Coated feed additive as well as preparation method and application thereof

Abstract

The invention relates to the technical field of feed additives, and discloses a coated feed additive as well as a preparation method and application thereof. The coated feed additive comprises a pellet core and a coating layer coating the pellet core, the pill core comprises the following components: tannic acid, bile acid and a crude fiber filling agent. According to the coated feed additive provided by the invention, the active ingredients are coated by the coating layer, so that the degradation of the active ingredients in the production and storage processes can be reduced, and the content and stability of the active ingredients are maintained; the feed additive can effectively relieve oxidative stress of livers of aquatic animals, improve growth and increase hypoxia resistance, tannic acid is utilized to play an antibacterial role, use of antibiotics is reduced, and the feed additive is suitable for ecological and healthy culture, can promote safe development of aquaculture and reduce environmental pollution; the aquatic feed is stable in raw material source and low in price, contains the enveloped feed additive, and can relieve the problems of oxidative stress of livers of aquatic animals, growth limitation, reduced stress resistance and the like caused by feeding a large amount of high-sugar and high-fat feed.

Description

Technical Field

[0001] The present invention relates to the technical field of feed additives, and particularly relates to a coated feed additive, a preparation method thereof, and an application thereof. Background Art

[0002] The grass carp (Ctenopharyngodon idella), also known as grass carp, Chinese grass carp, and white amur, belongs to the order Cypriniformes, family Cyprinidae, and genus Ctenopharyngodon in taxonomy. The grass carp has a breeding history of more than 1,700 years in China. It is the most widely cultured fish species in fresh water in China. It is deeply loved by consumers because of its fast growth rate, good meat quality, and rich nutrition, and has been introduced for breeding in more than 100 countries.

[0003] Plant raw materials such as soybean meal have been used as the main components of aquatic animal feed for a long time due to their rich nutritional value and high cost performance. The annual import volume of soybean meal in China exceeds 90 million tons. To reduce the dependence on imported protein raw materials such as soybean meal, the development of low-protein feed is imperative. Compared with high-protein raw materials such as soybean meal, the prices of oil and high-sugar raw materials are relatively low. Therefore, high-sugar and high-fat feeds are widely used in the aquaculture industry.

[0004] However, the excessive use of high-sugar and high-fat feeds will increase the metabolic burden on the liver of fish, lead to increased oxidative stress, endanger the health of aquatic animals, and restrict their growth. In the market, functional additives are selected to be added to commercial feeds to alleviate the negative effects brought by high-sugar and high-fat feeds. During the use of additives, the additives are usually directly mixed with other feed raw materials to make commercial feeds, ignoring the impact of the smell of the additives themselves on farmed animals, as well as the degradation and loss of active ingredients during storage and use, which directly affects the intake of active ingredients of functional additives by aquatic animals and weakens the role of functional additives. Summary of the Invention

[0005] The present invention aims to solve at least one of the above technical problems in the prior art. For this reason, one of the purposes of the present invention is to provide a coated feed additive; the second purpose of the present invention is to provide a preparation method of this coated feed additive; the third purpose of the present invention is to provide an aquatic feed; the fourth purpose of the present invention is to provide an application of this coated feed additive or an aquatic feed.

[0006] In order to achieve the above purposes, the technical solutions adopted by the present invention are as follows:

[0007] The first aspect of the present invention provides a coated feed additive, which includes a core and a coating layer covering the core; the core includes the following components: tannic acid, bile acid, and crude fiber filler.

[0008] In some embodiments of the present invention, by mass parts, the pill core comprises the following components: 1-40 parts of tannic acid, 1-40 parts of bile acid, and 20-100 parts of crude fiber filler.

[0009] In some specific embodiments of the present invention, by mass parts, the pill core comprises the following components: 20-40 parts of tannic acid, 20-40 parts of bile acid, and 20-60 parts of crude fiber filler.

[0010] In some embodiments of the present invention, the crude fiber filler is selected from at least one of rice husk powder, rice bran powder, wheat bran, corncob powder, and soybean hull powder.

[0011] In some specific embodiments of the present invention, the crude fiber filler is rice husk powder.

[0012] In some embodiments of the present invention, the material of the coating layer is selected from at least one of ethyl cellulose, carboxymethyl cellulose, hydroxyethyl methyl cellulose, and ethyl methyl cellulose.

[0013] In some preferred embodiments of the present invention, the material of the coating layer is ethyl cellulose.

[0014] In some embodiments of the present invention, the dosage of the coating layer material is 0.4%-0.8% of the mass of the pill core.

[0015] In some specific embodiments of the present invention, the dosage of the coating layer material is 0.4%-0.6% of the mass of the pill core.

[0016] The basic principle of the present invention is described as follows:

[0017] 1) For the coated feed additive provided by the present invention, the components of the pill core include tannic acid, bile acid, and crude fiber filler. Tannic acid can scavenge free radicals in aquatic animals, reduce oxidative stress, protect cells from damage, and at the same time, tannic acid has certain antibacterial activity and can inhibit the growth of certain bacteria and fungi by interacting with bacterial cell membranes and extracellular proteins, improving the stress tolerance and disease resistance of aquatic animals; bile acid can emulsify fat and promote fat metabolism, which has a certain promoting effect on the growth of aquatic animals. Adding bile acid can make up for the lack of bile acid caused by the extensive use of plant proteins in aquatic feeds and the abnormal lipid metabolism and growth restriction caused by the widespread use of high-sugar and high-fat feeds; the raw materials of the crude fiber filler are easily available. It can not only be used as an adhesive to bond the active ingredients tannic acid and bile acid to form stable particles, but also provide dietary fiber to improve the intestinal health of aquatic animals.

[0018] 2) The coated feed additive provided by the present invention has a core pellet coated with a coating layer. Cellulose ether compounds such as ethyl cellulose have good water solubility, adhesiveness, and film-forming ability, and are easy to form a coating layer. After coating the core pellet, it has the effects of controlled release, taste masking, and stability maintenance on the active ingredient, can greatly reduce the influence of the additive odor on the feeding attraction of aquatic animals, and can also reduce the degradation of the active ingredient during the production mixing and finished product storage processes, reduce the dissolution loss of the additive in the water body after the feed is fed, and ensure the effective intake of the additive; by controlling the dosage of the coating layer material, it is avoided that due to excessive dosage of the coating layer material and too thick coating layer, the slow-release time and normal metabolism of the additive in the intestinal tract of aquatic animals are affected; and it is avoided that due to too little dosage of the coating layer material and too thin coating layer, the additive is dissolved and lost after the feed containing the additive is soaked in water for too long, affecting the effect.

[0019] The second aspect of the present invention provides a preparation method of the coated feed additive described in the first aspect of the present invention, including the following steps:

[0020] Mix the components of the core pellet, and then form a coating layer on the surface to obtain the coated feed additive.

[0021] In some embodiments of the present invention, the coating layer is formed by using a coating machine.

[0022] The third aspect of the present invention provides an aquatic feed, including the coated feed additive described in the first aspect of the present invention; the content of the coated feed additive is ≤ 5 wt%.

[0023] In some embodiments of the present invention, the content of the coated feed additive in the aquatic feed is 2 wt% - 5 wt%.

[0024] In some specific embodiments of the present invention, the content of the coated feed additive in the aquatic feed is 2 wt% - 3 wt%.

[0025] In some embodiments of the present invention, the aquatic feed further includes a basic feed; by mass percentage, the basic feed includes the following components: 5% - 10% fish meal, 8% - 15% corn protein powder, 25% - 35% soybean meal, 15% - 25% rapeseed meal, 15% - 25% wheat, 1% - 5% soybean oil, 1% - 5% soybean lecithin oil, 1% - 5% monocalcium phosphate, 0.5% - 2% vitamin premix, 1% - 5% mineral premix.

[0026] In some specific embodiments of the present invention, by mass percentage, the basic feed includes the following components: 7%-10% fish meal, 8%-10% corn gluten meal, 25%-30% soybean meal, 15%-20% rapeseed meal, 15%-20% wheat, 1%-4% soybean oil, 1%-4% soy lecithin oil, 1%-4% calcium dihydrogen phosphate, 0.5%-1% vitamin premix, 1%-4% mineral premix.

[0027] In some embodiments of the present invention, the mineral premix includes the following components: MnSO4, MgSO4, FeSO4, CoSO4, Na2SeO3, CuSO4, KCl, NaCl, ZnSO4, H2CaIO4 and CoCl2.

[0028] In some specific embodiments of the present invention, the mineral premix includes the following components: MnSO4 40 - 50 mg / kg, MgSO4 750 - 850 mg / kg, FeSO4 50 - 150 mg / kg, CoSO4 0.01 - 0.05 mg / kg, Na2SeO3 1 - 3 mg / kg, CuSO4 5 - 15 mg / kg, KCl 2500 - 3500 mg / kg, NaCl 1000 - 2000 mg / kg, ZnSO4 10 - 100 mg / kg, H2CaIO4 10 - 100 mg / kg, CoCl2 10 - 100 mg / kg.

[0029] In some embodiments of the present invention, the vitamin premix includes the following components: vitamin B1, vitamin B2, vitamin B6, vitamin B 12 , vitamin D3, vitamin E, vitamin K, folic acid, biotin, inositol, vitamin C, niacinamide and choline.

[0030] In some specific embodiments of the present invention, the vitamin premix includes the following components: vitamin B1 20 - 30 mg / kg, vitamin B2 10 - 20 mg / kg, vitamin B6 25 - 35 mg / kg, vitamin B 12 0.1 - 0.3 mg / kg, vitamin D3 1 - 10 mg / kg, vitamin E 150 - 250 mg / kg, vitamin K 10 - 20 mg / kg, folic acid 15 - 25 mg / kg, biotin 55 - 65 mg / kg, inositol 550 - 650 mg / kg, vitamin C 200 - 250 mg / kg, niacinamide 150 - 250 mg / kg, choline 900 - 1100 mg / kg.

[0031] In some embodiments of the present invention, the aquatic feed is prepared by a method including the following steps:

[0032] Mix the coated feed additive with the basal feed to obtain the aquatic feed described above.

[0033] The third aspect of the present invention provides the application of the coated feed additive described in the first aspect of the present invention, or the aquatic feed described in the second aspect of the present invention, in the preparation of a product for alleviating oxidative stress in the liver of aquatic animals and / or promoting the growth of aquatic animals and / or increasing the hypoxia tolerance of aquatic animals.

[0034] In some embodiments of the present invention, the aquatic animals include fish.

[0035] In some specific embodiments of the present invention, the aquatic animals include grass carp.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] 1) For the coated feed additive provided by the present invention, the active ingredient is wrapped by a coating layer, which can reduce the degradation of the active ingredient during production and storage, and maintain the content and stability of the active ingredient;

[0038] 2) For the coated feed additive provided by the present invention, it can effectively alleviate oxidative stress in the liver of aquatic animals, improve the growth of aquatic animals, and increase the hypoxia tolerance. It uses tannic acid to exert antibacterial effects, reduces the use of antibiotics, is suitable for ecological and healthy aquaculture, can promote the safe development of aquaculture, and reduce environmental pollution;

[0039] 3) The preparation method of the coated feed additive provided by the present invention has simple steps and is suitable for large-scale production;

[0040] 4) For the aquatic feed provided by the present invention, the raw material source is stable, the price is low, the production process is simple, and it contains a coated feed additive, which can alleviate problems such as oxidative stress in the liver of aquatic animals, growth restriction, and reduced stress tolerance caused by excessive feeding of high-sugar and high-fat feeds. Description of the Drawings

[0041] Figure 1 It is a comparison chart of the effect of the coated feed additive on the content of malondialdehyde in the liver of grass carp in the test example;

[0042] Figure 2 It is a comparison chart of the effect of the coated feed additive on the activity of superoxide dismutase in the liver of grass carp in the test example;

[0043] Figure 3 It is a comparison chart of the effect of the coated feed additive on the total antioxidant capacity in the liver of grass carp in the test example;

[0044] Figure 4 It is a comparison chart of the effect of the coated feed additive on the growth of grass carp in the test example;

[0045] Figure 5 It is a comparison chart of the effect of the coated feed additive on the hypoxia tolerance of grass carp in the test examples. Detailed implementation manners

[0046] The content of the present invention will be further described in detail below through specific examples. The raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial channels or by existing technical methods without special instructions. Unless otherwise specified, the test or measurement methods are conventional methods in the art.

[0047] Unless otherwise specified, "parts" in the following examples and comparative examples all refer to "parts by mass".

[0048] Example 1

[0049] In this example, a coated feed additive was prepared as follows:

[0050] First, 20 parts of tannic acid, 20 parts of bile acid and 60 parts of rice husk powder were mixed to obtain a core, and then 0.5 part of ethyl cellulose was used to coat the core in a coating machine to form a coating layer, obtaining the coated feed additive.

[0051] Example 2

[0052] In this example, a coated feed additive was prepared as follows:

[0053] First, 40 parts of tannic acid, 40 parts of bile acid and 20 parts of rice husk powder were mixed to obtain a core, and then 0.5 part of ethyl cellulose was used to coat the core in a coating machine to form a coating layer, obtaining the coated feed additive.

[0054] Comparative Example 1

[0055] In this comparative example, a coated feed additive was prepared as follows:

[0056] First, 20 parts of tannic acid and 80 parts of rice husk powder were mixed to obtain a core, and then 0.5 part of ethyl cellulose was used to coat the core in a coating machine to form a coating layer, obtaining the coated feed additive.

[0057] Comparative Example 2

[0058] In this comparative example, a coated feed additive was prepared as follows:

[0059] First, 40 parts of tannic acid and 60 parts of rice husk powder were mixed to obtain a core, and then 0.5 part of ethyl cellulose was used to coat the core in a coating machine to form a coating layer, obtaining the coated feed additive.

[0060] Comparative Example 3

[0061] This comparative example prepares a coated feed additive, and the steps are as follows:

[0062] First, 20 parts of bile acid and 80 parts of rice husk powder are mixed to obtain the core, and then 0.5 part of ethyl cellulose is used in a coating machine to coat the core to form a coating layer, obtaining the coated feed additive.

[0063] Comparative Example 4

[0064] This comparative example prepares a coated feed additive, and the steps are as follows:

[0065] First, 40 parts of bile acid and 60 parts of rice husk powder are mixed to obtain the core, and then 0.5 part of ethyl cellulose is used in a coating machine to coat the core to form a coating layer, obtaining the coated feed additive.

[0066] Comparative Example 5

[0067] This comparative example prepares a non-coated feed additive, which is different from Example 1 in that it does not contain a coating layer. The preparation steps are as follows:

[0068] 20 parts of tannic acid, 20 parts of bile acid and 60 parts of rice husk powder are mixed to obtain the non-coated feed additive.

[0069] Comparison of additive dissolution performance

[0070] Explore the dissolution performance of the additives in Example 1 and Comparative Example 5 in water:

[0071] The additives in Example 1 and Comparative Example 5 with the same mass are respectively put into water. After 8 minutes, the contents of tannic acid and bile acid in the water are detected. In the water containing the additive of Comparative Example 5, tannic acid and bile acid are detected, indicating that the non-coated feed additive in Comparative Example 5 has dissolved in water within 8 minutes. While in the water containing the additive of Example 1, the core components are not detected, indicating that the coated feed additive in Example 1 does not dissolve in water within 8 minutes. During normal breeding, 8 minutes is sufficient to ensure that the feed is ingested by the breeding animals. Therefore, the coated feed additive provided by the present invention can delay the dissolution time of the additive in water after coating the core, thereby ensuring the effective intake of aquatic animals.

[0072] Application Example

[0073] In this application example, the coated feed additives in Example 1, 2 and Comparative Examples 1-4 are respectively mixed with the basic feed to obtain aquatic feeds 1-6, and rice husk powder is used to replace the coated feed additive and mixed with the basic feed to obtain aquatic feed 7. The formulations of aquatic feeds 1-7 are shown in Table 1:

[0074] Table 1 Formulations of Aquatic Feeds 1-6

[0075]

[0076] Among them, the vitamin premix contains the following components: vitamin B1 25 mg / kg, vitamin B2 15 mg / kg, vitamin B6 30 mg / kg, vitamin B 12 0.1 mg / kg, vitamin D3 5 mg / kg, vitamin E 200 mg / kg, vitamin K1 5 mg / kg, folic acid 20 mg / kg, biotin 60 mg / kg, inositol 600 mg / kg, vitamin C 250 mg / kg, nicotinamide 200 mg / kg, choline 1000 mg / kg;

[0077] The mineral premix contains the following components: MnSO4 45 mg / kg, MgSO4 800 mg / kg, FeSO4 100 mg / kg, CoSO4 0.02 mg / kg, Na2SeO3 1 mg / kg, CuSO4 10 mg / kg, KCl 3000 mg / kg, NaCl 1500 mg / kg, ZnSO4 50 mg / kg, H2CaIO4 50 mg / kg, CoCl2 50 mg / kg.

[0078] Test examples

[0079] The aquatic feeds 1 - 7 prepared in the application examples were used for grass carp farming to investigate the effects of the coated feed additives in Examples 1, 2 and Comparative Examples 1 - 4 on the oxidative stress, growth and hypoxia tolerance of grass carp liver:

[0080] The farming test was carried out in the aquariums of the Panyu test base of Guangdong Haida Group. Before the test, the test fish were temporarily raised for 2 weeks to adapt to the farming environment. Before the formal start of the farming test, the test fish were starved for 24 h. 840 grass carps with uniform specifications and an average weight of 27.4 ± 0.1 g were randomly selected. The test fish were randomly divided into 28 300 - L circulating aquariums, with 30 fish in each aquarium. The 28 aquariums were divided into 7 groups according to every 4 aquariums as a group. Groups 1 - 6 were respectively fed with aquatic feeds TB - 20, TB - 40, T - 20, B - 20, T - 40 and B - 40 as the test groups, and the 7th group was fed with aquatic feed CON as the control group. They were fed quantitatively 3 times a day (the feeding times were 08:00, 12:00 and 16:00 respectively), and the farming test period lasted for 8 weeks.

[0081] After the aquaculture experiment ended, the survival rate of the experimental fish in all aquariums was 100%. The experimental fish were starved for 24 h, and the mass of the experimental fish in each aquarium was recorded. Three uniformly sized experimental fish were taken from each aquarium, dissected, and the liver tip parts were collected and quickly frozen in liquid nitrogen for later use in the detection of subsequent liver biochemical indexes (liver malondialdehyde content, liver superoxide dismutase activity, and total antioxidant capacity of the liver). The detection was carried out using a commercial kit, and the detection method was referred to the kit instruction manual.

[0082] After sampling, eight uniformly sized experimental fish were randomly selected from each aquarium, and 32 fish in the same treatment group were transferred to a new aquarium for the hypoxia stress experiment. Before the experiment started, the experimental fish in the seven treatment groups were temporarily raised in the seven new aquariums for 1 day. During the temporary raising period, it was ensured that the oxygen supply in the aquariums was sufficient and the dissolved oxygen levels were consistent. After 1 day of temporary raising, at the same time, the oxygen supply to each aquarium was completely cut off, and the cumulative death of grass carp in each aquarium at different oxygen cut-off times was observed and counted.

[0083] The experimental data were statistically analyzed by one-way analysis of variance in SPSS 19.0. After significant differences, Tukey's multiple comparisons were performed, and the significance level was p < 0.05. The obtained experimental data were expressed as mean ± standard error (n = 4).

[0084] Figure 1 It is a comparison chart of the effects of the coated feed additive on the liver malondialdehyde content of grass carp in the test examples. In the figure, the same letters represent no significant differences (p > 0.05), and different letters represent significant differences (p < 0.05). From Figure 1 It can be seen that in the groups fed with aquatic feeds TB-20, TB-40, T-20, B-20, T-40, and B-40, after the aquaculture experiment ended, the liver malondialdehyde contents of grass carp were 0.0240 mmol / mg protein, 0.0267 mmol / mg protein, 0.0661 mmol / mg protein, 0.0472 mmol / mg protein, 0.0575 mmol / mg protein, and 0.0330 mmol / mg protein, respectively. Compared with the control group fed with aquatic feed CON (0.0695 mmol / mg protein), the liver malondialdehyde contents of grass carp decreased. Among them, in the groups fed with aquatic feeds containing the coated feed additives in Examples 1 and 2 (TB-20 and TB-40), the liver malondialdehyde contents of grass carp were significantly lower than those of the control group (p < 0.05), indicating that after adding the coated feed additive provided by the present invention to the basal feed, it can significantly reduce the content of lipid peroxide malondialdehyde in the liver of grass carp, thereby reducing liver oxidative stress and protecting cells from damage by free radicals.

[0085] Figure 2This is a comparison chart of the effect of the coated feed additive on the superoxide dismutase activity in the liver of grass carp in the test examples. In the chart, the same letters represent no significant difference (p > 0.05), and different letters represent significant differences (p < 0.05). From Figure 2 it can be seen that in the groups fed with aquatic feeds TB-20, TB-40, T-20, B-20, T-40, and B-40, after the breeding test, the superoxide dismutase activities in the livers of grass carp were 0.53 U / mg protein, 0.46 U / mg protein, 0.32 U / mg protein, 0.33 U / mg protein, 0.35 U / mg protein, and 0.36 U / mg protein respectively. Compared with the control group fed with aquatic feed CON (0.29 U / mg protein), in the groups fed with aquatic feeds containing the coated feed additives in Examples 1 and 2 (TB-20 and TB-40), the superoxide dismutase activities in the livers of grass carp were significantly increased (p < 0.05). Superoxide dismutase is an important antioxidant enzyme in grass carp, which can catalyze the conversion of superoxide anions into oxygen and water. The increase in its activity means that grass carp can more effectively scavenge free radicals in the body, enhance the overall antioxidant capacity, and protect cells from oxidative damage. This once again proves that after adding the coated feed additive provided by the present invention to the basal feed, it can alleviate the oxidative stress of aquatic animal livers.

[0086] Figure 3 This is a comparison chart of the effect of the coated feed additive on the total antioxidant capacity in the liver of grass carp in the test examples. In the chart, the same letters represent no significant difference (p > 0.05), and different letters represent significant differences (p < 0.05). From Figure 3 it can be seen that in the groups fed with aquatic feeds TB-20, TB-40, T-20, B-20, T-40, and B-40, after the breeding test, the total antioxidant capacities in the livers of grass carp were 0.025 U / mg protein, 0.025 U / mg protein, 0.017 U / mg protein, 0.017 U / mg protein, 0.016 U / mg protein, and 0.017 U / mg protein respectively. Compared with the control group fed with aquatic feed CON (0.014 U / mg protein), in the groups fed with aquatic feeds containing the coated feed additives in Examples 1 and 2 (TB-20 and TB-40), the total antioxidant capacities in the livers of grass carp were significantly increased (p < 0.05), indicating that after adding the coated feed additive provided by the present invention to the basal feed, it helps to reduce the damage of free radicals to cells and tissues, thereby reducing oxidative stress.

[0087] Figure 4 This is a comparison chart of the effect of the coated feed additive on the growth of grass carp in the test examples. In the chart, the same letters represent no significant difference (p > 0.05), and different letters represent significant differences (p < 0.05). From Figure 4It can be seen that compared with before the experiment, after the breeding experiment ended in the groups fed with aquafeeds CON, TB-20, TB-40, T-20, B-20, T-40, and B-40, the weight gain rates of grass carp were 261.1%, 319.5%, 316.5%, 267.5%, 266.5%, 267.4%, and 282.5% respectively. Compared with the control group fed with aquafeed CON, in the groups fed with aquafeeds containing the coated feed additives in Examples 1 and 2 (TB-20 and TB-40), the weight gain rate of grass carp was significant, indicating that after adding the coated feed additive provided by the present invention to the basal feed, it is beneficial to promote the growth of grass carp.

[0088] Figure 5 It is a comparison chart of the influence of the coated feed additive on the hypoxia tolerance ability of grass carp in the test example. Figure 5 It can be seen that compared with the control group fed with aquafeed CON, feeding aquafeeds containing the coated feed additives in Examples 1, 2, and Comparative Examples 1-4 can all delay the initial death time of grass carp after oxygen cut-off, that is, it can improve the hypoxia tolerance ability of grass carp. Among them, feeding aquafeeds containing the coated feed additives in Examples 1 and 2 has the most obvious improvement in the hypoxia tolerance ability of grass carp.

[0089] The coated feed additive provided by the present invention can relieve the oxidative stress of grass carp liver, protect the liver from oxidative damage, promote the growth of grass carp, improve its hypoxia tolerance ability, and can relieve problems such as oxidative stress, growth restriction, and reduced stress tolerance ability of grass carp liver caused by feeding a large amount of high-sugar and high-fat feed.

Claims

1. A coated feed additive, characterized in that: The invention comprises a pellet core and a coating layer for coating the pellet core; the pellet core comprises the following components: tannic acid, bile acid and a crude fiber filler.

2. The film-coated feed additive according to claim 1, characterized in that: The pellet core comprises the following components by weight: 1-40 parts of tannic acid, 1-40 parts of bile acid and 20-100 parts of crude fiber filler.

3. The film-coated feed additive according to claim 1 or 2, characterized in that: The crude fiber filler is selected from at least one of rice husk powder, rice bran powder, wheat bran, corn cob powder and soybean hull powder.

4. The film-coated feed additive according to claim 1, characterized in that: The material of the coating layer is selected from at least one of ethyl cellulose, carboxymethyl cellulose, hydroxyethyl methyl cellulose and ethyl methyl cellulose.

5. The film-coated feed additive according to claim 4, characterized in that: The amount of the coating layer material is 0.4%-0.8% of the mass of the pellet core.

6. The method for preparing the coated feed additive according to any one of claims 1 to 5, characterized in that: The following steps are involved: The components of the pellet core are mixed, and then a coating layer is formed on the surface to obtain the coated feed additive.

7. An aquatic feed, characterized in that: The coated feed additive comprises the coated feed additive according to any one of claims 1 to 5; the content of the coated feed additive is ≤5wt%.

8. The aquatic feed according to claim 7, characterized in that: The aquatic feed also includes a basic feed; calculated by mass percentage, the basic feed includes the following components: 5%-10% fish meal, 8%-15% corn gluten meal, 25%-35% soybean meal, 15%-25% rapeseed meal, 15%-25% wheat, 1%-5% soybean oil, 1%-5% soybean lecithin oil, 1%-5% monocalcium phosphate, 0.5%-2% vitamin premix, and 1%-5% mineral premix.

9. Use of the coated feed additive according to any one of claims 1 to 5, or the aquatic feed according to claim 7 or 8, in the preparation of a product for alleviating liver oxidative stress in aquatic animals and / or promoting growth of aquatic animals and / or increasing hypoxia tolerance of aquatic animals.

10. The use according to claim 9, characterized in that: The aquatic animals include fish.

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