Compound feed protein source prepared based on defatted hermetia illucens larva powder and application

Abstract

The invention belongs to the technical field of feed, and particularly relates to a composite feed protein source prepared based on defatted hermetia illucens larva powder and application, the composite feed protein source is prepared by mixing 59-61 parts by weight of defatted hermetia illucens larva powder, 32-34 parts by weight of fermented soybean meal, 4.5-5.5 parts by weight of peanut meal and 1.5-2.5 parts by weight of rapeseed meal; the compound feed protein source can be used for preparing an aquatic feed, and after the compound feed protein source is used for replacing part of fish meal in a conventional aquatic feed, the nutritional value of the conventional aquatic feed can be improved. The carnivorous fish compound feed is obtained by replacing 25wt%-50wt% of fish meal in a conventional aquatic feed with the compound feed protein source, and after the carnivorous fish compound feed is fed, the specific growth rate, apparent digestibility, meat percentage, meat quality and intestinal immunity of carnivorous fishes can be remarkably improved, and the carnivorous fish compound feed has good application prospects and market value.

Description

Technical Field

[0001] The invention belongs to the technical field of feed, and in particular relates to a composite feed protein source prepared based on defatted black soldier fly larvae powder and application thereof. Background Art

[0002] Carnivorous fish are a type of fish that feed mainly on animal bait. Because they are rich in high-quality protein, unsaturated fatty acids and a variety of essential amino acids for the human body, they have important nutritional and economic value. There are two main traditional feeding methods for carnivorous fish. The first is to feed natural live bait, such as zooplankton, aquatic insects, small fish and shrimp, etc., but the acquisition of live bait is restricted by season and region, and the supply is unstable, which is difficult to meet the needs of large-scale breeding; the second is to feed chilled feed, mostly small fish, which is relatively convenient to store and feed, and can provide high-quality protein, but chilled feed often carries pathogens, which can easily cause fish diseases after feeding, affect fish growth and reduce fish meat quality; at the same time, chilled feed decomposes in water and produces harmful substances such as ammonia nitrogen, which pollutes water quality and increases the difficulty of breeding management and breeding benefits.

[0003] Black soldier fly ( Hermetia illucens ) The larvae meal has comprehensive nutritional ingredients and rich content, which can meet the nutritional needs of farmed animals. It can be used as a high-quality feed protein source to replace fish meal. It can also produce a large amount of antibacterial substances to inhibit the growth and reproduction of bacteria, fungi, and viruses. As an immunopotentiator, it improves the nonspecific immune function of farmed fish and enhances the disease resistance of farmed fish. However, black soldier fly larvae meal cannot completely replace fish meal. According to existing research, this may be related to the high fat content in black soldier fly larvae meal and the large difference in its amino acid composition and ratio from fish meal. Therefore, how to better use black soldier fly larvae meal to replace fish meal and develop a functional feed product based on black soldier fly larvae meal is a key issue that needs to be urgently solved in the aquaculture and feed industries. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a compound feed protein source prepared based on defatted black soldier fly larvae powder and its application. The present invention obtains a compound feed protein source by compounding defatted black soldier fly larvae powder with a plant protein source. The compound feed protein source can be used to prepare a carnivorous fish compound feed that improves the growth performance, fish meat quality and fish immunity of carnivorous fish; the present invention also provides a carnivorous fish compound feed, which can significantly improve the specific growth rate, apparent digestibility, meat yield, meat quality and intestinal immunity of carnivorous fish after feeding the carnivorous fish compound feed.

[0005] In the first aspect of the present invention, a compound feed protein source prepared based on defatted black soldier fly larvae powder is provided. By weight, the compound feed protein source is obtained by mixing 59 parts to 61 parts of defatted black soldier fly larvae powder, 32 parts to 34 parts of fermented soybean meal, 4.5 parts to 5.5 parts of peanut meal, and 1.5 parts to 2.5 parts of rapeseed meal.

[0006] In the second aspect of the present invention, an application of the above-mentioned compound feed protein source in the preparation of aquatic feed is provided, and the aquatic feed is a compound feed for carnivorous fish.

[0007] Furthermore, the compound feed for carnivorous fish is used to improve the growth performance of carnivorous fish, or improve the fish meat quality, or improve the fish body immunity.

[0008] Furthermore, the improvement of the growth performance of carnivorous fish is to improve the specific growth rate, apparent digestibility, or meat yield of carnivorous fish.

[0009] Furthermore, the improvement of the fish meat quality is to reduce the crude fat content of the fish meat, or increase the protein content of the fish meat, or increase the mineral content of the fish meat, or increase the content of essential amino acids in the fish meat, or increase the content of umami amino acids in the fish meat, or increase the firmness of the fish meat, or increase the tenderness of the fish meat.

[0010] Furthermore, the improvement of the fish body immunity is to enhance the integrity of the fish intestinal mucosa, or inhibit the release of pro-inflammatory factors, or promote the secretion of immune substances by the fish intestinal mucosa, or increase the abundance of probiotics in the fish intestine.

[0011] Furthermore, the pro-inflammatory factors are TNF-α or IL-1β.

[0012] Furthermore, the probiotics are one or several of the strains of Cetobacterium, Lactobacillus, Bifidobacterium, Bacillus, and Actinobacillus.

[0013] In the third aspect of the present invention, a compound feed for improving carnivorous fish is provided. The compound feed for carnivorous fish is prepared by the following steps: after replacing 25wt% to 50wt% of the fish meal in the conventional aquatic feed with the compound feed protein source, the compound feed for carnivorous fish is obtained.

[0014] Furthermore, the carnivorous fish compound feed contains the following components in parts by weight: 25 to 37.5 parts of fish meal, 12.5 to 25 parts of compound feed protein source, 6 parts of shrimp meal, 10 parts of wheat flour, 5 parts of brewer's yeast, 5 parts of squid paste, 3 parts of gluten, 2.16 to 3.63 parts of fish oil, 0 to 6.22 parts of microcrystalline cellulose, 0.5 parts of multivitamins, 1.5 parts of calcium dihydrogen phosphate, 0.75 parts of multiminerals, 0.5 parts of 50wt% choline chloride, 3 parts of zeolite, 0.3 parts of sodium polyacrylate, 0.2 parts of methionine, 0.03 parts of carbendazim, 0.03 parts of ethoxyquinoline dry powder, and 0.5 parts of chromium trioxide.

[0015] The fourth aspect of the present invention provides a method for improving growth performance, specifically comprising: feeding the above-mentioned carnivorous fish compound feed to carnivorous fish for more than 90 days.

[0016] A fifth aspect of the present invention provides a method for improving fish meat quality, specifically comprising: feeding the above-mentioned carnivorous fish compound feed to carnivorous fish for more than 90 days.

[0017] The sixth aspect of the present invention provides a method for improving fish immunity, specifically comprising: feeding the above-mentioned carnivorous fish compound feed to carnivorous fish for more than 90 days.

[0018] Compared with the prior art, the present invention has the following beneficial effects: After degreasing the black soldier fly larvae powder, the fat content in the black soldier fly larvae powder is reduced in the present invention, and then it is compounded with plant-based protein sources. Specifically, 59 to 61 parts of degreased black soldier fly larvae powder, 32 to 34 parts of fermented soybean meal, 4.5 to 5.5 parts of peanut meal, and 1.5 to 2.5 parts of rapeseed meal are mixed to obtain a compound feed protein source prepared based on degreased black soldier fly larvae powder. This compound feed protein source can be used to prepare compound feed for carnivorous fish, can partially replace the fish meal component in conventional aquatic feed, and improve the nutritional value of conventional aquatic feed. After replacing 25wt% to 50wt% of the fish meal in the conventional aquatic feed with the compound feed protein source of the present invention, a compound feed for carnivorous fish is obtained. Experiments show that compared with the conventional aquatic feed, this compound feed for carnivorous fish can improve the nutritional value of the conventional aquatic feed, manifested as: First, it can significantly improve the levels of growth indexes such as the specific growth rate, apparent digestibility, and meat yield of carnivorous fish; Second, it can also significantly improve the meat quality of fish, including reducing the crude fat content of fish meat, increasing the protein and mineral contents of fish meat, enhancing the contents of essential amino acids and umami amino acids in fish meat, and improving the firmness and tenderness of fish meat; Finally, it can also significantly improve the immunity of fish, including enhancing the integrity of the intestinal mucosa of fish, effectively inhibiting the release of pro-inflammatory factors, increasing the secretion of intestinal mucosal immune substances, having better intestinal fold neatness, and increasing the abundance of probiotics in the intestine. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for description in the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 It is a diagram showing the influence on the muscle structure of largemouth bass after feeding with the compound feed for carnivorous fish. Among them, the feeds fed in Figures A, B, C, and D are D-FC, FC0, FC1, and FC2 respectively.

[0021] Figure 2 It is a diagram showing the influence on the intestinal structure of largemouth bass after feeding with the compound feed for carnivorous fish. Among them, the feeds fed in Figures A, B, C, and D are D-FC, FC0, FC1, and FC2 respectively.

[0022] Figure 3 It is a diagram showing the influence on the intestinal flora structure (at the genus level) of largemouth bass after feeding with the compound feed for carnivorous fish. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention. The experimental methods described in the embodiments of the present invention are conventional methods unless otherwise specified, and the materials, reagents, etc. used in the following embodiments can be obtained from commercial channels unless otherwise specified.

[0024] Black soldier fly ( Hermetia illucens ) Larvae meal has comprehensive nutritional ingredients and can be used as a high-quality feed protein source to replace fish meal. It can also be used as an immunopotentiator to improve the nonspecific immune function of farmed fish and enhance the disease resistance of farmed fish. However, black soldier fly larvae meal cannot completely replace fish meal. This may be related to the high fat content in black soldier fly larvae meal and the large difference in its amino acid composition and ratio from fish meal. Therefore, how to better use black soldier fly larvae meal to replace fish meal and develop a functional feed product based on black soldier fly larvae meal is a key issue that needs to be solved urgently in the aquaculture and feed industries.

[0025] The invention provides a composite feed protein source prepared based on defatted black soldier fly larvae powder and application thereof. The composite feed protein source is obtained by mixing 59 to 61 parts of defatted black soldier fly larvae powder, 32 to 34 parts of fermented soybean meal, 4.5 to 5.5 parts of peanut meal and 1.5 to 2.5 parts of rapeseed meal by weight. The composite feed protein source provided by the invention can be used to prepare a carnivorous fish composite feed by replacing part of fish meal in conventional aquatic feed. Experiments show that the compound feed for carnivorous fish to which the compound feed protein source of the present invention is added can improve the nutritional value of conventional aquatic feed: first, it can significantly improve the levels of growth indicators such as specific growth rate, apparent digestibility and meat yield of carnivorous fish; second, it can also significantly improve the meat quality of fish, including reducing the crude fat content of fish meat, increasing the protein and mineral content of fish meat, increasing the content of essential amino acids and umami amino acids in fish meat, and improving the firmness and tenderness of fish meat; finally, it can also significantly improve the immunity of fish, including enhancing the integrity of the intestinal mucosa of fish, effectively inhibiting the release of pro-inflammatory factors, increasing the secretion of intestinal mucosal immune substances, improving the neatness of intestinal folds, and increasing the abundance of probiotics in the intestine.

[0026] In some embodiments of the present invention, the black soldier fly larvae were donated from Tianjin Agricultural Reclamation Group Co., Ltd.; and the largemouth sea bass were purchased from Tianjin Jiahe Tianyuan Ornamental Fish Breeding Co., Ltd.

[0027] Example 1: A composite feed protein source prepared based on defatted black soldier fly larvae powder, the preparation method of which comprises the following steps: S1. Obtaining defatted black soldier fly larvae powder: drying the black soldier fly larvae at 60° C. at low temperature, grinding them into powder, and then defatting them by extrusion to obtain defatted black soldier fly larvae powder as a feed raw material.

[0028] S2. Preparation of a compound feed protein source: Calculated by weight, 60 parts of defatted black soldier fly larvae powder, 33 parts of fermented soybean meal, 5 parts of peanut meal and 2 parts of rapeseed meal are mixed to obtain a compound feed protein source.

[0029] Example 2: A composite feed protein source prepared based on defatted black soldier fly larvae powder, the preparation method of which comprises the following steps: S1. Obtaining defatted black soldier fly larvae powder: drying the black soldier fly larvae at 60° C., grinding them into powder, and then defatting them by extrusion to obtain defatted black soldier fly larvae powder as a feed raw material.

[0030] S2. Preparation of a compound feed protein source: Calculated by weight, 59 parts of defatted black soldier fly larvae powder, 32 parts of fermented soybean meal, 4.5 parts of peanut meal and 1.5 parts of rapeseed meal are mixed to obtain a compound feed protein source.

[0031] Example 3: A composite feed protein source prepared based on defatted black soldier fly larvae powder, the preparation method of which comprises the following steps: S1. Obtaining defatted black soldier fly larvae powder: drying the black soldier fly larvae at 60° C., grinding them into powder, and then defatting them by extrusion to obtain defatted black soldier fly larvae powder as a feed raw material.

[0032] S2. Preparation of a compound feed protein source: Calculated by weight, 61 parts of defatted black soldier fly larvae powder, 34 parts of fermented soybean meal, 5.5 parts of peanut meal and 2.5 parts of rapeseed meal are mixed to obtain a compound feed protein source.

[0033] Examples 1 to 3 have similar effects. For the convenience of subsequent discussion and reference, taking the test results of Example 1 as an example, the effects of replacing part of the fish meal in conventional aquatic feed with a compound feed protein source on relevant indicators are further explored.

[0034] Conventional aquatic feed is prepared by the following preparation steps: S1. Grind fish meal, shrimp meal, wheat flour, brewer's yeast, gluten, microcrystalline cellulose, multivitamins, calcium dihydrogen phosphate, multiminerals, 50wt% choline chloride, methionine, zeolite powder, sodium polyacrylate, ethoxyquinoline powder, carbendazim and chromium trioxide and pass through a 60-mesh sieve.

[0035] S2. Preparation of conventional aquatic feed: Calculated by weight, 50 parts of fish meal, 6 parts of shrimp meal, 10 parts of wheat flour, 5 parts of brewer's yeast, 5 parts of squid paste, 3 parts of gluten powder, 4.37 parts of fish oil, 9.32 parts of microcrystalline cellulose, 0.5 parts of multivitamins, 1.5 parts of calcium dihydrogen phosphate, 0.75 parts of complex minerals, 0.5 parts of 50wt% choline chloride, 0.2 parts of methionine, 3 parts of zeolite powder, 0.3 parts of sodium polyacrylate, 0.03 parts of ethoxyquinoline dry powder, 0.03 parts of carbendazim, and 0.5 parts of chromium trioxide are mixed, stirred step by step, extruded into feed particles with a specification of 3 mm by a meat grinder, and dried in an oven at 65°C to obtain conventional aquatic feed (FC0).

[0036] In conventional aquatic feed FCO, the ratio of the compound feed protein source prepared in Example 1 replacing fish meal in conventional aquatic feed FCO is 0%, and the conventional aquatic feed contains 0% defatted black soldier fly larvae powder.

[0037] Embodiment 4: A compound feed for carnivorous fish, the preparation method of which comprises the following steps: S1. The compound feed protein source prepared in Example 1, fish meal, shrimp meal, wheat flour, brewer's yeast, gluten, microcrystalline cellulose, complex vitamins, calcium dihydrogen phosphate, complex minerals, 50% choline chloride, methionine, zeolite powder, sodium polyacrylate, ethoxyquinoline powder, carbendazim and chromium trioxide are crushed and passed through a 60-mesh sieve.

[0038] S2. Preparation of carnivorous fish compound feed: Calculated by weight, 12.5 parts of the compound feed protein source prepared in Example 1 (37.5 parts of fish meal, 1.08 parts of rapeseed meal, 9.48 parts of defatted black soldier fly larvae meal, 4.06 parts of fermented soybean meal, and 1.71 parts of peanut meal) and 37.5 parts of fish meal, 3.63 parts of fish oil, 6.22 parts of microcrystalline cellulose, 6 parts of shrimp meal, 10 parts of wheat flour, 5 parts of brewer's yeast, 5 parts of squid paste, 3 parts of gluten powder, 0. 0.5 parts of multivitamins, 1.5 parts of calcium dihydrogen phosphate, 0.75 parts of multiminerals, 0.5 parts of 50% choline chloride, 0.2 parts of methionine, 3 parts of zeolite powder, 0.3 parts of sodium polyacrylate, 0.03 parts of ethoxyquinoline dry powder, 0.03 parts of carbendazim and 0.5 parts of chromium trioxide are mixed, stirred step by step, extruded into feed particles with a specification of 3mm by a meat grinder, and dried in an oven at 65℃ to obtain carnivorous fish compound feed (FC1).

[0039] In the compound feed FC1 for carnivorous fish, the compound feed protein source prepared in Example 1 replaces the fish meal in the conventional aquatic feed FC0 at a ratio of 25wt%, and the compound feed FC1 for carnivorous fish contains 9.48wt% of defatted black soldier fly larvae powder.

[0040] Embodiment 5: A compound feed for carnivorous fish, the preparation method of which comprises the following steps: S1. The compound feed protein source prepared in Example 1, fish meal, shrimp meal, wheat flour, brewer's yeast, gluten, microcrystalline cellulose, complex vitamins, calcium dihydrogen phosphate, complex minerals, 50% choline chloride, methionine, zeolite powder, sodium polyacrylate, ethoxyquinoline powder, carbendazim and chromium trioxide are crushed and passed through a 60-mesh sieve.

[0041] S2. Preparation of carnivorous fish compound feed: Calculated by weight, 25 parts of the compound feed protein source prepared in Example 1 (25 parts of fish meal, 2.17 parts of rapeseed meal, 18.97 parts of defatted black soldier fly larvae meal, 8.12 parts of fermented soybean meal, 3.43 parts of peanut meal) and 25 parts of fish meal, 2.9 parts of fish oil, 3.1 parts of microcrystalline cellulose, 6 parts of shrimp meal, 10 parts of wheat flour, 5 parts of brewer's yeast, 5 parts of squid paste, 3 parts of gluten powder, 0.5 parts of compound fish meal were mixed. Vitamins, 1.5 parts of calcium dihydrogen phosphate, 0.75 parts of complex minerals, 0.5 parts of 50wt% choline chloride, 0.2 parts of methionine, 3 parts of zeolite powder, 0.3 parts of sodium polyacrylate, 0.03 parts of ethoxyquinoline dry powder, 0.03 parts of carbendazim and 0.5 parts of chromium trioxide are mixed, stirred step by step, extruded into feed particles with a specification of 3mm by a meat grinder, and dried in an oven at 65℃ to obtain carnivorous fish compound feed (FC2).

[0042] In the compound feed FC2 for carnivorous fish, the compound feed protein source prepared in Example 1 replaces the fish meal in the conventional aquatic feed FC0 at a ratio of 50wt%, and the compound feed FC2 for carnivorous fish contains 18.97wt% of defatted black soldier fly larvae powder.

[0043] Comparative Example 1: A compound feed for carnivorous fish, the preparation method of which comprises the following steps: S1. The compound feed protein source prepared in Example 1, fish meal, shrimp meal, wheat flour, brewer's yeast, gluten, multivitamins, calcium dihydrogen phosphate, multiminerals, 50% choline chloride, methionine, zeolite powder, sodium polyacrylate, ethoxyquinoline powder, carbendazim and chromium trioxide are crushed and passed through a 60-mesh sieve.

[0044] S2. Preparation of carnivorous fish compound feed: Calculated by weight, 37.5 parts of the compound feed protein source prepared in Example 1 (12.5 parts of fish meal, 3.25 parts of rapeseed meal, 28.45 parts of defatted black soldier fly larvae meal, 12.18 parts of fermented soybean meal, 5.14 parts of peanut meal) and 12.5 parts of fish meal, 2.16 parts of fish oil, 6 parts of shrimp meal, 10 parts of wheat flour, 5 parts of brewer's yeast, 5 parts of squid paste, 3 parts of gluten powder, 0.5 parts of compound vitamin C were added. The mixture is mixed with 1.5 parts of calcium dihydrogen phosphate, 0.75 parts of complex minerals, 0.5 parts of 50wt% choline chloride, 0.2 parts of methionine, 3 parts of zeolite powder, 0.3 parts of sodium polyacrylate, 0.03 parts of ethoxyquinoline dry powder, 0.03 parts of carbendazim and 0.5 parts of chromium trioxide, stirred step by step, extruded into feed particles with a specification of 3mm by a meat grinder, and dried in an oven at 65℃ to obtain a carnivorous fish compound feed (D-FC).

[0045] In the compound feed D-FC for carnivorous fish, the compound feed protein source prepared in Example 1 replaces the fish meal in the conventional aquatic feed FCO at a ratio of 75wt%, and the compound feed FC2 for carnivorous fish contains 28.45wt% of defatted black soldier fly larvae powder.

[0046] Experimental Example 1: Analysis of nutritional components of compound feed for carnivorous fish The present invention analyzed the nutritional components of conventional aquatic feed (FC0), the compound feed for carnivorous fish prepared in Example 4 (FC1), the compound feed for carnivorous fish prepared in Example 5 (FC2), and the compound feed for carnivorous fish prepared in Comparative Example 1 (D-FC). The results are shown in Table 1.

[0047] Table 1 Nutritional composition analysis (%) As can be seen from Table 1, the contents of crude protein, crude fat, crude ash and essential amino acids in each feed group were similar.

[0048] Largemouth bass ( Micropterus salmoides ) is a precious carnivorous fish with delicious meat, strong disease resistance, rapid growth, easy to catch, and a wide range of temperature adaptability. As one of the representatives of carnivorous fish, the present invention uses largemouth bass as experimental animals and further explores the effects of feed on fish-related indicators through feed feeding experiments.

[0049] Experimental Example 2: Effects of compound feed for carnivorous fish on fish growth indicators The same quality of conventional aquatic feed and the compound feed for carnivorous fish prepared in Examples 4-5 were continuously fed to largemouth bass for 90 days. The experiment was divided into the FC0 group fed with FC0, the FC1 group fed with FC1, the FC2 group fed with FC2, and the D-FC group fed with D-FC. After 90 days, 45 fish were randomly selected from each group to measure and calculate the relevant morphological indexes of each fish.

[0050] The calculation formulas for the morphological indexes are as follows: Among them, W f represents the average final weight (g), W i represents the average initial weight (g), W 空壳 represents the empty shell weight of the fish body after removing the visceral mass (g), L represents the body length (cm), W F represents the total amount of feed consumed (g), W0 represents the average feeding amount per fish in the whole breeding cycle (g), T represents the breeding cycle (90 days), Conc. Cr2O3 in diets represents the concentration of the marker chromium sesquioxide added to the feed; Conc. Cr2O3 in feces represents the concentration of the marker chromium sesquioxide in the feces after ingestion and digestion; FI represents the feed intake; Pc represents the protein content in the feed; N I represents the initial number of fish in each group before the experiment, N F represents the number of surviving fish in each group at the end of the breeding cycle. The experimental results are shown in Table 2.

[0051] Table 2 Growth, feeding and survival rate of largemouth bass Note: The letters a, b, c, d represent correlations. The same letters indicate no significant difference between groups, and different letters indicate significant differences between groups.

[0052] As shown in Table 2, compared with the FC0 group, the fish body weight gain rate in the FC2 group increased by 25.03%, and the specific growth rate increased by 16.98%. From the perspective of feed utilization comparison, the feed intake of the fish body in the FC2 group decreased significantly, the protein efficiency was significantly improved, and the apparent digestibility also increased by 3%, reducing the waste of feed to a certain extent and being more friendly to the aquaculture water environment. From the perspective of the morphology of the fed fish body, the condition factor of the largemouth bass fed with the carnivorous fish compound feed in the FC1 group increased by 1.96%, and the condition factor of the fish body fed in the FC2 group increased by 5.23%, but there was no obvious change in the condition factor of the fish body in the FC0 group. In addition, both the FC1 and FC2 groups significantly increased the meat yield of the largemouth bass and prevented the death of the cultured fish body to a certain extent. However, when the level of replacing fish meal with the compound feed protein source was further increased, the prepared feed (D-FC feed) had a negative impact on feed utilization, fish body growth, and morphological indicators.

[0053] Experimental Example 3: Effect of Carnivorous Fish Compound Feed on Fish Meat Quality The largemouth bass was continuously fed the same quality of conventional aquatic feed and the carnivorous fish compound feed prepared in Examples 4-5 for 90 days; the experiment was divided into the FC0 group fed with FC0, the FC1 group fed with FC1, the FC2 group fed with FC2, and the D-FC group fed with D-FC; after 90 days, 45 fish were randomly selected from each group to detect the fish meat quality of the largemouth bass, and the results are shown in Table 3.

[0054] Table 3 Fish Meat Quality of Largemouth Bass Note: The indicators marked with a single underline are essential amino acids; the indicators marked with a double underline are non-essential amino acids; the indicators with * represent umami amino acids; the letters a, b, c indicate the differences between groups, the same letters indicate no significant difference between groups, and different letters indicate significant differences between groups.

[0055] From Table 3 and Figure 1 it can be found that feeding the FC1 and FC2 feeds can significantly improve the fish meat quality, and the specific performance is as follows: After continuously feeding the FC1 and FC2 to the largemouth bass for 90 days, the crude fat content in the fish meat decreased significantly, effectively alleviating the fat deposition phenomenon caused by long-term feeding of fish meal feed, and also helping to increase the content of minerals (crude ash) in the fish meat and increase the content of protein (crude protein) in the fish meat (Table 3). However, when the level of replacing fish meal in the conventional aquatic feed with the compound feed protein source ≥ 75 wt% (D-FC feed), this feed instead caused a significant decrease in the protein content in the fish body muscle.

[0056] Detection of the content of essential amino acids and umami amino acids in fish meat found that, compared with the FC0 group, the diets of the FC1 and FC2 groups could significantly increase the content of each essential amino acid and umami amino acid in fish meat, and showed a dose-dependent increase. However, excessive compound feed protein sources in the diet led to a significant decrease in the content of each essential amino acid and umami amino acid in fish meat (Table 3).

[0057] Microscopic observation of H&E stained sections prepared from the muscle tissues of fish in each group found that when using the compound protein source prepared based on defatted black soldier fly larvae powder to replace the fish meal component in the conventional aquatic feed, the muscle fiber density of the fish body was positively correlated with the replacement level of the compound protein source, while the muscle fiber gap was negatively correlated with the replacement level of the compound protein source. Compared with the FC0 group, the FC1 group and the FC2 group significantly improved the firmness and tenderness of the fish meat, indicating that the defatted black soldier fly larvae powder containing 9.48wt% - 18.97wt% could significantly improve the firmness and tenderness of the fish meat ( Figure 1 ). However, when a higher proportion of the compound protein source in the D-FC group replaced fish meal (or the diet contained >18.97wt% of defatted black soldier fly larvae powder), it would instead have a negative impact on the texture of the cultured fish meat, that is: the muscle fiber gap increased, the muscle fiber density decreased, and the firmness and tenderness of the fish meat decreased.

[0058] Experimental Example 4: Effect of Compound Feed on the Intestinal Immune Barrier of Fish The same quality of conventional aquatic feed and the compound feed for carnivorous fish prepared in Examples 4 - 5 were continuously fed to largemouth bass for 90 days; the experiment was divided into the FC0 group fed with FC0, the FC1 group fed with FC1, the FC2 group fed with FC2, and the D-FC group fed with D-FC; after 90 days, 45 fish were randomly selected from each group to detect the level of the intestinal immune barrier of largemouth bass, and the intestinal tissues were subjected to H&E staining sections, and the results are shown in Table 4 and Figure 2 as follows.

[0059] Table 4 Effect of Compound Feed on the Intestinal Immune Barrier of Largemouth Bass Note: The letters a, b, c in the table represent the differences between groups. The same letter indicates that there is no significant difference between groups, and different letters indicate that there are significant differences between groups.

[0060] From the detection results in Table 4, it can be found that feeding the FC1 and FC2 feeds can significantly enhance the integrity of the fish intestinal mucosa: compared with the FC0 group, after feeding the compound feed for carnivorous fish prepared in Examples 4 - 5, FC1 and FC2 can significantly increase the content of tight junction proteins in the intestine of largemouth bass (Table 4), that is: enhance the integrity of the intestinal mucosa, which is consistent with the observation results of the H&E staining sections of the intestinal tissues ( Figure 2 ).

[0061] Compared with the FC0 group, the results of the FC1 group and the FC2 group showed that with the increase in the level of compound protein source replacing fish meal in the compound feed, the secretion of immunoglobulin in the intestine of Micropterus salmoides decreased, and the immunity of pro-inflammatory factors also showed a downward trend. This indicates that the feed prepared from the compound feed protein source provided by the present invention can effectively inhibit the release of pro-inflammatory factors, increase the secretion of intestinal mucosal immune substances, enhance the immune disease resistance of the intestine of the cultured fish body, and prevent the occurrence of intestinal tissue damage and enteritis ( Figure 2 ). The effects of the D-FC feed on the intestinal mucosal integrity, the secretion of pro-inflammatory factors and immune substances, and the immune disease resistance of the cultured fish body were opposite to those of the FC1 and FC2 feeds, and even worse than those of the FC0 group.

[0062] Table 5 Effects of compound feed on the intestinal immune barrier of Micropterus salmoides Note: The letters a, b, and c in the table indicate the differences between groups. The same letter indicates no significant difference between groups, and different letters indicate significant differences between groups.

[0063] From the results of Table 5 and Figure 2 , it can be seen that the intestinal fold regularity of Micropterus salmoides in the FC1 group and the FC2 group was better, no intestinal mucosal damage was found, and the changes in indicators such as the height of microvilli, the width of intestinal folds, the length of intestinal folds, the thickness of the lamina propria, and the depth of crypts all showed a dose-dependent significant increase with the increase in the content of compound protein source in the feed, which were all better than those of the FC0 group and the D-FC group, and the breeding effect of the FC2 group was better than that of the FC1 group.

[0064] In addition, the present invention also detected the abundance of probiotics in the intestine of Micropterus salmoides after feeding with the FC0, FC1, and FC2 feeds.

[0065] The results are as Figure 3 shown. Compared with the FC0 or D-FC feed, feeding the FC1 and FC2 feeds to Micropterus salmoides can promote the abundance of probiotics in the intestine of Micropterus salmoides: Cetobacterium ( Cetobacterium ), Clostridium ( Clostridium ), Lactobacillus ( Lactobacillus ), Bacillus ( Bacillus ), and Bifidobacterium ( Bifidobacterium ), while inhibiting the abundance of opportunistic pathogens such as Chlamydia ( Chlamydia ), Aeromonas ( Aeromonas ), and Vibrio ( Vibrio ), ultimately enhancing the intestinal homeostasis and the intestinal mucosal immune barrier function of the cultured fish body and promoting the healthy growth of the fish body.

[0066] It should be noted that when the present invention involves a numerical range, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the adopted step method is the same as that of the embodiment, in order to prevent redundancy, the present invention describes the preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0067] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A compound feed protein source prepared based on defatted black soldier fly larvae powder, characterized in that, According to weight, the compound feed protein source is obtained by mixing 59 to 61 parts of defatted black soldier fly larvae powder, 32 to 34 parts of fermented soybean meal, 4.5 to 5.5 parts of peanut meal and 1.5 to 2.5 parts of rapeseed meal.

2. Use of the compound feed protein source according to claim 1 in the preparation of aquatic feed, characterized in that, The aquatic feed is a compound feed for carnivorous fish.

3. The application according to claim 2, wherein The carnivorous fish compound feed is used for improving the growth performance of carnivorous fish, improving the quality of fish meat, or improving the immunity of fish.

4. The application according to claim 3, characterized in that, The improving the growth performance of carnivorous fish is to improve the specific growth rate or apparent digestibility or meat yield of carnivorous fish.

5. The application according to claim 3, wherein The improving of fish meat quality is to reduce the crude fat content of fish meat, increase the protein content of fish meat, increase the mineral content of fish meat, increase the essential amino acid content of fish meat, increase the umami amino acid content of fish meat, increase the firmness of fish meat, or increase the tenderness of fish meat.

6. A compound feed for carnivorous fish, characterized in that, The carnivorous fish compound feed is prepared by the following steps: replacing 25wt% to 50wt% of fish meal in conventional aquatic feed with the compound feed protein source according to claim 1 to obtain the carnivorous fish compound feed.

7. The compound feed for carnivorous fish according to claim 6, characterized in that, The carnivorous fish compound feed comprises the following components in parts by weight: 25 to 37.5 parts of fish meal, 12.5 to 25 parts of compound feed protein source, 6 parts of shrimp meal, 10 parts of wheat flour, 5 parts of brewer's yeast, 5 parts of squid paste, 3 parts of gluten powder, 2.16 to 3.63 parts of fish oil, 0 to 6.22 parts of microcrystalline cellulose, 0.5 parts of complex vitamins, 1.5 parts of calcium dihydrogen phosphate, 0.75 parts of complex minerals, 0.5 parts of 50wt% choline chloride, 3 parts of zeolite, 0.3 parts of sodium polyacrylate, 0.2 parts of methionine, 0.03 parts of carbendazim, 0.03 parts of ethoxyquinoline dry powder, and 0.5 parts of chromium trioxide.

8. A method for improving the growth performance of carnivorous fish, characterized in that, The compound feed for carnivorous fish according to claim 6 is fed to carnivorous fish for more than 90 days.

9. A method for improving the quality of the flesh of carnivorous fish, characterized in that, The compound feed for carnivorous fish according to claim 6 is fed to carnivorous fish for more than 90 days.

10. A method for improving the immunity of carnivorous fish, characterized in that, The compound feed for carnivorous fish according to claim 6 is fed to carnivorous fish for more than 90 days.

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