Application of lanosterol substances in preparation of feed additives for hard bony fish and feed

Abstract

This invention provides the application of lanosterols in the preparation of feed additives for bony fish and the feed itself, including lanosterols or their feed-acceptable esters, in the preparation of feed additives for bony fish to improve the growth performance, muscle quality, and physiological health of bony fish, including enhancing their antioxidant capacity and / or immunity. This invention provides a novel, efficient, and cost-optimized functional additive for bony fish feed, offering an effective cholesterol alternative or supplement to reduce feed costs; simultaneously, it significantly improves the growth performance and muscle quality of bony fish, enhances immune function and stress resistance, thereby improving aquaculture efficiency and feed utilization.

Description

Technical Field

[0001] This invention relates to the technical field of feed additives, specifically to the application of lanosterols in the preparation of feed additives for bony fish and the feed itself. Background Technology

[0002] Boneless fish widely farmed in my country, such as cold-water marine cultured turbot ( Scophthalmus maximus These fish species are highly industrialized and dependent on feed, making them sensitive to feed nutrient composition and functional additives. Due to their relatively low lipid content in muscle, muscle lipid composition is easily affected by feed factors. In recent years, with increasing farming density and rising demands for efficient and environmentally friendly feed, improving the growth performance, muscle quality, and physiological health of bony fish through nutritional regulation has become a critical technical issue that the industry urgently needs to address.

[0003] Currently, feed formulations for bony fish on the market mainly rely on animal-derived ingredients such as fishmeal and fish oil to meet the fish's nutritional needs for sterols. To achieve sustainable development in aquaculture and control aquatic feed production costs, the industry has widely adopted plant protein sources with lower cholesterol content to replace traditional cholesterol-rich animal protein sources, such as fishmeal, in recent years. However, this substitution of protein sources can lead to an imbalance in feed nutrient composition. Although bony fish are believed to be able to synthesize cholesterol themselves, low-fishmeal feeds still result in decreased growth performance, abnormal body composition, and physiological stress in bony fish.

[0004] However, natural cholesterol is expensive and has limited sources. Adding cholesterol would significantly reduce the cost advantage of low-fishmeal feed and limit its large-scale application. At the same time, relying heavily on cholesterol as a single feed additive makes the feed susceptible to market supply fluctuations and makes it impossible to guarantee a stable supply and use of feed additives.

[0005] Currently, the industry lacks novel feed additives that meet functional requirements, have stable sources, and are more cost-effective. Furthermore, there is an urgent need for a multifunctional feed additive that can simultaneously improve fish growth performance, muscle quality, and physiological health, thereby enhancing the farming efficiency and feed utilization of bony fish. Therefore, developing low-cost, more stable-source novel alternatives and multifunctional feed additives has become a key technological challenge that the aquaculture feed industry urgently needs to overcome.

[0006] Lanosterols are a class of tetracyclic triterpenoids, appearing as white, odorless powders. They can be obtained through natural extraction or biochemical synthesis, serving as important steroidal intermediates and functional active substances. In the pharmaceutical field, lanosterols can be used in the synthesis of drug intermediates, the prevention and treatment of ophthalmic diseases such as cataracts, and immunomodulation. In the cosmetics field, lanosterols, due to their excellent permeability, water absorption, and lubricating properties, can be used as functional additives in the preparation of various high-end cosmetics, especially suitable for skincare and makeup products with moisturizing, repairing, and soothing effects. In the chemical industry, lanosterols, as typical representatives of tetracyclic triterpenoids, can be used as raw materials for chemical synthesis to prepare various terpene derivatives, surfactants, lubricants, and other chemical products. Currently, there are no publicly reported applications of lanosterols in feed additives, especially for bony fish. Summary of the Invention

[0007] This invention aims to overcome the shortcomings of existing technologies and provide a novel, efficient, and cost-optimized sterol functional additive—lanosterol—for application in the feed of bony fish. On the one hand, it provides an effective alternative or supplement for cholesterol, reducing feed costs; on the other hand, it significantly improves the growth performance, muscle quality, immune function, and stress resistance of bony fish, thereby enhancing aquaculture efficiency and feed utilization.

[0008] The first aspect of the invention is to provide the use of lanosterols or their feed-acceptable esters in the preparation of feed additives for bony fishes to improve the growth performance of bony fishes.

[0009] According to a preferred embodiment of the present invention, the growth performance of bony fish is improved, specifically by increasing the final average weight, weight gain rate, specific growth rate and / or reducing the feed conversion ratio of bony fish.

[0010] A second aspect of the invention is to provide the use of lanosterols or their feed-acceptable esters in the preparation of feed additives for bony fishes to improve muscle quality.

[0011] According to a preferred embodiment of the present invention, the muscle quality of bony fish is improved by increasing the total body fat content of bony fish, reducing muscle hardness, increasing muscle triglyceride content and / or increasing flavor amino acid content.

[0012] A third aspect of the invention is to provide the use of lanosterols or their feed-acceptable esters in the preparation of feed additives for bony fishes to maintain the physiological health of bony fishes.

[0013] According to a preferred embodiment of the present invention, maintaining the physiological health of bony fish includes improving the antioxidant capacity of bony fish and / or improving the immunity of bony fish.

[0014] According to a preferred embodiment of the present invention, the antioxidant capacity of bony fish is improved, specifically by increasing the activity of superoxide dismutase (SOD) in bony fish.

[0015] According to a preferred embodiment of the present invention, the immunity of bony fish is improved, specifically by increasing lysozyme activity and / or inhibiting the expression of pro-inflammatory factors.

[0016] According to a preferred embodiment of the present invention, the bony fish is any one of turbot, flounder, Atlantic salmon, rainbow trout, grouper, large yellow croaker, pomfret, and sea bass. The above three aspects are applied in the preparation of bony fish feed additives, especially for flounder, including turbot and flounder.

[0017] According to a preferred embodiment of the present invention, the application in the preparation of bony fish feed additives for improving the growth performance and muscle quality of bony fish is for feeds where the animal protein source is added at a low or high content due to the substitution or non-substitution of some animal protein source by plant protein sources or other protein sources. That is, the aforementioned applications for improving growth performance and muscle quality are for feeds with high or low animal protein sources. The content of animal protein source in the feed is generally not higher than 60%, preferably 30%-55%. The content of animal protein source in the feed is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, or any value between these values.

[0018] Preferably, the animal protein source in the feed includes fishmeal. In the first two aspects mentioned above, the application in the preparation of feed additives for bony fish to improve growth performance and muscle quality is for feeds where fishmeal is added in low or high amounts due to the substitution or non-substitution of some fishmeal by plant protein sources or other protein sources. That is, the aforementioned applications in improving growth performance and muscle quality are for feeds with high or low fishmeal content. The fishmeal content in the feed generally does not exceed 60%, preferably 30%-55%. The fishmeal content in the feed is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, or any value between these values.

[0019] According to a preferred embodiment of the present invention, the third aspect described above, in the preparation of a feed additive for maintaining the physiological health of bony fish, is for feeds where the animal protein source is added at a low level because plant protein sources or other protein sources replace a portion of the animal protein source. That is, the above-described application for maintaining the physiological health of bony fish is for feeds with low animal protein sources. The content of animal protein source in the feed is generally not higher than 50%, preferably not higher than 40% or 30%-40%. The content of animal protein source in the feed is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any value between these values.

[0020] Preferably, the animal protein source in the feed includes fishmeal. In the third aspect described above, the application in the preparation of feed additives for maintaining the physiological health of bony fish is for feeds where fishmeal is added in a low amount due to the substitution of some fishmeal by plant protein sources or other protein sources. That is, the aforementioned application for maintaining the physiological health of bony fish is for feeds with low fishmeal content. The fishmeal content in the feed is generally not higher than 50%, preferably not higher than 40% or 30%-40%. The fishmeal content in the feed is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any value between these values.

[0021] According to a preferred embodiment of the present invention, lanosterols include one or more of lanosterol, dihydrolanosterol, 24-methylenedihydrolanosterol, and parkol.

[0022] According to a preferred embodiment of the present invention, feed-acceptable esters of lanosterols include esterification products obtained by combining lanosterols with fatty acids of any form, or mixtures of lanosterols with partially esterified products. The aforementioned fatty acids of any form include single fatty acids or mixed fatty acids.

[0023] The esters of lanosterols that are acceptable in feed include, but are not limited to, one or more of the following: lanosterol formate, lanosterol acetate, lanosterol oleate, lanosterol palmitate, and lanosterol laurate.

[0024] The lanosterols are preferably a mixture of lanosterol and dihydrolanosterol, the structural formulas of which are shown in formula (I) and formula (II), respectively.

[0025] (I) (II) The mass ratio of lanosterol to dihydrolanosterol is (0.5~5):1, preferably (1~3):1. The mass ratio of lanosterol to dihydrolanosterol is 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1 or any value between them.

[0026] Preferably, the mass ratio of lanosterol to dihydrolanosterol is 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3.0:1, or any value between them.

[0027] According to a preferred embodiment of the present invention, the amount of lanosterols or their feed-acceptable esters added to the feed is 0.02% to 0.5% or 0.1% to 0.5%, preferably 0.1% to 0.2% or 0.2% to 0.5%. The amount of lanosterols or their feed-acceptable esters added to the feed is 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, or any value between these values.

[0028] A fourth aspect of the invention is to provide a feed for bony fish, comprising the aforementioned lanosterols or feed-acceptable esters thereof.

[0029] According to a preferred embodiment of the present invention, the bony fish feed comprises the following components, based on dry weight: (1) Animal protein source 30%~60%; (2) Plant protein source 0%~35%; (3) Carbohydrates 10%~30%; (4) Fat 5%~15%; (5) Nutritional supplements and excipients 1% to 15%, including lanosterols or their feed-acceptable esters.

[0030] According to a preferred embodiment of the present invention, the bony fish feed comprises the following components, based on dry weight: (1) Animal protein source 30%~50%; (2) Plant protein source 20%~30%; (3) Carbohydrates 10%~20%; (4) Fat 5%~10%; (5) 5% to 15% of nutritional supplements and excipients, including lanosterols or their feed-acceptable esters, wherein the amount of lanosterols or their feed-acceptable esters added to the feed is 0.02% to 0.5% or 0.1% to 0.5%, preferably 0.1% to 0.2% or 0.2% to 0.5%.

[0031] The present invention has the following beneficial effects: (1) The application of lanosterols or their feed-acceptable esters in the preparation of feed additives for bony fishes in this invention provides an effective alternative or supplementary solution for cholesterol addition in feed, thereby reducing feed costs and having the potential for cost optimization. It provides feed production enterprises with a new option to reduce formulation costs while maintaining the performance of high-end products.

[0032] (2) The addition of lanosterols or their feed-acceptable esters to feed can significantly improve the growth performance and feed utilization of bony fish, improve muscle quality, promote the accumulation of flavor substances, and increase the added value of products.

[0033] (3) The addition of lanosterols or their feed-acceptable esters to the feed can enhance the ability to defend against oxidative stress, improve immunity, and maintain the health of fish under low fishmeal feed conditions. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0035] Unless otherwise specified, the raw materials and equipment used in the following embodiments of the present invention are commercially available.

[0036] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this invention are based on weight, unless being based on weight would not be in accordance with the common understanding of those skilled in the art.

[0037] The "range" disclosed herein is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that the ranges of 60-110 and 80-120 will also be understood. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers.

[0038] Unless otherwise specified in this application, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0039] Unless otherwise specified, all technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0040] In this application, unless otherwise specified, the terms "comprising" and "including" as used herein are open-ended or closed-ended. For example, "comprising" and "including" may mean that other components not listed may also be included, or that only the listed components may be included.

[0041] In this description, it should be noted that, unless otherwise stated, "above" and "below" include the stated number, and "multiple" in "one or more" means two or more.

[0042] This invention discloses a method for using lanosterols or their feed-acceptable esters as feed additives in bony fish, such as turbot. Specifically, exogenously adding a specific dosage range of lanosterols or their feed-acceptable esters to a high-fishmeal (e.g., 50% fishmeal) feed can further improve the growth performance of bony fish and optimize muscle quality. Exogenously adding a specific dosage range of lanosterols or their feed-acceptable esters to a low-fishmeal (e.g., 40% fishmeal) feed can improve the growth performance of bony fish, optimize muscle quality, enhance immune function and stress resistance, and maintain the physiological health of the fish.

[0043] The overall implementation path of this program is as follows: A basic feed containing 50% and 40% fishmeal was formulated according to aquaculture requirements. Different dosages of lanosterol were then added to this feed, with the lanosterol product uniformly mixed into the feed in powder form with a purity ≥96.6%. The formulated mixed feed was processed into pellets and fed to juvenile turbot using an apparent satiety feeding method. Experimental groups included a control group (without lanosterol product) and groups with different addition amounts. The growth performance, body composition and muscle quality, antioxidant and immune indicators of the turbot were measured and analyzed. Specific experiments and results are as follows.

[0044] 1. Experimental materials and feed formulation: Experimental animals: turbot ( Scophthalmus maximus The juvenile fish, with an initial weight of approximately 18±0.5 g, are in good health and are a mix of males and females.

[0045] Test substance: Lanosterol product (purity ≥96.6%) was provided by Zhejiang Garden Biomedical Co., Ltd. as a test additive. This lanosterol product is a mixture of lanosterol and dihydrolanosterol, with a content ratio of (2±0.2):1.

[0046] Feed formulation: An isonitrogenous and isolithic diet was used. The high-fishmeal group contained 50% fishmeal and a mixed plant protein source (soybean meal + corn gluten meal + wheat gluten), while the low-fishmeal group used a mixed plant protein source to replace 10% of the fishmeal in the feed. Fish oil and phospholipid oil were used as fat sources. The experimental feed formulations are shown in Table 1.

[0047] Experimental group: H0 group: high fishmeal control group, 50% fishmeal group, 0g / kg lanosterol product.

[0048] Group H0.1: 50% fish meal, with 1g / kg lanosterol added.

[0049] Group H0.2: 50% fish meal, with 2g / kg lanosterol added.

[0050] Group H0.5: 50% fish meal, with 5g / kg lanosterol added.

[0051] L0 group: low fishmeal control group, 40% fishmeal group, 0g / kg lanosterol product.

[0052] Group L0.1: 40% fish meal, with 1g / kg lanosterol added.

[0053] Group L0.2: 40% fish meal, with 2g / kg lanosterol added.

[0054] Group L0.5: 40% fish meal, with 5g / kg lanosterol added.

[0055] Table 1

[0056] Table 2

[0057] After crushing the raw materials using a grinder, they were passed through an 80-mesh sieve. According to the feed formula shown in Table 1, the raw materials were weighed from small to large quantities and mixed evenly. After mixing, the mixture was passed through a 60-mesh sieve. The sieved raw materials were then processed into slow-sinking feed with a particle size of 3.3 mm using an extrusion pelleting machine. The feed was then dried in a forced-air drying oven at 55°C for 12 hours to obtain the feed.

[0058] The crude protein and crude fat levels in the feed were determined according to the AOAC method, and the results are shown in Table 2. The crude protein content in the feed was determined using a Dumas nitrogen analyzer, and the crude fat was extracted using a Soxhlet extractor. The crude fat content of the sample was then calculated by measuring the difference.

[0059] 2. Test conditions and procedures: The experiment was conducted in a recirculating aquaculture system with a water temperature of 18±0.5℃, salinity of 29‰, dissolved oxygen ≥7 mg / L, and ammonia nitrogen ≤0.1 mg / L. A randomized controlled trial design was used, with three replicates per treatment and 40 fish per pond. The fry were reared for 8 weeks and fed twice daily at a set time according to apparent satiety to ensure adequate feeding. Weight and length were measured before and after the experiment, and the number of surviving fish was recorded.

[0060] 3. Indicator Measurement: After the breeding period ended, the animals were withheld from feeding for 24 hours, and their weight was measured to calculate growth performance indicators such as final average weight, weight gain rate (WGR), and specific growth rate (SGR).

[0061] Texture testing was used to evaluate the muscle quality of turbot from the perspectives of hardness, cohesion, and adhesion.

[0062] Muscle tissue was collected, and biochemical indicators such as muscle triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C, LDL-C) were measured.

[0063] Antioxidant indicators include malondialdehyde (MDA), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and catalase (CAT) in the liver and plasma; immune indicators include serum lysozyme activity and interleukin-1β (IL-1β). IL-1β Gene expression.

[0064] 4. Results and Analysis

[0065] 4.1 Growth performance

[0066] The initial average weight, final average weight, weight gain rate, and specific growth rate of turbot in each group were measured.

[0067]

[0068] W t The average body weight of turbot at the end of the experiment (unit: g / fish); W0 represents the average body weight of turbot at the start of the experiment (unit: g / fish). t is the test period (unit: days); M represents the total weight of the feed given (in g). n is the number of turbot used in the experiment (unit: fish).

[0069] As shown in Table 3, compared with the high-fishmeal control group, the addition of appropriate amounts of lanosterol to the high-fishmeal diet resulted in improved final average weight, weight gain rate, and specific growth rate. In particular, the addition of lanosterol at concentrations of 0.1%-0.2% significantly improved these parameters. At a concentration of 0.1%, turbot exhibited even better growth performance.

[0070] The low fishmeal group resulted in slow growth, significantly reduced weight gain and specific growth rate, and low feed utilization efficiency (increased feed conversion ratio) in turbot. Adding lanosterol to the low fishmeal diet improved the final average weight, weight gain, and specific growth rate of turbot. Specifically, adding 0.1%-0.5% lanosterol to the low fishmeal diet significantly improved these parameters, and at a 0.2% addition level, turbot exhibited even better growth performance, recovering to a level not significantly different from the high fishmeal group (50% fishmeal).

[0071] Meanwhile, the addition of lanosterol products to low-fishmeal feeds showed a decreasing trend in feed conversion ratio. A lower feed conversion ratio means less undigested nutrient discharge, which helps reduce the pollution load on aquaculture water bodies, aligns with environmentally friendly sustainable development principles, and contributes to the improvement of the aquaculture environment.

[0072] The addition of appropriate amounts of lanosterol products can improve the growth performance and feed conversion efficiency of turbot in both high- and low-fishmeal feeds. The preferred addition level of lanosterol products in feed is 0.1%-0.2%.

[0073] Table 3. Effects of lanosterol on the growth performance of turbot.

[0074] Note: Data are mean ± standard error. Different letters in the same row indicate significant differences. P <0.05).

[0075] 4.2 Body composition and muscle quality

[0076] As shown in Table 4, compared with the high-fishmeal control group, the whole-body fat content of the high-fishmeal group increased after the addition of lanosterol to the diet. In particular, the addition of lanosterol at levels of 0.1%-0.2% significantly increased the whole-body fat content. P <0.05).

[0077] Reducing the fishmeal level in feed significantly decreases fat deposition in fish. However, adding lanosterol to low-fishmeal feed can restore body fat content to some extent, reaching the level of the high-fishmeal control group. For example, adding 0.1%-0.5% lanosterol to low-fishmeal feed significantly increases the total body fat content of turbot, with an even better result at a 0.2% addition level.

[0078] Table 4. Effects of lanosterol on turbot body composition

[0079] Note: Data are mean ± standard error. Different letters in the same row indicate significant differences. P <0.05).

[0080] As shown in Table 5, in the texture test, the addition of lanosterol products in the feed significantly reduced muscle hardness in both the high-fishmeal and low-fishmeal groups. P <0.05).

[0081] In both high-fishmeal and low-fishmeal diets, the addition of lanosterol did not significantly alter the total cholesterol (TC) content in turbot muscle. However, under low-fishmeal conditions, the addition of lanosterol dose-dependently increased muscle triglyceride (TG) content. P <0.05). This type of lipid accumulation can provide flavor enhancement to muscle.

[0082] The results of amino acid analysis on muscle flavor showed that adding lanosterol to high-fishmeal feed tended to increase glutamate levels. Adding lanosterol to low-fishmeal feed also tended to increase glutamate levels, and at a concentration of 0.2% lanosterol, the glutamate content in muscle significantly increased, indicating that lanosterol enhances the umami flavor of muscle. Adding 0.5% lanosterol to low-fishmeal feed tended to decrease glycine, a sweet amino acid in muscle, but the difference was not statistically significant.

[0083] Therefore, adding lanosterol to turbot feed has the effect of regulating muscle quality, significantly reducing muscle hardness, increasing muscle triglyceride levels (low fishmeal group), and increasing the content of flavor amino acids. By optimizing muscle structure, it promotes the accumulation of unsaturated fatty acids and flavor compounds, thereby increasing the added value of the product.

[0084] Table 5. Effects of lanosterol on the muscle quality of turbot.

[0085] Note: Data are mean ± standard error. Different letters in the same row indicate significant differences. P <0.05).

[0086] TC, total cholesterol; TG, triglycerides; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol.

[0087] 4.3 Antioxidant and immune indicators

[0088] Regarding antioxidant capacity, as shown in Table 6, in the liver, the addition of lanosterol to the feed had no effect on the high-fishmeal diet group. However, the addition of lanosterol to the feed significantly affected the antioxidant capacity of turbot in the low-fishmeal diet group. P <0.05). For example, adding lanosterol to low-fishmeal feed can increase the activity of superoxide dismutase (SOD) in turbot, especially at an addition level of 0.2%-0.5%, where the activity increases significantly. Simultaneously, the addition of lanosterol to low-fishmeal feed shows an increasing trend in catalase (CAT) and total antioxidant capacity (T-AOC). Malondialdehyde (MDA) is one of the final products of lipid peroxidation, and the results indicate that adding lanosterol to the feed has no effect on MDA levels. These results suggest that lanosterol may effectively enhance the antioxidant capacity of fish under low-fishmeal feed conditions by maintaining redox balance through enhanced SOD activity.

[0089] Regarding immunity, the high-fishmeal group, with an added 0.5% lanosterol product, showed a significant increase in lysozyme activity. This significant increase in lysozyme activity indicates enhanced non-specific immunity, improved disease resistance, and increased stress tolerance. In contrast, the low-fishmeal group showed... IL-1β Suppression of expression. IL-1β Suppression of expression means a decrease in the body's inflammation level and a more stable immune status.

[0090] Therefore, adding lanosterol to turbot feed can improve fish health, significantly enhancing antioxidant capacity (low fishmeal group) and immunity. It also enhances the activity of superoxide dismutase (SOD) in the liver and inhibits the expression of pro-inflammatory factors, thereby strengthening oxidative stress defense and maintaining fish health.

[0091] Table 6. Effects of lanosterol on the antioxidant and immune capabilities of turbot.

[0092] Note: Data are mean ± standard error. Different letters in the same column indicate significant differences. P <0.05). MDA, malondialdehyde; SOD, superoxide dismutase; T-AOC, total antioxidant capacity; CAT, catalase; LZM, lysozyme; IL-1β, interleukin-1β.

[0093] In summary, lanosterol products, as functional additives in turbot feed, have significant promoting effects on improving turbot growth performance, regulating muscle quality, and maintaining physiological health. The addition dosage in low-fishmeal feed is 0.02%-0.5%, preferably 0.1%-0.2% or 0.2%-0.5%.

[0094] In terms of growth performance, adding 0.1%-0.2% lanosterol to high-fishmeal feed significantly improved the final average weight, weight gain rate, and specific growth rate of turbot. Adding 0.1%-0.5% lanosterol to low-fishmeal feed also significantly improved these parameters. However, the feed conversion ratio tended to decrease after adding lanosterol to low-fishmeal feed.

[0095] In terms of muscle quality regulation, adding 0.1%-0.2% lanosterol to high-fishmeal feed significantly increases the total body fat content of turbot. Adding 0.1%-0.5% lanosterol to low-fishmeal feed also significantly increases the total body fat content of turbot. Simultaneously, in both high- and low-fishmeal feeds, the addition of lanosterol significantly reduces muscle firmness and tends to increase the content of the flavor amino acid glutamic acid. Furthermore, in low-fishmeal feeds, the addition of lanosterol increases muscle triglyceride (TG) content, contributing to flavor improvement.

[0096] Regarding antioxidant capacity, adding lanosterol to low-fishmeal feed significantly increases SOD enzyme activity in turbot, enhancing its antioxidant capacity. In terms of immunity, appropriate addition of lanosterol to high-fishmeal feed significantly increases lysozyme activity. Adding lanosterol to low-fishmeal feed can inhibit... IL-1β The expression of [something] can enhance the body's immune function.

[0097] 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. The use of lanosterols or their feed-acceptable esters in the preparation of feed additives for bony fish, characterized in that, Used to improve the growth performance of bony fish.

2. The use of lanosterols or their feed-acceptable esters in the preparation of feed additives for bony fish, characterized in that, Used to improve the muscle quality of bony fish.

3. The use of lanosterols or their feed-acceptable esters in the preparation of feed additives for bony fish, characterized in that, Used to maintain the physiological health of bony fish, enhance their antioxidant capacity and / or improve their immunity.

4. The application according to any one of claims 1-3, characterized in that, The bony fish mentioned are any one of turbot, flounder, Atlantic salmon, rainbow trout, grouper, large yellow croaker, pomfret, and sea bass.

5. The application according to any one of claims 1-2, characterized in that, The content of animal protein sources in feed shall not exceed 60%.

6. The application according to claim 5, characterized in that, The animal protein source mentioned in the feed includes fishmeal, with a fishmeal content of 30%-55%.

7. The application according to claim 3, characterized in that, The content of animal protein sources in feed shall not exceed 50%.

8. The application according to claim 7, characterized in that, The animal protein source mentioned in the feed includes fishmeal, and the fishmeal content is no more than 40%.

9. The application according to any one of claims 1-3, characterized in that, The lanosterols include one or more of lanosterol, dihydrolanosterol, 24-methylenedihydrolanosterol, and parkol; The amount of the lanosterol or its feed-acceptable ester added to the feed is 0.02% to 0.5%.

10. The application according to claim 9, characterized in that, The amount of the lanosterol or its feed-acceptable ester added to the feed is 0.1%~0.2% or 0.2%~0.5%.

11. The application according to claim 9, characterized in that, The lanosterols include lanosterol and dihydrolanosterol, with a mass ratio of lanosterol to dihydrolanosterol of (0.5~5):

1.

12. The application according to claim 11, characterized in that, The mass ratio of lanosterol to dihydrolanosterol is (1~3):

1.

13. A feed for bony fish, characterized in that, Includes any one of the lanosterols or their feed-acceptable esters as claimed in claims 1-3.

14. The feed according to claim 13, characterized in that, The feed, based on its dry weight, comprises the following components: (1) Animal protein source 30%~60%; (2) Plant protein source 0%~35%; (3) Carbohydrates 10%~30%; (4) Fat 5%~15%; (5) Nutritional supplements and excipients, 1% to 15%, including the lanosterols or their feed-acceptable esters.

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