Granular bait as well as preparation and application thereof

Abstract

The invention relates to the field of aquaculture, and discloses granular bait as well as preparation and application thereof, the granular bait comprises a core material, and at least one nutrient substance layer and at least one disintegrating agent layer which alternately coat the core material. The granular bait solves the problems that algae powder sinks to the bottom, an oil layer floats on the surface of a water body and the like when the algae powder is fed for aquaculture. The release speed of algae can be controlled through slow release, and the concentration of algae in a water body in unit time is reduced, so that pollution and waste caused by sinking of algae to the bottom are reduced. Meanwhile, according to the granular bait disclosed by the invention, slow-release dissolved algae cells can be dispersed into single cells, the particle size is less than 20 microns, and the granular bait can be well used in the early stage of aquatic animals, such as a shellfish planktonic stage and before a shrimp seed zoeae.

Description

Technical Field

[0001] The present invention relates to the field of aquaculture, and particularly to a granular bait and its preparation and application. Background Art

[0002] Currently, for the early feeding of aquatic animals, live single-celled microalgae are mostly used. When live single-celled microalgae are lacking, feeds such as slow-release cakes prepared from mixed algal powders are also used. However, the particles of the slow-release cakes prepared from mixed algal powders exist in the form of aggregates of multiple cells and cannot be effectively dispersed into single-cell state, and the particle size is relatively large. Therefore, when used for feeding early-stage aquatic animals such as the planktonic stage of shellfish and the zoea stage of shrimp larvae, the food intake is significantly less and the growth condition is not ideal. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problem that the bait microalgae slow-release cake in the prior art cannot be used before the early stage of aquatic animals such as the planktonic stage of shellfish and the zoea stage of shrimp larvae, and to provide a granular bait and its preparation and application.

[0004] To achieve the above purpose, on the one hand, the present invention provides a granular bait, which comprises a core material and at least one nutrient layer and at least one disintegrant layer alternately coated on the core material.

[0005] On the second hand, the present invention provides a method for preparing a granular bait, which comprises: alternately coating at least one nutrient layer and at least one disintegrant layer on the core material.

[0006] On the third hand, the present invention provides an application of the above granular bait in aquaculture.

[0007] Through the above technical solutions, the present invention can at least obtain the following beneficial effects:

[0008] (1) Solve the problems such as the algal powder sinking to the bottom and the oil layer floating on the water surface in aquaculture feeding. The release rate of the slow-release controllable algae is reduced, and the concentration of algae in the water body per unit time is decreased, thereby reducing the pollution and waste caused by the sinking of algae to the bottom.

[0009] (2) For the granular bait of the present invention, the slow-release and dissolved algal cells can be dispersed into single cells, and the particle size is all below 20 μm, which can be well used before the early stage of aquatic animals such as the planktonic stage of shellfish and the zoea stage of shrimp larvae.

[0010] (3) For the granular bait of the present invention, algal paste can be used instead of algal powder to prepare the nutrient layer, reducing the processing procedures of algal cells, enabling the algal cells, especially the bait microalgae without cell walls, to maintain better cell integrity and nutrient components, and at the same time reducing the processing cost. Detailed Embodiments

[0011] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0012] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustration and explanation of the present invention, and are not used to limit the present invention.

[0013] In the first aspect of the present invention, there is provided a granular bait, characterized in that the granular bait comprises a core material and at least one nutrient layer and at least one disintegrant layer alternately coated on the core material.

[0014] In the present invention, the weight ratio of adjacent nutrient layer and disintegrant layer is preferably 80-120:1.

[0015] In the present invention, those skilled in the art can determine the size of the core material according to the feeding amount; preferably, relative to 3 g of the nutrient layer, the cross-sectional diameter of the core material can be 5-10 mm.

[0016] In the present invention, the core material is selected from hollow core materials that can float in water, preferably polyethylene hollow spheres.

[0017] In the present invention, preferably, the moisture content difference between adjacent two nutrient layers is 5-20% by weight, and the moisture content of the nutrient layer closer to the core material is lower. Controlling the moisture content in this way can further control the viscosity and sedimentation of the nutrient layer.

[0018] In the present invention, the nutrient layer closest to the core material is defined as the first nutrient layer, and the layers away from the core material are defined as the second nutrient layer, the third nutrient layer, the fourth nutrient layer, and so on. In the present invention, there is no particular limitation on the number of layers of the nutrient layer, as long as the sustained release rate and sedimentation of the granular bait can be balanced. Preferably, the nutrient layer can be 2-6 layers; more preferably, the nutrient layer can be 3 layers; further preferably, the moisture content of the first nutrient layer is 55-65% by weight, the moisture content of the second nutrient layer is 70-75%, and the moisture content of the third nutrient layer is 75-85% by weight.

[0019] In a preferred embodiment of the present invention, the dosage of diatomaceous earth or Bacillus in the first nutrient layer does not exceed 6% of the algal paste, and the sedimentation situation is improved. And in order to better demold, low-substituted hydroxypropyl cellulose (L-HPC) needs to be added; the addition of Bacillus and diatomaceous earth in the second nutrient layer will make the algal paste have a granular feeling, so the use of these two substances is reduced in the second nutrient layer.

[0020] In the present invention, it is only necessary to alternately coat the nutrient layer and the disintegrant layer.

[0021] In the present invention, the raw materials of the nutrient layer are conventional raw materials in the art, mainly providing nutrients for early-stage aquatic animals, enabling early-stage aquatic animals to ingest sufficient nutrients to achieve the purpose of normal growth. Additives can also be added to make the nutrients play a role in reducing sedimentation. In the present invention, each nutrient layer independently contains algal paste, disintegrant A, and additive A. "Algal paste" refers to one or several of Isochrysis galbana, Phaeodactylum tricornutum, Tetraselmis suecica, Chlorella vulgaris, Nannochloropsis oculata, Chaetoceros sp., Thalassiosira sp., Cyclotella sp., Nitzschia sp. obtained by concentrating algal cells through centrifugation, membrane concentration, or plate and frame filtration methods.

[0022] In the present invention, the algal paste can be selected from at least one of Isochrysis galbana, Phaeodactylum tricornutum, Tetraselmis suecica, Chlorella vulgaris, Nannochloropsis oculata, Chaetoceros sp., Thalassiosira sp., Cyclotella sp., Nitzschia sp.; preferably Phaeodactylum tricornutum.

[0023] In the present invention, the disintegrant A can be selected from at least one of sodium carboxymethyl cellulose (CMC-Na), corn starch, polyvinylpyrrolidone K30, microcrystalline cellulose, diatomaceous earth, dry starch, sodium carboxymethyl starch, cross-linked polyvinylpyrrolidone, sodium alginate; preferably sodium carboxymethyl cellulose.

[0024] In the present invention, the additive A can be selected from at least one of Bacillus, photosynthetic bacteria, nitrifying bacteria, EM bacteria, yeast, low-substituted hydroxypropyl cellulose (L-HPC), diatomaceous earth, zeolite powder, talc powder, dolomite powder; further preferably, at least one of zeolite powder or talc powder can be used in combination with low-substituted hydroxypropyl cellulose. In the present invention, the weight ratio of algal paste, disintegrant A, and additive A in each nutrient layer is 1:0 - 0.4:0 - 0.1; preferably, the weight ratio of algal paste, disintegrant A, and additive A in the first nutrient layer is 1:0.1 - 0.4:0 - 0.1; more preferably 1:0.2 - 0.3:0.05 - 0.07; the weight ratio of algal paste, disintegrant A, and additive A in the second nutrient layer is 1:0.05 - 0.1:0 - 0.1; more preferably 1:0.05 - 0.07:0.01 - 0.03; the third nutrient layer only contains algal paste.

[0025] In the present invention, the raw materials of the disintegrant layer are conventional raw materials in the art, mainly for the purpose of accelerating the dissolution of granular bait. In order to further improve the dissolution rate, in the present invention, each disintegrant layer independently contains disintegrant B and additive B.

[0026] In the present invention, the disintegrant B can be selected from at least one of sodium carboxymethylcellulose, corn starch, polyvinylpyrrolidone K30, microcrystalline cellulose, diatomaceous earth, dry starch, sodium carboxymethyl starch, crosslinked polyvinylpyrrolidone, sodium alginate, etc., and is further preferably sodium carboxymethylcellulose.

[0027] In the present invention, the additive B can be selected from at least one of bacillus, photosynthetic bacteria, nitrifying bacteria, EM bacteria, yeast, diatomaceous earth, zeolite powder, talc powder, dolomite powder or low-substituted hydroxypropyl cellulose; more preferably at least one of bacillus, photosynthetic bacteria, nitrifying bacteria, EM bacteria or yeast; further preferably bacillus.

[0028] In the present invention, the weight ratio of disintegrant B to additive B in each disintegrant layer is 2-10:1; preferably 3-5:1; further preferably 4:1.

[0029] In the second aspect of the present invention, a method for preparing the above-mentioned granular bait is provided, and the method includes alternately coating at least one nutrient layer and at least one disintegrant layer on the core material.

[0030] In the present invention, the selection and dosage ratio of each layer of substances are as described above, and will not be elaborated here.

[0031] In the present invention, the method for preparing the granular bait is a conventional method in the art, mainly for alternately coating at least one nutrient layer and at least one disintegrant layer on the core material. In order to further make the operation during wrapping and the wrapping amount easy to control, the method for preparing the granular bait further includes: controlling the moisture content between different nutrient layers.

[0032] In the third aspect of the present invention, an application of the above-mentioned granular bait in aquaculture is provided. The granular bait of the present invention is suitable for the early feeding of aquatic animals, and is particularly suitable for feeding planktonic shellfish and / or mysis shrimp larvae.

[0033] In the present invention, although the slow-release bait can control the release rate of algae, reduce the concentration of algae in the water body per unit time, and reduce the pollution and waste caused by the sedimentation of algae, it is not the slower the better. When the average slow-release rate of algae is lower than 0.25 g / h, the number of algal cells in the nursery pond is too small, resulting in insufficient nutrients ingested by the seedlings, slow development, and affecting the quality of the seedlings.

[0034] In the present invention, the usage method of the granular bait preferably includes: putting the granular bait into the aquaculture pond, where the granular bait slowly disperses in water, and the dispersed single-celled microalgae are ingested by the fry of aquatic animals, such as the larvae of shellfish in the planktonic stage and the shrimp fry before the zoea stage.

[0035] The present invention will be described in detail below through examples. For those not specifying specific conditions in the following examples and comparative examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial channels.

[0036] Preparation method of Phaeodactylum tricornutum algal paste: The Phaeodactylum tricornutum algal solution cultured to the late logarithmic phase, with a cell concentration of about 20 - 30 million cells / ml, is concentrated by centrifugation, membrane filtration or plate-frame filtration, and the concentrated algal paste has a cell concentration of about 6 - 12 billion cells / ml.

[0037] Dissolution rate = total mass of bait / total dissolution time.

[0038] Example 1

[0039] The core material is a spherical core material with a diameter of 5 mm having a floating effect; 1 g of CMC-Na and 0.25 g of Bacillus are mixed as the disintegrant layer; 40 g of Phaeodactylum tricornutum algal paste, 10.24 g of CMC-Na, 1.28 g of L-HPC and 1.28 g of talc are mixed as the first nutrient layer, and the moisture content of the first nutrient layer is 61.62% by weight, and the mass of the first layer of each sustained-release pellet is about 1 g; 50 g of Phaeodactylum tricornutum algal paste, 3 g of CMC-Na and 1 g of L-HPC are mixed as the second nutrient layer, and the moisture content of the second nutrient layer is 73.31% by weight, and the mass of the second layer of each sustained-release pellet is about 1.2 g; 30 g of Phaeodactylum tricornutum algal paste is directly used as the third nutrient layer, and the moisture content of the third nutrient layer is 79.63% by weight, and the mass of the third layer of each sustained-release pellet is about 0.8 g; the nutrient layer and the disintegrant layer are stacked in sequence, and the mass of each layer of the disintegrant layer of each sustained-release pellet is about 0.01 g to make a three-layer sustained-release pellet.

[0040] Example 2

[0041] The core material is a spherical core material with a diameter of 5 mm that has a floating effect; 1 g of CMC-Na and 0.25 g of Bacillus are mixed as the disintegrant layer; 40 g of Phaeodactylum tricornutum paste, 10.24 g of CMC-Na, and 2.56 g of L-HPC are mixed as the first nutrient layer. The moisture content of the first nutrient layer is 61.33% by weight, and the mass of the first layer of each sustained-release pellet is about 1 g; 50 g of Phaeodactylum tricornutum paste, 3 g of CMC-Na, and 1 g of L-HPC are mixed as the second nutrient layer. The moisture content of the second nutrient layer is 73.63% by weight, and the mass of the second layer of each sustained-release pellet is about 1.2 g; 30 g of Phaeodactylum tricornutum paste is directly used as the third nutrient layer. The moisture content of the third nutrient layer is 79.63% by weight, and the mass of the third layer of each sustained-release pellet is about 0.8 g; the nutrient layers and the disintegrant layer are stacked in sequence, and the mass of each layer of the disintegrant layer of each sustained-release pellet is about 0.01 g to produce a three-layer sustained-release pellet.

[0042] Example 3

[0043] The core material is a spherical core material with a diameter of 5 mm that has a floating effect; 1 g of CMC-Na and 0.25 g of Bacillus are mixed as the disintegrant layer; 40 g of Phaeodactylum tricornutum paste and 12.8 g of CMC-Na are mixed as the first nutrient layer. The moisture content of the first nutrient layer is 59.24% by weight, and the mass of the first layer of each sustained-release pellet is about 1 g; 50 g of Phaeodactylum tricornutum paste, 3 g of CMC-Na, and 1 g of L-HPC are mixed as the second nutrient layer. The moisture content of the second nutrient layer is 72.41% by weight, and the mass of the second layer of each sustained-release pellet is about 1.2 g; 30 g of Phaeodactylum tricornutum paste is directly used as the third nutrient layer. The moisture content of the third nutrient layer is 79.63% by weight, and the mass of the third layer of each sustained-release pellet is about 0.8 g; the nutrient layers and the disintegrant layer are stacked in sequence, and the mass of each layer of the disintegrant layer of each sustained-release pellet is about 0.01 g to produce a three-layer sustained-release pellet.

[0044] Example 4

[0045] The core material is a spherical core material with a diameter of 5 mm that has a floating effect; 2 g of CMC-Na and 0.5 g of Bacillus are mixed as the disintegrant layer; 40 g of Phaeodactylum tricornutum paste, 10.24 g of CMC-Na, 1.28 g of L-HPC, and 1.28 g of talcum powder are mixed as the first nutrient layer. The moisture content of the first nutrient layer is 61.62% by weight, and the mass of the first layer of each sustained-release pellet is about 1 g; 50 g of Phaeodactylum tricornutum paste, 3 g of CMC-Na, and 1 g of L-HPC are mixed as the second nutrient layer. The moisture content of the second nutrient layer is 73.31% by weight, and the mass of the second layer of each sustained-release pellet is about 1.2 g; 30 g of Phaeodactylum tricornutum paste is directly used as the third nutrient layer. The moisture content of the third nutrient layer is 79.63% by weight, and the mass of the third layer of each sustained-release pellet is about 0.8 g; the nutrient layers and the disintegrant layer are stacked in sequence, and the mass of each layer of the disintegrant layer of each sustained-release pellet is about 0.04 g to produce a three-layer sustained-release pellet.

[0046] Example 5

[0047] The core material is a spherical core material with a diameter of 5 mm that has a floating effect; 1 g of CMC-Na and 0.25 g of Bacillus are mixed as the disintegrant layer; 40 g of Phaeodactylum tricornutum paste, 12 g of CMC-Na, and 4 g of L-HPC are mixed as the first nutrient layer. The moisture content of the first nutrient layer is 57.72% by weight, and the mass of the first layer of each sustained-release pellet is about 1 g; 50 g of Phaeodactylum tricornutum paste and 10 g of L-HPC are mixed as the second nutrient layer. The moisture content of the second nutrient layer is 68.43% by weight, and the mass of the second layer of each sustained-release pellet is about 1.2 g; 30 g of Phaeodactylum tricornutum paste is directly used as the third nutrient layer. The moisture content of the third nutrient layer of each sustained-release pellet is 80.91% by weight, and the mass of the third layer is about 0.8 g; the nutrient layers and the disintegrant layer are stacked in sequence, and the mass of each layer of the disintegrant layer of each sustained-release pellet is about 0.01 g to produce a three-layer sustained-release pellet.

[0048] Example 6

[0049] The core material is spherical with a diameter of 5 mm and has a floating effect; 1 g of CMC-Na and 0.25 g of Bacillus are mixed as the disintegrant layer; 40 g of Phaeodactylum tricornutum paste, 12 g of CMC-Na and 4 g of L-HPC are mixed as the first nutrient layer, and the moisture content of the first nutrient layer is 57.73% by weight, and the mass of the first layer of each sustained-release pellet is about 1 g; 50 g of Phaeodactylum tricornutum paste, 5 g of CMC-Na and 5 g of L-HPC are mixed as the second nutrient layer, and the moisture content of the second nutrient layer is 69.28% by weight, and the mass of the second layer of each sustained-release pellet is about 1.2 g; 30 g of Phaeodactylum tricornutum paste is directly used as the third nutrient layer, and the moisture content of the third nutrient layer is 80.91% by weight, and the mass of the third layer of each sustained-release pellet is about 0.8 g; the nutrient layer and the disintegrant layer are stacked in sequence, and the mass of each layer of the disintegrant layer of each sustained-release pellet is about 0.01 g to produce a three-layer sustained-release pellet.

[0050] Comparative Example 1

[0051] Mix the raw materials except the core material evenly according to the types and dosages of Example 1 to make pellets of equal mass.

[0052] Comparative Example 2

[0053] Prepare granular bait according to the preparation method of Example 1, the difference is that: the disintegrant A and additive A in the nutrient layer and the disintegrant B and additive B in the disintegrant layer are equally replaced with Phaeodactylum tricornutum powder.

[0054] Test Example

[0055] Take 1 pellet of the bait prepared in the examples and comparative examples, put it into a 100-mesh net bag, and place it in a 1-L Erlenmeyer flask containing 800 ml of tap water. Shake it on a shaker at 80 rpm, and record the time taken for the bait to completely dissolve, which is denoted as the dissolution time. Microscopic examination of the bait dissolution solution is carried out to observe the dispersion of the algal cells released by slow release and dissolution. Fill the above data into Table 1.

[0056] Table 1

[0057]

[0058] Conclusion: The above results show that the method for preparing granular bait provided by the present invention can achieve the purpose of controlling the release rate of microalgal cells into the water body, and for the granular bait obtained in Examples 1-6, the algal cells released by slow release and dissolution are dispersed into single cells, and the particle size is all below 20 μm, which can meet the feeding requirements of different cultured animals at different culture stages.

[0059] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A granular bait, characterized in that, the granular bait comprises a core material and at least one nutrient layer and at least one disintegrant layer alternately coated on the core material.

2. The granular bait according to claim 1, wherein, the weight ratio of adjacent nutrient layer and disintegrant layer is 80 - 120:

1.

3. The granular bait according to claim 1, wherein, relative to the total weight of 3 g of the nutrient layer, the cross-sectional diameter of the core material is 5 - 10 mm; and / or, the core material is selected from hollow core materials capable of floating in water, preferably polyethylene hollow spheres.

4. The granular bait according to claim 1, wherein, the moisture content difference between adjacent two nutrient layers is 5 - 20% by weight, and the moisture content of the nutrient layer closer to the core material is lower; preferably, the total number of nutrient layers is 2 - 6 layers; more preferably, the number of nutrient layers is 3 layers; further preferably, the moisture content of the first nutrient layer is 55 - 65% by weight, the moisture content of the second nutrient layer is 70 - 75% by weight, and the moisture content of the third nutrient layer is 75 - 85% by weight.

5. The granular bait according to claim 1, wherein, each nutrient layer independently contains algal paste, disintegrant A and additive A; preferably, the algal paste is selected from at least one of Isochrysis galbana, Phaeodactylum tricornutum, Tetraselmis suecica, Chlorella vulgaris, Nannochloropsis oculata, Chaetoceros sp., Thalassiosira sp., Cyclotella sp., Nitzschia sp.; preferably Phaeodactylum tricornutum; preferably, the disintegrant A is selected from at least one of sodium carboxymethyl cellulose, corn starch, polyvinylpyrrolidone K30, microcrystalline cellulose, diatomaceous earth, dry starch, sodium carboxymethyl starch, cross-linked polyvinylpyrrolidone, sodium alginate; preferably sodium carboxymethyl cellulose; preferably, the additive A is selected from at least one of Bacillus sp., photosynthetic bacteria, nitrifying bacteria, EM bacteria, yeast, diatomaceous earth, zeolite powder, talc powder, dolomite powder or low-substituted hydroxypropyl cellulose; further preferably at least one of zeolite powder or talc powder is used in combination with low-substituted hydroxypropyl cellulose.

6. The granular bait according to claim 5, wherein, the weight ratio of algal paste, disintegrant A and additive A in each nutrient layer is 1:0 - 0.4:0 - 0.1; preferably, the weight ratio of algal paste, disintegrant A and additive A in the first nutrient layer is 1:0.1 - 0.4:0 - 0.1; more preferably 1:0.2 - 0.3:0.05 - 0.07; the weight ratio of algal paste, disintegrant A and additive A in the second nutrient layer is 1:0.05 - 0.1:0 - 0.1; more preferably 1:0.05 - 0.07:0.01 - 0.03; the third nutrient layer contains only algal paste.

7. The granular bait according to claim 1, wherein, each disintegrant layer independently contains disintegrant B and additive B; Preferably, the disintegrant B is selected from at least one of sodium carboxymethylcellulose, corn starch, polyvinylpyrrolidone K30, microcrystalline cellulose, diatomaceous earth, dry starch, sodium carboxymethyl starch, cross-linked polyvinylpyrrolidone, sodium alginate, and is further preferably sodium carboxymethylcellulose; Preferably, the additive B is selected from at least one of bacillus, photosynthetic bacteria, nitrifying bacteria, EM bacteria, yeast, diatomaceous earth, zeolite powder, talc powder, dolomite powder or low-substituted hydroxypropyl cellulose; more preferably at least one of bacillus, photosynthetic bacteria, nitrifying bacteria, EM bacteria or yeast; further preferably bacillus.

8. The granular bait according to claim 7, wherein, The weight ratio of the disintegrant B to the additive B in each disintegrant layer is 2-10:1; preferably 3-5:1; further preferably 4:

1.

9. A method for preparing the granular bait according to any one of claims 1-6, characterized in that, The method includes: alternately coating at least one nutrient layer and at least one disintegrant layer on the core material.

10. An application of the granular bait according to any one of claims 1-8 in aquaculture.

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