Feed additive with specific egg yolk antibodies and its use in nutritional intervention against bacterial chronic periodontal disease in cats

Abstract

This invention discloses a feed additive with specific egg yolk antibodies and its application in nutritional intervention for feline bacterial chronic periodontitis. Using *Porphyromonas gingivalis*, *Porphyromonas canis*, *Actinomyces actinomycetes*, and *Prevotella intermedius* as targets among feline periodontal pathogens, a multivalent inactivated vaccine is prepared through isolation, inactivation, and adjuvant emulsification. Specific IgY egg yolk antibodies are extracted, purified, and freeze-dried from the egg yolks of laying hens after immunization. The antibodies are then compounded with a feed carrier or wet food matrix to obtain a feed additive for nutritional intervention in feline chronic periodontitis. The egg yolk antibodies obtained by this invention can specifically bind to feline oral periodontal pathogens, inhibiting their proliferation, adhesion, and biofilm formation, blocking inflammatory pathway activation, and alleviating periodontal tissue damage. It can be added to cat food or wet food as a safe, long-lasting, and non-invasive daily nutritional intervention, providing both passive immune protection and nutritional supply. It is palatable and has no antibiotic residues or drug resistance risks.

Description

Technical Field

[0001] This invention belongs to the field of functional pet feed and passive immunization biotechnology, specifically relating to feed additives with specific egg yolk antibodies and their application in nutritional intervention for feline bacterial chronic periodontitis. Background Technology

[0002] With the continuous increase in pet ownership in China, cats have become the mainstream companion pets, and the demand for pet health care is gradually shifting towards refinement, functionality, and nutrition. Periodontal disease is the most common chronic inflammatory oral disease in cats, caused by microbial infection, affecting the supporting tissues of the teeth, such as the gums, periodontal ligament, alveolar bone, and cementum. Periodontal disease is usually divided into two stages: gingivitis and periodontitis. Gingivitis is limited to the gums and can be reversed with proper care; periodontitis, on the other hand, affects deeper supporting structures, leading to attachment loss, gingival recession, periodontal pocket formation, and alveolar bone resorption, and the bone loss is irreversible without surgical intervention. Epidemiological studies show that about 70% of cats aged 2 years and older suffer from various types of periodontitis, and as many as 90% of cats are reported to have signs of periodontal disease by age 1. Due to the insidious clinical symptoms, clinical treatment often begins only in the later stages of the disease, leading to difficulty eating, malnutrition, and complications in multiple organs such as the kidneys, heart, and liver, seriously affecting the cat's lifespan and quality of life. Currently, there is a lack of safe, long-lasting, and convenient daily nutritional intervention methods on the market.

[0003] The core pathogenic bacteria of feline periodontitis are melanin-producing Gram-like anaerobic bacilli such as Porphyromonas gingivalis, Porphyromonas gulae, Aggregatibacter actinomycetemcomitans, and Prevotella intermedia. These pathogens form dental plaque and tartar on the tooth surface, continuously stimulating periodontal tissues and triggering an immune inflammatory response, which destroys periodontal connective tissue and alveolar bone.

[0004] Current clinical interventions primarily involve ultrasonic scaling and antibiotic treatment. Scaling requires anesthesia, is costly, stressful, and has a high recurrence rate; long-term antibiotic use easily leads to drug resistance and oral flora imbalance. At the feed level, current oral care pet foods often achieve physical cleaning or reduce tartar buildup by adding dietary fiber and phosphates (such as sodium polyphosphate) to coat dry food pellets, but this is only effective for dry food and has no precise intervention for existing periodontal inflammation; furthermore, the effects of phosphates are limited. Natural plant extracts and probiotics have weak effects due to the complex oral flora.

[0005] Egg yolk antibody (IgY) is a specific immunoglobulin that accumulates in the yolk of poultry after antigen immunization. Compared to mammalian IgG, IgY has a smaller molecular weight, stronger permeability, higher specificity, and no drug residue or risk of drug resistance, making it a green and safe passive immunization factor. IgY can maintain its activity below 75℃, is stable in the pH range of 3.5-11, and can be stored at 4℃ for more than 5 years. It also has high laying hen yield (100-200 mg / egg), low cost, and is easy to purify. Anti-caries IgY toothpaste and other products are already available abroad, and passive immunization against dental plaque with IgY has been proven effective in rat models and human subjects. However, there are no systematic studies or product reports on the preparation of periodontitis-specific IgY for cats and its application in pet feed. Problems exist, such as unclear proportions of functional factors, poor adaptability of processing technology, and lack of verification of feeding effects.

[0006] Furthermore, wet food, due to its high moisture content and palatability, is more suitable for cats' eating habits. However, literature shows that long-term feeding of wet food is more likely to promote plaque formation than dry food. How to retain the advantages of wet food while reducing its adverse effects on oral health is a technical problem that needs to be solved in this field. Summary of the Invention

[0007] To address the shortcomings of the existing technology, the present invention aims to provide a specific anti-feline periodontal disease pathogenic bacterium egg yolk antibody feed additive, its preparation method and application. A multivalent inactivated vaccine is prepared using feline periodontal disease core pathogens as the target, and high-titer specific IgY is obtained by immunizing laying hens. The IgY is then compounded into cat feed or wet food to construct a "nutritional regulation + passive immune intervention" feline periodontal disease prevention and control model, realizing daily prevention and mild symptom intervention.

[0008] Therefore, the present invention adopts the following technical solution: The first aspect of the present invention provides a feed additive having specific egg yolk antibodies, including a specific anti-feline periodontal disease pathogenic egg yolk antibody active component and a feed-acceptable carrier and / or excipient; Based on the total mass of the feed additive, the content of each component is as follows: The titer of the specific egg yolk antibody is not less than 1:3200, and the amount added is 0.5~5.0 wt% based on protein content. The remainder is the carrier and / or excipients; The pathogenic bacteria targets for feline periodontitis are selected from one or more of Porphyromonas gingivalis, Porphyromonas canis, Aggregobacter actinomycetes, and Prevotella intermedius.

[0009] Preferably, the specific egg yolk antibody is prepared by inactivating the feline periodontal disease pathogen, emulsifying it with an adjuvant to form a multivalent inactivated vaccine, immunizing laying hens aged 23-25 ​​weeks, collecting eggs laid 14-40 days after immunization, and extracting, purifying, and freeze-drying the egg yolk.

[0010] Preferably, the adjuvant is selected from one or more of Freund's adjuvant, Astragalus polysaccharide adjuvant, ISCOM adjuvant, and white oil adjuvant; the inactivation is performed using a 0.3-0.5 wt% formaldehyde aqueous solution at 4°C for 18-30 h, and the bacterial concentration after inactivation is adjusted to (2-5)×10⁻⁶. 9 CFU / mL.

[0011] Preferably, the carrier and / or excipients are selected from one or more of the following: dry cat food matrix, wet food matrix, corn starch, dextrin, bran powder, fish meal, chicken meal, taurine, vitamin premix, and mineral element premix; the feed additives can be made into dry food coating agents, wet food additive powders, or chewable tablets.

[0012] Preferably, when the specific egg yolk antibody in the feed additive is added at 0.8~3.0 wt% based on IgY protein, it is used for daily prevention of chronic periodontitis in cats; when the addition amount is 2.0~5.0 wt%, it is used for adjunctive nutritional intervention for mild to moderate periodontitis in cats.

[0013] This invention also discloses a method for preparing the feed additive with specific egg yolk antibodies described above, comprising the following steps: Step 1: Collect samples from the periodontal pockets of cats with periodontal disease, isolate, purify, and identify the pathogenic bacteria of feline periodontal disease, and select one or more of the following strains as target strains: Porphyromonas gingivalis, Porphyromonas canis, Aggregates actinomycetes, and Prevotella intermedius. Step 2: The target strain was cultured on plates and in liquid culture to prepare a bacterial suspension. After adjusting the suspension to McFarland turbidity, the suspension was washed and inactivated with 0.4±0.1 wt% formaldehyde aqueous solution at 4℃ for 20~28 h. The suspension was then centrifuged and washed to remove formaldehyde, and the bacterial concentration was adjusted to (2.5~3.5)×10⁻⁶. 9 CFU / mL was used as the antigen solution; Step 3: Emulsify the antigen solution and adjuvant at a volume ratio of 1:1 to 1:3 to prepare a water-in-oil multivalent inactivated vaccine; Step 4: Select healthy laying hens aged 22-24 weeks and administer 1.0-1.5 mL of vaccine per hen subcutaneously or intramuscularly. Vaccinate once every 8-10 days for a total of 4-5 times. Collect eggs regularly starting 10-14 days after the first vaccination. Step 5: Separate the egg yolks from the collected eggs, dilute with water, adjust the pH to 5.0-5.5 with acid to cause the impurities to flocculate and precipitate, centrifuge to collect the supernatant, concentrate by ultrafiltration, freeze dry to obtain specific egg yolk antibody dry powder; Step 6: Mix the obtained egg yolk antibody powder with the carrier and / or excipients evenly to obtain a feed additive.

[0014] Preferably, the flocculant system used in step five for flocculation and sedimentation is selected from the chitosan-sodium alginate-calcium chloride system or the chitosan-sodium tripolyphosphate system; the flocculation conditions are: chitosan dosage 0.05~0.20 wt%, sodium alginate dosage 0.02~0.10 wt%, calcium chloride dosage 0.05~0.15 wt%, or sodium tripolyphosphate dosage 0.03~0.08 wt%, flocculation time 20~60 min, and temperature 4~15℃.

[0015] Preferably, in step five, the ultrafiltration concentration uses a 30~100 kDa ultrafiltration membrane with a concentration factor of 5~15 times; the freeze-drying process is as follows: pre-freezing at -40~-30℃ for 2~4 h, sublimation drying at -20~10℃, vacuum degree of 10~30 Pa for 18~30 h, and desorption drying at 15~25℃ for 6~12 h.

[0016] Preferably, the IgY titer in the egg yolks collected after the third immunization in step four reaches 1:1600 or higher, and the titer stabilizes at 1:6400~1:12800 after the fifth immunization; the binding titer of the IgY to the target strain is determined by ELISA.

[0017] This invention also discloses the application of the feed additive with specific egg yolk antibodies described above. The feed additive is used to prepare functional dry food, wet food, dental treats or oral nutritional paste for cats, for daily prevention and mild nutritional intervention of feline chronic periodontitis, reducing plaque index, tartar index and gingivitis index, and reducing the abundance of Porphyromonas gingivalis, Porphyromonas canis, Aggregates actinomycetes and Prevotella intermedius in the oral cavity.

[0018] The beneficial effects of this invention are as follows: This invention prepares a multivalent inactivated vaccine for immunizing laying hens by separating, inactivating, and emulsifying with adjuvants. Specific IgY yolk antibodies are extracted from the yolk and then compounded with cat feed carriers or wet food substrates. This method requires no anesthesia, is non-invasive, and carries no risk of antibiotic resistance, filling the gap in the current market for functional feed products that target the daily prevention and mild intervention of feline periodontal disease.

[0019] The specific egg yolk antibody prepared in this invention can precisely bind to periodontal pathogens in the feline oral cavity, inhibiting their proliferation, adhesion, and biofilm formation, blocking inflammatory pathway activation, and significantly reducing plaque index, tartar index, gingivitis index, and the abundance of target pathogens in the oral cavity. Simultaneously, it downregulates serum inflammatory factors such as IL-1β and TNF-α, achieving a gentle intervention for periodontitis at the etiological level. Compared with existing antibiotic treatments, this invention's product does not cause rebound inflammation after discontinuation and does not affect the balance of normal oral flora, resulting in higher safety. Compared with existing physical dental cleaning pet foods, this invention has a clear targeted antibacterial and anti-inflammatory function, with significantly improved efficacy.

[0020] The IgY egg yolk antibody used in this invention exhibits excellent physicochemical stability—maintaining activity below 75℃, stable within the pH range of 3.5–11, and capable of storage at 4℃ for over 5 years. It is well-suited to wet feed processing, overcoming the inherent drawback of wet feed's soft texture, which promotes plaque formation. This allows wet feed to retain its high palatability, high moisture content, and easy digestibility while also providing oral immune protection. Furthermore, IgY is widely available, inexpensive, produces high levels of immune antibodies in laying hens, and has a simple extraction process, making it suitable for large-scale industrial production and possessing significant economic benefits and industrial promotion value. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the research and development process of the specific egg yolk antibody of this invention for nutritional intervention in feline periodontal disease; Figure 2 This is a schematic diagram of the preparation process of the specific egg yolk antibody of this invention. Detailed Implementation

[0022] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it.

[0024] Example 1: Isolation, identification and preparation of multivalent inactivated vaccine for feline periodontal disease pathogens Fresh samples were scraped from periodontal pockets of cats clinically diagnosed with periodontal disease using a sterile curette and placed in 900 μL PBS. After serial dilution, the samples were streaked onto BHI blood agar plates and anaerobically cultured for 5–7 days, observing for black colonies. Four to five black colonies approximately 1 mm in diameter were picked and inoculated into 5 mL of BHI sheep blood somatic culture medium for enrichment. After purification, 16S rDNA sequencing identified four target bacteria: *Porphyromonas gingivalis*, *Porphyromonas gulae*, *A. actinomycetemcomitans*, and *P. intermedia*. All four bacteria were melanin-producing Gram-negative anaerobic bacilli.

[0025] Four bacterial strains were cultured separately on plates and then amplified in liquid form. Bacterial samples were scraped and placed in McFarland turbidimetric tubes to adjust the concentration. After washing, 0.4 wt% formaldehyde aqueous solution was added, and the culture was inactivated at 4°C for 24 hours. The inactivated bacterial solution was centrifuged and washed to remove formaldehyde. The four bacterial strains were then mixed in equal proportions, and the bacterial concentration was adjusted to 3 × 10⁻⁶. 9CFU / mL. Under ice-water bath conditions, the bacterial solution and Freund's incomplete adjuvant were emulsified by high-speed stirring at a volume ratio of 1:2 to prepare a water-in-oil quadrivalent inactivated vaccine.

[0026] Example 2: Extraction and purification of immune and specific IgY in laying hens Twenty healthy Hy-Line Brown laying hens aged 23 weeks were selected, with five hens in each group. Examples 2-1 to 2-4 correspond to four vaccine groups: Freund's adjuvant, Astragalus polysaccharide adjuvant, ISCOM adjuvant, and white oil adjuvant, respectively. The following details the Freund's adjuvant group as an example.

[0027] Each hen was subcutaneously injected with 1.0 mL of vaccine, and booster immunizations were given on days 9, 18, 27, and 36, for a total of 5 immunizations. Eggs were collected daily starting 10 days after the first immunization and stored under cold storage.

[0028] Eggs were collected on day 40 post-immunization. The yolks were separated and diluted with deionized water at a ratio of 1:8 (w / v). After stirring, the pH was adjusted to 5.2 with 1 mol / L HCl. Chitosan (0.12 wt%), sodium alginate (0.06 wt%), and calcium chloride (0.10 wt%) were added. Flocculation was carried out at 4°C for 40 min, followed by centrifugation at 8000 rpm for 15 min. The supernatant was collected. The supernatant was concentrated 10-fold via 50 kDa ultrafiltration, desalted by PBS, and freeze-dried to obtain IgY powder.

[0029] The binding titers of IgY against four target bacteria were determined by ELISA: 1:12800 in the Freund's adjuvant group after the 5th immunization, 1:9600 in the Astragalus polysaccharide adjuvant group, 1:11200 in the ISCOM adjuvant group, and 1:6400 in the white oil adjuvant group.

[0030] Example 3: Preparation of specific IgY feed additives and their application in wet diet formulation Take the Freund's adjuvant group IgY dry powder from Example 2, mix it evenly with the cat chicken flavored wet food matrix (chicken meat paste + fish oil + taurine + vitamin and mineral premix + moisture adjusted to 78 wt%) at 2.5 wt% based on IgY protein, vacuum package and sterilize to obtain functional cat wet food, with the final IgY concentration corresponding to the total mass of feed additives of 2.5 wt%.

[0031] Separately, 1.0 wt% of IgY dry powder was mixed with a dry food pellet spray carrier (corn starch + taurine + flavoring agent) and sprayed onto the surface of puffed dry food to obtain a dry food coating additive product.

[0032] Comparative Example 1: Non-specific IgY control Using the same process, but with inactivated Escherichia coli as the antigen to immunize laying hens to obtain nonspecific IgY, it was added to the same wet feed substrate at 2.5 wt%, and the other conditions were the same as in Example 3.

[0033] Comparative Example 2: Antibody-free wet diet control The wet grain substrate is the same as in Example 3, but without the addition of any IgY component.

[0034] Comparative Example 3: Antibiotic Intervention Control The commonly used clinical regimen is metronidazole + amoxicillin, which should be mixed into wet food and fed according to the dosage prescribed by the veterinarian for 14 consecutive days.

[0035] Feeding trials and testing Forty-eight domestic shorthaired cats aged 2-5 years diagnosed with mild to moderate periodontitis (periodontal pocket depth 0.5-2 mm, gingivitis index 1-2) were randomly divided into 6 groups (n=8): Example 3 wet food group, Example 3 dry food group, Comparative Example 1, Comparative Example 2, Comparative Example 3, and blank control (conventional commercial cat food). The feeding period was 90 days, with assessments every 30 days. Detailed assessment data are shown in the table below.

[0036] Table 1 Summary of vaccine and IgY preparation processes in each embodiment

[0037] Table 2. Changes in key indicators after 90 days of feeding (rate of change relative to initial values, ±%)

[0038] As shown in Table 2, the wet diet group in Example 3 was significantly superior to the non-specific IgY group in Comparative Example 1 and the antibody-free group in Comparative Example 2 in terms of PLI, CI, GI, target bacterial abundance, and inflammatory factors (p<0.01), indicating that the nutritional intervention effect of the specific IgY of this invention is clear. The antibiotic group in Comparative Example 3 had a slightly better short-term effect, but the rebound rate of PLI and GI reached 42% after 30 days of drug withdrawal (not all are listed in the table), and the palatability was low, with a risk of drug resistance with long-term use. In contrast, the group in Example 3 showed no rebound within 90 days and had the best palatability.

[0039] Table 3. IgY activity retention rate after sterilization at 80℃ / 15 min in wet grains

[0040] Sterilization conditions for wet grains: 80℃ water bath for 15 min (simulating canned food sterilization), ELISA titer detection.

[0041] Table 3 shows that the activity retention rate of IgY reaches 95% at the wet grain processing temperature, which is consistent with the literature report that IgY is stable below 75℃, indicating that the IgY of this invention is well adapted to the wet grain process.

[0042] 200 g each of the wet grain product from Example 3 and the antibody-free wet grain from Comparative Example 2 were packaged in sealed aluminum foil bags and stored at 25°C and 60% RH for 90 days. IgY titer and sensory properties were then tested. Results showed that after 90 days of sealed storage, the IgY titer decreased from 1:3040 to 1:2835, with a retention rate of 93.3%, and the wet grain showed no sensory abnormalities. After 90 days of storage with the bags opened, the titer decreased to 1:2189 (retention rate of 72.0%), indicating that the product should be stored in a sealed container and consumed as soon as possible after opening, but it is still superior to most protein-based active additives.

[0043] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0044] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A feed additive containing specific egg yolk antibodies, characterized in that, This includes specific active components of egg yolk antibodies against feline periodontal disease pathogens, as well as feed-acceptable carriers and / or adjuvants; Based on the total mass of the feed additive, the content of each component is as follows: The titer of the specific egg yolk antibody is not less than 1:3200, and the amount added is 0.5~5.0 wt% based on protein content. The remainder is the carrier and / or excipients; The pathogenic bacteria targets for feline periodontitis are selected from one or more of Porphyromonas gingivalis, Porphyromonas canis, Aggregobacter actinomycetes, and Prevotella intermedius.

2. The feed additive with specific egg yolk antibodies according to claim 1, characterized in that, The specific egg yolk antibody is prepared by inactivating the feline periodontal disease pathogen, emulsifying it with an adjuvant to form a multivalent inactivated vaccine, immunizing laying hens aged 23-25 ​​weeks, collecting eggs laid 14-40 days after immunization, and extracting, purifying, and freeze-drying the yolk.

3. The feed additive with specific egg yolk antibodies according to claim 2, characterized in that, The adjuvant is selected from one or more of Freund's adjuvant, Astragalus polysaccharide adjuvant, ISCOM adjuvant, and white oil adjuvant; the inactivation is performed using a 0.3-0.5 wt% formaldehyde aqueous solution at 4°C for 18-30 h, and the bacterial concentration after inactivation is adjusted to (2-5) × 10⁻⁶. 9 CFU / mL.

4. The feed additive with specific egg yolk antibodies according to claim 1, characterized in that, The carrier and / or excipients are selected from one or more of the following: dry food substrate for cats, wet food substrate, corn starch, dextrin, bran powder, fish meal, chicken meal, taurine, vitamin premix, and mineral element premix; the feed additives can be made into dry food coating agents, wet food additive powders, or chewable tablets.

5. The feed additive with specific egg yolk antibodies according to claim 1, characterized in that, When the specific egg yolk antibody in the feed additive is added at a rate of 0.8-3.0 wt% based on IgY protein, it is used for daily prevention of chronic periodontitis in cats; when the addition rate is 2.0-5.0 wt%, it is used for adjunctive nutritional intervention for mild to moderate periodontitis in cats.

6. A method for preparing a feed additive with specific egg yolk antibodies as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Collect samples from the periodontal pockets of cats with periodontal disease, isolate, purify, and identify the pathogenic bacteria of feline periodontal disease, and select one or more of the following strains as target strains: Porphyromonas gingivalis, Porphyromonas canis, Aggregates actinomycetes, and Prevotella intermedius. Step 2: The target strain was cultured on plates and in liquid culture to prepare a bacterial suspension. After adjusting the suspension to McFarland turbidity, the suspension was washed and inactivated with 0.4±0.1 wt% formaldehyde aqueous solution at 4℃ for 20~28 h. The suspension was then centrifuged and washed to remove formaldehyde, and the bacterial concentration was adjusted to (2.5~3.5)×10⁻⁶. 9 CFU / mL was used as the antigen solution; Step 3: Emulsify the antigen solution and adjuvant at a volume ratio of 1:1 to 1:3 to prepare a water-in-oil multivalent inactivated vaccine; Step 4: Select healthy laying hens aged 22-24 weeks and administer 1.0-1.5 mL of vaccine per hen subcutaneously or intramuscularly. Vaccinate once every 8-10 days for a total of 4-5 times. Collect eggs regularly starting 10-14 days after the first vaccination. Step 5: Separate the egg yolks from the collected eggs, dilute with water, adjust the pH to 5.0-5.5 with acid to cause the impurities to flocculate and precipitate, centrifuge to collect the supernatant, concentrate by ultrafiltration, freeze dry to obtain specific egg yolk antibody dry powder; Step 6: Mix the obtained egg yolk antibody powder with the carrier and / or excipients evenly to obtain a feed additive.

7. The method for preparing the feed additive with specific egg yolk antibodies according to claim 6, characterized in that, The flocculant system used in step five for flocculation sedimentation is selected from the chitosan-sodium alginate-calcium chloride system or the chitosan-sodium tripolyphosphate system; The flocculation conditions are as follows: chitosan dosage 0.05~0.20 wt%, sodium alginate dosage 0.02~0.10 wt%, calcium chloride dosage 0.05~0.15 wt%, or sodium tripolyphosphate dosage 0.03~0.08 wt%, flocculation time 20~60 min, and temperature 4~15℃.

8. The method for preparing the feed additive with specific egg yolk antibodies according to claim 6, characterized in that, In step five, ultrafiltration concentration uses a 30~100 kDa ultrafiltration membrane with a concentration factor of 5~15 times; The freeze-drying process is as follows: pre-freezing at -40~-30℃ for 2~4 h, sublimation drying at -20~10℃, vacuum degree of 10~30 Pa for 18~30 h, and desorption drying at 15~25℃ for 6~12 h.

9. The method for preparing the feed additive with specific egg yolk antibodies according to claim 6, characterized in that, In step four, the IgY titer in the egg yolks collected after the third immunization reached over 1:1600, and after the fifth immunization, the titer stabilized at 1:6400~1:12800; the binding titer of the IgY to the target strain was determined by ELISA.

10. The application of a feed additive with specific egg yolk antibodies as described in any one of claims 1 to 5, characterized in that, The feed additives are used to prepare functional dry food, wet food, dental treats or oral nutritional pastes for cats, for daily prevention and mild nutritional intervention of chronic periodontitis in cats, to reduce plaque index, tartar index and gingivitis index, and to reduce the abundance of Porphyromonas gingivalis, Porphyromonas canis, Aggregates actinomycetes and Prevotella intermedia in the oral cavity.

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