Low-protein feed containing largemouth bass polypeptide and application thereof

Abstract

The present invention discloses a low-protein feed containing a largemouth bass polypeptide and its application. The amino acid sequence of the largemouth bass polypeptide is shown in SEQ ID NO. 1. By adding a largemouth bass polypeptide (MSNP) to the feed and combining it with fermented soybean meal, the present invention improves the largemouth bass's ability to digest the feed and absorb and utilize nutrients, promotes the growth and weight gain of the largemouth bass, reduces the total protein content of the feed and the amount of fish meal added, helps save feed costs, improves aquaculture efficiency, and reduces pollution pressure on aquaculture water bodies. The invention has broad application value in the largemouth bass aquaculture industry.

Description

Technical Field

[0001] The present invention relates to the technical field of feed, in particular to a low-protein feed containing largemouth bass polypeptide and application thereof. Background Art

[0002] Largemouth bass is an important freshwater fish species, with industrialized aquaculture both domestically and internationally. To ensure and improve the quality of largemouth bass compound feeds, enhance their effectiveness, and facilitate effective supervision by regulatory authorities, ensure product quality, and promote the healthy development of the largemouth bass aquaculture industry, my country formulated the Largemouth Bass Compound Feed Standard (20214587-T-469) in 2021. According to the standard, the crude protein levels in largemouth bass compound feeds are as follows: 43-48% for fry (weighing 10g-100g), 38-44% for fingerling feeds, and 35-40% for adult fish feeds.

[0003] Imported high-quality fish meal is the primary source of protein in fish feed in my country, making my country a major consumer of fish meal globally, with an annual demand of approximately 1.7 million tons. This significantly increases feed costs and squeezes production profits. Relatively inexpensive plant-based protein is the best alternative to fish meal. However, most plant-based proteins contain a high level of anti-nutritional factors, which hinder the absorption of nutrients by largemouth bass from feed. Furthermore, the amino acid composition of plant-based protein differs significantly from that of fish meal, which can affect fish growth and immunity. Uneaten feed, left in the aquaculture water, is prone to decay and deterioration. The deteriorated protein in the feed can easily cause eutrophication, leading to deterioration of water quality. Therefore, to reduce the need for fish meal, improve aquaculture efficiency, and reduce the risk of feed contamination, there is an urgent need to develop a low-protein, low-fishmeal, high-growth-efficiency largemouth bass feed. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a low-protein feed containing largemouth bass polypeptide and application thereof.

[0005] The first object of the present invention is to provide an application of a largemouth bass polypeptide in promoting the growth of largemouth bass.

[0006] The second object of the present invention is to provide the use of a largemouth bass polypeptide in preparing a largemouth bass feed additive or a largemouth bass feed.

[0007] The third object of the present invention is to provide the use of largemouth bass polypeptide and fermented soybean meal in promoting the growth of largemouth bass.

[0008] The fourth object of the present invention is to provide the use of largemouth bass polypeptide and fermented soybean meal in preparing largemouth bass feed.

[0009] A fifth object of the present invention is to provide a composition.

[0010] The sixth object of the present invention is to provide a low-protein feed containing largemouth bass polypeptide.

[0011] The seventh object of the present invention is to provide the use of the low-protein feed containing the largemouth bass polypeptide in promoting the growth of largemouth bass.

[0012] In order to achieve the above object, the present invention is implemented through the following scheme:

[0013] The present invention refers to the 2021 National Standard Project Plan 20214587-T-469 and the crude protein content of largemouth black bass compound feed on the market. By preparing high-protein feed (45%) and low-protein feed (40%) for largemouth black bass, and replacing fish meal with fermented soybean meal, MSNP solution (0.3 μg / g feed) is added to the aquatic feed, and largemouth black bass polypeptide MSNP is sprayed into the feed as an additive. Through feeding experiments, it is clear that in feed, especially low-protein feed, the combined addition of fermented soybean meal and MSNP can greatly improve the growth performance of largemouth black bass species, thereby reducing the fish meal content in the feed, as well as reducing the total protein content of the feed, thereby improving economic benefits.

[0014] Therefore, the present invention seeks protection for the following:

[0015] The invention relates to the use of a largemouth bass polypeptide in promoting the growth of largemouth bass. The amino acid sequence of the largemouth bass polypeptide is shown in SEQ ID NO.1.

[0016] Preferably, the largemouth bass comprises juvenile largemouth bass.

[0017] More preferably, the weight of the juvenile largemouth bass is 10 g to 100 g.

[0018] Further preferably, the weight of the juvenile largemouth black bass is 28g to 100g.

[0019] The invention relates to an application of a largemouth bass polypeptide in the preparation of a largemouth bass feed additive or a largemouth bass feed. The amino acid sequence of the largemouth bass polypeptide is shown in SEQ ID NO.1.

[0020] Application of a largemouth bass polypeptide and fermented soybean meal in promoting the growth of largemouth bass. The amino acid sequence of the largemouth bass polypeptide is shown in SEQ ID NO.1.

[0021] Application of a largemouth bass polypeptide and fermented soybean meal in preparing largemouth bass feed, wherein the amino acid sequence of the largemouth bass polypeptide is shown in SEQ ID NO.1.

[0022] A composition comprises a largemouth bass polypeptide and fermented soybean meal, wherein the amino acid sequence of the largemouth bass polypeptide is shown as SEQ ID NO.1.

[0023] A low-protein feed containing largemouth bass polypeptide, wherein the crude protein content of the low-protein feed is 39% to 42%, and the low-protein feed comprises the composition.

[0024] Preferably, the crude protein content of the low-protein feed is 41% to 42%.

[0025] More preferably, the crude protein content of the low-protein feed is 41.76%.

[0026] Preferably, the crude fat content of the low-protein feed is 10% to 15%.

[0027] More preferably, the crude fat content of the low-protein feed is 12.5%.

[0028] Preferably, the low-protein feed further comprises 20% w / w to 22% w / w fish meal.

[0029] More preferably, the content of fish meal is 21.62% w / w.

[0030] More preferably, the content of the fermented soybean meal is 12% w / w to 14% w / w.

[0031] Further preferably, the content of the fermented soybean meal is 12.60% w / w.

[0032] More preferably, the content of the largemouth bass polypeptide is 0.25 μg / g to 0.35 μg / g, that is, each gram of the low-protein feed contains 0.25 μg to 0.35 μg of the largemouth bass polypeptide.

[0033] Further preferably, the content of the largemouth bass polypeptide is 0.3 μg / g.

[0034] In some specific embodiments, the low-protein feed further comprises chicken meal, soy protein concentrate, corn protein, fish oil, soybean oil, soy lecithin, flour, methionine, lysine, nitrogen-free bone meal, vitamin and mineral premix, calcium dihydrogen phosphate, and choline chloride.

[0035] In some specific embodiments, the low protein feed further comprises 8% w / w to 12% w / w chicken meal, 8% w / w to 12% w / w soy protein concentrate, 8% w / w to 12% w / w corn gluten, 2.5% w / w to 3.5% w / w fish oil, 3% w / w to 4% w / w soybean oil, 2.5% w / w to 3.5% w / w soy lecithin, 10% w / w to 14% w / w flour, 0.1% w / w to 0.3% w / w methionine, 0.5% w / w to 0.7% w / w lysine, 8% w / w to 12% w / w nitrogen-free bone meal, 1% w / w to 2% w / w vitamin and mineral premix, 1% w / w to 2% w / w calcium dihydrogen phosphate, and 0.4% w / w to 0.6% w / w choline chloride.

[0036] In some embodiments, the low protein feed further comprises 10% w / w chicken meal, 10% w / w soy protein concentrate, 10% w / w corn gluten, 3% w / w fish oil, 3.49% w / w soybean oil, 3% w / w soy lecithin, 12% w / w flour, 0.2% w / w methionine, 0.6% w / w lysine, 10% w / w nitrogen-free bone meal, 1.5% w / w vitamin and mineral premix, 1.5% w / w calcium dihydrogen phosphate, and 0.5% w / w choline chloride.

[0037] Preferably, the largemouth bass polypeptide is sprayed on the low-protein feed. The MSNP is sprayed on the surface of the feed before feeding, and the feed is fed immediately after each spraying.

[0038] Use of any low-protein feed containing largemouth bass polypeptide in promoting the growth of largemouth bass.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention improves the ability of largemouth bass to digest feed and absorb and utilize nutrients by adding largemouth bass polypeptide MSNP and fermenting soybean meal to feed, promotes the growth and weight gain of largemouth bass, reduces the total protein content of feed and the amount of fish meal added in the feed, helps to save feed costs, improve breeding efficiency, and reduce the pollution pressure of breeding water bodies. It has wide promotion and application value in the largemouth bass breeding industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Statistical results of weight gain rate of largemouth bass fed HF, LF, HSN and LSN diets. All data in the figure are expressed as mean ± standard error (N = 3). One-way ANOVA and Duncan's multiple comparison were used. Different letters indicate significant differences among treatment groups, p < 0.05.

[0042] Figure 2Statistical results of specific growth rate of largemouth bass fed HF, LF, HSN and LSN diets. All data in the figure are expressed as mean ± standard error (N = 3). One-way ANOVA and Duncan's multiple comparison were used. Different letters indicate significant differences among treatment groups, p < 0.05.

[0043] Figure 3 Statistical results of weight gain rate of largemouth bass fed HF, LF, HS and LS diets. All data in the figure are expressed as mean ± standard error (N = 3). One-way ANOVA and Duncan's multiple comparison were used. Different letters indicate significant differences among treatment groups, p < 0.05.

[0044] Figure 4 Statistical results of specific growth rate of largemouth bass fed HF, LF, HS and LS diets. All data in the figure are expressed as mean ± standard error (N = 3). One-way ANOVA and Duncan's multiple comparison were used. Different letters indicate significant differences among treatment groups, p < 0.05.

[0045] Figure 5 Statistical results of weight gain rate of largemouth bass fed LS and LSN diets. All data in the figure are expressed as mean ± standard error (N = 3), independent sample t test, * indicates significant difference between treatment groups (p < 0.05).

[0046] Figure 6 Statistical results of specific growth rate of largemouth bass fed LS and LSN diets. All data in the figure are expressed as mean ± standard error (N = 3), independent sample t test, * indicates significant difference among treatment groups (p < 0.05). DETAILED DESCRIPTION

[0047] The present invention is further described in detail below with reference to the accompanying drawings and specific examples. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods used in the following examples are conventional methods unless otherwise specified; the materials and reagents used are commercially available unless otherwise specified.

[0048] Example 1 Preparation and spraying of largemouth bass polypeptide

[0049] The amino acid sequence of largemouth bass polypeptide (MSNP) from N-terminus to C-terminus is YPVKPENPGEDAPADELAKYYSALRHYINLITRQR (SEQ ID NO. 1), and the C-terminus is amidated and modified. The MSNP dry powder with a purity greater than 90% was synthesized by Shanghai Qiangyao Company.

[0050] MSNP is added to the feed by spraying. The preparation method of the spraying liquid and the spraying method are as follows:

[0051] 1. Take out the MSNP dry powder from the -80℃ refrigerator and centrifuge it in a small centrifuge for 3 minutes. After the dry powder is completely placed at the bottom of the tube, slowly add 1 ml of double-distilled water along the tube wall. Vortex and centrifuge it three times. Use double-distilled water to prepare a stock solution with an MSNP concentration of 0.9 mg / ml. Store it at -20℃ for use.

[0052] 2. Calculate the amount of storage solution according to the feeding amount: the number of fish in each group is recorded as a, the average body weight is recorded as b kg, the MSNP concentration of the storage solution is 0.9 μg / μL, and the fish are fed a fixed amount of 3% w / w of their body weight every day, that is, the feeding amount of MSNP is 0.3 μg / g feed. The final result obtained according to the calculation formula: (a×b×3×0.3) / 0.9 is the final result, which is the volume of storage solution required for each group of fish.

[0053] 3. Use a pipette to add the required amount of storage solution into a 5 mL spray bottle, then add ddH2O to make a final volume of 2 mL spray solution, and mix well with a pipette.

[0054] 4. Weigh the feed raw materials according to the formula, spray the spray liquid into them with a spray bottle, stir the feed evenly while spraying, so that the spray liquid is evenly distributed in the feed, let it stand for 5 minutes, and feed it when the feed is half dry, once in the morning and once in the evening.

[0055] Example 2: Substituting fermented soybean meal and MSNP for part of fish meal in feed can promote the growth of largemouth bass

[0056] 1. Feed formula

[0057] According to standard 20214587-T-469, the crude protein level in the feed fed to largemouth bass fry (weighing 10g to 100g) is 43-48% w / w. This embodiment uses four largemouth bass feeds with the formula shown in Table 1, of which the feed with a protein ratio of 45% w / w is a high-protein feed, and the feed with a protein ratio of 40% w / w is a low-protein feed. Compared with HF in the high-protein feed, HSN replaced 30% w / w of fish meal with fermented soybean meal and MSNP; compared with LF in the low-protein feed, LSN replaced 30% w / w of fish meal with fermented soybean meal and MSNP.

[0058] Table 1 Formula and nutritional composition of largemouth bass feed in Example 2

[0059]

[0060]

[0061] Table Notes: Protein ratio is the proportion of total crude protein in the feed calculated based on the feed ingredients; the crude protein content of fish meal is 68%, and the crude fat content is 7%; the crude protein content of fermented soybean meal is 50%; the crude protein content of chicken meal is 65%; the crude protein content of soy protein concentrate is 65%; the crude protein content of corn protein is 60%; the addition of MSNP in HSN and LSN is very small, and its effect on the total protein level of the feed is very small and basically negligible; in order to ensure the consistency of crude fat content and essential amino acid addition in the four feeds, in addition to fish meal and fermented soybean meal, the content of soybean oil, methionine and lysine was also adjusted accordingly. Defatted feed bone meal was used to balance the total weight of the feed to 100%; defatted feed bone meal was purchased from Starmark, product number 20010018.

[0062] 2. Feed preparation

[0063] Preparation method of high-protein feed HF and low-protein feed LF: Before feeding, weigh the raw materials according to the formula, mix, and then spray with 2ml ddH2O while stirring until mixed evenly, and let it stand until semi-dry before feeding.

[0064] Preparation method of high-protein feed HSN and low-protein feed LSN: Before feeding, weigh the raw materials according to the formula, mix them, and then spray them with MSNP according to the method of Example 1. Let them stand until they are semi-dry before feeding.

[0065] 3. Feeding experiment

[0066] (1) Experimental groups

[0067] Largemouth black bass of uniform weight (each weighing 30 ± 1 g) were randomly divided into groups of 30 and fed with the four feeds of this example. The groups corresponding to each feed were recorded as HF group, HSN group, LF group and LSN group, respectively. Three replicates were set for each feed, for a total of 12 groups.

[0068] (2) Adaptation to feeding

[0069] Before the experiment, each group of largemouth bass was fed with the high-protein feed HF listed in Table 1. The adaptation period was 7 days, and the feeding amount was 3% of the largemouth bass body weight. The feeding was quantitatively administered at 8 am and 16 pm every day.

[0070] (3) Formal experiment

[0071] At the start of the experiment, each group of largemouth bass was weighed and recorded, with this weight recorded as the total initial body weight. Each group was fed a diet of 3% w / w of their initial body weight, administered daily at 8:00 AM and 4:00 PM for 60 days. Fish were weighed every 15 days, and feed amounts were adjusted based on the weights. Fish activity (including swimming and feeding) was regularly monitored.

[0072] On day 60 of the formal experiment, 10 largemouth bass were randomly selected from each group, and their body length and weight were measured and recorded. The livers were dissected and dissected, and their weights were measured and recorded. At the end of the formal experiment, the remaining largemouth bass in each group were weighed to determine the total final weight, provided there were no fish deaths or illnesses, and that they were feeding and moving normally.

[0073] (4) Data Analysis

[0074] According to the data measured during the formal experiment, the growth indicators of each group of largemouth bass were analyzed and the calculation formula was as follows:

[0075] Initial average weight = total initial weight / number of fish; Final average weight = total final weight / number of fish; Weight gain rate = (final average weight - initial average weight) / initial average weight × 100%; Feed coefficient = total weight of feed added throughout the entire process / (total final weight - total initial weight); Liver-to-body ratio = liver weight / fish weight; Fatness = body weight / body length 3 × 100%; specific growth rate = (ln final average mass - ln initial average mass) / number of experimental days × 100%; survival rate = (number of fish at the beginning of the experiment - number of fish at the end of the experiment) / number of fish at the beginning of the experiment × 100%.

[0076] (5) Experimental results

[0077] Table 2 Effects of feeding different diets in Example 2 for 60 days on the growth performance of largemouth bass

[0078]

[0079] Table Notes: All data are expressed as mean ± standard error (n = 3). One-way ANOVA was used for multiple comparisons with Duncan's multiple range method. Different letters in the same row indicate significant differences among the groups (p < 0.05).

[0080] As shown in Table 2 and Figures 1-2As shown in the figure, the initial weight and fatness of the four groups of largemouth bass were basically the same, and all survived; compared with the HF group, the liver-to-body ratio of the LF group was basically the same, while the final average weight, weight gain rate and specific growth rate were significantly reduced, and the feed coefficient was significantly increased, indicating that reducing the crude protein in the feed by 5% significantly inhibited the growth of largemouth bass and reduced feed utilization; compared with the HF group, the final average weight, feed coefficient, weight gain rate and specific growth rate of the HSN group were basically the same, while the liver-to-body ratio was significantly reduced, indicating that replacing part of the fish meal in the high-protein feed with fermented soybean meal and MSNP did not affect Normal growth of largemouth bass; the final average weight, weight gain rate and specific growth rate of the LSN group were significantly higher than those of the LF group, and were equivalent to or even higher than those of the HF group and the HSN group. In addition, the liver-to-body ratio and feed coefficient of the LSN group were significantly lower than those of the LF group and the HF group, and were basically equivalent to those of the HSN group. This shows that adding fermented soybean meal and MSNP to low-protein feed can make up for the reduced crude protein, which is comparable to a high-fish meal and high-protein feed with 45% total protein. Under the same growth conditions, while reducing the amount of protein added in the feed, it also significantly reduces the consumption of fish meal in the feed.

[0081] The above results show that adding fermented soybean meal and MSNP to the feed of largemouth black bass can reduce the total protein content, promote the fish's utilization and absorption of low-protein feed, and reduce the addition of fish meal (accounting for only 21.6% w / w of the raw materials). The amount of fish meal saved is as high as 16.62% (i.e., the amount of fish meal added in the HF group feed - the amount of fish meal added in the LSN group feed), thereby reducing feed costs while improving the production efficiency of largemouth black bass farming.

[0082] Example 3: Substituting fermented soybean meal for part of fish meal in feed can promote the growth of largemouth black bass

[0083] 1. Feed formula

[0084] In this example, based on the high-protein feed HF and low-protein feed LF in Example 2, fermented soybean meal was used to replace 30% of the fish meal to obtain high-protein feed HS and low-protein feed LS, respectively. The specific formulas are shown in Table 3.

[0085] Table 3 Formula and nutritional composition of largemouth bass feed of Example 3

[0086]

[0087]

[0088] Table Notes: Protein ratio is the proportion of total crude protein in the feed calculated based on the feed ingredients; the crude protein content of fish meal is 68%, and the crude fat content is 7%; the crude protein content of fermented soybean meal is 50%; the crude protein content of chicken meal is 65%; the crude protein content of soy protein concentrate is 65%; and the crude protein content of corn protein is 60%; to ensure that the crude fat content and the addition amount of essential amino acids of the four feeds are consistent, in addition to fish meal and fermented soybean meal, the content of soybean oil, methionine and lysine are also adjusted accordingly. Defatted feed bone meal is used to balance the total mass of the feed to 100%; defatted feed bone meal was purchased from Starmark, item number 20010018.

[0089] 2. Feed preparation

[0090] According to the method for preparing high-protein feed HF and low-protein feed LF in Example 2, high-protein feed HS and low-protein feed LS were prepared, and the feeds were allowed to stand until semi-dry before feeding.

[0091] 3. Feeding experiment

[0092] (1) Experimental groups

[0093] According to the method of Example 2, largemouth black bass with uniform weight (each weighing 30 ± 1 g) were randomly divided into groups of 30 and fed with the high-protein feed HS and low-protein feed LS of this example, respectively. The groups corresponding to each feed were sequentially recorded as HS group and LS group. Three replicates were set for each feed, for a total of 6 groups.

[0094] (2) Adaptation to feeding

[0095] Same as Example 2.

[0096] (3) Formal experiment

[0097] Same as Example 2.

[0098] (4) Data Analysis

[0099] Based on the data measured during the formal experiment of this example, combined with the data of the HF group, LF group and LSN group in Example 2, the growth indicators of each group of largemouth bass were analyzed, and the data analysis method was the same as in Example 2.

[0100] (5) Experimental results

[0101] Table 4 Effects of feeding different diets in Example 3 for 60 days on the growth performance of largemouth bass

[0102]

[0103] Table Notes: All data are expressed as mean ± standard error (n = 3). One-way ANOVA was used for multiple comparisons with Duncan's multiple range method. Different letters in the same row indicate significant differences among the groups (p < 0.05).

[0104] As shown in Table 4 and Figures 3-4 As shown, the initial weight and fatness of the four groups of largemouth bass were basically the same, and all survived; compared with the HF group, the liver-to-body ratio of the LF group was basically the same, while the final average weight, mass gain rate and specific growth rate were significantly reduced, and the feed coefficient was significantly increased, indicating that reducing the crude protein in the diet by 5% significantly inhibited the growth of largemouth bass and reduced feed utilization; compared with the HF group, the final average weight, feed coefficient, mass gain rate and specific growth rate of the HS group were basically the same, while the liver-to-body ratio was significantly reduced, indicating that replacing part of the fish meal in the high-protein diet with fermented soybean meal did not affect the normal growth of largemouth bass; the final average weight, mass gain rate and specific growth rate of the LS group were significantly increased compared with the LF group, and were basically the same as those of the HF and HS groups, and the liver-to-body ratio and feed coefficient of the LS group were significantly lower than those of the LF and HF groups, and were basically the same as those of the HSN group, indicating that replacing part of the fish meal in the low-protein diet with fermented soybean meal can promote the growth of largemouth bass.

[0105] Further comparison of the mass gain rate and specific growth rate of the LS group of this example and the LSN group of Example 2 is shown in FIG. Figures 5-6 As shown in the results, the weight gain rate and specific growth rate of the LSN group were significantly higher than those of the LS group, indicating that spraying MSNP on the low-protein feed prepared from fermented soybean meal can more significantly promote the growth of largemouth bass.

[0106] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art will readily appreciate that other variations or modifications may be made based on the above descriptions and concepts. It is not necessary and impossible to provide an exhaustive list of all possible implementations. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. Application of largemouth bass polypeptide and fermented soybean meal in preparing largemouth bass feed, characterized in that: The amino acid sequence of the largemouth bass polypeptide is shown in SEQ ID NO.1; the crude protein content of the largemouth bass feed is 39% w / w to 42% w / w, comprising 20% w / w to 22% w / w fish meal, 0.25 μg / g to 0.35 μg / g largemouth bass polypeptide and 12% w / w to 14% w / w fermented soybean meal; the largemouth bass is juvenile largemouth bass.

2. Use of a low-protein feed containing a largemouth bass polypeptide in promoting the growth of largemouth bass, characterized in that: The crude protein content of the low-protein feed is 39% w / w to 42% w / w, and the low-protein feed comprises 20% w / w to 22% w / w fish meal, 0.25 μg / g to 0.35 μg / g largemouth bass polypeptide and 12% w / w to 14% w / w fermented soybean meal; the amino acid sequence of the largemouth bass polypeptide is shown in SEQ ID NO.1; and the largemouth bass is a juvenile largemouth bass.

3. The use according to claim 2, characterized in that The crude fat content of the low-protein feed is 10% to 15%.

4. The use according to claim 3, characterized in that The crude fat content of the low-protein feed is 12.5%.

5. The use according to claim 2, characterized in that The crude protein content of the low-protein feed is 41.76%.

6. The use according to claim 2, characterized in that The content of the fish meal is 21.62% w / w.

7. The use according to claim 2, characterized in that The content of the fermented soybean meal is 12.60% w / w.

8. The use according to claim 2, characterized in that The content of the largemouth bass polypeptide is 0.3 μg / g.

9. The use according to claim 2, characterized in that The low-protein feed also contains 8%w / w to 12%w / w chicken meal, 8%w / w to 12%w / w soy protein concentrate, 8%w / w to 12%w / w corn protein, 2.5%w / w to 3.5%w / w fish oil, 3%w / w to 4%w / w soybean oil, 2.5%w / w to 3.5%w / w soy lecithin, 10%w / w to 14%w / w flour, 0.1%w / w to 0.3%w / w methionine, 0.5%w / w to 0.7%w / w lysine, 8%w / w to 12%w / w nitrogen-free bone meal, 1%w / w to 2%w / w vitamin and mineral premix, 1%w / w to 2%w / w calcium dihydrogen phosphate and 0.4%w / w to 0.6%w / w choline chloride.

10. The use according to claim 9, characterized in that The low-protein feed also contains 10% w / w chicken meal, 10% w / w soy protein concentrate, 10% w / w corn gluten, 3% w / w fish oil, 3.49% w / w soybean oil, 3% w / w soy lecithin, 12% w / w flour, 0.2% w / w methionine, 0.6% w / w lysine, 10% w / w nitrogen-free bone meal, 1.5% w / w vitamin and mineral premix, 1.5% w / w calcium dihydrogen phosphate and 0.5% w / w choline chloride.

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