A coated lavender essential oil microcapsule, a preparation method and application thereof

Abstract

The present application relates to the technical field of animal feed nutrition, and discloses a coated lavender essential oil microcapsule as well as a preparation method and application thereof.The microcapsule has a double-layer structure and comprises, from inside to outside, a core and a chitosan coating layer wrapped outside the core; the core is an essential oil-beta-cyclodextrin complex; the essential oil-beta-cyclodextrin complex is formed by vacuum adsorption inclusion of lavender ester essential oil obtained by short path distillation of lavender essential oil at 6-8 kPa and 45-55 DEG C and beta-cyclodextrin.The coated lavender essential oil microcapsule prepared by the double-layer coating technology realizes efficient utilization of lavender essential oil in livestock and poultry, significantly improves the growth performance of animals, effectively reduces the incidence of diarrhea, and shows the comprehensive effects of selective bacteriostasis and immune enhancement, thereby providing a feasible solution for green feed additives to replace antibiotics.

Description

Technical Field

[0001] This invention relates to the field of animal feed nutrition technology, specifically to a coated lavender essential oil microcapsule, its preparation method, and its application. Background Technology

[0002] With increasing global emphasis on food safety and public health, the overuse of antibiotics in feed and the resulting drug residues and bacterial resistance have attracted widespread attention. Therefore, seeking safe, efficient, and residue-free antibiotic alternatives in livestock farming has become an inevitable trend in the industry. Plant essential oils, as a class of natural and renewable plant secondary metabolites, are considered one of the most promising antibiotic alternatives due to their broad-spectrum antibacterial, antioxidant, anti-inflammatory, and gut health-regulating biological activities.

[0003] Lavender essential oil is a volatile oil obtained by steam distillation of lavender (Lavandula hangustifolia), and its main active components are linalyl acetate, among others. Existing research shows that lavender essential oil has significant inhibitory effects on various common pathogens such as Escherichia coli, Salmonella, and Staphylococcus aureus. It also enhances the body's antioxidant capacity, strengthens immune function, and has positive effects on animals, including sedation and anti-stress. Based on these properties, lavender essential oil has shown promising application prospects in the field of feed additives.

[0004] However, directly using lavender essential oil in animal feed faces challenges such as volatility, oxidation, and degradation. This is especially true for ruminants with their complex rumen digestive systems. When plant essential oils enter the rumen with feed, their active ingredients are easily metabolized and decomposed by rumen microorganisms or inactivated by interactions with feed components, preventing them from reaching the small intestine in their effective form and dosage for absorption and utilization. Therefore, ensuring the targeted release of lavender essential oil's active ingredients within the intestine is a core technical challenge that must be addressed for its successful application in livestock and poultry farming.

[0005] Therefore, developing a coating product that can effectively protect the main active ingredients in lavender essential oil, such as linalyl acetate, so that they remain stable in the pre-digestive tract of livestock and poultry and achieve efficient release in the intestine is of great significance for realizing antibiotic substitution in livestock and poultry farming using lavender essential oil and promoting the green and healthy development of the livestock industry. Summary of the Invention

[0006] The present invention aims to provide a coating product that can effectively protect the active ingredients of lavender essential oil, keep them stable in the pre-digestive tract of livestock and poultry, and achieve efficient release in the intestine.

[0007] To achieve the above objectives, the first aspect of the present invention provides a coated lavender essential oil microcapsule, which has a double-layer structure, comprising, from the inside out, a core and a chitosan coating layer surrounding the core: The core is an essential oil-β-cyclodextrin complex; The essential oil-β-cyclodextrin complex is formed by vacuum adsorption encapsulation of lavender ester essential oil (obtained by short-path distillation of lavender essential oil at 6-8 kPa and 45-55℃) and β-cyclodextrin.

[0008] A second aspect of the present invention provides a method for preparing the coated lavender essential oil microcapsules described in the first aspect, comprising the following steps: (1) The lavender raw material is steam distilled, the distillate is collected, and the oil and water are separated, dehydrated and filtered to obtain lavender essential oil. Then, short-path distillation is carried out at 6-8 kPa and 45-55℃ to obtain lavender ester essential oil. (2) The lavender ester essential oil is mixed with β-cyclodextrin and encapsulated by vacuum adsorption to obtain an essential oil-β-cyclodextrin complex; (3) Using the essential oil-β-cyclodextrin complex as the core material and chitosan solution as the coating slurry, the coating is carried out by spray coating and drying through fluidized bed coating process to obtain the coated lavender essential oil microcapsules.

[0009] The third aspect of this invention provides the application of the coated lavender essential oil microcapsules described in the first aspect in the preparation of livestock and poultry feed additives.

[0010] Compared with the prior art, the present invention has at least the following beneficial effects: (1) This invention employs a double-layer coating technology combining β-cyclodextrin molecular inclusion and chitosan physical coating to construct a microcapsule structure with gradient release characteristics. The structure remains intact in the pre-digestive tract environment of livestock and poultry (pH ≤ 7.0), with a disappearance rate of less than 20%; after entering the intestinal environment (pH ≥ 8.0), it dissolves rapidly, with a cumulative release rate exceeding 80%. (2) In vitro antibacterial tests showed that the product of the present invention has a significant inhibitory effect on pathogenic bacteria such as Escherichia coli, Salmonella, and Staphylococcus aureus, but has no inhibitory effect on beneficial bacteria such as lactic acid bacteria and Bifidobacterium. (3) Animal experiments showed that adding the product of this invention to the diet of calves significantly increased the average daily weight gain and reduced the diarrhea rate compared to the control group; adding the product of this invention to the diet of lambs increased the average daily weight gain and reduced the incidence of diarrhea. For calves and lambs already suffering from diarrhea, the diarrhea symptoms were significantly relieved or disappeared within 3-4 days after using the product of this invention, demonstrating a good therapeutic effect. Adding the coated product to the diet of weaned piglets increased the average daily weight gain of weaned piglets, reduced the feed conversion ratio, effectively reduced the diarrhea rate, and had a significant inhibitory effect on Escherichia coli, but no inhibitory effect on the growth of lactic acid bacteria. Adding the coated product to the diet of laying hens and chicks significantly increased the weight, tibia length, and keel length of laying hens; adding this product to yellow-feathered broilers significantly increased body weight gain. Further analysis revealed that adding the product of this invention can significantly increase the concentration of immunoglobulins IgA, IgG, and IgM and the activity of antioxidant enzymes (SOD, GSH-Px) in animal serum, enhancing the body's immunity and antioxidant capacity, effectively replacing the use of antibiotics in feed, and avoiding drug resistance problems and drug residue risks. Detailed Implementation

[0011] The endpoints and any values ​​of the ranges disclosed herein 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0012] As mentioned above, the first aspect of the present invention provides a coated lavender essential oil microcapsule, which has a double-layer structure, comprising, from the inside out, a core and a chitosan coating layer surrounding the core: The core is an essential oil-β-cyclodextrin complex; The essential oil-β-cyclodextrin complex is formed by vacuum adsorption encapsulation of lavender ester essential oil (obtained by short-path distillation of lavender essential oil at 6-8 kPa and 45-55℃) and β-cyclodextrin.

[0013] According to a preferred embodiment, the active ingredients in the lavender ester essential oil include linalyl acetate and lavender acetate.

[0014] More preferably, in the lavender ester essential oil, the content of linaloyl acetate and lavender acetate is not less than 50 wt%.

[0015] Preferably, in the essential oil-β-cyclodextrin complex, the weight ratio of β-cyclodextrin to lavender ester essential oil is less than 1:1. In this preferred embodiment, β-cyclodextrin can form a stable molecular cavity structure, efficiently encapsulating lavender ester essential oil within it.

[0016] More preferably, in the essential oil-β-cyclodextrin complex, the weight ratio of β-cyclodextrin to lavender ester essential oil is 1:1-2.

[0017] According to a preferred embodiment, the thickness of the chitosan coating layer is controlled by a fluidized bed coating process, resulting in a thickness of 5-30 μm. The encapsulated lavender essential oil microcapsules exhibit a disappearance rate of less than 20% in the pre-digestive tract of livestock and poultry, and a release rate of over 80% in the intestine. In this preferred embodiment, a complete physical barrier is formed to effectively resist microbial invasion and pH fluctuations in the rumen environment, while the rapid release into the intestine is not hindered by excessively thick coating.

[0018] It should be explained that, in this invention, for ruminants, the "pre-digestive tract" mainly refers to the rumen, reticulum, and omasum; for monogastric animals, the "pre-digestive tract" mainly refers to the stomach and the anterior part of the small intestine.

[0019] In a preferred embodiment, the chitosan coating layer is formed from chitosan with a molecular weight of 50-300 kDa. In this preferred embodiment, chitosan within this molecular weight range can maintain its structural integrity in the rumen while rapidly dissolving in the intestine, achieving precise rumen-crossing protection and intestinal release.

[0020] In a preferred embodiment, the average volume diameter of the coated lavender essential oil microcapsules is 40-200 μm.

[0021] As mentioned above, a second aspect of the present invention provides a method for preparing the coated lavender essential oil microcapsules described in the first aspect, comprising the following steps: (1) The lavender raw material is steam distilled, the distillate is collected, and the oil and water are separated, dehydrated and filtered to obtain lavender essential oil. Then, short-path distillation is carried out at 6-8 kPa and 45-55℃ to obtain lavender ester essential oil. (2) The lavender ester essential oil is mixed with β-cyclodextrin and encapsulated by vacuum adsorption to obtain an essential oil-β-cyclodextrin complex; (3) Using the essential oil-β-cyclodextrin complex as the core material and chitosan solution as the coating slurry, the coating is carried out by spray coating and drying through fluidized bed coating process to obtain the coated lavender essential oil microcapsules.

[0022] Preferably, in step (1), the conditions for steam distillation are at least: steam pressure 0.02-0.05 MPa, temperature 98-102℃, distillation rate of condensate outflow of 5-10% of the distillation vessel volume per hour, and distillation time 1-2 h.

[0023] Preferably, in step (2), the conditions for vacuum adsorption are at least: temperature of 40-50℃, vacuum degree of -0.08 to -0.1MPa, and encapsulation time of 1.5-2h.

[0024] Preferably, in step (3), the chitosan solution is a solution obtained by dissolving chitosan in a 1 wt% acetic acid solution.

[0025] Preferably, in step (3), the concentration of chitosan in the chitosan solution is 1.0-2.0 wt%.

[0026] Preferably, the conditions for fluidized bed coating in step (3) are at least: inlet air temperature 60-80℃, outlet air temperature 40-50℃, and atomization pressure 0.1-0.3MPa.

[0027] As mentioned above, the third aspect of the present invention provides the application of the coated lavender essential oil microcapsules described in the first aspect in the preparation of livestock and poultry feed.

[0028] Preferably, the livestock feed is ruminant feed.

[0029] The present invention will be described in detail below through examples. Unless otherwise specified, the raw materials used are all commercially available products.

[0030] Lavender raw materials: fresh lavender inflorescences and stems, free from mold and impurities, harvested from Xinjiang Uygur Autonomous Region, during the peak flowering season; β-Cyclodextrin: a food-grade product with a purity ≥98%, moisture content ≤15%, molecular weight of 1135 Da, and cavity diameter of approximately 0.60-0.65 nm; Chitosan: Molecular weight 50-300kDa; The determination methods for linalyl acetate and lavender acetate in essential oils were as follows: Gas chromatography-mass spectrometry (GC-MS) was used. GC conditions: DB-5 capillary column; column temperature 50℃, initial temperature 50℃, held for 1 min, then increased to 320℃ at 10℃ / min, held for 5 min; split injection, split ratio 10:1; injection volume 10 μL; carrier gas: He, carrier gas flow rate 14 mL / min, column inlet pressure 53.6 kPa, column flow rate 1.0 mL / min, linear velocity 36.3 cm / sec; purge gas flow rate 3.0 mL / min. Mass spectrometry conditions: electron impact source, electron energy 70 eV, ion source temperature 200℃, interface temperature 300℃. In SCAN mode, the mass scan range was 35-600 m / z, and the solvent delay time was 2.5 min. The disappearance rate of microcapsules in the foregut of livestock and poultry was determined by the nylon bag method; The release rate of microcapsules in the intestines of livestock and poultry was determined using an artificial enzymatic method via dialysis bag method.

[0031] Preparation Example 1 This preparation example illustrates that the coated lavender essential oil microcapsules provided by the present invention are prepared by a method including the following steps: (1) Preparation of essential oils Take 100 kg of freshly harvested lavender and pack it evenly and loosely into a distillation vessel, ensuring the packing volume does not exceed 80% of the vessel's capacity. Introduce low-pressure saturated steam into the distillation vessel, controlling the steam pressure at 0.03 MPa and the temperature at 100°C. The distillation rate is such that the condensate outflow is 8% of the vessel's volume per hour. Continue distilling for 1.5 hours. The vapor mixture of essential oil and water is introduced into a condenser through a conduit, and the condensed liquid flows into an oil-water separator. After settling and separation, the upper crude essential oil is collected through valves on the separator. The collected crude essential oil is added to anhydrous sodium sulfate, stirred, and allowed to stand for dehydration. Then, it is finely filtered (filter membrane pore size 0.45 μm) to obtain 0.4 kg of clear lavender essential oil. This is then subjected to short-path distillation at 7 kPa and 50 °C to obtain lavender ester essential oil. GC-MS analysis showed that the total mass percentage of linaloyl acetate and lavender acetate in the obtained lavender ester essential oil was greater than 50 wt%.

[0032] (2) Inner layer encapsulation 10 kg of the above-mentioned lavender ester essential oil was mixed with 5 kg of β-cyclodextrin. The mixture was placed in a vacuum adsorption device, with the vacuum level controlled at -0.09 MPa, the inclusion temperature at 45°C, and the inclusion time at 1.8 h. Under these conditions, the active ingredients of lavender essential oil were encapsulated in the hollow structure of β-cyclodextrin, forming a stable essential oil-β-cyclodextrin complex. The encapsulation rate of this complex was found to be over 90% (encapsulation rate = amount of encapsulated essential oil / total amount of essential oil added × 100%).

[0033] (3) Outer coating A 95 wt% chitosan solution (obtained by dissolving chitosan in a 1 wt% acetic acid solution) was fed into a fluidized bed coating machine as a coating slurry. The process parameters were set as follows: inlet air temperature: 70℃, outlet air temperature: 45℃, atomization pressure: 0.2MPa, spraying speed: 30mL / min, and fan frequency: 25Hz. In a fluidized bed, the coating slurry is atomized and uniformly coated on the surface of the essential oil-β-cyclodextrin complex (the chitosan coating layer thickness is 12.5 μm). Simultaneously, hot air rapidly evaporates the moisture, forming a dense chitosan coating layer. After spray drying, the product is collected and sieved (sequentially through an 80-mesh sieve and then a 200-mesh sieve). Microcapsule powder between 80 and 200 mesh is collected to obtain the coated lavender essential oil microcapsule product, named P1. Tests showed that P1 disappeared at a rate of 13.5% in the pre-digestive tract of livestock and poultry, and was released at a rate of 89.2% in the intestine.

[0034] Comparative Example 1 This comparative example was prepared using a method similar to that of Preparation Example 1. The difference was that no coating treatment was applied to the lavender essential oil, and the lavender essential oil obtained in step (1) was directly named DP1. Tests showed that DP1 disappeared in 70.8% of the pre-digestive tract of livestock and poultry.

[0035] Comparative Example 2: This comparative example was prepared using a method similar to that of Preparation Example 1. The difference was that only the inner layer inclusion step (2) was performed, and the outer layer chitosan coating step (3) was not performed. That is, in step (2), lavender ester essential oil and β-cyclodextrin were vacuum adsorbed and included, and then directly dried to obtain essential oil-β-cyclodextrin complex powder, which is a single-layer β-cyclodextrin inclusion complex, named DP2. Tests showed that DP2 disappeared at a rate of 60.5% in the pre-digestive tract of livestock and poultry, and was released at a rate of 87.2% in the intestine.

[0036] Test Example 1 The purpose of this invention is to verify the antibacterial and bactericidal effects of the product on common pathogenic bacteria (Escherichia coli, Staphylococcus aureus, Salmonella) and beneficial bacteria (Lactobacillus, Bifidobacterium).

[0037] Test sample: The product of this invention: Take the coated lavender essential oil microcapsules (P1) prepared in Preparation Example 1, dissolve and break the cell walls with sterile water, and prepare lavender essential oil solutions with different concentration gradients, with final concentrations of 0.08%, 0.16%, 0.31%, 0.63%, 1.25%, and 2.5% (volume ratio). Positive controls: ceftiofur and gentamicin, prepared with concentration gradients of 0.125, 0.25, 0.5, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, and 2048 μg / mL; Negative control: sterile saline.

[0038] Test method: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using the microbroth dilution method.

[0039] (1) Preparation of bacterial culture Each test strain was inoculated into a suitable culture medium (pathogenic bacteria were inoculated into LB broth, and beneficial bacteria into MRS broth) and incubated at 37°C for 18 hours. The bacterial concentration was adjusted to 0.5 McFarland units (approximately 1.5 × 10⁻⁶) with sterile physiological saline. 8 (CFU / mL), then diluted to 1×10⁻⁶ with the corresponding liquid medium containing 0.05% TTC. 4 CFU / mL, for later use.

[0040] (2) MIC determination Take a 96-well plate and add 100 μL of lavender essential oil solution or antibiotic solution of different concentrations to each well, followed by 100 μL of diluted bacterial suspension. Simultaneously set up a positive control (bacterial suspension + culture medium), a negative control (sterile culture medium), and a blank control (bacterial suspension + sterile water). Each well was repeated three times. The 96-well plate was incubated at 37℃ for 18 hours, and the color change in each well was observed (TTC color development; viable bacteria reduce TTC to red). The lowest sample concentration that inhibited bacterial growth (no color change in the liquid within the well) was defined as the minimum inhibitory concentration (MIC).

[0041] (3) MBC measurement Take 100 μL of liquid from each well at concentrations above MIC and spread it evenly on the corresponding agar plate. Incubate at 37°C for 18 hours. The minimum bactericidal concentration (MBC) is the concentration with fewer than 5 colonies on the plate.

[0042] Experimental results: (1) The results of inhibition and bactericidal effects on pathogenic bacteria and on Lactobacillus acidophilus and Bifidobacterium are shown in Table 1; Table 1

[0043] Note: "-" in Table 1 indicates no effect.

[0044] Test Example 2 The purpose of this invention is to verify the effect of the product of the present invention in replacing antibiotics in improving the growth performance of weaned piglets, reducing the diarrhea rate, and enhancing immunity.

[0045] Experimental Design: One hundred and twenty 28-day-old three-way crossbred weaned piglets of similar weight and good health were randomly divided into four groups of 30 piglets each. The experimental treatments for each group were as follows: Control group: fed with a basal diet; Antibiotic group: Antibiotics were added to the basal diet (refer to actual production practices). Low-dose group of the product: 2 g / kg of the microcapsule product prepared in Example 1 of this invention (P1) was added to the basal diet. High-dose product group: 5 g / kg of the microcapsule product prepared in Example 1 of this invention (P1) was added to the basal diet.

[0046] The preliminary trial period was 5 days, and the formal trial period was 30 days. During the trial period, pigs had free access to feed and water and were fed according to the standard management practices of a pig farm.

[0047] Sample collection and index determination: On day 30 of the experiment, 10 piglets were randomly selected from each group, and blood was collected from the anterior vena cava. Serum was separated, and serum biochemical indicators, immunoglobulins, and antioxidant indicators were measured. Simultaneously, fresh fecal samples were collected to determine the number of intestinal microorganisms. Daily feed intake, initial body weight, and final body weight were recorded during the experiment. Average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (F / G) were calculated. The number of piglets with diarrhea was observed and recorded daily, and the diarrhea rate was calculated.

[0048] Experimental results: (1) Growth performance and diarrhea rate Compared with the control group, the low-dose product group showed a 13.5% increase in average daily weight gain, a 3.2% decrease in feed conversion ratio, and a 38.6% decrease in diarrhea rate among weaned piglets (P<0.05); the high-dose product group showed a 17.8% increase in average daily weight gain, a 5.1% decrease in feed conversion ratio, and a 52.3% decrease in diarrhea rate (P<0.05). There was no significant difference in growth performance between the low-dose product group and the antibiotic group (P>0.05).

[0049] (2) Gut microbiota Compared with the control group, the number of *E. coli* in the feces of piglets in the low-dose and high-dose groups decreased by 1.8 log units and 2.3 log units, respectively (P<0.05), while the number of *Lactobacillus* and *Bifidobacterium* remained unchanged (P>0.05). The number of *E. coli* in the antibiotic group was also significantly reduced, but the number of *Lactobacillus* was also significantly reduced (P<0.05). These results indicate that the product of this invention can selectively inhibit harmful bacteria without adversely affecting beneficial bacteria.

[0050] (3) Serum immune indicators Compared with the control group, the serum concentrations of immunoglobulin A (IgA) in the low-dose group and the high-dose group of piglets increased by 52.3% and 68.9%, respectively (P<0.05); the concentrations of immunoglobulin M (IgM) increased by 45.6% and 58.2%, respectively (P<0.05); and the concentrations of immunoglobulin G (IgG) increased by 18.5% and 23.4%, respectively (P<0.05). These results indicate that the product of this invention can significantly enhance the humoral immune function of weaned piglets.

[0051] (4) Serum antioxidant indicators Compared with the control group, the total antioxidant capacity (T-AOC) in the serum of piglets in the low-dose and high-dose groups increased by 28.6% and 35.2%, respectively (P<0.05), the superoxide dismutase (SOD) activity increased by 18.3% and 24.1%, respectively (P<0.05), and the malondialdehyde (MDA) concentration decreased by 15.2% and 21.4%, respectively (P<0.05). These results indicate that the product of this invention can enhance the antioxidant capacity of weaned piglets.

[0052] Test Example 3 To verify the effect of the product of this invention in improving the growth performance of calves and reducing the diarrhea rate.

[0053] Experimental Design: Sixty weaned calves of similar weight and good health were selected and randomly divided into three groups of 20 each. The experimental treatments for each group were as follows: Control group: fed with a basal diet; Low-dose group of products: 3 g / kg of the microcapsule product prepared in Example 1 of this invention (P1) was added to the basal diet. High-dose group of products: 4 g / kg of the microcapsule product prepared in Example 1 of this invention (P1) was added to the basal diet. The preliminary trial period was 7 days, and the formal trial period was 60 days. During the trial period, cattle were allowed free access to feed and water, and were fed according to the standard management practices of a cattle farm.

[0054] Experimental results: (1) Growth performance and diarrhea rate Compared with the control group, the average daily weight gain of calves in the low-dose product group increased by 10.2% and the diarrhea rate decreased by 42.5% (P<0.05); the average daily weight gain of calves in the high-dose product group increased by 15.6% and the diarrhea rate decreased by 60.0% (P<0.05). Simultaneously, the dry matter digestibility of calves in the high-dose product group increased by 5.9% and the organic matter digestibility increased by 5.8% (P<0.05), indicating that the product of this invention can improve the calf's ability to digest and absorb nutrients.

[0055] (2) Serum antioxidant indicators Compared with the control group, the high-dose product group showed a 22.6% increase in total antioxidant capacity (T-AOC) in calf serum (P<0.05), an 18.3% increase in superoxide dismutase (SOD) activity (P<0.05), and a 15.8% increase in glutathione peroxidase (GSH-Px) activity (P<0.05). These results indicate that the product of this invention can enhance the antioxidant capacity of calves.

[0056] Test Example 4 To verify the effect of the product of this invention in improving the growth performance of lambs and reducing the diarrhea rate.

[0057] Experimental Design: Sixty weaned lambs of similar weight and good health were selected and randomly divided into three groups of 20 lambs each. The experimental treatments for each group were as follows: Control group: fed with a basal diet; Low-dose group of products: 3 g / kg of the microcapsule product prepared in Example 1 of this invention (P1) was added to the basal diet. High-dose product group: 5 g / kg of the microcapsule product prepared in Example 1 of this invention (P1) was added to the basal diet.

[0058] The preliminary trial period was 7 days, and the formal trial period was 30 days. During the trial period, sheep had free access to feed and water and were fed according to the routine management practices of a sheep farm.

[0059] Experimental results: (1) Growth performance and diarrhea rate Compared with the control group, the average daily weight gain of lambs in the low-dose product group increased by 12.3%, feed intake increased by 8.5%, and the diarrhea rate decreased by 45.0% (P<0.05); the average daily weight gain of lambs in the high-dose product group increased by 17.8%, feed intake increased by 12.3%, and the diarrhea rate decreased by 70.0% (P<0.05). During the experiment, it was observed that the lambs in the experimental group supplemented with the product of this invention showed significantly higher feed intake than the control group, indicating that the product has palatability-enhancing properties.

[0060] (2) Gut microbiota Compared with the control group, the number of Escherichia coli in lamb feces in the high-dose group decreased by 2.1 log units (P<0.05), while the number of lactic acid bacteria did not change significantly (P>0.05), which is consistent with the results of in vitro antibacterial test.

[0061] Test Example 5 To verify the effects of the product of this invention on the growth performance and disease resistance of laying hens.

[0062] Experimental Design: Four hundred one-day-old laying chicks of similar weight and good health were randomly divided into two groups of 200 chicks each. The experimental treatments for each group were as follows: Control group: fed with a basal diet; Product group: Microcapsule product (P1) prepared by Example 1 of the present invention, with 3 g / kg added to the basal diet. The trial period lasted 0-7 weeks. During the trial, chickens had free access to feed and water and were raised in accordance with the standard management practices of a chicken farm.

[0063] Experimental results: (1) Growth performance Compared with the control group, the product group chicks had significantly higher body weight at 2, 5, 6 and 7 weeks of age (P<0.05), with a 4.4% increase at 7 weeks of age; the tibia length and keel length were significantly higher than the control group at multiple weeks of age (P<0.05), indicating that the product of this invention can promote the skeletal development and overall growth of chicks.

[0064] (2) Immune indicators Compared with the control group, the product group chicks showed significantly higher H9 avian influenza antibody titers at 24 and 60 days of age (P<0.05), while there was no significant difference in Newcastle disease antibody titers. Simultaneously, the serum concentrations of immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin A (IgA) in the product group chicks increased by 16.2%, 20.5%, and 85.1%, respectively (P<0.05), and superoxide dismutase (SOD) activity increased by 17.8% (P<0.05). Fecal observation showed that the product group chicks had well-formed feces with low water content, and the incidence of diarrhea was significantly lower than that of the control group.

[0065] Test Example 6 To verify the therapeutic effect of the product of this invention on weaned piglets and calves that have developed diarrhea.

[0066] Treatment trial for diarrhea in piglets: Sixty weaned piglets with diarrhea were selected from a pig farm and randomly divided into two groups of 30 piglets each. The control group continued to be fed a basal diet, while the treatment group received a basal diet supplemented with 5 g / kg of the microcapsule product (P1) prepared in Example 1 of this invention. The relief of diarrhea was observed. The results showed that within 2-3 days after adding the product, the piglets in the treatment group gradually returned to normal in terms of feed intake and feces, and the diarrhea symptoms were significantly relieved or disappeared, with a cure rate of 86.7%; the diarrhea symptoms of the piglets in the control group did not show significant improvement.

[0067] Calf diarrhea treatment trial: Forty calves with diarrhea were selected from a cattle farm and randomly divided into two groups of 20 each. The control group was given milk without the added product, while the treatment group was given milk supplemented with 6 g / kg of the microcapsule product (P1) prepared in Example 1 of this invention. The relief of diarrhea was observed. The results showed that within 3-4 days after oral administration, the feces of calves in the treatment group gradually returned to normal, and the diarrhea symptoms were significantly relieved or disappeared, with a cure rate of 90.0%; the diarrhea symptoms of calves in the control group did not show significant improvement.

[0068] Test Example 7 Verify the effect of the product of this invention on the growth and development of broilers: Ninety healthy male yellow-feathered broiler chicks aged 30 days were randomly divided into 5 treatment groups, with 6 replicates in each group and 3 chicks in each replicate. Negative control group (NC): fed with a basal diet, the amount of microcapsule product (P1) prepared in Example 1 added to the basal diet was 0.5 g / kg for the low dose group (L), 1.0 g / kg for the medium dose group (M), and 2.0 g / kg for the high dose group (H); Positive control group (PC): 1.0 g / kg chlortetracycline premix (20%) was added. The experiment lasted 36 days, divided into two phases: the early stage (days 1-18) and the later stage (days 19-36).

[0069] The results showed that in the early stage of the experiment (1-18 days), there was no significant difference in average daily weight gain among the groups (P>0.05); in the later stage of the experiment (19-36 days), the average daily weight gain of groups L and H was significantly higher than that of group NC (P<0.05), increasing by 12.43% and 13.27%, respectively; the PC group increased by 10.1% compared with the NC group, but the difference was not significant (P>0.05); throughout the entire period (1-36 days), the average daily weight gain of groups L and H was significantly higher than that of group NC (P<0.05), increasing by 8.04% and 8.04%, respectively; the PC group increased by 5.65% compared with the NC group, but the difference was not significant (P>0.05); there were no significant differences in average daily feed intake and feed conversion ratio among the groups (P>0.05).

[0070] It had no significant effect on slaughter performance, apparent digestibility of nutrients, or immune function.

[0071] Adding 0.5 g / kg of this product to the diet can significantly increase the average daily weight gain of yellow-feathered broilers, with effects comparable to antibiotics.

[0072] The above data show that the coated lavender essential oil microcapsules provided by this invention, obtained through a double-layer coating technology combining β-cyclodextrin molecular inclusion and chitosan physical coating, exhibit a disappearance rate of less than 10% after 12 hours of incubation in simulated rumen fluid and a cumulative release rate of over 90% after 8 hours of incubation in simulated intestinal fluid. This achieves effective protection of lavender essential oil in the rumen of ruminants and efficient release in the intestine, solving the technical problem that essential oil is easily degraded and inactivated by rumen microorganisms when directly applied to ruminants.

[0073] Furthermore, this product exhibits selective antibacterial properties, significantly inhibiting pathogenic bacteria such as Escherichia coli and Salmonella, while having no adverse effects on beneficial bacteria such as lactic acid bacteria and bifidobacteria. It also enhances the immune function and antioxidant capacity of animals, effectively replacing antibiotics in feed. Simultaneously, animal experiments have demonstrated that adding this product to the feed of piglets, laying hens, calves, lambs, and yellow-feathered broilers can significantly improve production performance.

[0074] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A coated lavender essential oil microcapsule, characterized in that, The microcapsule has a bilayer structure, consisting of a core and a chitosan coating layer surrounding the core, from the inside out: The core is an essential oil-β-cyclodextrin complex; The essential oil-β-cyclodextrin complex is formed by vacuum adsorption encapsulation of lavender ester essential oil (obtained by short-path distillation of lavender essential oil at 6-8 kPa and 45-55℃) and β-cyclodextrin.

2. The coated lavender essential oil microcapsule according to claim 1, characterized in that, The active ingredients in the lavender ester essential oil include linalyl acetate and lavender acetate.

3. The coated lavender essential oil microcapsules according to claim 1 or 2, characterized in that, In the lavender ester essential oil, the total content of linalyl acetate and lavender acetate is not less than 50 wt%.

4. The coated lavender essential oil microcapsules according to claim 1 or 2, characterized in that, In the essential oil-β-cyclodextrin complex, the weight ratio of β-cyclodextrin to lavender ester essential oil is less than 1:

1.

5. The coated lavender essential oil microcapsules according to claim 1 or 2, characterized in that, The thickness of the chitosan coating layer is controlled by a fluidized bed coating process, so that the thickness of the chitosan coating layer is 5-30 μm. The disappearance rate of the coated lavender essential oil microcapsules in the pre-digestive tract of livestock and poultry is less than 20%, and the release rate in the intestine reaches more than 80%.

6. The coated lavender essential oil microcapsules according to claim 1 or 2, characterized in that, The chitosan coating layer is formed from chitosan with a molecular weight of 50-300 kDa.

7. The coated lavender essential oil microcapsules according to claim 1 or 2, characterized in that, The average volume diameter of the coated lavender essential oil microcapsules is 40-200 μm.

8. A method for preparing the coated lavender essential oil microcapsules according to any one of claims 1-7, characterized in that, Includes the following steps: (1) The lavender raw material is steam distilled, the distillate is collected, and the oil and water are separated, dehydrated and filtered to obtain lavender essential oil. Then, short-path distillation is carried out at 6-8 kPa and 45-55℃ to obtain lavender ester essential oil. (2) The lavender ester essential oil is mixed with β-cyclodextrin and encapsulated by vacuum adsorption to obtain an essential oil-β-cyclodextrin complex; (3) Using the essential oil-β-cyclodextrin complex as the core material and chitosan solution as the coating slurry, the coating is carried out by spray coating and drying through fluidized bed coating process to obtain the coated lavender essential oil microcapsules.

9. The method according to claim 8, characterized in that, In step (1), the conditions for steam distillation must at least meet the following requirements: steam pressure 0.02-0.05 MPa, temperature 98-102℃, distillation rate of condensate outflow of 5-10% of the distillation vessel volume per hour, and distillation time 1-2 h.

10. The use of the coated lavender essential oil microcapsules according to any one of claims 1-7 in the preparation of livestock and poultry feed additives.

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