Low-protein medicago sativa silage compound pellet feed and application thereof in grass carp culture

Abstract

The invention discloses a low-protein medicago sativa silage compound pellet feed and application thereof in the field of grass carp culture. The low-protein medicago sativa silage compound pellet feed comprises the following components in percentage by mass: 45%-65% of a protein premix, 10%-20% of corn, 10%-20% of wheat bran, 1%-25% of medicago sativa and 0.5%-5% of rice bran. The alfalfa silage is adopted to replace traditional protein feed, so that the cost is reduced, the safety, the reliability and the usability are ensured, and the contents of alpha-linolenic acid, DHA (Docosahexaenoic Acid) in the fish meat and lysine, phenylalanine and other functional amino acids for tonifying kidney and strengthening brain can be increased. The silage has a wide application prospect in the breeding industry, and is long in preservation time and high in health-care and nutritional value. The alfalfa silage is matched with the pellet feed, so that the protein digestion performance of the grass carps and the nutritional value of fish meat are improved, and no adverse effect is generated at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of aquatic product breeding and feed preparation and processing, and particularly relates to a low-protein alfalfa silage compound granular feed and application thereof in grass carp breeding. Background Art

[0002] Alfalfa is a perennial herbaceous plant of the genus Alfalfa in the Leguminosae family. It is rich in nutrients such as protein and various minerals, but there is no report on the use of alfalfa silage as a dietary component for grass carp. Silage is an important forage preparation, processing and storage method, which has important research and experimental significance for ensuring stable factory production and high yield of grass carp throughout the year.

[0003] At present, grass carp feed mainly uses soybean meal, rapeseed meal and cottonseed meal as protein sources, and such plant protein raw materials are also widely used in human food and livestock feed industries, resulting in competition between humans, livestock and aquaculture for plant protein raw materials. Therefore, it is imperative to open up new sources of protein raw materials. In addition, new protein raw materials have potential efficacy and are the development direction of healthy and sustainable breeding of high-quality grass carp, such as making fish meat rich in α-linolenic acid, DHA, lysine and phenylalanine. α-linolenic acid is a polyunsaturated fatty acid with three double bonds. It is a kind of ω-3 essential fatty acid. It plays the role of improving intelligence, anti-thrombosis, and protecting the liver, and is of great significance to human health. DHA, namely docosahexaenoic acid, brain gold, plays the role of assisting brain cell development, anti-aging, improving blood circulation and lowering blood lipids, and is a polyunsaturated fatty acid necessary for the human body. Lysine and phenylalanine are amino acids that are essential to the human body and play important functions. Lysine promotes human growth, neurological and intellectual development, enhances the body's immunity, resists viruses, promotes fat oxidation, and relieves anxiety. Phenylalanine is involved in muscle growth and repair, and maintains normal growth and development of the human body. It can be converted into tyrosine, and then synthesized into neurotransmitters such as dopamine, adrenaline, norepinephrine, etc., to regulate the function of the nervous system and play a role in nourishing the kidney and brain. Phenylalanine can also participate in the metabolism of tyrosine in the blood, regulate the concentration of creatine in the blood, help improve athletic ability and endurance, and reduce fatigue.

[0004] The present invention utilizes alfalfa silage harvested at different times to replace part of the protein premix to prepare a low-protein alfalfa silage combined with pellet feed for feeding grass carp. The results show that the alfalfa silage combined with pellet feed at the early flowering stage increases the intestinal protease activity of grass carp, the content of total fatty acids, α-linolenic acid and DHA in fresh meat, and functional amino acids such as lysine and phenylalanine that nourish the kidney and brain, and reduces the cost of feed breeding, which has great application value in production. Summary of the invention

[0005] The purpose of the present invention is to provide a low-protein alfalfa silage compound feed and its application in grass carp farming in order to solve the technical problem of the shortage of protein feed sources in intensive grass carp farming. The present invention uses alfalfa silage to replace a part of traditional feed to prepare a low-protein alfalfa silage compound feed, which can be used in grass carp farming to significantly improve the protein digestibility and quality of grass carp, reduce feed farming costs, and has great application value in production.

[0006] The invention achieves the above-mentioned purpose through the following technical solutions:

[0007] In the first aspect, the present invention claims protection for a low-protein alfalfa silage compound granular feed, which comprises the following components by mass percentage: 45% to 65% protein premix, 10% to 20% corn, 10% to 20% wheat bran, 1% to 25% alfalfa and 0.5% to 5% rice bran; the sum of the mass percentages of the various components is 100%.

[0008] As a preferred technical solution, the low-protein alfalfa silage compound granular feed comprises the following components by mass percentage: 45% to 60% protein premix, 10% to 20% corn, 10% to 20% wheat bran, 5% to 20% alfalfa and 1% to 4% rice bran.

[0009] Further preferably, the low-protein alfalfa silage compound pellet feed comprises the following components by mass percentage: 48% to 58% protein premix, 10% to 20% corn, 10% to 20% wheat bran, 10% to 20% alfalfa and 1% to 3% rice bran.

[0010] More preferably, the low-protein alfalfa silage compound pellet feed comprises the following components by mass percentage: 50% to 56% protein premix, 12% to 18% corn, 12% to 18% wheat bran, 12% to 18% alfalfa and 1% to 3% rice bran.

[0011] Most preferably, the low-protein alfalfa silage compound pellet feed comprises the following components by mass percentage: 53% protein premix, 15% corn, 15% wheat bran, 15% alfalfa and 2% rice bran.

[0012] As a preferred technical solution, the method for preparing the low-protein alfalfa silage compound pellet feed comprises the following steps:

[0013] (I) After the alfalfa to be ensiled is cut, rice bran is added according to the formula ratio and mixed evenly, and 1×10 lactic acid bacteria are added 5 ~1×10 7cfu / g, and then stored in sealed form at room temperature anaerobically to make mixed silage of alfalfa and rice bran;

[0014] (II) The protein premix, corn, wheat bran, alfalfa and rice bran mixed silage are mixed according to the formula ratio and then made into dry pellet feed by a pellet machine.

[0015] As a preferred technical solution, the alfalfa described in the present invention is alfalfa in the early flowering stage or alfalfa in the full flowering stage, and is more preferably alfalfa in the early flowering stage.

[0016] In a second aspect, the present invention claims protection for the use of the low-protein alfalfa silage compound pellet feed in at least one of the following:

[0017] (1) Grass carp farming;

[0018] (2) Improve the intestinal protease activity of grass carp;

[0019] (3) Improve the quality of grass carp.

[0020] Furthermore, the improvement of grass carp quality is to increase the content of α-linolenic acid, DHA and functional amino acids in grass carp muscle. Furthermore, the functional amino acids are lysine and / or phenylalanine.

[0021] Furthermore, the above application is to use the aforementioned low-protein alfalfa silage in combination with pellet feed to culture grass carp to improve the quality of grass carp; the alfalfa is alfalfa in the early flowering period or alfalfa in the full flowering period.

[0022] Furthermore, the above application is to use the aforementioned low-protein alfalfa silage in combination with pellet feed to culture grass carp to improve the intestinal protease activity of grass carp; the alfalfa is alfalfa in the early flowering period.

[0023] In a third aspect, the present invention claims a method for improving the intestinal protease activity of grass carp and / or the quality of grass carp, wherein the aforementioned low-protein alfalfa silage is used in combination with pellet feed to breed grass carp to improve the quality of grass carp; the alfalfa is alfalfa in the early flowering stage or alfalfa in the full flowering stage;

[0024] The aforementioned low-protein alfalfa silage is used in combination with pellet feed to culture grass carp to improve the intestinal protease activity of grass carp; the alfalfa is alfalfa in the early flowering period.

[0025] The improvement of grass carp quality is to increase the content of α-linolenic acid, DHA and functional amino acids in grass carp muscle. Furthermore, the functional amino acids are lysine and / or phenylalanine.

[0026] The low-protein alfalfa silage compounded with pelleted feed of the present invention is used for grass carp farming to increase the intestinal protease activity of grass carp and / or the content of α-linolenic acid, DHA and functional amino acids in grass carp muscle. The method uses alfalfa, especially alfalfa in the early flowering period, to make low-protein alfalfa silage compounded with pelleted feed instead of a part of traditional protein premix for grass carp farming.

[0027] During the research process, the present invention provides two types of alfalfa, specifically alfalfa in the early flowering period and alfalfa in the full flowering period. The alfalfa and rice bran mixed silage prepared after being mixed with rice bran for silage has a high lactic acid bacteria content and can be prepared using a conventional silage preparation method and stored at room temperature.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) Using the high protein content of alfalfa to replace traditional protein feed is low-cost, safe, reliable and easy to use.

[0030] (2) Silage can be used in large quantities in the breeding industry, has a long shelf life and high nutritional value.

[0031] (3) The mixed pellet feed used in the present invention improves the protein digestibility and quality of grass carp without causing any adverse effects. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. 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 present invention.

[0033] Example 1: Preparation of low-protein alfalfa silage and pellet feed

[0034] 1 Materials and methods

[0035] 1.1 Sources of silage materials

[0036] Alfalfa is planted at the Baima Teaching and Research Practice Base of Nanjing Agricultural University. It is harvested when it reaches the early flowering stage and the full flowering stage respectively. Corn, wheat bran, rice bran and protein premix are commercially available raw materials.

[0037] 1.2 Preparation of mixed pellet feed

[0038] Calculated by mass percentage, the formula of low-protein alfalfa silage compound pellet feed is as follows:

[0039] Formula 1: 53% protein premix, 15% corn, 15% wheat bran, 15% alfalfa and 2% rice bran.

[0040] Formula 2: 50% protein premix, 15% corn, 15% wheat bran, 18% alfalfa and 2% rice bran.

[0041] Formula 3: 56% protein premix, 15% corn, 15% wheat bran, 12% alfalfa and 2% rice bran.

[0042] Control group: protein premix 68%, corn 15%, wheat bran 15%, rice bran 2%.

[0043] Preparation process of low-protein alfalfa silage pellet feed:

[0044] Preparation of mixed silage of alfalfa and rice bran (I): Cut fresh alfalfa into 1-2 cm pieces and mix them evenly. Mix 18.0 kg of alfalfa with 2.4 kg of rice bran and add 1×10 lactic acid bacteria. 6 cfu / g, and evenly divided into 3 polyethylene plastic bags (60×90cm, 19 threads), each bag is about 6.8kg. After vacuuming, seal and store at room temperature (32-39℃) for 60 days before use. The fermentation quality and nutritional components are shown in Table 1.

[0045] Preparation of mixed silage of alfalfa and rice bran (II): 18.0 kg of alfalfa and 2.0 kg of rice bran were mixed evenly, and other operations were the same as (I).

[0046] Preparation of alfalfa and rice bran mixed silage (III): 18.0 kg of alfalfa and 3.0 kg of rice bran were mixed evenly, and the other operations were the same as (I).

[0047] Preparation of low-protein alfalfa silage pellet feed: After the silage fermentation was completed, it was mixed with other dietary raw materials according to the formula, and a pellet machine (Model 125, Xingbai Agricultural Machinery Factory, Zhengzhou) was used to make 1-2 cm particles with a moisture content of about 15%, which were placed in a ziplock bag and vacuum-sealed for storage. The lactic acid bacteria content in the mixed pellet feed of the early flowering group was 4.21 lg cfu / g FW, and the lactic acid bacteria content in the mixed pellet feed of the full flowering group was 4.34 lg cfu / g FW.

[0048] Among them, formula one of the low-protein alfalfa silage compound pellet feed uses a mixed silage of alfalfa and rice bran (one); formula two uses a mixed silage of alfalfa and rice bran (two); and formula three uses a mixed silage of alfalfa and rice bran (three).

[0049] During the study, two types of mixed silage of alfalfa and rice bran were used to prepare low-protein alfalfa silage pellet feeds, namely, early flowering alfalfa silage pellet feed (CH) and full flowering alfalfa silage pellet feed (KH). Table 2 shows the nutritional components of the control group and the two low-protein alfalfa silage pellet feeds prepared according to formula 1.

[0050] Table 1 Nutritional composition of mixed silage of alfalfa and rice bran

[0051]

[0052]

[0053] Table 2 Silage feed raw material composition % (w / w)

[0054]

[0055] Example 2: Experiment on feeding grass carp with low-protein alfalfa silage and pelleted feed

[0056] 1 Materials and methods

[0057] The breeding experiment lasted for 60 days. The pond was divided into three areas, with 50 grass carps in each area. The aerator was turned on from 9:00 am to 6:00 pm every day for oxygenation. The grass carps had normal body color and morphology, strong physique, good feeding, and an initial body weight of 1000±50g. In each area, 15 silver carps of 500±50g and 200 yellow catfish of 5-8 cm were raised in the grass carp, equipped with an aerator, which was turned on from 9:00 am to 6:00 pm every day. At 7:00 am and 5:00 pm, 1000g of low-protein alfalfa silage pellet feed prepared according to Formula 1 in Example 1 was fed respectively, which was equivalent to 4% of the initial total weight of each group of grass carps per day. The water environment conditions during the experiment are shown in Table 3.

[0058] Table 3 Water environment for feeding experiment

[0059]

[0060] 2 Grass carp sampling steps and methods

[0061] Prepare fish anticoagulant and injection lubricant before sampling. Anticoagulant: 0.2g heparin sodium + 5mL ultrapure water; injection lubricant: 0.1g heparin sodium + 5mL saline, stored at 4°C. Then prepare anticoagulant tubes. Take 2mL centrifuge tube injection and add 2 to 3 drops of anticoagulant to the centrifuge tube, close the lid and flick the centrifuge tube with your fingers to evenly distribute the anticoagulant on the tube wall. Open the tube cover and put it in a 65°C oven to dry for use. Cover the centrifuge tube cover and store at -20°C. 0.86% saline: 8.6g sodium chloride plus double distilled water to 1000mL. Lubricate the needle in advance on the day of sampling and suck the prepared injection lubricant into the syringe and inject it. Cover the needle cap. Open the low-speed centrifuge in advance for precooling. Centrifuge program settings: 3000×g, 4°C, 10min.

[0062] After taking the fish, the morphological indicators were measured first, and the weight and body length (length from the snout to the base of the tail fin) were measured. Then, blood was collected from the tail vein and placed in a 2mL anticoagulant centrifuge tube. After the blood was collected, it was immediately centrifuged, and the supernatant was aspirated and placed in a 1.5mL centrifuge tube and stored at -20°C. The same fish was dissected, cut from the tail cloaca upward to the fish head, the viscera were weighed, and the fish head was cut off to measure the head weight. The fish intestines, liver and abdominal fat were separated, weighed separately and placed in 5mL centrifuge tubes, and stored at 4°C. Take 3×3×1cm of muscle below the dorsal fin of the fish and put it in a ziplock bag.

[0063] 3. Determination method of grass carp index

[0064] The calculation formulas for growth and morphological indicators are as follows:

[0065] wWGR=(mt-m0) / m0×100%

[0066] SGR=(lnmt-lnm0) / t×100%

[0067] CF=100m / L3

[0068] wVSI=mv / m×100%

[0069] wHSI=mh / m×100%

[0070] wRGW=mG / m×100%

[0071] I=LG / L

[0072] RS=nt / n0×100%

[0073] Wherein, wWGR is mass gain rate (%), SGR is specific growth rate (% / d), CF is fatness, wVSI is visceral-somatic index (%), wHIS is liver-somatic index (%), wRGW is intestinal-somatic index (%), I is specific intestinal length, RS is survival rate (%), t is feeding days (d), m0 is initial mass (g), mt is final mass (g), mv is visceral mass (g), mh is liver mass (g), mG is intestinal mass (g), LG is intestinal length (cm), m is body mass (g), L is body length (cm), n0 and nt are the number of fish (tails) at the beginning and end of the experiment in each group, respectively.

[0074] 1cm×1cm×0.5cm back muscle was taken and muscle texture analysis was performed using a texture analyzer (TMS-Pro, FTC, USA). The test indicators included hardness, adhesiveness, cohesiveness, springiness, gumminess, chewiness, and resilience. A 25mm×25mm cylindrical probe was used, the contact sensing force was 5gf, the test speed was 1mm / s, the target mode was deformation, the deformation amount was 50%, and the time was 2.5s. Each sample was measured twice and the average value was taken.

[0075] Determination of digestive enzyme activity in the intestine and liver: Under freezing conditions, take 0.10-0.20g of sample, mix according to the sample volume: physiological saline (0.69%) 1:9, fully homogenize in an ice water bath, centrifuge the homogenate at 4°C, 3000r / min for 15min, and take the supernatant for the determination of protease, amylase, and lipase activities. Protease, amylase, and lipase assay kits were purchased from Nanjing Wanqing Biotechnology Co., Ltd., and the absorbance was measured using an ultraviolet spectrophotometer according to the instructions, and the digestive enzyme activity was determined using the standard curve.

[0076] Serum biochemical index determination: After the experimental fish was anesthetized, blood was collected from the tail vein using a 2 mL sterile syringe (pre-moistened with sodium heparin anticoagulant) and immediately centrifuged at 3500 r / min for 10 min. The supernatant was frozen at -20 °C. The assay kits were purchased from Nanjing Wanqing Biotechnology Co., Ltd. for the determination of aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood protein (ALB), glucose (GLU), triglyceride (TG), total cholesterol (TC), and lactic acid (LA).

[0077] Fish fatty acid detection method: Fatty acids were detected by gas chromatography. Chromatographic conditions: TRACE GC gas chromatograph; chromatographic column: Agilent HP-88 (100×0.25mm), carrier gas: helium, injection: 40μL, split ratio: 100:1, injection port temperature: 270℃, detector temperature: 280℃, detector auxiliary gas: hydrogen flow rate: 30mL / min, air flow rate: 30mL / min. Heating program: 100℃ for 4min, 15℃·min -1 After heating to 180℃ for 6min, -1 The temperature was raised to 200°C and continued for 15 min at 8°C / min. -1 The temperature was raised to 230°C and maintained for 10 min.

[0078] Excel was used to organize the data, and SPSS22 statistical analysis software was used to analyze the experimental data. Based on the one-way analysis of variance, the t-test method was used to test whether there were significant differences among the groups. P<0.05 was considered to be a significant difference.

[0079] 4 Results Analysis

[0080] 2.1 Effects of low-protein alfalfa silage combined with pelleted feed on growth performance indicators of grass carp

[0081] As shown in Table 4, CH and KH did not have significant differences with the CON group in terms of final body weight, mass gain rate and specific growth rate, indicating that the effect of low-protein alfalfa silage combined with pelleted feed on fish growth performance is the same as that of traditional feed.

[0082] Table 4 Effects of alfalfa silage on growth performance indicators of grass carp

[0083]

[0084] Note: Different lowercase letters indicate significant differences (P<0.05).

[0085] 2.2 Effects of low-protein alfalfa silage combined with pelleted feed on morphological parameters of grass carp

[0086] As shown in Table 5, feeding alfalfa silage mixed pellet feed in the flowering period significantly increased the organ-to-body ratio index (P<0.05), among which there was no significant effect between the CON group and the CH group (P>0.05). There was no significant effect on fatness, liver-to-body ratio, specific intestine length and intestine-to-body ratio (P>0.05), indicating that grass carp had the same degree of digestion for the three feeds.

[0087] Table 5 Effects of low-protein alfalfa silage combined with pelleted feed on morphological parameters of grass carp

[0088]

[0089] Note: Different lowercase letters indicate significant differences (P<0.05).

[0090] 2.3 Effects of low-protein alfalfa silage combined with pelleted feed on the intestinal tract of grass carp

[0091] As shown in Table 6, feeding alfalfa silage had a significant effect on the intestinal protease and amylase activities of grass carp (P<0.05). The intestinal protease activity of the CH group was significantly higher than that of the CON and KH groups (P<0.05), and the protease activity of the KH group was significantly lower than that of the CON group (P<0.05). The intestinal amylase of grass carp in the CH and KH groups was significantly lower than that in the CON group (P<0.05), and the protease activity of the KH group was significantly lower than that of the CH group (P<0.05).

[0092] Table 6 Effects of alfalfa silage on intestinal digestive enzymes in grass carp

[0093]

[0094] Note: Different lowercase letters indicate significant differences (P<0.05).

[0095] 2.4 Effects of low-protein alfalfa silage combined with pelleted feed on grass carp muscle texture

[0096] As shown in Table 7, feeding alfalfa silage had no significant effect on the hardness, adhesion, elasticity, cohesion, viscosity, chewiness and recovery of grass carp meat. Compared with the CON group, the hardness, elasticity, viscosity and chewiness of the CH and KH groups showed a decreasing trend (0.05 <P<0.1)。

[0097] Table 7 Effects of low-protein alfalfa silage combined with pelleted feed on muscle texture of grass carp

[0098]

[0099] Note: Different lowercase letters indicate significant differences (P<0.05).

[0100] 2.5 Effects of low-protein alfalfa silage combined with pelleted feed on serum biochemical parameters of grass carp

[0101] As shown in Table 8, the KH group had a significant effect on the plasma AST, ALT and total cholesterol of grass carp (P<0.05). The AST and ALT in the KH group were significantly higher than those in the CH and CON groups (P<0.05), and the total cholesterol concentration was significantly lower than that in the CH and CON groups (P<0.05).

[0102] Table 8 Effects of low-protein alfalfa silage combined with pelleted feed on serum biochemical parameters of grass carp

[0103]

[0104] Note: Different lowercase letters indicate significant differences (P<0.05).

[0105] 2.6 Effect of low-protein alfalfa silage combined with pelleted feed on amino acids in fish meat

[0106] As shown in Table 9, the aspartic acid content in the fish meat of the control group was the highest among all amino acids, followed by proline, serine, and methionine. The aspartic acid content in the early flowering group was the highest among all amino acids, followed by proline, glutamic acid, and methionine. The proline content in the full flowering group was the highest among all amino acids, followed by methionine, glutamic acid, and aspartic acid. The contents of aspartic acid, proline, serine, and glutamic acid showed significant differences among the three groups of feed (P<0.05), among which the contents of glutamic acid, leucine, and lysine in the early flowering group were the highest (P<0.05), the contents of alanine, methionine, and proline in the full flowering group were the highest (P<0.05), and the content of glycine in the control group was the highest (P<0.05). The serine content in the control group was the highest (P<0.05). The total amount of amino acids was the highest in the early flowering group (P<0.05).

[0107] Table 9 Amino acid analysis of fish meat

[0108]

[0109] Note: Different lowercase letters indicate significant differences (P<0.05).

[0110] 2.7 Effect of low-protein alfalfa silage combined with pelleted feed on fish fatty acids

[0111] As shown in Table 10, a total of 14 fatty acids were detected in this study, including 4 saturated fatty acids and 10 unsaturated fatty acids. Except for linoleic acid (P>0.05), the three groups of feeds fed grass carp had a significant effect on the fatty acid content of fish meat (P<0.05), among which the palmitoleic acid, heptadecanoic acid, elaidic acid, trans-linoleic acid, and arachidic acid contents of the control group were significantly lower than those of the two treatment groups (P<0.05), and the contents of α-linolenic acid, heneicosanoic acid, and docosanoic acid in the flowering period group were the highest (P<0.05), the contents of nervonic acid and docosahexaenoic acid in the early flowering period group were the highest (P<0.05), and the content of erucic acid in the control group was the highest (P<0.05). The total fatty acids, total unsaturated fatty acids, and total saturated fatty acids in the early flowering period group were all the highest (P<0.05).

[0112] Table 10 Effect of feeding low-protein alfalfa silage pelleted feed on fish fatty acids

[0113]

[0114] Note: Different lowercase letters indicate significant differences (P<0.05).

[0115] 2.8 Economic benefits of replacing grass carp protein meal with alfalfa silage

[0116] As shown in Table 11, without reducing the weight gain of grass carp, using CH and KH groups of alfalfa silage to replace protein premix reduced feed costs by 17.51% and 17.60%.

[0117] Table 11 Breeding cost accounting

[0118]

Claims

1. A low-protein alfalfa silage compound pellet feed, It is characterized in that The low-protein alfalfa silage compound granular feed comprises the following components in percentage by mass: 45% to 65% of protein premix, 10% to 20% of corn, 10% to 20% of wheat bran, 1% to 25% of alfalfa and 0.5% to 5% of rice bran; the sum of the percentage by mass of each component is 100%.

2. The low-protein alfalfa silage compound feed pellet according to claim 1, It is characterized in that The preparation method comprises the following steps: (I) After the alfalfa to be ensiled is cut, rice bran is added according to the formula ratio and mixed evenly, and 1×10 lactic acid bacteria are added 5 ~1×10 7 cfu / g, and then stored in sealed form at room temperature anaerobically to make mixed silage of alfalfa and rice bran; (II) The protein premix, corn, wheat bran, alfalfa and rice bran mixed silage are mixed according to the formula ratio and then made into dry pellet feed by a pellet machine.

3. The low-protein alfalfa silage compound feed pellet according to claim 1 or 2, It is characterized in that The alfalfa is alfalfa in the early flowering period or alfalfa in the full flowering period.

4. Use of the low-protein alfalfa silage compound pellet feed according to any one of claims 1 to 3 in at least one of the following: (1) Grass carp farming; (2) Improve the intestinal protease activity of grass carp; (3) Improve the quality of grass carp.

5. The use according to claim 4, It is characterized in that The method for improving the quality of grass carp is to increase the contents of α-linolenic acid, DHA and functional amino acids in grass carp muscles.

6. The use according to claim 5, It is characterized in that The functional amino acids are lysine and / or phenylalanine.

7. The use according to claim 4, It is characterized in that The low-protein alfalfa silage and pellet feed described in claim 1 or 2 are used to breed grass carp to improve the quality of grass carp; the alfalfa is alfalfa in the early flowering stage or alfalfa in the full flowering stage.

8. The use according to claim 4, It is characterized in that The low-protein alfalfa silage and pellet feed described in claim 1 or 2 are used to breed grass carp to improve the intestinal protease activity of grass carp; the alfalfa is alfalfa in the early flowering stage.

9. A method for improving the intestinal protease activity of grass carp and / or the quality of grass carp, It is characterized in that The low-protein alfalfa silage and pellet feed according to claim 1 or 2 are used to breed grass carp to improve the quality of grass carp; the alfalfa is alfalfa in the early flowering stage or alfalfa in the full flowering stage; The low-protein alfalfa silage and pellet feed described in claim 1 or 2 are used to breed grass carp to improve the intestinal protease activity of grass carp; the alfalfa is alfalfa in the early flowering stage.

10. The method according to claim 9, It is characterized in that The method for improving the quality of grass carp is to increase the contents of α-linolenic acid, DHA and functional amino acids in grass carp muscles.

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