposition in pigs and its preparation method. The feed additive, through multiple synergistic effects, can significantly reduce the accumulation of heavy metals in target organs of pigs, while avoiding the loss of feed nutrients. It can simultaneously improve the stress resistance and growth efficiency of pigs, reduce meat safety risks from the source, and provide key technical support for the green and healthy transformation of animal husbandry.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A feed additive for reducing heavy metal deposition in pigs, comprising, by weight, the following components: 10-20 parts corn starch, 10-20 parts highland barley starch, 5-15 parts compound microorganisms, 4-12 parts whey powder, 4-8 parts microalgae powder, 2-6 parts fish meal, 4-12 parts active additive, and 0.5-5 parts vitamin C; the preparation method of the active additive includes the following steps: mixing, stirring, sieving, and vacuum drying traditional Chinese medicine extracts and modified activated carbon to obtain the active additive.

[0009] Preferably, the method for preparing the modified activated carbon includes the following steps:

[0010] (1) Disperse activated carbon in an aqueous acetic acid solution, add succinic anhydride, heat and stir under a nitrogen atmosphere, filter, wash, distill and dry the product to obtain anhydride-treated activated carbon;

[0011] Anhydride modification: After ring opening, one carboxyl group forms an ester bond (CO-CO-R) with the hydroxyl group of activated carbon, while the other carboxyl group remains free on the surface. Heating enhances ester bond formation, while nitrogen protection inhibits carboxyl group oxidation. The resulting byproducts and unreacted succinic anhydride are removed through solvent cycling. The product exhibits a carboxylic acid-functionalized surface, providing active sites for subsequent condensation.

[0012] Preferably, in step (1), the ratio of activated carbon, acetic acid aqueous solution, and succinic anhydride is 10g: 120~180mL: 12~26g; the concentration of acetic acid in the acetic acid aqueous solution is 60~80wt%.

[0013] Preferably, in step (1), the heating and stirring conditions are 80~120℃ and 400~600r / min for 8~14h; the product is washed with acetic acid and deionized water 3~5 times in sequence, unreacted substances are removed by vacuum distillation at 40~60℃, and vacuum dried at 60~80℃ to constant weight.

[0014] (2) Disperse the anhydride activated carbon and chitosan powder into glacial acetic acid buffer, stir and mix evenly, add molecular sieve to the container, react under vacuum, centrifuge and freeze dry the product to obtain grafted activated carbon.

[0015] Chitosan covalent grafting: At high temperature, the carboxylic acid groups (R-COOH) of anhydride-treated activated carbon undergo α-H deprotonation to form an enol activation intermediate (RC=O). - The deacetylated amino group (-NH2) of chitosan remains in a non-protonated state under vacuum conditions, launching a directed nucleophilic attack on the activated carboxyl carbon to generate a β-hydroxylamine intermediate (RC(OH)-NH-chitosan). With the help of molecular sieves, the generated water molecules are continuously adsorbed, which promotes the β-hydroxyl elimination reaction and finally forms a stable amide bond (R-CONH-chitosan).

[0016] Preferably, in step (2), the ratio of the amount of acid-anhydride activated carbon, chitosan, glacial acetic acid buffer, and molecular sieve is 10g: 13~24g: 200~300mL: 10~20g; the pH of the glacial acetic acid buffer is 4.8~5.2, and the molecular sieve is a 3Å molecular sieve.

[0017] Preferably, in step (2), the chitosan has a molecular weight of 10,000 to 200,000 Daltons and a degree of deacetylation of 85% or more.

[0018] Preferably, in step (2), the vacuum reaction conditions are 120~150℃ and ≤0.1kPa for 18~24h.

[0019] (3) The grafted activated carbon is dispersed in a calcium hydroxide solution, ultrasonically dispersed and then cooled, carbon dioxide is introduced, and the product is centrifuged and washed to obtain the modified activated carbon.

[0020] In-situ calcium carbonate recombination: controlled by CO2-induced deposition kinetics; Ca(OH)2 solution provides Ca 2+ CO2 is introduced to produce HCO3 - And gradually release CO3 2- , with Ca 2+ Nucleation occurs through binding. Low temperatures reduce interfacial energy differences, forcing CO32- to bind together. 2- Oriented stacking along a specific crystal axis endows modified activated carbon with a high specific surface area and heavy metal capture sites.

[0021] Preferably, in step (3), the ratio of grafted activated carbon to calcium hydroxide solution is 10g: 300~500mL; the concentration of calcium hydroxide solution is 0.02~0.1mol / L; the temperature is lowered to 15~25℃; carbon dioxide is stopped when the pH drops to 7.0~7.5; and the solution is rinsed with 0.1mol / L sodium hydroxide solution.

[0022] Preferably, the composite microorganism is prepared by mixing Aspergillus niger, Bacillus tarda, Bacillus subtilis, Bacillus amyloliquefaciens, and Lactobacillus plantarum in a weight ratio of 1:1~2:1~2:1~2:1; the ratio of the herbal extract to the modified activated carbon is 10mL:1~3g; the stirring conditions are 50~100r / min for 10~30min; the mixture is passed through a 40~100 mesh sieve, and the vacuum drying temperature is 38~48℃.

[0023] Preferably, the preparation method of the herbal extract includes the following steps: washing, draining, and mixing 10-20 parts of Astragalus membranaceus, 10-20 parts of Magnolia officinalis, 10-20 parts of Paeonia lactiflora, 5-15 parts of Taraxacum mongolicum, 5-10 parts of Crataegus pinnatifida, 5-10 parts of Prunus mume, and 5-10 parts of Glycyrrhiza uralensis, pulverizing them to 40-80 mesh, then mixing them with 150-200 parts of water, ultrasonically treating for 15-30 minutes, boiling and extracting at 60-80℃ for 30-60 minutes, filtering and retaining the filtrate to obtain the herbal extract.

[0024] Preferably, the amount of the feed additive added to the pig feed is 0.5~1.2wt%.

[0025] The present invention also claims a method for preparing the feed additive for reducing heavy metal deposition in pigs, comprising the following steps: mixing corn starch, barley starch, compound microorganisms, whey powder, microalgae powder, fish meal, active additives, and vitamins evenly to obtain the feed additive for reducing heavy metal deposition in pigs.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The feed additive provided by this invention effectively reduces heavy metal residues in pigs through the synergistic effect of multiple components. The soluble fiber in corn flour and barley flour forms a network structure in the intestine, physically adsorbing heavy metals such as lead and cadmium, reducing their absorption into the bloodstream; organic acids such as lactic acid and propionic acid produced by the metabolism of compound microorganisms (such as Bacillus and Lactobacillus) can promote the dissolution of heavy metals and their excretion in feces; microalgae powder contains natural complexing components (such as chlorophyll derivatives), which can directly bind to heavy metals and reduce their biological activity; the milk protein in whey powder can stabilize the binding of metal ions to prevent their diffusion, while vitamin C can reduce oxidative damage caused by heavy metals by scavenging free radicals; the calcium carbonate supported on modified activated carbon can gradually release the active ingredients of traditional Chinese medicine (such as astragaloside and magnolol) through gastric acid reaction, protecting them from strong acid destruction and delaying the release of drug effects.

[0028] 2. The active additives provided by this invention include: Astragalus membranaceus, which enhances the liver's detoxification and metabolic capacity and promotes the conversion of heavy metals into less toxic forms; Dandelion and Magnolia officinalis, which together inhibit intestinal inflammatory responses, protect the intestinal barrier function, reduce anorexia caused by intestinal mucosal damage, and increase feed intake; Paeonia lactiflora, which enhances detoxification efficiency by regulating the balance of intestinal flora; and the organic acid components in Hawthorn and Prunus mume, which accelerate intestinal peristalsis and promote nutrient absorption by promoting digestive enzyme activity. The modified activated carbon's adsorption function for traditional Chinese medicine further optimizes the release of medicinal effects: calcium carbonate gradually decomposes in gastric acid, regulating the porosity of activated carbon to achieve the on-demand release of traditional Chinese medicine components. At the same time, the oligosaccharides produced by chitosan hydrolysis can promote the proliferation of beneficial bacteria, improve the intestinal environment, and synergistically improve feed conversion rate with traditional Chinese medicine.

[0029] 3. This invention provides a modified activated carbon. Anhydride modification directionally enhances the targeted capture of heavy metals. Through density regulation of surface carboxylic acid groups, it significantly improves the chemical affinity for cations such as cadmium and lead, optimizes the selective adsorption of heavy metals, and enhances stability in complex biological environments. Natural chitosan chains form a dense three-dimensional network on the activated carbon surface through a reaction. Its amino functional groups have specific adsorption capabilities for anionic pollutants such as arsenic and chromium, while simultaneously forming a slow-release barrier in the weakly acidic environment of the intestine, preventing the activated carbon itself from dissolving and releasing impurities. This structural design avoids carrier loss and synergistically enhances the heavy metal solidification effect with microalgae fibers. The calcium carbonate mineralization layer controls the release of active ingredients from traditional Chinese medicine through an acid-base response mechanism, ensuring the continuous action of detoxifying components in the intestine, ultimately achieving efficient removal of heavy metals. Detailed Implementation

[0030] 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. Of course, the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0031] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0032] A method for preparing a feed additive to reduce heavy metal deposition in pigs includes the following steps:

[0033] (1) Disperse 10g of activated carbon into 60-80wt% 120-180mL of acetic acid aqueous solution, add 12-26g of succinic anhydride, stir and react for 8-14h at 80-120℃ and 400-600r / min under nitrogen atmosphere, filter the product, wash with acetic acid and deionized water 3-5 times in sequence, remove unreacted substances by vacuum distillation at 40-60℃, and dry under vacuum at 60-80℃ to constant weight to obtain anhydride-modified activated carbon;

[0034] (2) Disperse 10g of anhydride activated carbon and 13-24g of chitosan into 200-300mL of glacial acetic acid buffer (pH 4.8-5.2), stir and mix evenly, add 10-20g of 3Å molecular sieve to the container, and react under vacuum at 120-150℃ and ≤0.1kPa for 18-24h. Centrifuge and freeze dry the product to obtain grafted activated carbon;

[0035] (3) Disperse 10g of grafted activated carbon into 300-500mL of 0.02-0.1mol / L calcium hydroxide solution, disperse by ultrasonication, cool to 15-25℃, introduce carbon dioxide, stop introducing carbon dioxide when pH drops to 7.0-7.5, centrifuge the product, and wash with 0.1mol / L sodium hydroxide solution to obtain the modified activated carbon;

[0036] (4) Mix Aspergillus niger, Bacillus tarda, Bacillus subtilis, Bacillus amyloliquefaciens, and Lactobacillus plantarum in a weight ratio of 1:1~2:1~2:1~2:1 to prepare a compound microorganism; wash, drain, mix, and pulverize 10~20 parts of Astragalus membranaceus, 10~20 parts of Magnolia officinalis, 10~20 parts of Paeonia lactiflora, 5~15 parts of Taraxacum mongolicum, 5~10 parts of Crataegus pinnatifida, 5~10 parts of Prunus mume, and 5~10 parts of Glycyrrhiza uralensis, then mix them and pulverize them to 40~80 mesh. Then mix them with 150~200 parts of water, sonicate for 15~30 min, boil and extract at 60~80℃ for 30~60 min, filter and retain the filtrate to obtain the herbal extract; mix 10 mL of the herbal extract with 1~3 g of modified activated carbon, stir at 50~100 r / min for 10~30 min, pass through a 40~100 mesh sieve, and vacuum dry at 38~48℃ to obtain the active additive;

[0037] (5) Mix 10-20 parts of corn yellow powder, 10-20 parts of barley powder, 5-15 parts of compound microorganisms, 4-12 parts of whey powder, 4-8 parts of microalgae powder, 2-6 parts of fish meal, 4-12 parts of active additives, and 0.5-5 parts of vitamin C evenly to obtain the feed additive used to reduce the deposition of heavy metals in pigs.

[0038] The feed additive is added to pig feed at a rate of 0.5~1.2 wt%.

[0039] The present invention will be further described below through specific embodiments.

[0040] Example 1

[0041] A method for preparing a feed additive to reduce heavy metal deposition in pigs includes the following steps:

[0042] (1) Disperse 10g of activated carbon into 150mL of 75wt% acetic acid aqueous solution, add 20g of succinic anhydride, stir and react for 10h at 110℃ and 500r / min under nitrogen atmosphere, filter the product, wash it with acetic acid and deionized water 4 times in sequence, remove unreacted substances by vacuum distillation at 50℃, and dry it under vacuum at 70℃ to constant weight to obtain anhydride activated carbon;

[0043] (2) Disperse 10g of anhydride activated carbon and 20g of chitosan into 250mL of glacial acetic acid buffer (pH 5.0), stir and mix evenly, add 15g of 3Å molecular sieve to the container, react under vacuum at 140℃ and ≤0.1kPa for 20h, centrifuge and freeze dry the product to obtain grafted activated carbon;

[0044] (3) Disperse 10g of grafted activated carbon into 400mL of 0.1mol / L calcium hydroxide solution, disperse by ultrasonication, cool to 20℃, introduce carbon dioxide, stop introducing carbon dioxide when pH drops to 7.2, centrifuge the product, and wash with 0.1mol / L sodium hydroxide solution to obtain the modified activated carbon;

[0045] (4) Mix Aspergillus niger, Bacillus tarda, Bacillus subtilis, Bacillus amyloliquefaciens and Lactobacillus plantarum in a weight ratio of 1:2:2:2:1 to prepare a compound microorganism; wash and drain 20g of Astragalus membranaceus, 20g of Magnolia officinalis, 20g of Paeonia lactiflora, 10g of Taraxacum mongolicum, 10g of Crataegus pinnatifida, 5g of Prunus mume and 5g of Glycyrrhiza uralensis, mix them, pulverize them to 80 mesh, then mix them with 200g of water, sonicate for 30min, boil and extract at 80℃ for 30min, filter and retain the filtrate to obtain the herbal extract; mix 10mL of the herbal extract with 2g of modified activated carbon, stir at 80r / min for 20min, pass through a 100-mesh sieve, and vacuum dry at 45℃ to obtain the active additive;

[0046] (5) Mix 180g of corn yellow powder, 180g of highland barley powder, 120g of compound microorganisms, 90g of whey powder, 70g of microalgae powder, 50g of fish meal, 100g of active additives and 35g of vitamin C evenly to obtain the feed additive used to reduce the deposition of heavy metals in pigs.

[0047] The feed additive is added to pig feed at a rate of 1.0 wt%.

[0048] Comparative Example 1

[0049] A method for preparing a feed additive to reduce heavy metal deposition in pigs includes the following steps:

[0050] (1) Disperse 10g of activated carbon into 150mL of 75wt% acetic acid aqueous solution, add 20g of succinic anhydride, stir and react for 10h at 110℃ and 500r / min under nitrogen atmosphere, filter the product, wash it with acetic acid and deionized water 4 times in sequence, remove unreacted substances by vacuum distillation at 50℃, and dry it under vacuum at 70℃ to constant weight to obtain anhydride activated carbon;

[0051] (2) Disperse 10g of anhydride activated carbon and 20g of chitosan into 250mL of glacial acetic acid buffer (pH 5.0), stir and mix evenly, add 15g of 3Å molecular sieve to the container, react under vacuum at 140℃ and ≤0.1kPa for 20h, centrifuge and freeze dry the product to obtain grafted activated carbon;

[0052] (3) Mix Aspergillus niger, Bacillus tarda, Bacillus subtilis, Bacillus amyloliquefaciens and Lactobacillus plantarum in a weight ratio of 1:2:2:2:1 to prepare a compound microorganism; wash and drain 20g of Astragalus membranaceus, 20g of Magnolia officinalis, 20g of Paeonia lactiflora, 10g of Taraxacum mongolicum, 10g of Crataegus pinnatifida, 5g of Prunus mume and 5g of Glycyrrhiza uralensis, mix them, pulverize them to 80 mesh, then mix them with 200g of water, sonicate them for 30min, boil them at 80℃ for 30min, filter and retain the filtrate to obtain the herbal extract; mix 10mL of the herbal extract with 3g of grafted activated carbon, stir at 80r / min for 20min, pass them through a 100-mesh sieve, and vacuum dry them at 45℃ to obtain the active additive;

[0053] (4) Mix 200g of corn yellow powder, 200g of highland barley powder, 150g of compound microorganisms, 120g of whey powder, 80g of microalgae powder, 60g of fish meal, 120g of active additives and 50g of vitamin C evenly to obtain the feed additive used to reduce the deposition of heavy metals in pigs.

[0054] The feed additive is added to pig feed at a rate of 1.0 wt%.

[0055] Comparative Example 2

[0056] A method for preparing a feed additive to reduce heavy metal deposition in pigs includes the following steps:

[0057] (1) Disperse 10g of activated carbon into 150mL of 75wt% acetic acid aqueous solution, add 20g of succinic anhydride, stir and react for 10h at 110℃ and 500r / min under nitrogen atmosphere, filter the product, wash it with acetic acid and deionized water 4 times in sequence, remove unreacted substances by vacuum distillation at 50℃, and dry it under vacuum at 70℃ to constant weight to obtain anhydride activated carbon;

[0058] (2) A compound microorganism was prepared by mixing Aspergillus niger, Bacillus tarda, Bacillus subtilis, Bacillus amyloliquefaciens and Lactobacillus plantarum in a weight ratio of 1:2:2:2:1; 20g of Astragalus membranaceus, 20g of Magnolia officinalis, 20g of Paeonia lactiflora, 10g of Taraxacum mongolicum, 10g of Crataegus pinnatifida, 5g of Prunus mume and 5g of Glycyrrhiza uralensis were washed, drained and mixed, pulverized to 80 mesh, then mixed with 200g of water, ultrasonically treated for 30min, boiled at 80℃ for 30min, filtered and retained the filtrate to obtain the herbal extract; 10mL of the herbal extract and 3g of anhydride activated carbon were mixed, stirred at 80r / min for 20min, passed through a 100-mesh sieve and vacuum dried at 45℃ to obtain the active additive;

[0059] (3) Mix 200g of corn yellow powder, 200g of highland barley powder, 150g of compound microorganisms, 120g of whey powder, 80g of microalgae powder, 60g of fish meal, 120g of active additives and 50g of vitamin C evenly to obtain the feed additive used to reduce the deposition of heavy metals in pigs.

[0060] The feed additive is added to pig feed at a rate of 1.0 wt%.

[0061] Comparative Example 3

[0062] A method for preparing a feed additive to reduce heavy metal deposition in pigs includes the following steps:

[0063] (1) A compound microorganism was prepared by mixing Aspergillus niger, Bacillus tarda, Bacillus subtilis, Bacillus amyloliquefaciens and Lactobacillus plantarum in a weight ratio of 1:2:2:2:1; 20g of Astragalus membranaceus, 20g of Magnolia officinalis, 20g of Paeonia lactiflora, 10g of Taraxacum mongolicum, 10g of Crataegus pinnatifida, 5g of Prunus mume and 5g of Glycyrrhiza uralensis were washed, drained and mixed, pulverized to 80 mesh, then mixed with 200g of water, ultrasonically treated for 30min, boiled at 80℃ for 30min, filtered and retained the filtrate to obtain the herbal extract; 10mL of the herbal extract and 3g of activated carbon were mixed, stirred at 80r / min for 20min, passed through a 100-mesh sieve and vacuum dried at 45℃ to obtain the active additive;

[0064] (2) Mix 200g of corn yellow powder, 200g of highland barley powder, 150g of compound microorganisms, 120g of whey powder, 80g of microalgae powder, 60g of fish meal, 120g of active additives and 50g of vitamin C evenly to obtain the feed additive used to reduce the deposition of heavy metals in pigs.

[0065] The feed additive is added to pig feed at a rate of 1.0 wt%.

[0066] Comparative Example 4

[0067] A method for preparing a feed additive to reduce heavy metal deposition in pigs includes the following steps:

[0068] (1) Disperse 10g of activated carbon into 150mL of 75wt% acetic acid aqueous solution, add 20g of succinic anhydride, stir and react for 10h at 110℃ and 500r / min under nitrogen atmosphere, filter the product, wash it with acetic acid and deionized water 4 times in sequence, remove unreacted substances by vacuum distillation at 50℃, and dry it under vacuum at 70℃ to constant weight to obtain anhydride activated carbon;

[0069] (2) Disperse 10g of anhydride activated carbon and 20g of chitosan into 250mL of glacial acetic acid buffer (pH 5.0), stir and mix evenly, add 15g of 3Å molecular sieve to the container, react under vacuum at 140℃ and ≤0.1kPa for 20h, centrifuge and freeze dry the product to obtain grafted activated carbon;

[0070] (3) Disperse 10g of grafted activated carbon into 400mL of 0.1mol / L calcium hydroxide solution, disperse by ultrasonication, cool to 20℃, introduce carbon dioxide, stop introducing carbon dioxide when pH drops to 7.2, centrifuge the product, and wash with 0.1mol / L sodium hydroxide solution to obtain the modified activated carbon;

[0071] (4) A composite microorganism was prepared by mixing Aspergillus niger, Bacillus tarda, Bacillus subtilis, Bacillus amyloliquefaciens, and Lactobacillus plantarum in a weight ratio of 1:2:2:2:1;

[0072] (5) Mix 200g of corn yellow powder, 200g of highland barley powder, 150g of compound microorganisms, 120g of whey powder, 80g of microalgae powder, 60g of fish meal, 120g of modified activated carbon and 50g of vitamin C evenly to obtain the feed additive used to reduce the deposition of heavy metals in pigs.

[0073] The feed additive is added to pig feed at a rate of 1.0 wt%.

[0074] Experimental Example 1

[0075] Two hundred Duroc × Large White × Landrace three-way crossbred growing pigs (60.10 ± 0.50 kg) were selected based on similar weight, age, and sex ratio. They were randomly divided into Example 1 and Comparative Examples 1–4, with four replicates per group and ten pigs per replicate. The formal experimental period was 42 days. The experimental diet was formulated according to the NRC (2012) nutrient requirements for pigs. Feed consumption for each group was recorded daily, and the feeding and management procedures during the experiment followed the standard commercial pig feeding and management manual.

[0076] At the beginning and end of the experiment, each group was weighed after fasting for 12 hours before weighing. The average daily weight gain of each group was calculated. At the end of the experiment, the feed consumption of each group was recorded, and the average daily feed intake was calculated. Specific data are shown in Table 1.

[0077] Table 1. Effects of feed additives on pig production performance

[0078]

[0079] Note: Significant differences between Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3: *p<0.05, **p<0.01, ***p<0.001; Significant differences between Comparative Example 4 and Example 1: #p<0.05, ##p<0.01, ###p<0.001.

[0080] Experiment Example 2

[0081] After 42 days of rearing, one pig from each replicate was euthanized by exsanguination via the jugular vein, and inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to detect the content of heavy metal elements in tissues and feces. Specific data are shown in Table 2.

[0082] Table 2. Effects of feed additives on heavy metal content in pig tissues and feces.

[0083]

[0084] Note: Significant differences between Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3: *p<0.05, **p<0.01, ***p<0.001; Significant differences between Comparative Example 4 and Example 1: #p<0.05, ##p<0.01, ###p<0.001.

[0085] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A feed additive for reducing heavy metal deposition in pigs, characterized in that, The active additive is prepared by weight of the following components: 10-20 parts corn starch, 10-20 parts highland barley starch, 5-15 parts compound microorganisms, 4-12 parts whey powder, 4-8 parts microalgae powder, 2-6 parts fish meal, 4-12 parts active additive, and 0.5-5 parts vitamin C. The preparation method of the active additive includes the following steps: mixing the herbal extract and modified activated carbon, stirring, sieving, and vacuum drying to obtain the active additive. The heavy metal is one or more of cadmium, lead, mercury, chromium, and arsenic; The method for preparing the modified activated carbon includes the following steps: (1) Disperse activated carbon in an aqueous acetic acid solution, add succinic anhydride, heat and stir under a nitrogen atmosphere, filter, wash, distill and dry the product to obtain anhydride-treated activated carbon; (2) Disperse the acid-anhydride activated carbon and chitosan powder into glacial acetic acid buffer, stir and mix evenly, add molecular sieve, react under vacuum, centrifuge and freeze dry the product to obtain grafted activated carbon. (3) The grafted activated carbon was dispersed in a calcium hydroxide solution, ultrasonically dispersed and then cooled, carbon dioxide was introduced, and the product was centrifuged and washed to obtain the modified activated carbon. The composite microorganisms were prepared by mixing Aspergillus niger, Bacillus tarda, Bacillus subtilis, Bacillus amyloliquefaciens, and Lactobacillus plantarum in a weight ratio of 1:1~2:1~2:1~2:1; the ratio of the herbal extract to the modified activated carbon was 10mL:1~3g; the stirring conditions were 50~100r / min for 10~30min; the mixture was passed through a 40~100 mesh sieve and vacuum dried at a temperature of 38~48℃. The preparation method of the herbal extract includes the following steps: washing, draining, and mixing 10-20 parts of Astragalus membranaceus, 10-20 parts of Magnolia officinalis, 10-20 parts of Paeonia lactiflora, 5-15 parts of Taraxacum mongolicum, 5-10 parts of Crataegus pinnatifida, 5-10 parts of Prunus mume, and 5-10 parts of Glycyrrhiza uralensis, pulverizing them to 40-80 mesh, then mixing them with 150-200 parts of water, ultrasonically treating them for 15-30 minutes, boiling them at 60-80℃ for 30-60 minutes, filtering and retaining the filtrate to obtain the herbal extract.

2. The feed additive according to claim 1, characterized in that, In step (1), the ratio of activated carbon, acetic acid aqueous solution, and succinic anhydride is 10g: 120~180mL: 12~26g; the concentration of acetic acid in the acetic acid aqueous solution is 60~80wt%.

3. The feed additive according to claim 1, characterized in that, In step (1), the heating and stirring conditions are 80~120℃ and 400~600r / min for 8~14h. The product is washed with acetic acid and deionized water 3~5 times in sequence, and unreacted substances are removed by vacuum distillation at 40~60℃. The product is then dried under vacuum at 60~80℃ to constant weight.

4. The feed additive according to claim 1, characterized in that, In step (2), the ratio of acid-anhydride activated carbon, chitosan, glacial acetic acid buffer, and molecular sieve is 10g: 13~24g: 200~300mL: 10~20g; the pH of the glacial acetic acid buffer is 4.8~5.2, and the molecular sieve is 3Å molecular sieve.

5. The feed additive according to claim 1, characterized in that, In step (2), the vacuum reaction conditions are 120~150℃ and ≤0.1kPa for 18~24h.

6. The feed additive according to claim 1, characterized in that, In step (3), the ratio of grafted activated carbon to calcium hydroxide solution is 10g: 300~500mL; the concentration of calcium hydroxide solution is 0.02~0.1mol / L; the temperature is lowered to 15~25℃; carbon dioxide is stopped when the pH drops to 7.0~7.5; and the solution is rinsed with 0.1 mol / L sodium hydroxide solution.

7. The feed additive according to claim 1, characterized in that, The feed additive is added to pig feed at a rate of 0.5~1.2 wt%.

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