Low-protein feed containing largemouth bass polypeptide and application of low-protein feed

Abstract

The invention discloses a low-protein feed containing micropterus salmoides polypeptide and application of the low-protein feed. The amino acid sequence of the micropterus salmoides polypeptide is as shown in SEQ ID NO. 1. The micropterus salmoides polypeptide MSNP combined fermented soybean meal is added into the feed, so that the capability of the micropterus salmoides for digesting the feed and absorbing and utilizing nutrient substances is improved, the growth and weight increment of the micropterus salmoides are promoted, the total protein content of the feed and the addition amount of fish meal in the feed are reduced, the feed cost is saved, the culture benefit is improved, and the economic benefit is increased. The pollution pressure of a culture water body is relieved, and the method has wide popularization and application values in the largemouth bass culture industry.

Description

Technical Field

[0001] The 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, and has formed an industrialized breeding scale at home and abroad. In order to ensure and improve the quality of largemouth bass compound feed products, improve the use effect of largemouth bass compound feed, and also help regulatory authorities to effectively supervise the quality of largemouth bass compound feed products, ensure product quality, and promote the healthy development of largemouth bass breeding industry, my country formulated the largemouth bass compound feed standard (20214587-T-469) in 2021. According to the standard, the crude protein level of largemouth bass compound feed is: 43-48% for fry (weight 10g-100g), 38-44% for fingerlings, and 35-40% for adult fish.

[0003] The main source of protein in fish feed in my country is imported high-quality fish meal, so my country is a major consumer of fish meal in the world, with an annual demand of about 1.7 million tons, which greatly increases feed costs and compresses production profits. Relatively cheap plant protein is the best choice to replace fish meal. However, most plant proteins contain more anti-nutritional factors, which are not conducive to the intake and absorption of nutrients by largemouth bass from feed. In addition, the amino acid composition of plant protein is quite different from that of fish meal, which will affect the growth and immunity of fish. Uneaten feed remains in the aquaculture water and is prone to rot and deterioration. The protein in it is prone to eutrophication of the water body after deterioration, leading to deterioration of water quality. Therefore, in order to reduce the addition of fish meal to improve aquaculture efficiency and reduce the risk of feed contamination of water bodies, it is urgent to develop 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 the use of 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 the preparation of 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 largemouth bass polypeptide in promoting the growth of largemouth bass.

[0012] In order to achieve the above object, the present invention is implemented by 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%) in the largemouth black bass fingerling stage, and replacing fish meal with fermented soybean meal. Feed, MSNP solution (0.3μg / g feed) is added to the aquatic feed, and largemouth black bass polypeptide MSNP is also sprayed into the feed as an additive. It is clear through feeding experiments that in feed, especially in feed with low protein content, the combined addition of fermented soybean meal and MSNP can greatly improve the growth performance of largemouth black bass fingerlings, thereby reducing the fish meal content in the feed, as well as reducing the total protein content of the feed, and improving the economic benefits.

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

[0015] Application of a largemouth bass polypeptide in promoting the growth of largemouth bass, wherein 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 fry of largemouth bass is 10 g to 100 g.

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

[0019] The invention discloses an application of a largemouth bass polypeptide in preparing a largemouth bass feed additive or a largemouth bass feed, wherein 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] More 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, monocalcium 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 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 monocalcium phosphate and 0.4% w / w to 0.6% w / w choline chloride.

[0036] In some specific embodiments, the low protein feed further comprises 10% w / w chicken meal, 10% w / w soy protein concentrate, 10% w / w corn protein, 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 monocalcium 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 sprayed and fed each time.

[0038] Application 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 invention adds largemouth bass polypeptide MSNP to feed and combines fermented soybean meal to improve the ability of largemouth bass to digest feed and absorb and utilize nutrients, 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 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 comparisons, 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 analysis of variance and Duncan's multiple comparisons. Different letters indicate significant differences among treatment groups, p < 0.05.

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

[0045] Figure 5 The statistical results of weight gain rate of largemouth bass fed with 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).

[0046] Figure 6 The specific growth rate statistics of largemouth bass fed with 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 in conjunction with the accompanying drawings and specific examples of the specification. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. The test methods used in the following examples are conventional methods unless otherwise specified; the materials and reagents used are reagents and materials that can be obtained from commercial channels 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% is synthesized by Shanghai Qiangyao Company.

[0050] The 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 storage solution with an MSNP concentration of 0.9 mg / ml, and place 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 quantitative 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 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 ddH 2 O was prepared into a spray solution with a final volume of 2 ml and mixed by blowing with a gun.

[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 again 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 black bass fry (weighing 10g to 100g) is 43 to 48% w / w. This embodiment uses 4 kinds of largemouth black bass feeds with formulas as 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 replaces 30% w / w of fish meal with fermented soybean meal and MSNP; compared with LF in the low-protein feed, LSN replaces 30% w / w of fish meal with fermented soybean meal and MSNP.

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

[0059]

[0060]

[0061] Table Notes: The protein ratio is the proportion of total crude protein in the feed calculated based on the feed raw materials; 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 soybean protein concentrate is 65%; the crude protein content of corn protein is 60%; the amount of MSNP added in HSN and LSN is very small, and the effect on the total protein level of the feed is very small and basically negligible; in order to ensure that the crude fat content and the amount of essential amino acids added in the four feeds are consistent, in addition to fish meal and fermented soybean meal, the content of soybean oil, methionine and lysine is also adjusted accordingly, and 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.

[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 them, and then use 2ml ddH 2 OStir while spraying until it is evenly mixed, and let it stand until it is 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 MSNP according to the method of Example 1, let it stand until it is semi-dry before feeding.

[0065] 3. Feeding experiment

[0066] (1) Experimental groups

[0067] Largemouth black bass of uniform weight (each weighing 30 ± 1g) were randomly divided into groups of 30 and fed with the four feeds of this example. The groups corresponding to the feeds 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) Adaptive feeding

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

[0070] (3) Formal Experiment

[0071] At the beginning of the formal experiment, each group of largemouth bass was weighed and recorded, and the weight at this time was recorded as the total initial weight. Each group of largemouth bass was fed with a corresponding feed at a fixed rate of 3% w / w of the initial body weight, and fed at 8:00 and 16:00 every day for 60 days. Weigh once every 15 days, and adjust the feed amount according to the weighing results. Regularly monitor whether the activity status of each group of fish is normal (including swimming status, feeding, etc.).

[0072] On the 60th day of the formal experiment, 10 largemouth bass were randomly selected from each group to measure and record their body length and weight. After the measurement, the liver was dissected and separated, and the liver weight was measured and recorded. After the formal experiment, there was no death or disease in each group of fish, and the fish had normal feeding and activity. The weight of the remaining largemouth bass in each group was weighed and recorded as the total final weight.

[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 is 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 put in during the whole 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 different feeds in Example 2 on the growth performance of largemouth bass for 60 days

[0078]

[0079] Table Notes: All data are expressed as mean ± standard error (n = 3), and one-way analysis of variance 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. 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 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 and 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 bass

[0083] 1. Feed formula

[0084] In this embodiment, based on the high-protein feed HF and low-protein feed LF in Example 2, fermented soybean meal is used to replace 30% of 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 in Example 3

[0086]

[0087]

[0088] Table Notes: The protein ratio is the proportion of total crude protein in the feed calculated based on the feed raw materials; 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 soybean protein concentrate is 65%; the crude protein content of corn protein is 60%; in order 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 is also adjusted accordingly, and 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 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±1g) were randomly divided into groups of 30, and fed with the high-protein feed HS and the low-protein feed LS of this example, respectively. The groups corresponding to each feed were recorded as HS group and LS group, and 3 replicates were set for each feed, for a total of 6 groups.

[0094] (2) Adaptive feeding

[0095] Same as Example 2.

[0096] (3) Formal Experiment

[0097] Same as Example 2.

[0098] (4) Data analysis

[0099] According to the data measured during the formal experiment of this embodiment, combined with the data of the HF group, LF group and LSN 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 Effect of different feeds of Example 3 on the growth performance of largemouth bass for 60 days

[0102]

[0103] Table Notes: All data are expressed as mean ± standard error (n = 3), and one-way analysis of variance 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 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, 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 feed 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 higher than those of the LF group, and were basically the same as those of the HF group and the HS group, and the liver-to-body ratio and feed coefficient of the LS group were significantly lower than those of the LF group and the HF group, and were basically the same as those of the HSN group, indicating that replacing part of the fish meal with fermented soybean meal in a low-protein feed 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, as shown in FIG. Figures 5-6 As shown in the figure, 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 only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. For ordinary technicians in this field, other different forms of changes or modifications can be made based on the above descriptions and ideas. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. The use of a largemouth bass polypeptide in promoting the growth of largemouth bass, characterized in that: The amino acid sequence of the largemouth bass polypeptide is shown in SEQ ID NO.

1.

2. Use of a largemouth bass polypeptide in the preparation of a largemouth bass feed additive or a largemouth bass feed, characterized in that: The amino acid sequence of the largemouth bass polypeptide is shown in SEQ ID NO.

1.

3. Application of largemouth bass polypeptide and fermented soybean meal in promoting the growth of largemouth bass, characterized in that: The amino acid sequence of the largemouth bass polypeptide is shown in SEQ ID NO.

1.

4. The use 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.

5. A composition, characterized in that The invention 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.

6. A low-protein feed containing largemouth bass polypeptide, 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 the composition according to claim 5.

7. The low-protein feed according to claim 6, characterized in that: The low protein feed also contains 20% w / w to 22% w / w fish meal.

8. The low-protein feed according to claim 7, characterized in that: The content of the fermented soybean meal is 12% w / w to 14% w / w.

9. The low-protein feed according to claim 7, characterized in that: The content of the largemouth bass polypeptide is 0.25 μg / g to 0.35 μg / g.

10. Use of the low-protein feed containing the largemouth bass polypeptide according to any one of claims 6 to 9 in promoting the growth of largemouth bass.

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