Functional feed for largemouth bass as well as preparation method and application of functional feed

Abstract

The invention provides a functional feed for micropterus salmoides as well as a preparation method and application of the functional feed. The components and the proportion in the feed are optimized, and the camellia oleifera shell extract is added; experiments prove that the camellia oleifera shell extract prepared by the invention can effectively inhibit the growth of vibrio harveyi, pseudomonas proteans, edwardsiella tarda, aeromonas hydrophila and vibrio alginolyticus; the functional feed can improve the immunocompetence or oxidation resistance of the micropterus salmoides and has the potential of resisting several common gram-negative bacteria in aquaculture.

Description

Technical Field

[0001] The invention relates to the technical field of aquatic feed and additives, in particular to a functional feed for largemouth bass and a preparation method and application thereof. Background Art

[0002] Largemouth bass (Micropterus salmoides), commonly known as California bass, belongs to the order Perciformes, family Heliopsidae, genus Perch. Largemouth bass is widely farmed in my country due to its strong adaptability, fast growth, easy catching and short breeding cycle. Its production will reach 888,030 tons by 2023, making it one of my country's important economic fish. However, with the rapid development of intensive aquaculture, the breeding density has increased significantly, resulting in increasingly serious disease outbreaks in largemouth bass during breeding, which has caused significant economic losses to farmers.

[0003] Antibiotics are commonly used drugs for treating diseases in aquaculture, and the frequent occurrence of diseases in farmed animals has led to an increasing frequency and dosage of antibiotic use in actual farming processes. However, the abuse of antibiotics will seriously threaten the ecological environment of water bodies, the quality and safety of aquatic products, and public health safety.

[0004] Therefore, "antibiotic reduction / antibiotic replacement" is the general trend in aquaculture, and finding effective alternatives is urgent. Summary of the invention

[0005] The purpose of the present invention is to provide a functional feed for largemouth seabass and a preparation method and application thereof. The functional feed uses camellia oleifera shell extract to replace antibiotics, and can respectively improve the growth rate, immune ability or antioxidant ability of largemouth seabass at different addition amounts of camellia oleifera shell extract, and has the potential to resist several common Gram-negative bacteria in aquaculture.

[0006] The technical solution of the present invention is as follows:

[0007] A functional feed for largemouth bass, comprising the following raw materials by weight:

[0008] 43 parts of Peruvian fish meal, 9 parts of corn starch, 20 parts of soybean meal, 9 parts of casein, 1 part of calcium dihydrogen phosphate, 1 part of composite premix, 0.05 parts of vitamin C, 0.5 parts of choline chloride, 10-11 parts of microcrystalline cellulose, 5.7 parts of fish oil, 0.05-0.2 parts of camellia oleifera shell extract;

[0009] Wherein, per 1kg of functional feed, the above-mentioned composite premix is ​​composed of the following raw materials: vitamin B1 10-11mg, riboflavin 8-9mg, pyridoxine hydrochloride 10-11mg, vitamin B12 0.2-0.3mg, vitamin K3 10-11mg, inositol 100-110mg, calcium pantothenate 20-22mg, niacin 50-52mg, folic acid 2-3mg, biotin 2-3mg, vitamin A (500,000 IU) 400-420mg, vitamin D 5-6mg, vitamin E (500,000 IU) 100-120mg, ethoxyquin 150-160mg, sub-powder 0.13-0.14g, potassium chloride 200 -220mg, potassium iodide 60-65mg, cobalt sulfate 100-110mg, copper sulfate 24-26mg, ferrous sulfate 400-420mg, zinc sulfate 170-175mg, manganese sulfate 75-80mg, magnesium sulfate 800-820mg, sodium selenite 5-52mg, zeolite powder 3.0-3.5g;

[0010] The camellia oleifera shell extract is obtained by hydrolyzing the camellia oleifera shell in 2wt% benzoic acid and then drying it, the hydrolysis material-liquid ratio is 0.1-2g:1-20mL, the hydrolysis temperature is 80-200°C, and the hydrolysis time is 0.5-2h.

[0011] In some possible implementations, the added amount of the camellia oleifera shell extract is 0.1 parts.

[0012] A method for preparing the above functional feed comprises the following steps:

[0013] (1) crushing Peruvian fish meal, corn starch, soybean meal, casein, microcrystalline cellulose and monocalcium phosphate, and then fully mixing them to obtain a mixture A;

[0014] (2) Mixture A, the composite premix, choline chloride, vitamin C and Caragana korshinskii extract are fully mixed, and then ultrafinely ground to obtain mixture B, and water is added to mixture B, and the mixture is fully mixed to obtain mixture C;

[0015] (3) The mixture C is tempered to prepare an expanded pellet feed, and the expanded pellet feed is dried and then vacuum-sprayed with oil, cooled and sieved to obtain a functional feed. The vacuum-sprayed oil temperature is 40-70°C.

[0016] In some possible implementations, the method for preparing the camellia oleifera shell extract comprises the following steps:

[0017] (1) After the oil-tea camellia shell is crushed, 2 wt% benzoic acid is added and the mixture is fully homogenized with the aid of a homogenizer;

[0018] (2) subjecting the mixture to acid hydrolysis at 0-10 MPa, filtering to remove the camellia oleifera shell, and then concentrating and spray-drying to obtain a camellia oleifera shell extract;

[0019] The solid-liquid ratio of camellia oleifera shell to benzoic acid is 0.1-2g:1-20mL, the temperature of acid hydrolysis is 80-200°C, and the time of acid hydrolysis is 0.5-2h.

[0020] In some possible implementations, the solid-liquid ratio of camellia oleifera shell to benzoic acid is 0.2-0.8 g: 6-12 mL, the temperature of acid hydrolysis is 120-180° C., and the time of acid hydrolysis is 0.5-1 h.

[0021] Application of the above functional feed in resistance to Gram-negative bacteria.

[0022] In some possible implementations, the Gram-negative bacteria is at least one of Vibrio harveyi, Pseudomonas proteus, Edwardsiella tarda, Aeromonas hydrophila, and Vibrio alginolyticus.

[0023] Application of the functional feed in improving the antioxidant capacity of largemouth bass.

[0024] Application of the above functional feed in improving the immunity of largemouth bass.

[0025] Application of the functional feed in promoting the growth of largemouth bass.

[0026] The present invention has at least the following beneficial effects:

[0027] The invention provides a functional feed for largemouth seabass, a preparation method thereof and an application thereof. The components and proportions in the feed are optimized and a camellia oleifera shell extract is added. Experiments have confirmed that the camellia oleifera shell extract prepared by the invention can effectively inhibit the growth of Vibrio harveyi, Pseudomonas proteus, Edwardsiella tarda, Aeromonas hydrophila and Vibrio alginolyticus. The functional feed can respectively improve the growth rate, immune ability or antioxidant ability of largemouth seabass at different addition amounts of the camellia oleifera shell extract and has the potential to resist several common Gram-negative bacteria in aquaculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings will be briefly introduced below. Obviously, the accompanying drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0029] Figure 1: This is a graph showing the effect of the functional feed provided by the present invention on the total superoxide dismutase in the serum of largemouth bass. Each group of data is marked with different letters. There is a significant difference between group a and group b (P<0.05). If no letters are marked, it means that there is no significant difference between the data groups, the same below;

[0030] Figure 2 This is a graph showing the effect of the functional feed provided by the present invention on serum catalase of largemouth bass;

[0031] Figure 3 This is a graph showing the effect of the functional feed provided by the present invention on the total antioxidant capacity of the serum of largemouth bass;

[0032] Figure 4 This is a graph showing the effect of the functional feed provided by the present invention on the serum malondialdehyde content of largemouth bass;

[0033] Figure 5 This is a graph showing the effect of the functional feed provided by the present invention on the weight gain rate of largemouth bass;

[0034] Figure 6 This is a graph showing the effect of the functional feed provided by the present invention on the feeding rate of largemouth bass;

[0035] Figure 7 This is a graph showing the effect of the functional feed provided by the present invention on the feed coefficient of largemouth bass;

[0036] Figure 8 This is a graph showing the effect of the functional feed provided by the present invention on serum alkaline phosphatase in largemouth bass;

[0037] Fig. 9 This is a graph showing the effect of the functional feed provided by the present invention on serum acid phosphatase of largemouth bass;

[0038] Fig.10 This is a graph showing the effect of the functional feed provided by the present invention on serum lysozyme of largemouth bass;

[0039] Fig.11 This is a graph showing the effect of the functional feed provided by the present invention on serum immunoglobulin M of largemouth bass. DETAILED DESCRIPTION

[0040] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. In the examples, those without specifying specific techniques or conditions are carried out according to the techniques or conditions described in the literature in this area or according to the product specification. Those without specifying the manufacturer of reagents or instruments used are all conventional products that can be obtained commercially. In the following examples, if not clearly stated, "%" refers to weight percentage.

[0041] In the following comparative examples and examples 1-3, per 1 kg of functional feed, the composition of the composite premix is ​​vitamin B1 10 mg, riboflavin 8 mg, pyridoxine hydrochloride 10 mg, vitamin B12 0.2 mg, vitamin K3 10 mg, inositol 100 mg, calcium pantothenate 20 mg, niacin 50 mg, folic acid 2 mg, biotin 2 mg, vitamin A (500,000 IU) 400 mg, vitamin D 5 mg, vitamin E (500,000 IU) 100 mg, ethoxyquin 150 mg, secondary powder 0.1328 g, potassium chloride 200 mg, potassium iodide 60 mg, cobalt sulfate 100 mg, copper sulfate 24 mg, ferrous sulfate 400 mg, zinc sulfate 174 mg, manganese sulfate 78 mg, magnesium sulfate 800 mg, sodium selenite 50 mg, yttrium trioxide 1 g, and zeolite powder 3.114 g.

[0042] The camellia oleifera shell extract in the specific embodiment and comparative example was prepared by acid hydrolysis (2% benzoic acid, solid-liquid ratio 1 g:10 mL, extraction temperature: 160° C., extraction time 0.5 h). After hydrolysis, the extract was cooled, the filtrate was collected, concentrated, and spray-dried to obtain the camellia oleifera shell extract.

[0043] The preparation method of the camellia oleifera shell extract is as follows:

[0044] (1) After the oil tea shell is crushed, 2 wt% benzoic acid (solid-liquid ratio is 1 g: 10 mL) is added and fully homogenized with the aid of a homogenizer;

[0045] (2) The mixture was placed in a stainless steel autoclave for acid hydrolysis at 0.1 MPa and 120° C. for 1 h, and the camellia oleifera shell was removed by filtration. The mixture was then concentrated and spray-dried to obtain a camellia oleifera shell extract. The yield of the camellia oleifera shell extract was calculated to be 29%.

[0046] Example 1 Preparation of functional feed

[0047] The raw materials for preparing the functional feed are as follows by weight: 43 parts of Peruvian fish meal, 9 parts of corn starch, 20 parts of soybean meal, 9 parts of casein, 1 part of calcium dihydrogen phosphate, 1 part of composite premix, 0.05 parts of vitamin C, 0.5 parts of choline chloride, 10.60 parts of microcrystalline cellulose, 5.7 parts of fish oil, and 0.05 parts of camellia oleifera shell extract.

[0048] The functional feed preparation method comprises the following steps:

[0049] (1) crushing Peruvian fish meal, corn starch, soybean meal, casein, microcrystalline cellulose and monocalcium phosphate, and then fully mixing them to obtain a mixture A;

[0050] (2) Mixture A, the composite premix, choline chloride, vitamin C and Caragana korshinskii extract are fully mixed, and then ultrafinely ground to obtain mixture B, and water is added to mixture B, and the mixture is fully mixed to obtain mixture C;

[0051] (3) The mixture C is tempered to prepare an expanded pellet feed, and the expanded pellet feed is dried and then vacuum-oiled at 60° C., cooled, and sieved to obtain a functional feed having a crude protein content of 45.88% and a crude fat content of 10.11%.

[0052] Example 2 Preparation of functional feed

[0053] The raw materials for preparing the functional feed are as follows by weight: 43 parts of Peruvian fish meal, 9 parts of corn starch, 20 parts of soybean meal, 9 parts of casein, 1 part of calcium dihydrogen phosphate, 1 part of compound premix, 0.05 parts of vitamin C, 0.5 parts of choline chloride, 10.65 parts of microcrystalline cellulose, 5.7 parts of fish oil, and 0.1 parts of camellia oleifera shell extract.

[0054] The functional feed preparation method comprises the following steps:

[0055] (1) crushing Peruvian fish meal, corn starch, soybean meal, casein, microcrystalline cellulose and monocalcium phosphate, and then fully mixing them to obtain a mixture A;

[0056] (2) Mixture A, the composite premix, choline chloride, vitamin C and Caragana korshinskii extract are fully mixed, and then ultrafinely ground to obtain mixture B, and water is added to mixture B, and the mixture is fully mixed to obtain mixture C;

[0057] (3) The mixture C is tempered to prepare an expanded pellet feed, and the expanded pellet feed is dried and then vacuum-oiled at 60° C., cooled, and sieved to obtain a functional feed with a crude protein content of 45.91% and a crude fat content of 10.08%.

[0058] Example 3 Preparation of functional feed

[0059] The raw materials for preparing the functional feed are as follows by weight: 43 parts of Peruvian fish meal, 9 parts of corn starch, 20 parts of soybean meal, 9 parts of casein, 1 part of calcium dihydrogen phosphate, 1 part of composite premix, 0.05 parts of vitamin C, 0.5 parts of choline chloride, 10.65 parts of microcrystalline cellulose, 5.7 parts of fish oil, and 0.2 parts of camellia oleifera shell extract.

[0060] The functional feed preparation method comprises the following steps:

[0061] (1) crushing Peruvian fish meal, corn starch, soybean meal, casein, microcrystalline cellulose and monocalcium phosphate, and then fully mixing them to obtain a mixture A;

[0062] (2) Mixture A, the composite premix, choline chloride, vitamin C and Caragana korshinskii extract are fully mixed, and then ultrafinely ground to obtain mixture B, and water is added to mixture B, and the mixture is fully mixed to obtain mixture C;

[0063] (3) The mixture C is tempered to prepare an expanded pellet feed, and the expanded pellet feed is dried and then vacuum-oiled at 60° C., cooled, and sieved to obtain a functional feed having a crude protein content of 45.78% and a crude fat content of 10.02%.

[0064] Comparative Example 1 Preparation of Comparative Feed

[0065] The raw materials for preparing the control feed were, by weight: 43 parts of Peruvian fish meal, 9 parts of corn starch, 20 parts of soybean meal, 9 parts of casein, 1 part of calcium dihydrogen phosphate, 1 part of composite premix, 0.05 parts of vitamin C, 0.5 parts of choline chloride, 10.65 parts of microcrystalline cellulose, 5.7 parts of fish oil, and 0 parts of camellia oleifera shell extract.

[0066] The comparative feed preparation method comprises the following steps:

[0067] (1) crushing Peruvian fish meal, corn starch, soybean meal, casein, microcrystalline cellulose and monocalcium phosphate, and then fully mixing them to obtain a mixture A;

[0068] (2) Mixture A, the composite premix, choline chloride, vitamin C and Caragana korshinskii extract are fully mixed, and then ultrafinely ground to obtain mixture B, and water is added to mixture B, and the mixture is fully mixed to obtain mixture C;

[0069] (3) The mixture C was tempered to prepare an expanded pellet feed, and the expanded pellet feed was dried and then vacuum-oiled at 60° C., cooled, and sieved to obtain a control feed.

[0070] Comparative Example 2 Preparation of Comparative Feed

[0071] The raw materials for preparing the comparative feed were, by weight: 43 parts of Peruvian fish meal, 9 parts of corn starch, 20 parts of soybean meal, 9 parts of casein, 1 part of calcium dihydrogen phosphate, 1 part of composite premix, 0.05 parts of vitamin C, 0.5 parts of choline chloride, 10.65 parts of microcrystalline cellulose, 5.7 parts of fish oil, and 0.4 parts of camellia oleifera shell extract.

[0072] The comparative feed preparation method comprises the following steps:

[0073] (1) crushing Peruvian fish meal, corn starch, soybean meal, casein, microcrystalline cellulose and monocalcium phosphate, and then fully mixing them to obtain a mixture A;

[0074] (2) Mixture A, the composite premix, choline chloride, vitamin C and Caragana korshinskii extract are fully mixed, and then ultrafinely ground to obtain mixture B, and water is added to mixture B, and the mixture is fully mixed to obtain mixture C;

[0075] (3) The mixture C was tempered to prepare an expanded pellet feed, and the expanded pellet feed was dried and then vacuum-oiled at 60° C., cooled, and sieved to obtain a comparative feed having a crude protein content of 45.82% and a crude fat content of 10.10%.

[0076] Performance Testing

[0077] 1. Antibacterial property test of camellia oleifera shell extract

[0078] The active ingredients in the camellia oleifera shell extract were analyzed by GC-MS. As shown in Table 1, the compounds contained in the camellia oleifera shell are divided into: ester compounds (15.42%), furan compounds (61.73%), phenolic compounds (8.43%) and ketone compounds (3.90%).

[0079] Table 1 Active ingredients in camellia oleifera shell extract

[0080]

[0081] Gentomycin sulfate, enrofloxacin and oxytetracycline are commonly used antibiotics for the prevention and control of aquaculture diseases. The above antibiotics and tea husk extract were respectively applied to Vibrio harveyi, Pseudomonas proteus, Edwardsiella tarda, Aeromonas hydrophila and Vibrio alginolyticus. The results are shown in Table 2. It can be seen that tea husk extract, gentamicin sulfate, enrofloxacin and oxytetracycline all showed high sensitivity to Vibrio harveyi and Edwardsiella tarda, tea husk extract and enrofloxacin showed high sensitivity to Pseudomonas proteus, gentamicin sulfate showed moderate sensitivity to Pseudomonas proteus, and oxytetracycline had a low antibacterial effect on Pseudomonas proteus. The antibacterial effects of these four test substances on Aeromonas hydrophila and Vibrio alginolyticus were: tea husk extract = gentamicin sulfate > enrofloxacin > oxytetracycline.

[0082] Table 2 In vitro antibacterial effect of tea oil shell extract on pathogenic bacteria

[0083]

[0084] Note: Result judgment criteria: Inhibition diameter ≥ 20mm is extremely sensitive "+++"; 15mm≤inhibition diameter < 20mm is highly sensitive "++"; 10mm≤inhibition diameter < 15mm is moderately sensitive "+"; Inhibition diameter < 10mm is low-sensitivity or ineffective "-". The dosages of antibiotics added are: gentamicin sulfate 100μg / well, enrofloxacin 5μg / well, oxytetracycline 25μg / well.

[0085] 2. Breeding test

[0086] The functional feed prepared in Example 1-3 and the comparative feed prepared in Comparative Example 1-2 were respectively fed to largemouth bass with an initial body weight of about 7.01 g. The feeding time was 8:00 and 17:00, and the fish were fed until they were full each time. The daily water replacement during the feeding process was about 30%. After 56 days, the growth rate, specific immune ability and oxidative stress ability were tested.

[0087] Survival rate (%) = final number of fish / initial number of fish × 100;

[0088] Weight gain rate (%) = (final total weight of fish - initial total weight of fish) / initial total weight of fish × 100;

[0089] Feeding rate (% / d) = total amount of feed ingested / (final total weight of fish / 2+initial total weight of fish / 2) / 56×100;

[0090] Feed coefficient = total food intake / (final body weight - initial body weight).

[0091] The survival rates of the cultured largemouth bass in the comparative example and each embodiment were all 100%.

[0092] ① The functional feed prepared in Examples 1-3 can improve the antioxidant capacity of largemouth bass

[0093] Total antioxidant capacity, total superoxide dismutase and catalase play an important role in removing free radicals from animal bodies, while malondialdehyde has a certain toxic effect on aquatic animal cells. Figure 1-3 The results show that the total superoxide dismutase activity of Examples 1-3 is slightly higher than that of Comparative Examples 1 and 2; the catalase activity of Examples 2 and 3 is relatively high and the catalase activity of Example 3 is significantly higher than that of Comparative Example 1. Although the catalase activity of Example 1 is slightly lower than that of Example 4, the difference is not significant; the total antioxidant capacity of Comparative Examples 1, 2 and 3 is not much different, while the total antioxidant capacity of Examples 1 and 2 is significantly higher than that of the Comparative Examples and Examples 1-3 have lower malondialdehyde content. Among them, the feed of Example 2 significantly increased the total superoxide dismutase activity and total antioxidant capacity of the serum of largemouth black bass and significantly reduced the content of malondialdehyde in the serum (P<0.05). In summary, largemouth black bass fed with the functional feed prepared by Examples 1-3 can more effectively cope with oxidative stress and maintain a better health state.

[0094] ② The functional feeds prepared in Examples 1 and 2 can promote the growth of largemouth bass

[0095] According to the breeding results of the comparative examples and the embodiments ( Figure 5-7) It can be concluded that, compared with the comparative example, the functional feeds prepared in Examples 1 and 2 increased the weight gain rate of largemouth black bass and decreased the feed coefficient, indicating that they can promote the growth of largemouth black bass and the utilization of feed. Among them, the weight gain rate of largemouth black bass raised in Example 2 was significantly increased (P<0.05), while the feed coefficient was significantly decreased (P<0.05).

[0096] ③ The functional feed prepared in Examples 1-3 can improve the immunity of largemouth bass

[0097] The levels of alkaline phosphatase, acid phosphatase, lysozyme and immunoglobulin M in serum can reflect the specific immune ability of fish. Figure 8-11 As shown, compared with the comparative example, the largemouth bass raised in Example 2 has a higher alkaline phosphatase activity, and the activity differences among Example 1, Example 3, Comparative Example 1 and Comparative Example 2 are small, among which the alkaline phosphatase activity of Example 3 is slightly higher than that of the other groups; there is no significant difference in the acid phosphatase activity among the data of each group, but the effect of Example 2 is slightly better than that of the other groups; in terms of lysozyme activity, Example 1 performs better; in terms of the content of immunoglobulin M, Example 2 performs better and has a significant difference with other groups (P<0.05), followed by Example 1. It shows that the functional feeds prepared by eating Examples 1-3 can improve the immunity of largemouth bass, and Example 2 is particularly good.

[0098] In summary, the oil tea shell extract prepared by the present invention has a good inhibitory effect on common aquatic pathogens: Vibrio harveyi, Pseudomonas proteus, Edwardsiella tarda, Aeromonas hydrophila and Vibrio alginolyticus. Adding it to the functional feed of largemouth bass, after culturing largemouth bass for 56 days, can improve the antioxidant capacity and immune capacity of largemouth bass, and when the addition amount is 0.05-0.1 parts, it can also improve the weight gain rate and feed utilization of largemouth bass.

[0099] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0100] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0101] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A functional feed for largemouth bass, characterized in that: By weight, it is composed of the following raw materials: 43 parts of Peruvian fish meal, 9 parts of corn starch, 20 parts of soybean meal, 9 parts of casein, 1 part of calcium dihydrogen phosphate, 1 part of composite premix, 0.05 parts of vitamin C, 0.5 parts of choline chloride, 10-11 parts of microcrystalline cellulose, 5.7 parts of fish oil, 0.05-0.2 parts of camellia oleifera shell extract; The composite premix is ​​composed of the following raw materials per 1kg of functional feed: vitamin B1 10-11mg, riboflavin 8-9mg, pyridoxine hydrochloride 10-11mg, vitamin B12 0.2-0.3mg, vitamin K3 10-11mg, inositol 100-110mg, calcium pantothenate 20-22mg, niacin 50-52mg, folic acid 2-3mg, biotin 2-3mg, vitamin A (500,000 IU) 400-420mg, vitamin D 5-6mg, vitamin E (500,000 IU) 100-120mg, ethoxyquinoline 150-160mg, secondary powder 0.13-0.14g, potassium chloride 200-220mg, potassium iodide 60-65mg, cobalt sulfate 100-110mg, copper sulfate 24-26mg, ferrous sulfate 400-420mg, zinc sulfate 170-175mg, manganese sulfate 75-80mg, magnesium sulfate 800-820mg, sodium selenite 5-52mg, zeolite powder 3.0-3.5g; The camellia oleifera shell extract is obtained by hydrolyzing the camellia oleifera shell in 2wt% benzoic acid and then drying it, the material-liquid ratio of the hydrolysis is 0.1-2g:1-20mL, the hydrolysis temperature is 80-200°C, and the hydrolysis time is 0.5-2h.

2. The functional feed according to claim 1, characterized in that The added amount of the camellia oleifera shell extract is 0.1 part.

3. A method for preparing the functional feed according to claim 1 or 2, characterized in that: The steps include: (1) crushing Peruvian fish meal, corn starch, soybean meal, casein, microcrystalline cellulose and dicalcium phosphate, and then fully mixing them to obtain a mixture A; (2) Mixture A, the composite premix, choline chloride, vitamin C and Caragana korshinskii extract are fully mixed, and then ultrafinely ground to obtain mixture B, and water is added to mixture B, and the mixture is fully mixed to obtain mixture C; (3) The mixture C is subjected to conditioning treatment to prepare an expanded pellet feed, and the expanded pellet feed is dried and then vacuum-sprayed with oil, cooled and sieved in sequence to obtain the functional feed, wherein the vacuum-sprayed oil temperature is 40-70°C.

4. The preparation method according to claim 3, characterized in that: The preparation method of the camellia oleifera shell extract comprises the following steps: (1) After the oil-tea camellia shell is crushed, 2 wt% benzoic acid is added and the mixture is fully homogenized with the aid of a homogenizer; (2) subjecting the mixture to acid hydrolysis at 0-10 MPa, filtering to remove the camellia oleifera shell, and then concentrating and spray-drying to obtain the camellia oleifera shell extract; The solid-liquid ratio of the oil-tea camellia shell to the benzoic acid is 0.1-2 g: 1-20 mL, the temperature of the acid hydrolysis is 80-200° C., and the time of the acid hydrolysis is 0.5-2 h.

5. The preparation method according to claim 4, characterized in that: The solid-liquid ratio of the oil-tea camellia shell to the benzoic acid is 0.2-0.8 g: 6-12 mL, the temperature of the acid hydrolysis is 120-180° C., and the time of the acid hydrolysis is 0.5-1 h.

6. Use of the functional feed according to claim 1 or 2 in resisting Gram-negative bacteria.

7. The use according to claim 6, characterized in that The Gram-negative bacteria is at least one of Vibrio harveyi, Pseudomonas proteus, Edwardsiella tarda, Aeromonas hydrophila and Vibrio alginolyticus.

8. Use of the functional feed according to claim 1 or 2 in improving the antioxidant capacity of largemouth bass.

9. Use of the functional feed according to claim 1 or 2 in improving the immunity of largemouth bass.

10. Use of the functional feed according to claim 1 or 2 in promoting the growth of largemouth bass.

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