Blood peptide rare earth chelate as well as preparation method and application thereof

Abstract

The invention relates to the technical field of rare earth chelates, and particularly discloses a hemepeptide rare earth chelate as well as a preparation method and application thereof. The preparation method comprises the steps of peptide solution preparation, rare earth pretreatment, chelation reaction, purification treatment and spray drying. Wherein the step of preparing the peptide solution comprises the following steps: adding an anticoagulant into animal blood, and centrifuging to obtain an animal blood cell solution; the method comprises the following steps: stabilizing the pH value of an animal blood cell solution to 7.4-8.0 by using a buffer solution, adding a stabilizer, and carrying out stepped homogenization under the pressure of 30-70Mpa to obtain a membrane-ruptured blood cell solution; and sequentially carrying out hemolysis treatment, enzymolysis treatment, separation treatment and ultrafiltration treatment on the membrane ruptured blood cell solution to obtain a peptide solution. The hemepeptide rare earth chelate prepared by the method has high yield and rare earth chelation rate, and can effectively overcome the problems of low chelation rate of organic rare earth and fishy red color, heavy fishy smell, poor palatability and low digestibility of a blood cell product.

Description

Technical Field

[0001] The present application relates to the technical field of rare earth chelates. More specifically, it relates to a blood peptide rare earth chelate, its preparation method and application. Background Art

[0002] Blood is one of the largest by-products during the slaughter process. Blood cells account for about 35% of whole blood and contain 36% protein, making it one of the animal protein raw materials with a relatively high protein content. Hemoglobin powder is a high-quality powdered animal protein raw material obtained through blood separation and then spray drying. However, due to reasons such as its bright red color, strong fishy smell, poor palatability, low digestibility, and unbalanced amino acids, its application in feed is severely restricted.

[0003] Rare earth elements can not only promote absorption, antibacterial and anti-inflammatory effects, and improve immune function, but also significantly enhance animal production performance by affecting the digestive tract flora, the activity of energy metabolism-related enzymes, or the levels of related hormones. Therefore, they have a wide range of applications in animal nutrition and feed additives. However, they also have some application limitations: for example, although inorganic rare earths have low cost and good stability, their bioavailability is low, they are difficult to be effectively absorbed by organisms, and may accumulate in the body due to their poor solubility, causing potential toxicity risks. Although organic rare earths have higher solubility and biological activity, and have better targeting and biocompatibility, they also face problems of low chelation rate and poor stability in practical applications.

[0004] Although hemoglobin powder has the resource advantage of high protein content, its inherent application defects (such as poor sensory properties and low digestibility and absorption rate) and the functional limitations of rare earth additives (such as low bioavailability of inorganic rare earths and insufficient chelation stability of organic rare earths) jointly restrict their efficient application in the feed field. Summary of the Invention

[0005] The present application provides a blood peptide rare earth chelate, its preparation method and application.

[0006] The blood peptide rare earth chelate prepared by the preparation method of the present application has a high yield and rare earth chelation rate, and can effectively overcome the problems of low chelation rate of organic rare earths and the bright red color, strong fishy smell, poor palatability, and low digestibility of blood cell products, greatly promoting the efficient synergistic application of organic rare earths and blood products in the feed field.

[0007] In the first aspect, the present application provides a preparation method of a blood peptide rare earth chelate, adopting the following technical scheme:

[0008] A preparation method of a blood peptide rare earth chelate, the preparation method specifically includes the following steps: preparing a peptide solution, rare earth pretreatment, chelation reaction, purification treatment, and spray drying;

[0009] Among them, the steps for preparing the peptide solution are as follows:

[0010] (1) Prepare an animal blood cell solution: Add an anticoagulant to fresh animal blood and centrifuge to obtain the animal blood cell solution;

[0011] (2) Perform membrane-breaking treatment: Stabilize the pH of the animal blood cell solution at 7.4 - 8.0 with a buffer solution, add a stabilizer, and perform stepwise homogenization at a pressure of 30 - 70 Mpa for 8 - 16 min to obtain a membrane-broken blood cell solution;

[0012] The addition amount of the stabilizer is 0.05 - 0.3% of the weight of the animal blood cell solution; the stabilizer includes an antioxidant and a surfactant;

[0013] The way of the stepwise homogenization is: Circulate and homogenize 2 - 4 times at the first pressure and the second pressure in sequence, and the homogenization time under each pressure is 2 min; the first pressure is 30 - 50 Mpa; the second pressure is 50 - 70 Mpa; the difference between the first pressure and the second pressure is 10 - 20 Mpa;

[0014] (3) Prepare the peptide solution: Subject the membrane-broken blood cell solution to hemolysis treatment, enzymatic hydrolysis treatment, separation treatment, and ultrafiltration treatment in sequence to obtain the peptide solution;

[0015] In the enzymatic hydrolysis treatment, add a compound protease to the hemolyzed solution, perform enzymatic hydrolysis at 45 - 55 °C for 7 - 9 h, and then inactivate the enzyme at 85 - 90 °C for 5 - 15 min to obtain an enzymatic hydrolysate; the addition amount of the compound protease is 2 - 4% of the dry matter weight in the hemolyzed solution;

[0016] In the ultrafiltration treatment, use an ultrafiltration membrane with a molecular weight cut-off of 4000 Da for treatment;

[0017] Among them, the steps for the rare earth pretreatment are as follows:

[0018] Mix the rare earth with a weak acid and react for 30 - 60 min to obtain the pretreated rare earth;

[0019] Among them, the steps for the chelation reaction are as follows:

[0020] Perform a chelation reaction on the peptide solution and the pretreated rare earth to obtain a crude chelate; the addition amount of the rare earth is 10 - 20% of the dry matter weight in the peptide solution; the conditions for the chelation reaction are: React in an environment with a pH of 3 - 4 and a temperature of 85 - 90 °C for 90 - 120 min.

[0021] The blood peptide rare earth chelate provided by this application, by using small peptide segments obtained by enzymatic hydrolysis of blood cells and rare earth ions (such as Ce 3+ 、La3+ )Directional binding has achieved the following breakthroughs: First, the flexible conformation of the small peptide and multiple coordination groups (-NH2, -COOH, etc.) can form a highly stable chelation structure, significantly improving the solubility and biological activity of rare earths; Second, the chelation process can effectively mask the fishy substances (such as aldehydes and sulfides) of hemoglobulins, and at the same time degrade macromolecular pigment proteins, improving the product color (changing from fishy red to light yellow / whitish yellow), thus breaking through the palatability bottleneck; Third, since the blood cell membrane is damaged and the macromolecular structure of globin is decomposed into small peptides, its digestibility is greatly improved. In addition, the chelate is efficiently absorbed through the intestinal peptide transport system (PEPT1) by simulating the absorption mechanism of natural metalloproteins, avoiding the mucosal irritation of free rare earths, and having both high safety and targeting. This technology not only promotes the high-value conversion of slaughter by-products, but also provides a theoretical and practical basis for the development of new feed additives with "function-nutrition" integration.

[0022] The yield of the blood peptide rare earth chelate prepared in this application is above 85%, and the chelation rates of cerium and lanthanum elements in the blood peptide rare earth chelate can both reach above 89%.

[0023] In this application, the membrane-breaking treatment can achieve a membrane-breaking rate of more than 90% for animal blood cell solution by adding stabilizers and combining with stepped homogenization. Homogenizing the animal blood cell solution can break the cell membrane in the blood cells, but during the homogenization process, if the homogenization is excessive, it will cause the coagulation of the animal blood cell solution, thus making it impossible to carry out subsequent operations and causing waste of raw materials. Through experiments, it is found that by adding stabilizers and performing stepped homogenization on the animal blood cell solution at a pressure of 30-70 Mpa for 8-16 minutes, the membrane-breaking rate of the animal blood cell solution can reach more than 90%, and at the same time, the coagulation of the animal blood cell solution can be prevented. The possible reasons for the coagulation of the animal blood cell solution are as follows: First, the homogenization process uses high pressure or shear force to break the blood cell membrane, thereby releasing components such as hemoglobin, cytoplasmic proteins, lipids, nucleic acids, and enzymes. A large amount of free hemoglobin (containing hydrophobic groups) and phospholipids in the cell membrane fragments combine with each other to form micelles or lipoprotein complexes, triggering flocculation. Second, the fragmentation of animal blood cells may also cause changes in the pH value of the solution, thus changing the isoelectric point of the solution and causing coagulation. Third, the gas-liquid interface (cavitation effect) generated by homogenization promotes the generation of oxygen free radicals, oxidizing Fe 2+ to Fe 3+ , forming methemoglobin precipitation.

[0024] The further optimization of the homogenization conditions in the membrane-breaking treatment in this application can improve the cell fragmentation efficiency while maximizing the protection of product activity and inhibiting solution coagulation, providing an efficient and low-loss cell fragmentation solution for the field of biomanufacturing.

[0025] In the present application, the protease used in the enzymatic hydrolysis treatment is a compound protease, and there is a synergistic effect among various enzymes in the compound enzyme. Papain can cleave the peptide bonds at the carboxyl terminus of hydrophobic amino acids (such as phenylalanine and tyrosine), preferentially releasing hydrophobic small peptides (which is beneficial for subsequent rare earth chelation); alkaline protease can cleave the peptide bonds at the carboxyl terminus of basic amino acids such as lysine and arginine, supplementing the decomposition of the region not cleaved by papain. The enzyme activity ratio of papain to alkaline protease of 2:1 can ensure a broad-spectrum coverage of cleavage sites, enabling the yield of small peptides (1000 - 4000 Da) to reach 85% - 90%.

[0026] In the present application, controlling the addition amount of the compound protease can increase the contents of chelated cerium and chelated lanthanum in the blood peptide rare earth chelate and the yield of the blood peptide rare earth chelate. When the addition amount of the compound protease is large, the substrate (such as globin) is saturated, and continuously increasing the enzyme amount only increases the initial rate, but has limited contribution to the total conversion rate, and the marginal benefit decreases, resulting in enzyme waste. At the same time, excessive alkaline protease may degrade papain during a long reaction, thereby reducing the synergistic effect; when the addition amount of the compound protease is low, the enzymatic reaction rate is low, and globin cannot be fully decomposed within 8 hours, and the small peptides in red blood cells cannot be completely decomposed, which will reduce the content of small peptides in the peptide solution, and further lead to a decrease in the contents of chelated cerium and chelated lanthanum in the blood peptide rare earth chelate and the yield.

[0027] In the present application, through the synergy between the membrane-breaking treatment and the enzymatic hydrolysis treatment, the yield and rare earth chelation rate of the blood peptide rare earth chelate can be increased, and thus a blood peptide rare earth chelate with high yield, high content of chelated cerium, and high content of chelated lanthanum can be prepared. The membrane-breaking treatment destroys the blood cell membrane structure, releases globin and improves the accessibility of the enzymatic hydrolysis substrate. The dispersed globin molecules are more likely to bind to the protease, enhancing the enzymatic hydrolysis rate. At the same time, the targeted cleavage of the protease hydrolyzes globin into small peptides. The peptide chain conformation of the small peptides is flexible and more likely to fit with rare earth ions. While the macromolecular protein may cause the masking of chelation sites due to its rigid structure, the increase in the appropriate molecular weight of small peptides not only provides more chelation sites, enhancing the binding amount of Ce 3+ 、La 3 +, but also the folded structure of the small peptides can provide more protection for the rare earth, making the chelate more stable. At the same time, in the present application, by adjusting the enzymatic hydrolysis time, temperature and enzyme activity, over-cutting to generate free amino acids is avoided to weaken its chelation ability, thereby ensuring the stability and yield of the blood peptide rare earth chelate.

[0028] In this application, when the amount of rare earth added is too little, some small peptides will not be able to chelate, thereby reducing the content of chelated rare earth in the blood peptide rare earth chelate; when the amount of rare earth added is too much, some rare earths will not be able to chelate, thereby increasing the content of free rare earth in the blood peptide rare earth chelate. When the free rare earth in the blood peptide rare earth chelate is not completely collected later, it will cause waste of rare earth. After testing, it was found that the temperature of the chelation condition is best controlled at 85-90 ° C. When the temperature is too high, the peptide chain easily aggregates to form irreversible precipitation (such as β-folding stacking), resulting in a reduction in effective coordination groups; Ce 3+ May oxidize to Ce at high temperature 4+ , thereby reducing the chelating ability; when the temperature is too low, the reaction rate is insufficient, the chelating time is prolonged, the peptide chain is not fully unfolded, the chelating site is insufficiently exposed, and the chelating rate is reduced.

[0029] Optionally, the animal blood is pig blood, duck blood, chicken blood, cow blood or sheep blood.

[0030] Optionally, the amount of the anticoagulant added is 10-15% of the weight of the animal's fresh blood.

[0031] Optionally, the anticoagulant is any one or more of sodium citrate anticoagulant, potassium fluoride anticoagulant, heparin anticoagulant, and hirudin anticoagulant.

[0032] Optionally, the centrifugal condition is: centrifugation at a speed of 3000-8000 r / min for 5-20 min.

[0033] Optionally, the amount of antioxidant added to the stabilizer is 0.1-0.3% by weight of the animal blood cell solution.

[0034] Optionally, the added amount of the surfactant in the stabilizer is 0.01-0.05% by weight of the animal blood cell solution.

[0035] Optionally, the buffer comprises any one of a phosphate buffer, a 4-hydroxyethylpiperazineethanesulfonic acid buffer, and a Tris-HCl buffer.

[0036] Optionally, the antioxidant includes any one of ascorbic acid, vitamin E, and propyl gallate.

[0037] Optionally, the surfactant includes any one of Tween-80, sodium dodecyl sulfate, and sodium dodecylbenzenesulfonate.

[0038] By adopting the above technical solution, the buffer can stabilize the pH value of the solution, the antioxidant can inhibit oxidative denaturation, and the surfactant can reduce interfacial tension and prevent aggregation.

[0039] Optionally, in the hemolysis treatment, deionized water is added to the membrane-lysed blood cell solution in a volume of 2-4 times to obtain a solution after hemolysis.

[0040] In a specific embodiment, in the hemolysis treatment, deionized water is added to the membrane-lysed blood cell solution in a volume of 3 times to obtain a solution after hemolysis.

[0041] By adopting the above technical solution, by controlling the addition amount of deionized water, the dry matter content in the membrane-lysed blood cell solution is ensured to be controlled at about 10%, which is beneficial to the subsequent enzymatic hydrolysis reaction.

[0042] Optionally, in the enzymatic hydrolysis treatment, the compound protease comprises papain and alkaline protease, the enzyme activity of papain is 150000-300000 U / ml, and the enzyme activity of alkaline protease is 50000-100000 U / ml.

[0043] Optionally, in the enzymatic hydrolysis treatment, the pH of the solution after hemolysis is adjusted to 8-10 before adding the compound protease.

[0044] Optionally, in the separation treatment, the enzymatic hydrolysate is separated by a ceramic membrane to obtain a blood peptide solution. The particle size of the ceramic membrane is 80-120 nm.

[0045] In a specific embodiment, the particle size of the ceramic membrane is 100 nm.

[0046] By adopting the above technical solution, the ceramic membrane can separate heme from the enzymatic hydrolysate to obtain a crude solution containing small peptides. Then, the undigested globin and compound protease are filtered out through an ultrafiltration membrane to obtain a peptide solution with higher purity, which is further beneficial to the chelation reaction between small peptides and rare earths in the later stage.

[0047] Optionally, in the rare earth pretreatment, the weight ratio of the rare earth to the weak acid is (5-7):(3-5).

[0048] In a specific embodiment, the weight ratio of the rare earth to the weak acid is 6:4.

[0049] Optionally, the weak acid is any one of acetic acid and lactic acid.

[0050] Optionally, the rare earth is selected from one or more of rare earth carbonate, rare earth nitrate, and rare earth chloride.

[0051] By adopting the above technical solution, compared with rare earth nitrates and rare earth chlorides, rare earth carbonates have more stable properties and do not produce dangerous gases such as ammonia or chlorine. Rare earth carbonates react with acetic acid to form rare earth acetates. In rare earth acetates, lanthanum and cerium are more soluble in water, and lanthanum and cerium are more likely to chelate with small peptides, free amino acids, etc. in blood peptides in ionic states.

[0052] Optionally, in the purification treatment, a nanofiltration membrane with a molecular weight cut-off of 150 - 800 Da is used for treatment.

[0053] Optionally, in the purification treatment, a nanofiltration membrane with a molecular weight cut-off of 200 - 300 Da is used for treatment.

[0054] In a specific embodiment, the molecular weight cut-off of the nanofiltration membrane is 200 Da.

[0055] In a specific embodiment, the molecular weight cut-off of the nanofiltration membrane is 300 Da.

[0056] During the animal feeding process, animals have low utilization rate of free rare earth in feed, resulting in the excretion of free rare earth from the animal body and causing waste of resources. In this application, the purification treatment can remove free rare earth, improve the utilization rate of rare earth and protect the environment at the same time. After the free rare earth is purified and removed, the concentration of free rare earth in the reaction system decreases. According to Le Chatelier's principle, the equilibrium shifts in the direction of forming chelates. At the same time, the high efficiency of the chelation reaction reduces the purification load, and the thoroughness of the purification provides high-purity raw materials for the next round of chelation, forming a process closed-loop.

[0057] The synergistic effect of the chelation reaction and the purification treatment is essentially a coupling mechanism of "chemical binding - physical separation - resource recycling" in one, that is: the chelation reaction locks rare earth through a thermodynamically stable coordination structure; the purification technology physically screens out free rare earth and recycles it; the two form a positive feedback loop, promoting the process to spontaneously optimize in the direction of high conversion rate and low loss. This synergistic strategy not only solves the problem of low utilization rate of free rare earth, but also realizes the industrial production closed-loop of "precision chelation - efficient separation - green recycling".

[0058] Optionally, the steps of the spray drying are as follows: spray dry the concentrated solution to obtain the blood peptide rare earth chelate.

[0059] Optionally, the specific operation of the spray drying is: homogenize the concentrated solution at a pressure of 40 - 80 Mpa for 10 - 20 min, and then carry out spray drying under the conditions of an inlet air temperature of 200 - 220 °C, an outlet air temperature of 75 - 80 °C, and a pressure of 180 - 200 kg / cm 2 for the conditions.

[0060] By homogenizing the concentrated solution, the chelate aggregates can be broken into smaller particles. The increased specific surface area can reduce the moisture diffusion path during drying, shorten the drying time, avoid excessive heat exposure, and enhance the stability between the rare earth and the chelating ligand structure, thereby ensuring the stability of the blood peptide rare earth chelate during spray drying. Meanwhile, during the two homogenization processes, the first homogenization can break the soft aggregates dominated by van der Waals forces, and the second homogenization can further refine the particles to overcome the hard aggregates caused by electrostatic adsorption.

[0061] Optionally, after the spray drying, the obtained blood peptide rare earth chelate is made into particles with a particle size of 1 mm by a double-roll dry granulator to obtain a blood peptide rare earth chelate product.

[0062] In a second aspect, the present application provides a blood peptide rare earth chelate prepared by the above preparation method.

[0063] In a third aspect, the present application provides the use of the above blood peptide rare earth chelate in the field of animal feed.

[0064] Optionally, the blood peptide rare earth chelate is used to prepare aquatic and / or piglet feed.

[0065] Optionally, the addition amount of the blood peptide rare earth chelate is 0.1-0.3% of the total weight of the feed.

[0066] Optionally, the addition amount of the blood peptide rare earth chelate is 0.2% of the total weight of the feed.

[0067] The blood peptide rare earth chelate prepared in the present application can be used as a substitute for antibiotics. After adding the blood peptide rare earth chelate to the feed and feeding aquatic products and piglets, it can improve the growth performance of aquatic products and piglets and reduce the incidence of diseases. Through experiments, it is found that the blood peptide rare earth chelate in the present application can increase the daily weight gain of piglets and reduce the content of harmful bacteria in the intestines of piglets, thereby reducing the feed-to-meat ratio and the incidence of diseases of piglets. In the present application, after adding the blood peptide rare earth chelate to the animal feed, the average daily weight gain of the animals increases by more than 10%, and the incidence of diseases decreases by more than 8%. Among them, the numbers of Escherichia coli and Salmonella in the animal intestines decrease.

[0068] In summary, the technical solution of the present application has the following beneficial effects:

[0069] (1) In the present application, through key processes such as stepped homogenization and membrane rupture, composite enzyme synergistic enzymatic hydrolysis, precise chelation, and nanofiltration purification, the membrane rupture rate, chelation rate, and free rare earth recovery rate are improved, successfully solving the technical problems of the traditional blood globulin with a scarlet color, poor palatability, and low rare earth bioavailability.

[0070] (2) Through the synergy between membrane rupture treatment and enzymatic hydrolysis treatment, the prepared blood peptide rare earth chelate has the advantages of high chelation rate (cerium and lanthanum chelation rates are both >89%), low color (light yellow), easy absorption (efficient uptake through the peptide transport system PEPT1), etc. The finished product rate is more than 85%, and the chelated cerium accounts for more than 2.7% of the total weight of the blood peptide rare earth chelate, and the chelated lanthanum accounts for more than 2.7% of the total weight of the blood peptide rare earth chelate.

[0071] (3) In the present application, the free rare earth in the crude chelate can be removed by purifying the crude chelate, so that the rare earth chelation rate in the blood peptide rare earth chelate can reach more than 90%. In addition, the free rare earth in the crude chelate is separated and the free rare earth is reused to avoid discharge and pollution of the environment.

[0072] (4) The blood peptide rare earth chelate prepared in this application can replace antibiotics as a feed additive, significantly improve animal production performance, increase daily weight gain, reduce feed-to-meat ratio, and significantly reduce morbidity through multiple mechanisms such as targeted antibacterial, immune activation and anti-oxidation.

[0073] (5) This application achieves high-value conversion of slaughter blood by-products, providing a new solution that is both functional and safe for green farming. DETAILED DESCRIPTION

[0074] Before describing the embodiments of the present application in detail, it should be understood that the terminology used herein is only for the purpose of describing particular embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the term belongs.

[0075] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. Furthermore, in the description of this application, unless otherwise specified, "plurality" means two or more.

[0076] The endpoints of the ranges and any values disclosed in this application are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0077] In this application, the term "comprise" or "include" is an open expression, that is, it includes the content specified in this application, but does not exclude other aspects of the content.

[0078] The present application provides a method for preparing a blood peptide rare earth chelate. The above-mentioned preparation method specifically includes the following steps: preparing a peptide solution, rare earth pretreatment, chelation reaction, purification treatment, and spray drying. Specifically as follows:

[0079] (1) Preparation of a peptide solution

[0080] (1) Preparation of an animal blood cell solution: Using commercially available animal fresh blood as a raw material, adding an anticoagulant and centrifuging to obtain an animal blood cell solution.

[0081] Among them, the addition amount of the anticoagulant is 10-15% of the weight of the animal fresh blood. The type of anticoagulant can be any one or more of sodium citrate anticoagulant, potassium fluoride anticoagulant, heparin anticoagulant, and hirudin anticoagulant. When the anticoagulant is sodium citrate anticoagulant, the concentration of sodium citrate is 3.8% or 3.2%.

[0082] Among them, the centrifugation conditions are: centrifuging at a speed of 3000-8000 r / min for 5-20 min. Preferably, the centrifugation conditions are centrifuging at a speed of 4000 r / min for 10 min.

[0083] (2) Membrane-breaking treatment: Using a buffer solution to stabilize the pH of the animal blood cell solution at 7.4-8.0, adding a stabilizer, and performing stepwise homogenization at a pressure of 30-70 Mpa for 8-16 min to obtain a membrane-broken blood cell solution.

[0084] Among them, the addition amount of the stabilizer is 0.05-0.3% of the animal blood cell solution. The stabilizer includes an antioxidant and a surfactant. Among them, the addition amount of the antioxidant is 0.1-0.3% of the weight of the animal blood cell solution, and the addition amount of the surfactant is 0.01-0.05% of the weight of the animal blood cell solution.

[0085] Among them, the buffer solution includes any one of phosphate buffer solution, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer solution, and Tris-HCl buffer solution; the antioxidant includes any one of ascorbic acid, vitamin E, and propyl gallate; the emulsifier includes any one of Tween-80, sodium dodecyl sulfate, and sodium dodecylbenzenesulfonate.

[0086] Among them, the stepwise homogenization method is: sequentially performing cyclic homogenization 2-4 times under the first pressure and the second pressure, and the homogenization time under each pressure is 2 min. Among them, the first pressure is 30-50 Mpa, the second pressure is 50-70 Mpa, and the difference between the first pressure and the second pressure is 10-20 Mpa.

[0087] (3) Preparation of a peptide solution: Subjecting the membrane-broken blood cell solution to hemolysis treatment, enzymatic hydrolysis treatment, separation treatment, and ultrafiltration treatment in sequence to obtain a peptide solution. Specifically as follows:

[0088] A. Hemolysis treatment: Add deionized water to the membrane-lysed blood cell solution at a volume of 2 - 4 times to control the dry matter content of the solution at about 10% to obtain the hemolyzed solution.

[0089] B. Enzymolysis treatment: Add compound protease to the hemolyzed solution, enzymolyze at 45 - 55 °C for 7 - 9 h, and then inactivate the enzyme at 85 - 90 °C for 5 - 15 min to obtain the enzymolyzed solution.

[0090] Among them, the addition amount of the compound protease is 2 - 4% of the dry matter weight in the hemolyzed solution.

[0091] Among them, the addition amount of the compound protease is 2%, 3%, 4%, 2 - 3%, 3 - 4% of the dry matter weight in the hemolyzed solution.

[0092] Among them, the enzymolysis time is 7 h, 8 h, 9 h, 7 - 8 h or 8 - 9 h.

[0093] Among them, the enzymolysis temperature is 45 °C, 50 °C, 55 °C, 45 - 50 °C, 50 - 55 °C.

[0094] Among them, the compound protease includes papain and alkaline protease. The enzyme activity of papain is 150000 - 300000 U / ml, and the enzyme activity of alkaline protease is 50000 - 100000 U / ml. In a specific embodiment, the enzyme activity of papain is 200000 U / ml, and the enzyme activity of alkaline protease is 100000 U / ml.

[0095] Optionally, adjust the pH of the hemolyzed solution to 8 - 10 before adding the compound protease to the hemolyzed solution.

[0096] C. Separation treatment: Separate the enzymolyzed solution with a ceramic membrane to obtain a blood peptide solution. Among them, the particle size of the ceramic membrane is 80 - 120 nm.

[0097] D. Ultrafiltration treatment: Separate the blood peptide solution through an ultrafiltration membrane with a cut-off molecular weight of 4000 Da to obtain a peptide solution.

[0098] (II) Rare earth pretreatment

[0099] Mix the rare earth with a weak acid and react for 30 - 60 min to obtain the pretreated rare earth.

[0100] Among them, the weight ratio of the rare earth to the weak acid is (5 - 7):(3 - 5). The weak acid can be any one of acetic acid and lactic acid.

[0101] (III) Chelation reaction

[0102] Mix the peptide solution and the pretreated rare earth for chelation reaction to obtain a crude chelate.

[0103] Among them, the addition amount of rare earth is 10-20% of the dry matter weight in the peptide solution.

[0104] Among them, the chelation conditions are: reacting for 90-120 min in an environment with a pH of 3-4 and a temperature of 85-90 °C.

[0105] Among them, the rare earth is any one or more of rare earth carbonate, rare earth nitrate, and rare earth chloride.

[0106] In a specific embodiment, the rare earth used is rare earth carbonate.

[0107] Among them, the proportion of small peptides with a molecular weight of 1000-4000 Da in the peptide solution reaches 85-90%.

[0108] (IV) Purification treatment

[0109] Filter the crude chelate with a nanofiltration membrane with a molecular weight cut-off of 150-800 Da to obtain a concentrate and a filtrate.

[0110] Optionally, the molecular weight cut-off of the nanofiltration membrane is 200-300 Da.

[0111] (V) Spray drying

[0112] Perform spray drying on the concentrate to obtain a blood peptide rare earth chelate.

[0113] Among them, the specific operation of spray drying is: homogenize the concentrate at a pressure of 40-80 Mpa for 10-20 min, and then place it under the conditions of an inlet air temperature of 200-220 °C, an exhaust air temperature of 75-80 °C, and a pressure of 180-200 kg / cm 2 for spray drying.

[0114] To make the purpose, technical solution, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application. The following described embodiments are exemplary and are only used to explain this application and should not be construed as a limitation of this application.

[0115] For those not specified in the embodiments in terms of specific techniques or conditions, follow the techniques or conditions described in the literature in this field or the product specifications. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0116] In the following embodiments, the animal blood used is commercially available duck blood.

[0117] In the following examples, the composite protease used includes papain with an enzyme activity of 200,000 U / ml and alkaline protease with an enzyme activity of 100,000 U / ml. Both papain and alkaline protease are commercially available.

[0118] In the following examples, the ultrafiltration membranes, nanofiltration membranes and ceramic membranes used are all commercially available.

[0119] In the following examples, the rare earth used is rare earth carbonate, which is a mixture of 50% lanthanum carbonate and 50% cerium carbonate and is sourced from Ganxian Hongjin Rare Earth Co., Ltd.

[0120] The present application is further described in detail below in conjunction with the examples and test results.

[0121] Example

[0122] Example 1

[0123] This embodiment provides a method for preparing a blood peptide rare earth chelate.

[0124] The above preparation method specifically includes the following steps: preparation of peptide solution, rare earth pretreatment, chelation reaction, purification treatment, and spray drying. The details are as follows:

[0125] (1) Preparation of peptide solution

[0126] (1) Preparation of animal blood cell solution: 1000 L of commercially available duck blood was taken, 3.8% sodium citrate anticoagulant was added at a rate of 10%, and the mixture was centrifuged at 4000 rpm for 10 min to obtain 425 L of animal blood cell solution and 575 L of plasma solution.

[0127] (2) Membrane rupture treatment: Add phosphate buffer to the animal blood cell solution to maintain the pH at 7.4-8.0. Then, add 500 g of ascorbic acid and 50 ml of Tween-80. Homogenize the solution twice at 30 MPa and then 50 MPa, with each homogenization time being 2 minutes. This will yield a membrane ruptured blood cell solution.

[0128] (3) Preparation of peptide solution: The membrane-ruptured blood cell solution is subjected to hemolysis, enzymatic hydrolysis, separation and ultrafiltration in sequence to obtain a peptide solution. The details are as follows:

[0129] A. Hemolysis: Add 1200 L of deionized water to the ruptured blood cell solution to obtain 1620 L of hemolyzed solution;

[0130] B. Enzymatic hydrolysis treatment: Adjust the pH of the hemolyzed solution to 8 - 10 (adjust the pH with sodium hydroxide or compound acid), adjust the temperature to 55 °C, add compound protease (the addition amount is 3% of the dry matter weight in the hemolyzed solution), and then stir continuously. During this period, maintain the temperature at 55 °C and the pH at 8 - 10, and carry out enzymatic hydrolysis for 8 h; then raise the temperature to 85 - 90 °C to inactivate the enzyme for 10 min to obtain the enzymatic hydrolysate;

[0131] C. Separation treatment: Separate the enzymatic hydrolysate with a 100 nm ceramic membrane to obtain a blood peptide solution;

[0132] D. Ultrafiltration treatment: Separate the blood peptide solution with an ultrafiltration membrane with a molecular weight cut-off of 4000 Da to obtain a peptide solution.

[0133] (II) Rare earth pretreatment

[0134] Mix rare earth carbonate and acetic acid in a weight ratio of 6:4, and react for 30 - 60 min to obtain rare earth acetate.

[0135] (III) Chelation reaction

[0136] Mix the peptide solution and rare earth acetate, and carry out a chelation reaction for 90 min in an environment with a pH of 3 - 4 and a temperature of 90 °C to obtain a crude chelate.

[0137] The addition amount of rare earth acetate is 10% of the dry matter weight in the peptide solution.

[0138] (IV) Purification treatment

[0139] Filter the crude chelate with a nanofiltration membrane with a molecular weight cut-off of 200 Da to obtain a concentrate and a filtrate.

[0140] (V) Spray drying

[0141] Homogenize the concentrate at a pressure of 65 Mpa for 10 min, and then place it under the conditions of an inlet air temperature of 200 °C, an outlet air temperature of 80 °C, and a pressure of 180 - 200 kg / cm 2 for spray drying to obtain a blood peptide rare earth chelate.

[0142] (VI) Granulation

[0143] Make the obtained blood peptide rare earth chelate into particles with a particle size of 1 mm by a double-roll dry granulator to obtain a blood peptide rare earth chelate product.

[0144] Examples 2 - 5

[0145] Examples 2-5 respectively provide a preparation method of a blood peptide rare earth chelate. The differences between the above examples and Example 1 are as follows: during the preparation of the peptide solution, the pressure settings for stepwise homogenization during the membrane-breaking treatment are shown in Table 1 specifically, and the remaining steps are the same as those in Example 1.

[0146] Comparative Example

[0147] Comparative Examples 1-2

[0148] Comparative Examples 1-2 respectively provide a preparation method of a blood peptide rare earth chelate. The differences between the above comparative examples and Example 3 are as follows: during the preparation of the peptide solution, the pressure settings for stepwise homogenization during the membrane-breaking treatment are shown in Table 1 specifically, and the remaining steps are the same as those in Example 3.

[0149] Comparative Example 3

[0150] Comparative Example 3 provides a preparation method of a blood peptide rare earth chelate. The differences between the above comparative example and Example 3 are as follows: during the preparation of the peptide solution, the step of stepwise homogenization is not carried out during the membrane-breaking treatment, as shown in Table 1 specifically, and the remaining steps are the same as those in Example 3.

[0151] Table 1 Partial parameter settings of examples and comparative examples

[0152]

[0153]

[0154] Examples 6-9

[0155] Examples 6-9 respectively provide a preparation method of a blood peptide rare earth chelate. The differences between the above examples and Example 3 are as follows: the parameter control in the enzymatic hydrolysis treatment step is shown in Table 1 specifically, and the remaining steps are the same as those in Example 3.

[0156] The specific differences are as follows:

[0157] The differences between Examples 6-7 and Example 3 are as follows: the addition amount of compound protease.

[0158] The differences between Examples 8-9 and Example 3 are as follows: the enzymatic hydrolysis time.

[0159] Comparative Examples 4-7

[0160] Comparative Examples 4-7 respectively provide a preparation method of a blood peptide rare earth chelate. The differences between the above comparative examples and Example 3 are as follows: the parameter control in the enzymatic hydrolysis treatment step is shown in Table 1 specifically, and the remaining steps are the same as those in Example 3.

[0161] The specific differences are as follows:

[0162] The difference between Comparative Example 4-5 and Example 3 is: the type of protease.

[0163] The difference between Comparative Example 6-7 and Example 3 is the amount of compound protease added.

[0164] Performance test 1

[0165] The membrane rupture rates of the membrane ruptured blood cell solutions in the above examples and comparative examples and the small peptide contents in the obtained peptide solutions were tested below.

[0166] (1) Rupture rate of membrane ruptured blood cell solution

[0167] Detection method: hemoglobin release method.

[0168] Principle of the method: After the blood cell membrane is ruptured, hemoglobin will be released into the solution. The concentration of hemoglobin can indirectly reflect the membrane rupture rate.

[0169] Detection steps: Take the blood cell solution after membrane permeabilization, centrifuge (e.g., 3000 rpm, 10 minutes) to separate the supernatant, and measure the hemoglobin concentration in the supernatant.

[0170] The membrane rupture rate is calculated as follows: Membrane rupture rate = supernatant hemoglobin concentration / total hemoglobin concentration × 100%. The total hemoglobin concentration can be measured on samples after complete membrane rupture.

[0171] (2) Small peptide content in peptide solution

[0172] Detection method: bicinchoninic acid method.

[0173] Principle of the method: The reducing groups in the peptide chain react with the BCA reagent to form a purple complex with a characteristic absorption peak at 562nm.

[0174] Assay steps: Take an appropriate amount of peptide solution and add BCA working solution. Incubate at 37°C for 30 minutes and measure absorbance at 562 nm. Calculate peptide content based on the standard curve.

[0175] (3) Test results

[0176] The test results are shown in Table 2.

[0177] Table 2 Detection of membrane rupture rate and small peptide content

[0178]

[0179] As can be seen from Table 2, using the preparation method of the present application, the membrane rupture rate of the animal blood cell solution can reach more than 90% after treatment, and the small peptide content in the peptide solution obtained after hemolysis, enzymatic hydrolysis, separation and ultrafiltration can reach 85-90%.

[0180] Performance Detection Test Two

[0181] The yield and rare earth chelation rate of the blood peptide rare earth chelate prepared in the above-mentioned examples and comparative examples were detected as follows.

[0182] (1) Contents and chelation degrees of chelated cerium and chelated lanthanum

[0183] The detection principle is as follows: In an HCl-NaAc buffer solution (pH = 3.0) in the presence of ethanol and cetyltrimethylammonium bromide (CTMA), lanthanum (La) and cerium (Ce) form a 1:3 complex with arsenazo (Ⅲ), having a maximum absorption peak at 665 nm, and the molar absorption coefficients are εLa = 1.58×10 5 L / mol / cm and εCe = 1.66×10 5 L / mol / cm. Other interfering elements can be masked with Zn-RDTA, and by changing the amount of Zn-EDTA, the absorbances of lanthanum (La) and cerium (Ce) can be changed. Then, according to Beer's law, a system of simultaneous equations for the relationship between the concentrations of lanthanum (La) and cerium (Ce) and absorbance can be established, so that the contents of lanthanum and cerium in the blood peptide rare earth chelate can be obtained.

[0184] The reagents used are as follows: Arsenazo (Ⅲ) solution: Weigh 0.25 g of AR-grade arsenazo (Ⅲ) into a 500 mL volumetric flask, add water and dilute to the mark to obtain a 0.05% solution. CTMA solution: Mix AR-grade CTMA with deionized water to prepare a 0.01 mol / L aqueous solution. HCI-NaAc buffer solution: Take equal volumes of a 1 mol / L HCl solution and a 1 mol / L NaAc solution, mix them evenly, and adjust the pH to 3.0 with 5% HCl and 1:1 ammonia water on a pH meter. Zn-EDTA solution: Weigh pure Zn powder (content ≥ 99.9%) and dissolve it with appropriate amount of HCl to prepare a 0.10 mol / L Zn zinc ion (divalent) solution. Additionally, weigh 7.445 g of EDTA Na2·2H20, dissolve it in 50 - 60 mL of water, add the above 20 mL of zinc ion solution, mix evenly, adjust the pH to 3.5, and then dilute to 100 mL. Mixed masking agent: Weigh 10 g of tartaric acid, 10 g of sodium pyrophosphate, and 1 g of citric acid, mix them, dissolve in an appropriate amount of water, adjust the pH to 3.0, and then dilute to 100 ml.

[0185] The instrument used is a 722-type spectrophotometer with a wavelength range of 200 nm - 1000 nm.

[0186] Preparation of standard solutions: Weigh 0.0266 g of CeC13·7H2O (cerous chloride, AR grade, content ≥ 99.0%), dissolve it with 30 mL of 5 mol / L HCl. After complete dissolution, transfer it into a 1000 mL volumetric flask, dilute it to the mark with water, shake well, and prepare a standard solution with a cerium concentration of 10 μg / mL; Weigh 0.0117 g of La2O3 (lanthanum oxide, content ≧ 99.99%), and similarly, prepare a standard solution with a lanthanum concentration of 10 μg / mL using 30 mL of 5 mol / L HCl; Prepare a mixed standard solution of lanthanum and cerium according to the ratio of cerium:lanthanum = 5:10.

[0187] Drawing the working curve: Pipette 0 mL, 0.5 mL, 1.0 mL, 1.5 mL, and 2.0 mL of the mixed standard solution of lanthanum and cerium into 25 mL colorimetric tubes respectively. Add 2 mL (for measuring La) or 4 mL (for measuring Ce) of Zn-EDTA solution and mix well. Then add 5.0 mL of HCI-NaAc buffer solution, 3.0 mL of 0.05% arsenazo (Ⅲ) aqueous solution, 1.0 mL of 0.01 mol / L CTMA solution, and 1.2 mL of absolute ethanol in sequence, and dilute to the mark with water to obtain 5 kinds of standard solutions of lanthanum or cerium with concentrations of 0 μg / 25 mL, 5 μg / 25 mL, 10 μg / 25 mL, 15 μg / 25 mL, and 20 μg / 25 mL; Shake well, let it stand for 5 min, then use a 1 cm colorimetric cell to detect at 665 nm on a 722-type spectrophotometer, using the corresponding reagent blank as the reference, and measure the absorbance; Take the absorbance as the ordinate and the number of micrograms of lanthanum or cerium contained in the pipetted solution as the abscissa to draw the working curve.

[0188] Detection of the total content of lanthanum (cerium) in the blood peptide rare earth chelate: Accurately weigh 0.3000 g of the sample, dissolve it with 3 mL of concentrated HNO3, transfer it into a 1000 mL volumetric flask, dilute it to the mark with water, shake well, then measure 10 mL and dilute it to 100 mL. The content of lanthanum or cerium in this solution is estimated to be 10 - 20 μg / mL (if the result is not appropriate, adjust according to the situation and re-prepare). Then measure the absorbance under the same conditions as the standard solution, and substitute the measured absorbances of lanthanum and cerium into their respective standard curves respectively. Thus, the contents of lanthanum and cerium in the sample can be obtained.

[0189] Detection of the content of free lanthanum (cerium) in the blood peptide rare earth chelate: Take 0.5000 g of the sample, stir it with 250 mL of water for 10 - 20 min, let it stand for 30 - 60 min, then take the upper clear liquid and use 0.05% arsenazo (Ⅲ) solution as the color-developing agent to measure the absorbance at 665 nm wavelength on a 722-type spectrophotometer, and calculate the contents of unchelated free lanthanum and cerium in the sample according to the working curve method.

[0190] The content of chelated cerium (chelated lanthanum) in the blood peptide rare earth chelate = the total content of lanthanum (cerium) in the blood peptide rare earth chelate - the content of free lanthanum (cerium) in the blood peptide rare earth chelate.

[0191] The rare earth chelation degree (%) = the content of chelated rare earth (lanthanum, cerium) / the total amount of rare earth (lanthanum, cerium) in the sample × 100%.

[0192] (2) Yield

[0193] The calculation method of the yield is as follows:

[0194] The yield (%) = the weight of the blood peptide rare earth chelate / (the weight of fresh blood + the weight of rare earth + the weight of acetic acid) × 100%.

[0195] (3) Test results

[0196] The test results are shown in Table 3.

[0197] Table 3 Rare earth content and yield in the blood peptide rare earth chelates of the examples and comparative examples

[0198]

[0199] As can be seen from Table 3, the rare earth chelation rate of the blood peptide rare earth chelate prepared by the preparation method of the present application can reach more than 90%, and the yield can reach more than 85%.

[0200] Application of the blood peptide rare earth chelate

[0201] The blood peptide rare earth chelate provided in Example 3 of the present application was added to animal feed to verify its application in animal feed.

[0202] 120 suckling piglets aged 1 - 2 weeks were selected and randomly divided into 6 groups with 20 piglets in each group. A feeding comparison test was carried out using feeds added with different blood peptide rare earth chelates (as shown in Table 4, the addition amount of the blood peptide rare earth chelate is the percentage of the weight of the suckling piglet feed). They were fed continuously for 20 days, and the growth of the test suckling piglets was recorded. The ileal contents of 5 suckling piglets in each group were taken back to the laboratory, and then the numbers of Escherichia coli and Salmonella were detected by the plate counting method. The results are shown in Table 5 below.

[0203] Table 4 Sources and addition amounts of the blood peptide rare earth chelates in the application examples

[0204]

[0205] Table 5 Data statistics on the growth of suckling piglets and the number of ileal bacteria

[0206]

[0207] As can be seen from Table 5, compared with Application Example 1, the average daily gain of suckling piglets in Application Examples 2-4 increased, while the feed-to-meat ratio, the content of Escherichia coli in the ileum and the incidence rate decreased. Therefore, when the addition amount of the blood peptide rare earth chelate prepared in this application is 0.1-0.3% of the total weight of the feed, the effect is the best.

[0208] Compared with Application Examples 2-4, the growth of suckling piglets in Application Examples 5-6 was poor and the incidence rate increased. It can be seen that adding cerium element and lanthanum element to the suckling piglet feed is beneficial to the growth of suckling piglets, and the absorption effect of the blood peptide rare earth chelate by suckling piglets is better than that of cerium element and lanthanum element.

[0209] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0210] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A preparation method of a blood peptide rare earth chelate, characterized in that, The preparation method specifically includes the following steps: preparing a peptide solution, rare earth pretreatment, chelation reaction, purification treatment, and spray drying; Among them, the steps for preparing the peptide solution are as follows: (1) Preparing an animal blood cell solution: adding an anticoagulant to animal fresh blood and centrifuging to obtain the animal blood cell solution; (2) Membrane-breaking treatment: stabilizing the pH of the animal blood cell solution at 7.4 - 8.0 with a buffer solution, adding a stabilizer, and performing stepwise homogenization at a pressure of 30 - 70 Mpa for 8 - 16 min to obtain a membrane-broken blood cell solution; The addition amount of the stabilizer is 0.05 - 0.3% of the weight of the animal blood cell solution; the stabilizer includes an antioxidant and a surfactant; The method of stepwise homogenization is: circulating and homogenizing 2 - 4 times successively at a first pressure and a second pressure, with the homogenization time at each pressure being 2 min; the first pressure is 30 - 50 Mpa; the second pressure is 50 - 70 Mpa; the difference between the first pressure and the second pressure is 10 - 20 Mpa; (3) Preparing a peptide solution: subjecting the membrane-broken blood cell solution to hemolysis treatment, enzymatic hydrolysis treatment, separation treatment, and ultrafiltration treatment in sequence to obtain a peptide solution; In the enzymatic hydrolysis treatment, adding a compound protease to the hemolyzed solution, performing enzymatic hydrolysis at 45 - 55 °C for 7 - 9 h, and then inactivating the enzyme at 85 - 90 °C for 5 - 15 min to obtain an enzymatic hydrolysate; the addition amount of the compound protease is 2 - 4% of the dry matter weight in the hemolyzed solution; In the ultrafiltration treatment, using an ultrafiltration membrane with a molecular weight cut-off of 4000 Da for treatment; Among them, the steps for rare earth pretreatment are as follows: Mixing rare earth with a weak acid and reacting for 30 - 60 min to obtain pretreated rare earth; Among them, the steps for the chelation reaction are as follows: Performing a chelation reaction on the peptide solution and the pretreated rare earth to obtain a crude chelate; the addition amount of the rare earth is 10 - 20% of the dry matter weight in the peptide solution; the conditions for the chelation reaction are: reacting in an environment with a pH of 3 - 4 and a temperature of 85 - 90 °C for 90 - 120 min.

2. The preparation method according to claim 1, characterized in that, The addition amount of the anticoagulant is 10 - 15% of the weight of the animal fresh blood; Optionally, the anticoagulant is any one or more of sodium citrate anticoagulant, potassium fluoride anticoagulant, heparin anticoagulant, and hirudin anticoagulant; Optionally, the conditions for centrifugation are: centrifuging at a rotation speed of 3000 - 8000 r / min for 5 - 20 min.

3. The preparation method according to claim 1, characterized in that, The addition amount of the antioxidant in the stabilizer is 0.1 - 0.3% of the weight of the animal blood cell solution; Optionally, the addition amount of the surfactant in the stabilizer is 0.01 - 0.05% of the weight of the animal blood cell solution; Optionally, the buffer solution includes any one of phosphate buffer solution, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer solution, and Tris-HCl buffer solution; Optionally, the antioxidant includes any one of ascorbic acid, vitamin E, and propyl gallate; Optionally, the surfactant includes any one of Tween-80, sodium dodecyl sulfate, and sodium dodecylbenzenesulfonate.

4. The preparation method according to claim 1, wherein, In the hemolysis treatment, deionized water is added to the membrane-lysed blood cell solution in a volume of 2 to 4 times to obtain a post-hemolysis solution.

5. The preparation method according to claim 1, characterized in that, In the enzymatic hydrolysis treatment, the complex protease comprises papain and alkaline protease. The enzyme activity of the papain is 150,000 - 300,000 U / ml, and the enzyme activity of the alkaline protease is 50,000 - 100,000 U / ml; Optionally, in the enzymatic hydrolysis treatment, the pH of the post-hemolysis solution is adjusted to 8 - 10 before adding the complex protease.

6. The preparation method according to claim 1, wherein In the rare earth pretreatment, the weight ratio of the rare earth to the weak acid is (5 - 7):(3 - 5); Optionally, the weak acid is any one of acetic acid and lactic acid.

7. The preparation method according to claim 1, characterized in that, The steps of the purification treatment are as follows: treating with a nanofiltration membrane with a cut-off molecular weight of 150 - 800 Da; Optionally, the spray drying step is as follows: spray drying the concentrated solution to obtain the blood peptide rare earth chelate; the specific operation of the spray drying is: homogenize the concentrated solution at a pressure of 40-80 Mpa for 10-20 min, and then place it under the conditions of an inlet air temperature of 200-220 °C, an exhaust air temperature of 75-80 °C, and a pressure of 180-200 kg / cm 2 for spray drying.

8. A blood peptide rare earth chelate prepared by the preparation method according to any one of claims 1 - 7.

9. An application of the blood peptide rare earth chelate according to claim 8 in the field of animal feed.

10. The application according to claim 9, wherein The blood peptide rare earth chelate is used for preparing aquatic and / or piglet feed; Optionally, the addition amount of the blood peptide rare earth chelate is 0.1 - 0.3% of the total weight of the feed.

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