Feed additive for reducing heavy metal deposition in pig body and preparation method thereof

Abstract

The present invention discloses a feed additive for reducing heavy metal deposition in pig bodies and a preparation method thereof, and relates to the technical field of feeds, the feed additive is prepared from the following components: 10-20 parts of corn gluten meal, 10-20 parts of highland 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; the active additive is prepared by mixing a Chinese herbal medicine extract and modified activated carbon; through the synergistic effect of multiple functions, the feed additive disclosed by the invention can significantly reduce heavy metal enrichment of target organs in pig bodies, avoid loss of feed nutrient elements, synchronously improve the stress resistance and growth efficiency of pigs, reduce the safety risk of meat products from the source, and provide key technical support for green and healthy transformation of animal husbandry.

Description

Technical Field

[0001] The present invention relates to the technical field of feed, and in particular to a feed additive for reducing heavy metal deposition in pigs and a preparation method thereof. Background Art

[0002] As cross-contamination between industry and agriculture intensifies, heavy metals such as lead (Pb), cadmium (Cd), arsenic (As), and chromium (Cr) migrate into the agricultural supply chain through soil, water, and air, with livestock and poultry being one of the primary affected sectors. Pigs, as a key economic animal in large-scale farming worldwide, are particularly at risk of heavy metal exposure. Studies have shown that pigs have a poor ability to metabolize heavy metals (for example, cadmium has a half-life of over 10 years in the liver). Contamination in conventional feed ingredients (corn, soybean meal, fish meal, etc.) during cultivation or processing can be a major route of heavy metal introduction. For example, when pigs ingest lead-contaminated corn (contains lead exceeding 5 mg / kg), approximately 40% accumulates in their bones and kidneys, with some escaping the food chain and entering the human body. This problem not only reduces pig growth performance (for example, cadmium exposure can increase feed-to-meat ratio by over 15%) but also poses a threat to food safety (lead residues in pig liver can exceed the permitted level by 8–10 times).

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

[0004] Current heavy metal emission reduction technologies primarily rely on single-function materials (such as adsorbents or chelating agents), which suffer from the following deficiencies: Poor targeting: They cannot distinguish between different heavy metal types (such as cadmium, lead, and arsenic), often competing for adsorption with nutrients like calcium and zinc, resulting in waste or nutrient loss; Lack of stability: Materials easily lose their effectiveness in animal gastric acid, leading to secondary release of heavy metals; Single function: They can only provide short-term adsorption or partial detoxification, failing to fully block heavy metal absorption and deposition.

[0005] The present invention provides a composite feed additive that selectively captures heavy metals through modification while avoiding interference with nutrients; the carrier material gradually decomposes in the intestine to ensure that the effective ingredients are stably released and continue to exert their effects; combined with the triple functions of adsorption, detoxification, and excretion promotion, it inhibits heavy metal deposition throughout the entire process from feed intake to metabolic excretion, taking into account both high efficiency and safety, and can significantly reduce heavy metal residues in pigs. Summary of the Invention

[0006] In order to address the deficiencies in the prior art, the purpose of the present invention is to provide a feed additive for reducing heavy metal deposition in pigs and a preparation method thereof. The feed additive can significantly reduce the accumulation of heavy metals in target organs in pigs through the synergistic effect of multiple functions, while avoiding the loss of nutrient elements in feed. 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] In order to achieve the above object, the present invention adopts the following technical solutions: A feed additive for reducing heavy metal deposition in pigs is prepared from the following components, measured by weight: 10-20 parts of corn yellow powder, 10-20 parts of highland barley powder, 5-15 parts of composite 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. A method for preparing the active additive comprises the following steps: mixing a Chinese herbal medicine extract and modified activated carbon, stirring, sieving, and vacuum drying to obtain the active additive.

[0008] Preferably, the preparation method of the modified activated carbon comprises the following steps: (1) Dispersing activated carbon into an acetic acid aqueous solution, adding succinic anhydride, heating and stirring under a nitrogen atmosphere, filtering, washing, distilling, and drying the product to obtain anhydride activated carbon; Anhydride modification: After the anhydride ring opens, one carboxyl group forms an ester bond (CO-CO-R) with the activated carbon hydroxyl group, leaving the other carboxyl group 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 circulation. The resulting product exhibits a carboxylic acid-functionalized surface, providing active sites for subsequent condensation.

[0009] Preferably, in step (1), the ratio of activated carbon, acetic acid aqueous solution, and succinic anhydride is 10 g:120-180 mL:12-26 g; and the concentration of acetic acid in the acetic acid aqueous solution is 60-80 wt %.

[0010] Preferably, in step (1), the heating and stirring conditions are 80-120° C., 400-600 r / min, and the stirring reaction is performed for 8-14 hours; the product is washed with acetic acid and deionized water 3-5 times in sequence, and unreacted substances are removed by reduced pressure distillation at 40-60° C., and vacuum dried at 60-80° C. to constant weight.

[0011] (2) Dispersing the anhydride activated carbon and chitosan powder into glacial acetic acid buffer, stirring and mixing evenly, adding molecular sieves into the container, vacuum reaction, centrifuging and freeze-drying the product to obtain grafted activated carbon; Chitosan covalent grafting: At high temperature, the carboxylic acid group (R-COOH) of the anhydride activated carbon undergoes α-H deprotonation to form an enol activated intermediate (RC=O - ), the deacetylamino group (-NH2) of chitosan remains in a non-protonated state under vacuum conditions, launching a directional nucleophilic attack on the activated carboxyl carbon to generate a β-hydroxylamine intermediate (RC(OH)-NH-chitosan); with the help of the molecular sieve continuously adsorbing the generated water molecules, the β-hydroxyl elimination reaction is promoted, and finally a stable amide bond (R-CONH-chitosan) is formed.

[0012] Preferably, in step (2), the ratio of anhydride activated carbon, chitosan, glacial acetic acid buffer, and molecular sieve is 10 g: 13-24 g: 200-300 mL: 10-20 g; the pH of the glacial acetic acid buffer is 4.8-5.2, and the molecular sieve is 3Å molecular sieve.

[0013] Preferably, in step (2), the molecular weight of chitosan is 10,000 to 200,000 Daltons, and the degree of deacetylation is above 85%.

[0014] Preferably, in step (2), the vacuum reaction conditions are 120-150° C. and ≤0.1 kPa for 18-24 hours.

[0015] (3) dispersing the grafted activated carbon into a calcium hydroxide solution, cooling the solution after ultrasonic dispersion, introducing carbon dioxide, centrifuging and eluting the product to obtain the modified activated carbon.

[0016] In situ calcium carbonate composite: controlled by CO2-induced deposition kinetics: Ca(OH)2 solution provides Ca 2+ , CO2 is introduced to generate HCO3 - and gradually release CO3 2- , and Ca 2+ Combined nucleation. Low temperature reduces the interfacial energy difference, forcing CO3 2- Directed stacking along specific crystal axes gives the modified activated carbon a high specific surface area and heavy metal capture sites.

[0017] Preferably, in step (3), the ratio of the grafted activated carbon to the calcium hydroxide solution is 10 g: 300-500 mL; the concentration of the calcium hydroxide solution is 0.02-0.1 mol / L; the temperature is lowered to 15-25°C; the introduction of carbon dioxide is stopped when the pH drops to 7.0-7.5; and the mixture is rinsed with 0.1 mol / L sodium hydroxide solution.

[0018] Preferably, the composite microorganism is prepared by mixing Aspergillus niger, Bacillus lentus, Bacillus subtilis, Bacillus amyloliquefaciens, and Lactobacillus plantarum in a weight ratio of 1:1~2:1~2:1~2:1; the dosage ratio of the Chinese herbal medicine extract and the modified activated carbon is 10mL:1~3g; the stirring condition is 50~100r / min and stirring for 10~30min; the mixture is sieved through a 40~100 mesh sieve, and the vacuum drying temperature is 38~48°C.

[0019] Preferably, the preparation method of the Chinese herbal medicine extract comprises the following steps: washing, draining, and mixing 10-20 parts of astragalus, 10-20 parts of magnolia bark, 10-20 parts of white peony root, 5-15 parts of dandelion, 5-10 parts of hawthorn, 5-10 parts of black plum, and 5-10 parts of licorice, crushing to 40-80 mesh, and then mixing with 150-200 parts of water, ultrasonically treating for 15-30 minutes, boiling and extracting at 60-80°C for 30-60 minutes, filtering and retaining the filtrate to obtain the Chinese herbal medicine extract.

[0020] Preferably, the feed additive is added in an amount of 0.5-1.2 wt % in pig feed.

[0021] The present invention also claims protection for a preparation method of the feed additive for reducing heavy metal deposition in pigs, comprising the following steps: uniformly mixing corn yellow powder, barley powder, composite microorganisms, whey powder, microalgae powder, fish meal, active additives, and vitamins to obtain the feed additive for reducing heavy metal deposition in pigs.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. The feed additive provided by the present invention effectively reduces heavy metal residues in pigs through the synergistic action of multiple components. The soluble fiber in corn yellow powder and highland barley flour forms a network structure in the intestine, physically adsorbing heavy metals such as lead and cadmium, reducing their absorption into the blood. Organic acids such as lactic acid and propionic acid produced by the metabolism of complex microorganisms (such as Bacillus and lactic acid bacteria) can promote the dissolution of heavy metals and their excretion through feces. Microalgae powder contains natural chelating components (such as chlorophyll derivatives) that can directly bind heavy metals and reduce their biological activity. The milk protein in whey powder can stabilize metal ions and prevent their diffusion, while vitamin C can reduce oxidative damage caused by heavy metals by scavenging free radicals. Calcium carbonate supported by modified activated carbon can gradually release the active ingredients of traditional Chinese medicines (such as astragaloside and magnolol) through gastric acid reaction, protecting them from strong acid damage and delaying the release of their efficacy.

[0023] 2. The active additives provided by the present invention include astragalus root, which enhances the liver's detoxification and metabolic capacity and promotes the conversion of heavy metals into low-toxic forms; dandelion root and magnolia bark, which jointly inhibit intestinal inflammatory responses, protect intestinal barrier function, reduce anorexia caused by intestinal mucosal damage, and increase feed intake; white peony root enhances detoxification efficiency by regulating the balance of intestinal flora; and the organic acid components in hawthorn and black plum accelerate intestinal peristalsis and accelerate nutrient absorption by promoting digestive enzyme activity. The traditional Chinese medicine adsorption function of modified activated carbon further optimizes the release of drug efficacy: calcium carbonate gradually decomposes in gastric acid, and the porosity of activated carbon is regulated to achieve the on-demand release of Chinese herbal medicine ingredients. At the same time, the oligosaccharides produced by chitosan hydrolysis can promote the proliferation of beneficial bacteria, improve the intestinal environment, and synergize with Chinese herbal medicine to improve feed conversion rate.

[0024] 3. The present invention provides a modified activated carbon. The anhydride modification directionally enhances the targeted capture of heavy metals. By regulating the density of surface carboxylic acid groups, the chemical affinity for cations such as cadmium and lead is significantly improved, the selective adsorption of heavy metals is optimized, and the stability in complex biological environments is improved. Natural chitosan chains form a dense three-dimensional network on the surface of activated carbon through reaction. Its amino functional groups have specific adsorption capacity for anionic pollutants such as arsenic and chromium. At the same time, they form a slow-release barrier in the weak acid environment of the intestine to prevent the activated carbon from dissolving and releasing impurities. This structural design can not only avoid carrier loss, but also synergize with microalgae fiber to enhance the heavy metal solidification effect. The calcium carbonate mineral layer controls the release of active ingredients of Chinese herbal medicines through an acid-base response mechanism, ensuring the continuous action of detoxification components in the intestine, and ultimately achieving efficient removal of heavy metals. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0026] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from commercially purchased raw materials.

[0027] A method for preparing a feed additive for reducing heavy metal deposition in pigs comprises the following steps: (1) Disperse 10 g of activated carbon into 60-80 wt% 120-180 mL of acetic acid aqueous solution, add 12-26 g of succinic anhydride, and stir the reaction at 80-120 °C and 400-600 r / min in a nitrogen atmosphere for 8-14 h. Filter the product, wash it with acetic acid and deionized water 3-5 times in sequence, remove the unreacted product by vacuum distillation at 40-60 °C, and dry it in vacuum at 60-80 °C to constant weight to obtain anhydride activated carbon. (2) Disperse 10 g of anhydride activated carbon and 13-24 g of chitosan in 200-300 mL of glacial acetic acid buffer (pH 4.8-5.2), stir and mix evenly, add 10-20 g of 3Å molecular sieves to the container, and react in a vacuum at 120-150 °C and ≤0.1 kPa for 18-24 h. Centrifuge the product and freeze-dry it to obtain grafted activated carbon; (3) Dispersing 10 g of the grafted activated carbon into 300-500 mL of a 0.02-0.1 mol / L calcium hydroxide solution, ultrasonically dispersing the mixture, cooling the mixture to 15-25°C, introducing carbon dioxide, and stopping the introduction of carbon dioxide when the pH drops to 7.0-7.5. The product was centrifuged and rinsed with a 0.1 mol / L sodium hydroxide solution to obtain the modified activated carbon. (4) Aspergillus niger, Bacillus lentus, Bacillus subtilis, Bacillus amyloliquefaciens and Lactobacillus plantarum are mixed in a weight ratio of 1:1~2:1~2:1~2:1 to prepare a composite microorganism; 10~20 parts of Astragalus membranaceus, 10~20 parts of Magnolia officinalis, 10~20 parts of White Peony Root, 5~15 parts of Taraxacum officinale, 5~10 parts of Crataegus pinnatifida, 5~10 parts of Prunus mume and 5~10 parts of Licorice root are washed, drained and mixed, crushed to 40~80 mesh, then mixed with 150~200 parts of water, ultrasonically treated for 15~30 minutes, boiled at 60~80℃ for 30~60 minutes, filtered and retained the filtrate to obtain a Chinese herbal medicine extract; 10 mL of the Chinese herbal medicine extract and 1~3 g of modified activated carbon are mixed, stirred at 50~100 r / min for 10~30 minutes, passed through a 40~100 mesh sieve, and vacuum dried at 38~48℃ to obtain an active additive; (5) 10-20 parts of corn yellow powder, 10-20 parts of highland barley powder, 5-15 parts of composite 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 are mixed uniformly to obtain the feed additive for reducing heavy metal deposition in pigs.

[0028] The feed additive is added in an amount of 0.5-1.2 wt % in pig feed.

[0029] The present invention will be further described below with reference to specific examples.

[0030] Example 1

[0031] A method for preparing a feed additive for reducing heavy metal deposition in pigs comprises the following steps: (1) Disperse 10 g of activated carbon into 150 mL of 75 wt% acetic acid aqueous solution, add 20 g of succinic anhydride, and stir the mixture at 110 °C and 500 r / min in a nitrogen atmosphere for 10 h. Filter the product, wash it four times with acetic acid and deionized water, remove the unreacted product by vacuum distillation at 50 °C, and dry it in a vacuum at 70 °C to constant weight to obtain anhydride activated carbon. (2) Disperse 10 g of anhydride activated carbon and 20 g of chitosan in 250 mL of glacial acetic acid buffer (pH 5.0), stir and mix evenly, add 15 g of 3Å molecular sieves into the container, and react in a vacuum at 140°C and ≤0.1 kPa for 20 h. Centrifuge the product and freeze-dry it to obtain grafted activated carbon; (3) Dispersing 10 g of grafted activated carbon into 400 mL of 0.1 mol / L calcium hydroxide solution, ultrasonically dispersing the solution, cooling the solution to 20°C, introducing carbon dioxide, and stopping the introduction of carbon dioxide when the pH drops to 7.2. The product was centrifuged and rinsed with 0.1 mol / L sodium hydroxide solution to obtain the modified activated carbon. (4) Aspergillus niger, Bacillus lentus, Bacillus subtilis, Bacillus amyloliquefaciens, and Lactobacillus plantarum were mixed in a weight ratio of 1:2:2:2:1 to prepare a composite microorganism; 20 g of Astragalus membranaceus, 20 g of Magnolia officinalis, 20 g of White Peony Root, 10 g of Taraxacum officinale, 10 g of Crataegus pinnatifida, 5 g of Prunus mume, and 5 g of Licorice root were washed, drained, mixed, and crushed to 80 mesh, then mixed with 200 g of water, ultrasonically treated for 30 min, boiled at 80 ° C for 30 min, and filtered to retain the filtrate to obtain the Chinese herbal medicine extract; 10 mL of the Chinese herbal medicine extract and 2 g of modified activated carbon were mixed, stirred at 80 r / min for 20 min, passed through a 100 mesh sieve, and vacuum-dried at 45 ° C to obtain an active additive; (5) 180 g of corn yellow powder, 180 g of highland barley powder, 120 g of composite microorganisms, 90 g of whey powder, 70 g of microalgae powder, 50 g of fish meal, 100 g of active additives, and 35 g of vitamin C are mixed uniformly to obtain the feed additive for reducing heavy metal deposition in pigs.

[0032] The feed additive is added in an amount of 1.0 wt % in pig feed.

[0033] Comparative Example 1 A method for preparing a feed additive for reducing heavy metal deposition in pigs comprises the following steps: (1) Disperse 10 g of activated carbon into 150 mL of 75 wt% acetic acid aqueous solution, add 20 g of succinic anhydride, and stir the mixture at 110 °C and 500 r / min in a nitrogen atmosphere for 10 h. Filter the product, wash it four times with acetic acid and deionized water, remove the unreacted product by vacuum distillation at 50 °C, and dry it in a vacuum at 70 °C to constant weight to obtain anhydride activated carbon. (2) Disperse 10 g of anhydride activated carbon and 20 g of chitosan in 250 mL of glacial acetic acid buffer (pH 5.0), stir and mix evenly, add 15 g of 3Å molecular sieves into the container, and react in a vacuum at 140°C and ≤0.1 kPa for 20 h. Centrifuge the product and freeze-dry it to obtain grafted activated carbon; (3) Aspergillus niger, Bacillus lentus, Bacillus subtilis, Bacillus amyloliquefaciens, and Lactobacillus plantarum were mixed in a weight ratio of 1:2:2:2:1 to prepare a composite microorganism; 20 g of Astragalus membranaceus, 20 g of Magnolia officinalis, 20 g of White Peony Root, 10 g of Taraxacum officinale, 10 g of Crataegus pinnatifida, 5 g of Prunus mume, and 5 g of Licorice root were washed, drained, mixed, and crushed to 80 mesh, then mixed with 200 g of water, ultrasonically treated for 30 min, boiled at 80 ° C for 30 min, and the filtrate was filtered to obtain a Chinese herbal medicine extract; 10 mL of the Chinese herbal medicine extract and 3 g of grafted activated carbon were mixed, stirred at 80 r / min for 20 min, passed through a 100 mesh sieve, and vacuum-dried at 45 ° C to obtain an active additive; (4) 200 g of corn yellow powder, 200 g of highland barley powder, 150 g of composite microorganisms, 120 g of whey powder, 80 g of microalgae powder, 60 g of fish meal, 120 g of active additives, and 50 g of vitamin C are mixed uniformly to obtain the feed additive for reducing heavy metal deposition in pigs.

[0034] The feed additive is added in an amount of 1.0 wt % in pig feed.

[0035] Comparative Example 2 A method for preparing a feed additive for reducing heavy metal deposition in pigs comprises the following steps: (1) Disperse 10 g of activated carbon into 150 mL of 75 wt% acetic acid aqueous solution, add 20 g of succinic anhydride, and stir the mixture at 110 °C and 500 r / min in a nitrogen atmosphere for 10 h. Filter the product, wash it four times with acetic acid and deionized water, remove the unreacted product by vacuum distillation at 50 °C, and dry it in a vacuum at 70 °C to constant weight to obtain anhydride activated carbon. (2) Aspergillus niger, Bacillus lentus, Bacillus subtilis, Bacillus amyloliquefaciens, and Lactobacillus plantarum were mixed in a weight ratio of 1:2:2:2:1 to prepare a composite microorganism; 20 g of Astragalus membranaceus, 20 g of Magnolia officinalis, 20 g of White Peony Root, 10 g of Taraxacum officinale, 10 g of Crataegus pinnatifida, 5 g of Prunus mume, and 5 g of Licorice root were washed, drained, mixed, and crushed to 80 mesh, then mixed with 200 g of water, ultrasonically treated for 30 min, boiled at 80°C for 30 min, and the filtrate was filtered to obtain a Chinese herbal medicine extract; 10 mL of the Chinese herbal medicine extract and 3 g of acid anhydride activated carbon were mixed, stirred at 80 r / min for 20 min, passed through a 100 mesh sieve, and vacuum dried at 45°C to obtain an active additive; (3) 200 g of corn yellow powder, 200 g of highland barley powder, 150 g of composite microorganisms, 120 g of whey powder, 80 g of microalgae powder, 60 g of fish meal, 120 g of active additives, and 50 g of vitamin C are mixed uniformly to obtain the feed additive for reducing heavy metal deposition in pigs.

[0036] The feed additive is added in an amount of 1.0 wt % in pig feed.

[0037] Comparative Example 3 A method for preparing a feed additive for reducing heavy metal deposition in pigs comprises the following steps: (1) Aspergillus niger, Bacillus lentus, Bacillus subtilis, Bacillus amyloliquefaciens, and Lactobacillus plantarum were mixed in a weight ratio of 1:2:2:2:1 to prepare a composite microorganism; 20 g of Astragalus membranaceus, 20 g of Magnolia officinalis, 20 g of White Peony Root, 10 g of Taraxacum officinale, 10 g of Crataegus pinnatifida, 5 g of Prunus mume, and 5 g of Licorice root were washed, drained, mixed, and crushed to 80 mesh, then mixed with 200 g of water, ultrasonically treated for 30 min, boiled at 80°C for 30 min, and the filtrate was filtered to obtain a Chinese herbal medicine extract; 10 mL of the Chinese herbal medicine extract and 3 g of activated carbon were mixed, stirred at 80 r / min for 20 min, passed through a 100 mesh sieve, and vacuum-dried at 45°C to obtain an active additive; (2) 200 g of corn yellow powder, 200 g of highland barley powder, 150 g of composite microorganisms, 120 g of whey powder, 80 g of microalgae powder, 60 g of fish meal, 120 g of active additives, and 50 g of vitamin C are mixed uniformly to obtain the feed additive for reducing heavy metal deposition in pigs.

[0038] The feed additive is added in an amount of 1.0 wt % in pig feed.

[0039] Comparative Example 4 A method for preparing a feed additive for reducing heavy metal deposition in pigs comprises the following steps: (1) Disperse 10 g of activated carbon into 150 mL of 75 wt% acetic acid aqueous solution, add 20 g of succinic anhydride, and stir the mixture at 110 °C and 500 r / min in a nitrogen atmosphere for 10 h. Filter the product, wash it four times with acetic acid and deionized water, remove the unreacted product by vacuum distillation at 50 °C, and dry it in a vacuum at 70 °C to constant weight to obtain anhydride activated carbon. (2) Disperse 10 g of anhydride activated carbon and 20 g of chitosan in 250 mL of glacial acetic acid buffer (pH 5.0), stir and mix evenly, add 15 g of 3Å molecular sieves into the container, and react in a vacuum at 140°C and ≤0.1 kPa for 20 h. Centrifuge the product and freeze-dry it to obtain grafted activated carbon; (3) Dispersing 10 g of grafted activated carbon into 400 mL of 0.1 mol / L calcium hydroxide solution, ultrasonically dispersing the solution, cooling the solution to 20°C, introducing carbon dioxide, and stopping the introduction of carbon dioxide when the pH drops to 7.2. The product was centrifuged and rinsed with 0.1 mol / L sodium hydroxide solution to obtain the modified activated carbon. (4) Aspergillus niger, Bacillus lentus, Bacillus subtilis, Bacillus amyloliquefaciens, and Lactobacillus plantarum are mixed in a weight ratio of 1:2:2:2:1 to prepare a composite microorganism; (5) 200 g of corn yellow powder, 200 g of highland barley powder, 150 g of composite microorganisms, 120 g of whey powder, 80 g of microalgae powder, 60 g of fish meal, 120 g of modified activated carbon, and 50 g of vitamin C were mixed uniformly to obtain the feed additive for reducing heavy metal deposition in pigs.

[0040] The feed additive is added in an amount of 1.0 wt % in pig feed.

[0041] Experimental Example 1 Two hundred Dulong × Dalong × Changlong hybrid growing pigs weighing 60.10 ± 0.50 kg were selected based on similar weight, age, and sex ratio. They were randomly divided into groups 1 to 4, as in Example 1 and Comparative Examples, with four replicates per group and ten pigs per replicate. The experimental period lasted 42 days. The experimental diets were formulated according to the National Research Council (NRC) (2012) guidelines for swine nutritional requirements. Feed consumption was recorded daily for each group. Feeding and management procedures during the experimental period followed the standard commercial pig feeding and management manual.

[0042] Each group was weighed at the beginning and end of the experiment. The pigs were fasted 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 counted and the average daily feed intake was calculated. Specific data are shown in Table 1.

[0043] Table 1 Effects of feed additives on pig production performance

[0044] Note: The significant differences between Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3: *p<0.05, **p<0.01, ***p<0.001; the significant differences between Comparative Example 4 and Example 1: #p<0.05, ##p<0.01, ###p<0.001.

[0045] Experimental Example 2 After 42 days of feeding, one pig from each replicate was sacrificed by jugular vein exsanguination, and heavy metal content in tissues and feces was determined using inductively coupled plasma spectroscopy. Specific data are shown in Table 2.

[0046] Table 2 Effects of feed additives on heavy metal levels in pig tissues and feces

[0047] Note: The significant differences between Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3: *p<0.05, **p<0.01, ***p<0.001; the significant differences between Comparative Example 4 and Example 1: #p<0.05, ##p<0.01, ###p<0.001.

[0048] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by 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 from the following components, in parts by weight: 10-20 parts of corn yellow powder, 10-20 parts of highland barley flour, 5-15 parts of composite 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. The preparation method of the active additive comprises the following steps: mixing a Chinese herbal medicine 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 preparation method of the modified activated carbon comprises the following steps: (1) Dispersing activated carbon into an acetic acid aqueous solution, adding succinic anhydride, heating and stirring under a nitrogen atmosphere, filtering, washing, distilling, and drying the product to obtain anhydride activated carbon; (2) Dispersing the anhydride activated carbon and chitosan powder into glacial acetic acid buffer, stirring and mixing evenly, adding molecular sieves, vacuum reaction, centrifuging and freeze-drying the product to obtain grafted activated carbon; (3) dispersing the grafted activated carbon into a calcium hydroxide solution, cooling the solution after ultrasonic dispersion, introducing carbon dioxide, centrifuging and eluting the product to obtain the modified activated carbon; The composite microorganism is prepared by mixing Aspergillus niger, Bacillus lentus, Bacillus subtilis, Bacillus amyloliquefaciens, and Lactobacillus plantarum in a weight ratio of 1:1-2:1-2:1-2:1; the amount ratio of the Chinese herbal medicine extract and the modified activated carbon is 10 mL: 1-3 g; the stirring condition is 50-100 r / min for 10-30 minutes; the mixture is sieved through a 40-100 mesh sieve and vacuum dried at a temperature of 38-48°C; The preparation method of the Chinese herbal medicine extract comprises the following steps: washing, draining, and mixing 10-20 parts of astragalus, 10-20 parts of magnolia bark, 10-20 parts of white peony root, 5-15 parts of dandelion, 5-10 parts of hawthorn, 5-10 parts of black plum, and 5-10 parts of liquorice, crushing the mixture to 40-80 mesh size, then mixing the mixture with 150-200 parts of water, ultrasonically treating the mixture for 15-30 minutes, boiling and extracting the mixture at 60-80°C for 30-60 minutes, and filtering and retaining the filtrate to obtain the Chinese herbal medicine 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 10 g:120-180 mL:12-26 g; the concentration of acetic acid in the acetic acid aqueous solution is 60-80 wt %.

3. The feed additive according to claim 1, characterized in that In step (1), the heating and stirring conditions are 80-120° C., 400-600 r / min, and the stirring reaction is performed for 8-14 hours; the product is washed with acetic acid and deionized water 3-5 times in sequence, and the unreacted matter is removed by reduced pressure distillation at 40-60° C., and then vacuum dried at 60-80° C. to constant weight.

4. The feed additive according to claim 1, characterized in that In step (2), the ratio of anhydride activated carbon, chitosan, glacial acetic acid buffer and molecular sieve is 10 g: 13-24 g: 200-300 mL: 10-20 g; 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° C. and ≤0.1 kPa for 18-24 hours.

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 10 g: 300-500 mL; the concentration of calcium hydroxide solution is 0.02-0.1 mol / L; the temperature is lowered to 15-25°C; the introduction of carbon dioxide is stopped when the pH drops to 7.0-7.5; and 0.1 mol / L sodium hydroxide solution is used for elution.

7. The feed additive according to claim 1, characterized in that The feed additive is added in an amount of 0.5-1.2 wt % in pig feed.

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