Method for determining feed for algae-eating fish and shellfish, method for feeding algae-eating fish and shellfish, and method for producing feed

Abstract

Provided is a technology which increases the feed ingestion rate of herbivorous fish / shellfish. This method for determining feed for herbivorous fish / shellfish includes providing multiple algal cell samples at different stages of growth or division to herbivorous fish / shellfish, and selecting, as feed to provide to the herbivorous fish / shellfish, algal cells at the same stage of growth or division as those which the herbivorous fish / shellfish most preferred to eat.

Description

[Technical field]

[0001] The present invention relates to a method for determining a feed for algae-eating fish and shellfish, a method for feeding algae-eating fish and shellfish, and a method for producing the feed. [Background technology]

[0002] Research has been conducted on the feeding of herbivorous fish and shellfish such as pearl oysters. For example, Non-Patent Document 1 is a document on the feeding of pearl oyster juveniles, and reports the feeding rate, digestion rate, and amount of plant pigments contained in the digestive cecum of pearl oyster juveniles on six types of microalgae. Non-Patent Document 2 is a document on the feeding of cured pearl oysters, and specifically reports the weight gain rate, protein content, and highly unsaturated fatty acid content of cured pearl oysters on two types of microalgae. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Comparison of feeding rate, digestibility and pigment content in the digestive ceca of juvenile pearl oysters fed six types of microalgae, Nippon Suisan Gakkaishi, 68(4), 534-537(2002) [Non-Patent Document 2] Effect of feeding microalgae on the growth of nursery pearl oysters, Bulletin of the Graduate School of Bioresource Science, Mie University, 44, 1-5 (2018) Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a technique for increasing the feeding efficiency of herbivorous fish and shellfish. [Means for solving the problem]

[0005] According to a first aspect of the present invention, Feeding each of a plurality of samples of algal cells at different stages of growth or division to an algae-eating fish or shellfish; selecting, as food to be given to the algae-eating fish and shellfish, the algae cells which are at the same stage of growth or division as those most preferably eaten by the algae-eating fish and shellfish; A method for determining a feed for an algae-eating fish or shellfish is provided, comprising:

[0006] According to a second aspect of the present invention, feeding one or more samples each containing algal cells at different stages of growth or division to a herbivorous fish or shellfish; selecting, as food to be given to the algae-eating fish and shellfish, the algae cells which are at the same stage of growth or division as those most preferably eaten by the algae-eating fish and shellfish; A method for determining a feed for an algae-eating fish or shellfish is provided, comprising:

[0007] According to a third aspect of the present invention, there is provided a method of feeding algae-eating fish and shellfish, comprising feeding the algae-eating fish and shellfish with the feed determined by the method according to the first or second aspect.

[0008] According to a fourth aspect of the present invention, there is provided a method for producing a feed determined by the method according to the first or second aspect, comprising the steps of: Cultivating the algal cells; obtaining, from the cultured algal cells, those at the same growth or division stage as those most preferred to be eaten by the algae-eating fish and shellfish as the feed; A method is provided that includes: Effect of the Invention

[0009] According to the present invention, a technique for increasing the feeding efficiency of algae-eating fish and shellfish is provided. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing how eukaryotic algal cells grow and divide. [Diagram 2] FIG. 2 is a schematic diagram showing an example of a feed determination method according to the first embodiment. [Diagram 3]FIG. 3 is a schematic diagram showing another example of the feed determination method according to the first embodiment. [Figure 4] FIG. 4 is a schematic diagram showing an example of a feed determination method according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described. The embodiments described below are more specific embodiments of any of the above aspects. The following items can be incorporated into each of the above aspects alone or in combination.

[0012] 1. How to determine the feed for herbivorous fish and shellfish 1-1. First embodiment The "method for determining a feed for herbivorous fish and shellfish" according to the first embodiment of the present invention is as follows: Feeding each of a plurality of samples of algal cells at different stages of growth or division to an algae-eating fish or shellfish; selecting, as food to be given to the algae-eating fish and shellfish, the algae cells which are at the same stage of growth or division as those most preferably eaten by the algae-eating fish and shellfish; Includes.

[0013] (Terminology explanation) The term "algae-eating fish and shellfish" is a general term for algae-eating aquatic animals such as algae-eating fish and shellfish, and refers to aquatic animals such as fish and shellfish that prey on algae. Algae-eating fish are, for example, juvenile fish, and algae-eating shellfish are, for example, pearl oysters.

[0014] The term "algae" refers to microalgae. Microalgae are, for example, photosynthetic eukaryotes, unicellular organisms or colonies thereof. Microalgae are, for example, unicellular green algae such as Chlamydomonas reinhardtti and Botryococcus, unicellular red algae such as Cyanidioschyzon merolae, diatoms such as Phaeodactylum, or colonies thereof. Microalgae do not have to be eukaryotic, but may be photosynthetic prokaryotes, for example bacteria such as cyanobacteria.

[0015] (Sample preparation process) In the method according to the first embodiment, first, "multiple samples with algal cells at different stages of growth or division" are prepared. In this method, algal cells contained in one sample are at one specific stage of growth or division. In this method, in order to compare which of the multiple samples is most preferred by algal-eating fish and shellfish, the multiple samples are identical except for the different stages of growth or division of the algal cells. In other words, the multiple samples contain algal cells of the same strain, and only the growth or division stages of the algal cells are different. The multiple samples refer to two or more types of samples, and there is no particular upper limit. The multiple samples can be, for example, 2 to 8 types of samples.

[0016] Algae multiply by repeating growth and division. The process in which a single cell grows immediately after division and then divides into two is called the cell cycle. The cell cycle is classified into eight phases, for example, G1 phase (preparatory phase for DNA synthesis), S phase (DNA synthesis phase), G2 phase (preparatory phase for division), M phase (mitosis) early phase, mid-M phase, late-M phase, late-M phase, and G0 phase (stationary phase).

[0017] FIG. 1 shows a schematic of the growth and division of eukaryotic algal cells. In FIG. 1, an algal cell 1 includes a cell wall 10 and a cytoplasm surrounded by the cell wall. The cytoplasm includes a nucleus 11 and chloroplasts 12. As shown in FIG. 1, in the G1 phase, DNA synthesis is prepared and the cell grows. Then, in the S phase, chromosomal DNA is replicated. When the replication of chromosomal DNA is completed, the algal cell enters the G2 phase and prepares for division. Then, in the early M phase, chromosomes are condensed, in the middle M phase, the nuclear membrane disappears and the chromosomes are aligned on the equator, in the late M phase, the chromatids are pulled by the spindle and separated, and in the telophase M phase, the chromatids are decondensed, the nuclear membrane is reformed, and the cytoplasm divides. The period when no cell growth or division occurs is called the G0 phase.

[0018] Therefore, as "multiple samples of algal cells at different stages of growth or division", for example, multiple samples of algal cells at different cell cycles can be prepared. Specifically, the following eight types of samples can be prepared. Sample A1: Algal cells in the G1 phase Sample A2: Algal cells in the S phase Sample A3: Algal cells in the G2 phase Sample A4: Algal cells in early M phase Sample A5: Algal cells in mid-M phase Sample A6: Algal cells at late M phase Sample A7: Algal cells at the end of M phase Sample A8: Algal cells in the G0 phase

[0019] These samples can be prepared by culturing algal cells in culture with the cell cycles aligned. The technique of culturing algal cells in culture with the cell cycles aligned is known as synchronized culture. For example, the cell cycles of algal cells can be aligned by culturing the algal cells in a culture environment that alternates between a light environment and a dark environment. Algal cells have the property that they photosynthesize in a light environment, and when the light environment is switched to a dark environment, their photosynthetic activity decreases and they transition from the G1 phase to the S phase to progress through the cell cycle, so that the cell cycles can be aligned. Alternatively, the cell cycles can be aligned by culturing the algal cells in a culture medium containing a cell division inhibitor or a cell proliferation inhibitor to stop the cell cycle at a specific stage, and then culturing them in the absence of the inhibitor. As such inhibitors, DNA replication inhibitors, microtubule formation inhibitors, etc. can be used.

[0020] (Sample administration step) In the method according to the first embodiment, each of the prepared samples (i.e., samples of algal cells at different stages of growth or division) is given to the herbivorous fish and shellfish. The samples are each, for example, 1×10 4 ~1×10 6 The algae-eating fish and shellfish can be fed with the sample so that individual algal cells are administered. The sample may be administered once or multiple times. In the case of multiple administrations, the sample may be administered every 2 to 12 hours. In the case of multiple administrations, the number of administrations is, for example, 2 to 28 times.

[0021] In this method, in order to compare which of a plurality of samples is most preferred by the algae-eating fish and shellfish, it is desirable to use the same test conditions, such as the administration conditions, for all samples. The test conditions include the concentration of the administered sample (i.e., the number of algal cells), the rearing environment of the algae-eating fish and shellfish before and during administration (e.g., the feeding conditions before administration), and the like. For example, it is desirable to fast the algae-eating fish and shellfish before feeding them with the samples for all samples. Alternatively, it is desirable to keep the algae-eating fish and shellfish in a full stomach state before feeding them with the samples for all samples.

[0022] (Feed selection process) After administering the sample to the algae-eating fish and shellfish, algae cells at the same stage of growth or division as the algae cells most preferred to be consumed by the algae-eating fish and shellfish are selected as a feed for the algae-eating fish and shellfish, where the algae cells are selected as at least a portion of the feed for the algae-eating fish and shellfish, i.e., the algae cells selected here may be used as a portion of the feed for the algae-eating fish and shellfish, or may be used as the entire feed for the algae-eating fish and shellfish.

[0023] The food selection can be performed by determining which of a number of samples is most favorably consumed by the herbivorous fish and shellfish.

[0024] Preferably, the selection of the feed can be performed by measuring the number of algal cells ingested by each of the algal-eating fish and shellfish administered the sample, and determining, based on the measurement results, which stage of growth or division of the algal cells is most preferred by the algal-eating fish and shellfish to be ingested. The number of algal cells ingested by the algal-eating fish and shellfish can be measured directly by removing the ingested algal cells from the algal-eating fish and shellfish and measuring the number of algal cells, or indirectly by measuring the number of algal cells remaining in the breeding water without being ingested. The number of algal cells can be measured, for example, using a hemocytometer or flow cytometry.

[0025] Alternatively, the selection of the feed can be performed by measuring the intake of algae-derived biological components (e.g., DHA, EPA, etc.) by each of the algae-eating fish and shellfish administered with the sample, and determining which stage of growth or division of the algae cells is most preferred to be consumed by the algae-eating fish and shellfish based on the measurement results. In this method, the intake of algae-derived biological components by the algae-eating fish and shellfish is first measured, for example, by analyzing lipids contained in the algae-eating fish and shellfish by GC-MS / MS (gas chromatography tandem mass spectrometry). Next, the measured intake is divided by the amount of biological components contained in one algae cell administered to the algae-eating fish and shellfish to calculate the number of algae cells consumed by the algae-eating fish and shellfish. This makes it possible to determine which stage of growth or division of the algae cells is most preferred to be consumed by the algae-eating fish and shellfish.

[0026] The selection of the feed can be carried out, for example, 1 to 5 hours after the administration of the sample. It is considered possible that the algal cells administered as a sample may progress in the growth or division stage between the administration of the sample and the selection of the feed. Therefore, it is preferable to confirm whether the sample (i.e., the algal cells) remaining in the rearing water, which is the sample most preferred by the algae-eating fish and shellfish, is in the growth or division stage at the time of the selection of the feed. If the growth or division stage of the sample is not advanced in this confirmation process, the algal cells having the same growth or division stage as the sample most preferred by the algae-eating fish and shellfish can be selected as the feed. Alternatively, if the growth or division stage is advanced in the confirmation process, the algal cells having the period from the growth or division stage of the sample at the time of administration to the advanced stage can be selected as the feed. In the latter case, by shortening the period between administration of the sample and food selection so that no growth or division stages occur between administration of the sample and food selection, it is possible to narrow down which stage of growth or division the sample that the herbivorous fish and shellfish most prefer to feed on is at.

[0027] (Example 1) Fig. 2 shows a schematic diagram of an example of the feed determination method according to the first embodiment. In Fig. 2, algae-eating shellfish 2 are cultured in culture water 4 contained in a culture vessel 3. In this example, the above-mentioned eight types of samples (samples A1 to A8) were administered to the algae-eating shellfish 2, but Fig. 2 shows a representative case in which samples A1 to A3 (i.e., algal cell 1a in the G1 phase, algal cell 1b in the S phase, and algal cell 1c in the G2 phase) were administered.

[0028] In Figure 2, the left column shows tests in which algal cells 1a in the G1 phase were administered as a sample, the center column shows tests in which algal cells 1b in the S phase were administered as a sample, and the right column shows tests in which algal cells 1c in the G2 phase were administered as a sample. In Figure 2, the upper figures in each column show the state immediately after the sample was administered to the algae-eating shellfish 2, and the lower figures in each column show the state a predetermined time after the sample was administered to the algae-eating shellfish 2.

[0029] In this example, for example, five algae-eating shellfish 2 are fasted for three days after the feeding is stopped, and then the sample is administered every 12 hours for a total of 28 times, and the number of algae cells ingested by the algae-eating shellfish 2 is measured three hours after each administration of the sample. Here, each administration of the sample is performed at a concentration of, for example, 1×10 4 ~1×10 6 The algal cells are administered in such a manner that one algal cell is administered. After the algae-eating shellfish is fasted, it is preferable to administer the sample multiple times. By administering the sample multiple times, the preference of the algae-eating shellfish can be examined more accurately. In FIG. 2, the algae-eating shellfish 2 most preferably feeds on the algae cells 1b in the S phase, and therefore the algae cells 1b in the S phase can be selected as the feed to be given to the algae-eating shellfish.

[0030] (Example 2) Fig. 3 is a schematic diagram showing another example of the feed determination method according to the first embodiment. In Fig. 3, algae-eating shellfish 2 are cultured in culture water 4 contained in a culture vessel 3. In this example, the above-mentioned eight types of samples (samples A1 to A8) were administered to the algae-eating shellfish 2, but Fig. 3 representatively shows a case in which samples A1 to A3 (i.e., algal cell 1a in the G1 phase, algal cell 1b in the S phase, and algal cell 1c in the G2 phase) were administered.

[0031] In Figure 3, the left column shows a test in which algal cells 1a in the G1 phase were administered as a sample, the center column shows a test in which algal cells 1b in the S phase were administered as a sample, and the right column shows a test in which algal cells 1c in the G2 phase were administered as a sample. In Figure 3, the upper figures in each column show the state after artificial feed 5 was administered to the algae-eating shellfish 2 to make them full prior to administering the sample to the algae-eating shellfish 2, the middle figures in each column show the state immediately after the sample was administered to the algae-eating shellfish 2, and the lower figures in each column show the state a predetermined time after the sample was administered to the algae-eating shellfish 2.

[0032] In this example, for example, five algae-eating shellfish 2 are administered the artificial feed 5 to reach a state of satiation, and then the sample is administered once, and the number of algal cells ingested by the algae-eating shellfish 2 is measured three hours after the administration of the sample. The state of satiation can be achieved by providing the artificial feed 5 in an amount such that the artificial feed 5 remains in the breeding water for a certain period of time after feeding. Note that, instead of the artificial feed 5, a mixture of algae cells at various stages of growth or division may be administered to achieve a state of satiation. The sample is administered in an amount of, for example, 1 x 10 cells per mL of the shellfish breeding water. 4 ~1×10 6 In Fig. 3, since the algal cells 1b in the S phase are most preferred by the algal-eating shellfish 2, the algal cells 1b in the S phase can be selected as the food to be given to the algal-eating shellfish.

[0033] 1-2. Second embodiment The "method for determining a feed for herbivorous fish and shellfish" according to the second embodiment of the present invention is as follows: feeding one or more samples each containing algal cells at different stages of growth or division to a herbivorous fish or shellfish; selecting, as food to be given to the algae-eating fish and shellfish, the algae cells which are at the same stage of growth or division as those most preferably eaten by the algae-eating fish and shellfish; Includes.

[0034] The method of the second embodiment will be described in detail below. In the following explanation, the content that overlaps with the method of the first embodiment will be omitted, and only the content that differs from the method of the first embodiment will be explained.

[0035] (Sample preparation process) In the method according to the first embodiment, "multiple samples with different growth or division stages of algal cells" are prepared as samples to be administered to the grazing fish and shellfish, whereas in the method according to the second embodiment, "one or more samples each containing algal cells with different growth or division stages" are prepared as samples to be administered to the grazing fish and shellfish. That is, in the method according to the first embodiment, the algal cells contained in one sample are at a specific growth or division stage, whereas in the method according to the second embodiment, a combination of algal cells with different growth or division stages is contained in one sample. In the method according to the second embodiment, samples may be prepared so that algal cells with different growth or division stages are contained in the same number of cells in one sample, or so that algal cells with different growth or division stages are contained in different numbers of cells in one sample. In either case, it is possible to investigate which stage of algal cells with different growth or division stages is most preferred by the grazing fish and shellfish.

[0036] Preferably, in the method according to the second embodiment, "multiple samples each containing algal cells at different stages of growth or division" are prepared as samples to be administered to the algae-eating fish and shellfish. The multiple samples are identical except that the algal cells are at different stages of growth or division. That is, the multiple samples contain algal cells of the same strain, and only the growth or division stages of the algal cells are different. Here, the expression "different" means that the growth or division stages are at least partially different. The multiple samples refer to two or more types of samples, and there is no particular upper limit. The multiple samples can be, for example, 2 to 8 types of samples.

[0037] As an example of "multiple samples each containing algal cells at different stages of growth or division," a sample that combines algal cells at two of the eight cell cycle stages can be used. In this case, the sample is specifically as follows: Sample B1: A mixture of G1 and S phase algal cells Sample B2: A mixture of G1 and G2 algal cells Sample B3: A mixture of G1-phase algal cells and early M-phase algal cells Sample B4: A mixture of algal cells in the G1 phase and mid-M phase Sample B5: A mixture of algal cells in the G1 phase and late M phase. Sample B6: A mixture of algal cells in the G1 phase and late M phase. Sample B7: A mixture of algal cells in the G1 and G0 phases Sample B8: A mixture of S-phase and G2-phase algal cells Sample B9: A mixture of S-phase algal cells and early M-phase algal cells Sample B10: A mixture of algal cells in the S phase and mid-M phase Sample B11: A mixture of algal cells in the S phase and late M phase Sample B12: A mixture of algal cells in the S phase and algal cells in the late M phase Sample B13: A mixture of S-phase and G0-phase algal cells Sample B14: A mixture of G2 and early M phase algal cells Sample B15: A mixture of algal cells in the G2 phase and mid-M phase Sample B16: A mixture of algal cells in the G2 phase and late M phase Sample B17: A mixture of algal cells in the G2 phase and late M phase Sample B18: A mixture of algal cells in the G2 and G0 phases Sample B19: A mixture of early M-phase and mid-M-phase algal cells Sample B20: A mixture of early M-phase algal cells and late M-phase algal cells Sample B21: A mixture of early M-phase algal cells and late M-phase algal cells Sample B22: A mixture of early M-phase algal cells and G0-phase algal cells Sample B23: A mixture of mid-M phase algal cells and late-M phase algal cells Sample B24: A mixture of mid-M phase and late-M phase algal cells Sample B25: A mixture of mid-M and G0 algal cells Sample B26: A mixture of late M-phase and late M-phase algal cells Sample B27: A mixture of late M-phase algal cells and G0-phase algal cells Sample B28: A mixture of algal cells in the late M phase and algal cells in the G0 phase

[0038] As the "multiple samples each containing algal cells at different stages of growth or division", all of the samples B1 to B28 may be used, or some of the samples B1 to B28 may be used. For example, seven types of samples B1 to B7 may be used as the "multiple samples each containing algal cells at different stages of growth or division".

[0039] Alternatively, each of "multiple samples each containing algal cells at different stages of growth or division" A sample combining algal cells from three of the eight cell cycle stages may be used; A sample combining algal cells from four of the eight cell cycle stages may be used; A sample combining algal cells from five of the eight cell cycle stages may be used; A sample combining algal cells from six of the eight cell cycle stages may be used; A sample combining algal cells from seven of the eight cell cycle stages may be used.

[0040] (Sample administration step) The sample can be administered to the algae-eating fish and shellfish in the same manner as in the method according to the first embodiment.

[0041] In the method according to the second embodiment, in order to compare which stage of algal cells at different stages of growth or division is most preferred by the algal-eating fish and shellfish, it is desirable to use the same test conditions, such as administration conditions, for all samples. For example, it is desirable to fast the algal-eating fish and shellfish before feeding them with the samples for all samples. Alternatively, it is desirable to keep the algal-eating fish and shellfish in a full stomach before feeding them with the samples for all samples.

[0042] (Feed selection process) As described above, in the second embodiment, a single sample contains a combination of algal cells at different stages of growth or division. Therefore, the selection of the feed can be performed by, for each of the algal-eating fish and shellfish administered the sample, removing the algal cells that the algal-eating fish and shellfish have fed on from the algal-eating fish and shellfish, identifying the stage of growth or division of the algal cells, measuring the number of algal cells that the algal-eating fish and shellfish have fed on for each stage of growth or division of the algal cells, and determining, based on the measurement results, which stage of growth or division of the algal cells is most preferred to be fed by the algal-eating fish and shellfish. The stage of growth or division of the algal cells can be identified by observation under a microscope.

[0043] (Example 3) Fig. 4 shows a schematic diagram of an example of a feed determination method according to the second embodiment. In Fig. 4, algae-eating shellfish 2 are cultured in culture water 4 contained in a culture vessel 3. In this example, the above-mentioned 28 types of samples (samples B1 to B28) were administered to the algae-eating shellfish 2, and Fig. 4 shows representative cases in which samples B1 to B3 (i.e., a mixture of G1-phase algal cells 1a and S-phase algal cells 1b, a mixture of G1-phase algal cells 1a and G2-phase algal cells 1c, and a mixture of G1-phase algal cells 1a and early M-phase algal cells 1d) were administered.

[0044] In Figure 4, the left column shows a test in which a mixture of G1-phase algal cells 1a and S-phase algal cells 1b was administered as a sample, the center column shows a test in which a mixture of G1-phase algal cells 1a and G2-phase algal cells 1c was administered as a sample, and the right column shows a test in which a mixture of G1-phase algal cells 1a and early M-phase algal cells 1d was administered as a sample. In Figure 4, the upper figures in each column show the state immediately after the sample was administered to the algae-eating shellfish 2, and the lower figures in each column show the state a predetermined time after the sample was administered to the algae-eating shellfish 2.

[0045] In this example, for example, five algae-eating shellfish 2 are fasted for three days after the feeding has been stopped, and then the sample is administered every 12 hours for a total of 28 times. Three hours after each administration of the sample, the stage of the cell cycle of the algae cells ingested by the algae-eating shellfish 2 is identified, and the number of algae cells ingested by the algae-eating fish and shellfish is measured for each stage of algae cell growth or division. Here, each administration of the sample is performed at a dose of, for example, 1×10 per mL of the shellfish breeding water. 4 ~1×10 6 In Fig. 4, since the algal cells 1b in the S phase are most preferred by the algal-eating shellfish 2, the algal cells 1b in the S phase can be selected as the food to be given to the algal-eating shellfish.

[0046] 1-3.Effects By determining which stage of growth or division of algal cells is preferred for feeding by algal-eating fish and shellfish according to the above-mentioned "method for determining a feed for algal-eating fish and shellfish", the feeding efficiency and nutrient intake efficiency of the algal-eating fish and shellfish can be increased by selectively feeding the determined algal cells to the algal-eating fish and shellfish, thereby promoting the growth of the algal-eating fish and shellfish and, as a result, improving the productivity of the algal-eating fish and shellfish.

[0047] By administering a combination of algal cells at different stages of growth or division according to the method of the second embodiment, it is possible to identify the algal cells that are specifically ingested from a mixture of algal cells at different stages of growth or division, making it possible to more accurately determine which stage of algal cells the algae-eating fish and shellfish prefer to feed on.

[0048] Conventionally, in the breeding and cultivation of algae-eating fish and shellfish, algae are fed without distinguishing between the growth or division stages of the algae cells, and the fed algae are a mixture of algae cells at various stages of growth or division. When the present inventors administered a combination of algae cells at different growth or division stages, only a portion of the algae fed was preferred by the algae-eating fish and shellfish. Therefore, in conventional breeding and cultivation, only a portion of the fed algae functions as food, and it is considered that the feeding efficiency and nutrient intake efficiency of the algae-eating fish and shellfish are low.

[0049] 2. Feeding methods for herbivorous fish and shellfish A "method of feeding algae-eating fish and shellfish" according to one embodiment of the present invention comprises feeding the algae-eating fish and shellfish with the feed determined by the above-mentioned "method of determining a feed for algae-eating fish and shellfish".

[0050] The "method of feeding algae-eating fish and shellfish" according to a preferred embodiment comprises: Feeding the herbivorous fish and shellfish with the feed determined by the above-mentioned "method for determining a feed for herbivorous fish and shellfish"; Cultivating the algal cells; obtaining, from the cultured algal cells, those at the same growth or division stage as those most preferred to be eaten by the algae-eating fish and shellfish as the feed; may include.

[0051] The "method of feeding algae-eating fish and shellfish" can also be expressed as a "method of raising algae-eating fish and shellfish" or a "method of producing algae-eating fish and shellfish".

[0052] (Feed administration process) The food should be, for example, 1 × 10 4 ~1×10 6 The algae-eating fish and shellfish can be fed such that individual algal cells are administered. The feed can be administered at intervals of, for example, 2 to 12 hours.

[0053] (Algae cell culture process) The algal cells can be cultured by suspension culture in a liquid medium containing sufficient concentrations of nutrients necessary for the algal cells to photosynthesize, grow, divide, etc. The algal cells can be cultured, for example, in an open culture tank called an open pond, or in a closed system called a closed photobioreactor.

[0054] (Food acquisition process) From the cultured algal cells, those at the same growth or division stage as that most preferred by the algae-eating fish and shellfish are obtained as feed and given to the algae-eating fish and shellfish.

[0055] The feed can be obtained according to the procedure described in the section "Sample preparation step" of the method according to the first embodiment described above. That is, the feed can be obtained by culturing algal cells in a uniform cell cycle during culture. For example, the cell cycle of the algal cells can be uniformed by culturing the algal cells in a culture environment that is alternately switched between a light environment and a dark environment. The algal cells have the property that they perform photosynthesis in a light environment, and when switched from a light environment to a dark environment, their photosynthetic activity decreases and they transition from the G1 phase to the S phase to advance the cell cycle, so that the cell cycle can be uniformed. Alternatively, the algal cells can be cultured in a culture solution containing a cell division inhibitor or a cell proliferation inhibitor to stop the cell cycle at a specific stage, and then cultured in the absence of the inhibitor, so that the cell cycle can be uniformed. As such inhibitors, DNA replication inhibitors, microtubule formation inhibitors, and the like can be used.

[0056] For example, "algal cells in the S phase of the cell cycle" can be obtained by culturing a mixture of algal cells in various stages of growth or division (hereinafter also referred to as raw cells) in a culture environment that is alternately switched between light and dark, and then recovering the cells after switching the culture environment from light to dark. Alternatively, "algal cells in the S phase of the cell cycle" can be obtained by culturing the raw cells in a culture medium containing a DNA replication inhibitor, and then culturing in the absence of the DNA replication inhibitor and recovering the cells.

[0057] (effect) In this method, the feed determined by the above-mentioned "method for determining a feed for algae-eating fish and shellfish" is selectively given to the algae-eating fish and shellfish, so that the feeding efficiency and nutrient intake efficiency of the algae-eating fish and shellfish can be improved, thereby promoting the growth of the algae-eating fish and shellfish, and as a result, improving the productivity of the algae-eating fish and shellfish.

[0058] 3. Feed manufacturing method The "method for producing a feed" according to one embodiment of the present invention is a method for producing a feed determined by the above-mentioned "method for determining a feed for herbivorous fish and shellfish", and this method comprises the steps of: Cultivating the algal cells; obtaining, from the cultured algal cells, those at the same growth or division stage as those most preferred to be eaten by the algae-eating fish and shellfish as the feed; Includes.

[0059] This method can be carried out according to the same procedure as described in "2. Feeding method for algae-eating fish and shellfish." This method makes it possible to produce a feed for algae-eating fish and shellfish that has excellent feeding efficiency and nutrient intake efficiency. [Explanation of symbols]

[0060] 1...Algae cells 1a…Algal cells in the G1 phase 1b…Algal cell in S phase 1c…Algal cells in the G2 phase 1d…Algal cell in early M phase 2…Algae-eating shellfish 3…Culture container 4. Water 5…Artificial feed 10...Cell wall 11…Nuclear 12...Chloroplast

Claims

1. Feeding each of a plurality of samples of algal cells at different stages of growth or division to an algae-eating fish or shellfish; selecting, as food to be given to the algae-eating fish and shellfish, the algae cells which are at the same stage of growth or division as those most preferably eaten by the algae-eating fish and shellfish; A method for determining a feed for herbivorous fish and shellfish, comprising:

2. 2. The method of claim 1, further comprising fasting the algae-eating seafood prior to feeding each of the plurality of samples to the algae-eating seafood.

3. 2. The method of claim 1, further comprising satiating the algae-eating fish prior to feeding each of the plurality of samples to the algae-eating fish.

4. providing a sample containing algal cells at different stages of growth or division to the phytophagous fish or shellfish, or providing each of two or more samples containing algal cells at different stages of growth or division to the phytophagous fish or shellfish; selecting, as food to be given to the algae-eating fish and shellfish, the algae cells which are at the same stage of growth or division as those most preferably eaten by the algae-eating fish and shellfish; A method for determining a feed for herbivorous fish and shellfish, comprising:

5. 5. The method of claim 4, further comprising fasting the algae-eating fish prior to feeding the sample to the algae-eating fish.

6. A method for feeding algae-eating fish and shellfish, comprising feeding the algae-eating fish and shellfish with the feed determined by the method according to any one of claims 1 to 5.

7. Cultivating the algal cells; obtaining, from the cultured algal cells, cells at the same growth or division stage as those most preferred by the algae-eating fish and shellfish as the feed; The method of claim 6 further comprising:

8. A method for producing the feed determined by the method according to any one of claims 1 to 5, Cultivating the algal cells; obtaining, from the cultured algal cells, cells at the same growth or division stage as those most preferred by the algae-eating fish and shellfish as the feed; A method including:

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