JP4530248B2 - Eel larvae feed - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a eel larvae feed that is indispensable for the production of eel seedlings containing soybean peptides treated with krill and / or phytic acid reduction. More specifically, the present invention relates to a eel larvae feed that contains soybean peptides treated with krill and / or phytic acid reduction and can grow eel larvae to glass eels. The present invention also relates to an eel seedling grown using these eel larvae feeds.
[0002]
[Prior art]
Eels are important aquaculture species with high production, but all seedlings depend on natural white eels. Therefore, the trading price of glass eels fluctuates greatly depending on the amount of catch, contributing to the destabilization of sericulture management. Eel seedling production, that is, if glass eels can be stably mass-produced in captivity, will contribute not only to stabilization of sericulture management but also to the protection of eel resources that have been rapidly decreasing in recent years. Now that eels can be artificially hatched, it is necessary to develop feed that grows and transforms larvae into glass eels.
[0003]
Natural eels are often enveloped in mysteries such as maturation, spawning grounds, hatching and larval growth. After hatching, eels grow from preleptocephalus to leptocephalus and then dramatically transform into glass eels. A large number of natural leptocephalus has been collected so far, and studies on gastrointestinal retention have been carried out, but the diet of leptocephalus is still unclear.
[0004]
More than 20 years have passed since eels became artificially hatched, and so far as eel larvae, such as biological feeds such as rotifers, commercially available initial feeds, commercially available fortified feeds, gonads and chicken eggs for seafood The substance has been tried. However, for the initial feed of eel larvae, other than the knowledge that the shark egg powder found by the research group of the National Fisheries Research Center (National Fisheries Research Institute) was effective (Patent Document 1) In spite of many attempts so far, no feed has been found that has feeding incentive and growth potential for eel larvae. Moreover, even with the shark eggs described above, it has been impossible to grow and transform Leptocephalus to shirasu.
[0005]
Subsequently, eel larvae were successfully grown to leptocephalus with a sedimentary feed containing soy peptide, vitamin mix, mineral mix, and krill water extract in shark egg powder (Non-patent Document 1). Even the glass eel did not grow or metamorphose.
[0006]
By the way, it is known that Antarctic krill ( Euphausia superba ) is excellent in growth and feeding as fish food. Antarctic krill as a raw material for fish feed is used as feed for breeding, and its utilization is raw or meal. As described above, the effectiveness of the krill water extract as a feed raw material for eel larvae has been shown, but it cannot be said that the functionality of krill has been fully utilized. However, in the form of use such as raw or meal, the functionality of krill could not be utilized to the maximum for eel larvae with weak digestive absorption ability.
[0007]
Moreover, although the effectiveness to the feed raw material of a soybean peptide has already been confirmed (nonpatent literature 1), it has not reached the feed which can grow an eel larva to a glass eel.
In addition, as a method for removing phytic acid from soybean, a method for removing phytic acid in a water extraction process of soybean protein using a salt (Patent Document 2, Patent Document 3), a method of decomposing phytic acid with phytase or the like And a method of removing it by adsorbing it to a resin or the like (Patent Document 4).
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-253111 [Patent Document 2]
Japanese Patent Laid-Open No. 8-173052 [Patent Document 3]
JP-A-9-121780 [Patent Document 4]
JP 2001-163800 A [Non-Patent Document 1]
Tanaka et al., Production of leptocephali of Japanese eel (Anguilla japonica) in captivity, Aquaculture, (Netherlands), Production of Leptocefari of Japanese eel (Anguilla japonica) in captivity , ELSEVIER SCIENCE BV, September 14, 2001, 201, 1-2, p.51-60
[0009]
[Problems to be solved by the invention]
An object of the present invention is to provide a feed for eel larvae that can grow and transform eel larvae to white eels.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have conducted intensive research, and as a result, a feed containing a krill degradation product and / or a soy peptide reduced in phytic acid has a feeding incentive and growth potential for eel larvae. I found out that I had this and completed this research.
[0011]
The present invention relates to a krill decomposition product, preferably a krill decomposition product using a krill endogenous enzyme in the decomposition treatment, a krill decomposition product that is denatured by an endogenous enzyme and then heat-denatured, and / or soybeans reduced in phytic acid. Eels containing peptides, preferably those obtained by allowing protease and phytase to act on soy protein, more specifically, phytic acid-reduced soy peptide having a phytic acid content of 1% or less of the soy peptide larvae and shall be the subject matter of eel larvae feed for growing up glass eel.
[0012]
In addition, the present invention contains a biological egg component, preferably an egg component derived from a fish egg or a chicken egg, and, if necessary, a highly unsaturated fatty acid-containing fat in addition to a krill degradation product and / or a phytic acid-reduced soybean peptide. The essence is a feed for eel larvae for growing eel larvae to glass eels.
In addition, the present invention provides a krill decomposition product, preferably a krill decomposition product using a krill endogenous enzyme for the decomposition treatment, a krill decomposition product that is heat-denatured after being decomposed by the endogenous enzyme, and / or a phytic acid reduction treatment. Soy peptide, preferably obtained by allowing protease and phytase to act on soy protein, more specifically, soy peptide reduced in phytic acid content is 1% or less of the soy peptide as phytic acid content An eel seedling that is a white eel grown using a feed for eel larvae for growing the eel larvae to the white eel .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the eel larvae to be targeted by the present invention include eel larvae to be cultured such as Japanese eel ( Anguilla japonica ) and European eel ( Anguilla anguilla ). The eel larvae referred to in the present invention refers to eel larvae at a stage prior to transformation into a glass eel such as pre-leptokephales and leptokephales.
Examples of krill used in the present invention include industrially useful krill ( Euphausiacea ), but it is preferable to use Antarctic krill ( Euphausia superba ). As for this krill, a degradation product obtained by endogenous enzymes (autolyzed product) or a degradation product obtained by externally adding a commercially available enzyme and enhancing degradation by endogenous enzymes may be used. The krill decomposition product can be obtained, for example, by making the krill mince and maintaining heating at 50 ° C. for 1 hour with stirring. Further, a krill decomposition product heat-denatured by a conventional method may be used.
[0014]
The phytic acid-reduced soybean peptide (hereinafter referred to as “low phytic soybean peptide”) used in the present invention is described below.
First, phytic acid is removed from soybean by (1) removing phytic acid in the water extraction process of soybean protein using salt (Patent Documents 2 and 3 above), (2) phytate using phytase, etc. There are a method of decomposing, a method of removing by adsorbing to a resin, etc. (the above-mentioned patent document 4), and the method of (2) is less complicated than the methods of (1) and (3). Is advantageous. A low phytin soy peptide can be produced by proteolysis by causing a protease to act on a raw material reduced in phytin by such a method. It should be noted that hypophytization and protease degradation can be performed first or simultaneously. Although it is desirable to completely remove the remaining phytic acid, the amount of residual phytic acid is usually 1.0% or less as determined by vanadomolybutenoic acid spectrophotometry (detection limit 5 mg / 100 g), preferably 0.5% or less. is there.
[0015]
The proteolytic enzyme (protease) used in the present invention may be exoprotease or endoprotease alone or in combination, and may be of animal origin, plant origin or microbial origin. Specifically, serine proteases (such as trypsin derived from animals, chymotrypsin, subtilisin derived from microorganisms, carboxypeptidase, etc.), Protin FN derived from Aspergillus oryzae (manufactured by Daiwa Kasei Co., Ltd.), Protease S (Amano Pharmaceutical) And Protin AC-10 (manufactured by Daiwa Kasei Co., Ltd.).
[0016]
The hydrolysis conditions of the present invention vary somewhat depending on the type of proteolytic enzyme to be used, but in general, an amount sufficient to hydrolyze low-phytized soybean protein in the pH range and temperature range of the protease. It is good to use. The degree of hydrolysis is about 5 to 98%, more usually about 50 to 90% of soybean protein degradation rate, which is 15% trichloroacetic acid solubility of protein components. The time for which the proteolytic enzyme is allowed to act is usually about 5 minutes to 12 hours, preferably about 30 minutes to 5 hours, although it depends on the activity and amount of the protease used. If the enzymatic degradation time is too long, it tends to cause spoilage.
[0017]
Examples of egg components used in the present invention include those derived from fish eggs or chicken eggs. Examples of fish eggs include shark eggs, sukeko, madarako, red sea bream eggs, and shark eggs are particularly preferred. These may be either liquid eggs or powders, but it is particularly preferable to use liquid eggs.
The highly unsaturated fatty acid-containing fat used in the present invention may be of animal origin, plant origin or microbial origin. Specific examples include sardine feed oil, cod liver oil, and refined fish oil containing ω-3 and ω-6 highly unsaturated fatty acids at high concentrations.
[0018]
The feed for eel larvae of this invention is manufactured by mixing the above-mentioned component suitably. At this time, the krill degradation product and the low phytic soybean peptide may be used alone or in combination. In any case, the blending amount is not limited, but the krill degradation product is 3 to 50% and the low phytin soy peptide is 3 to 50% with respect to the whole feed. For example, a combination of 20% egg components, 3% krill degradation product, 3% low phytic acid soybean peptide, 4% DHA-rich oil, and 70% distilled water can be used.
[0019]
[Action]
The present invention is a feed for eel larvae characterized by comprising a krill degradation product, preferably a krill degradation product using a krill endogenous enzyme for degradation treatment and / or a low phytic soybean peptide. By using Antarctic krill and / or low phytin soy peptide as feed or feed material, it is possible to grow and transform eel artificially hatched larvae to white eel.
[0020]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited by these examples.
[0021]
Example 1
Tests to confirm the growth of eel larvae with various ingredients <br/> Eating eel larvae 8 days after hatching, which hatched from fertilized eggs obtained by artificial ripening and formed eyes and mouth organs It was fish. Twelve 5L acrylic bowl-shaped tanks were used, each containing approximately 200 eel larvae. The breeding water temperature was 21.5 ° C. Since the number of days without survival was around 15 days after hatching, the feeding period was set to 10 days.
The test plots were shark egg feeding zone (feed 1), shark egg + low phytin soy peptide group (feed 2), shark egg + krill degradation product group (feed 3), and shark egg + low phytin soybean peptide + krill degradation product group. (Feed 4). Table 1 shows the feed composition. The shark egg liquid egg has a water content of 50%.
[0022]
[Table 1]
[0023]
The feed feeding method is disclosed in JP-A-11-253111 (Patent Document 1) and Tanaka et al. (Non-Patent Document 1 (H. Tanaka, H. Kagawa, H. Ohta, Aquqculture 201 (2001) 51-60). ]. That is, about 5 ml was injected with a Komagome pipette to the bottom of the water tank which was prepared on the day before or on the day of feeding and stored at 0 to 1 ° C., and water injection was stopped immediately before feeding. 30 minutes after feeding, temperature-controlled filtered seawater was injected at 0.4 L / min, and the aquarium was kept clean by pouring the breeding seawater. Feeding was performed 5 times a day, every 2 hours, and the larvae were moved to a clean aquarium using a siphon at night every day. For statistical processing of breeding results, Tukey multiple comparison was performed for items that were significant by analysis of variance. The results are shown in FIG. 1 (survival rate of eel larvae in each test group), FIG. 2 (effect of krill degradation product and low phytic acid soybean peptide on the total length of eel larvae), and FIG. 3 (krill degradation product and low phytic acid soybean peptide). (Effects of eel larvae on body height), FIG. 4 (effects of krill degradation product and low phytic acid soybean peptide on body height / full length of eel larvae), and Table 2 (feeding results on growth).
[0024]
As a result, the larvae showed good food intake and grew well with any feed. The average survival rate after 10 days of feeding was 33.1% for feed 1, 38.2% for feed 2, 37.7% for feed 3, and 54.7% for feed 4. Survival rates were higher when shark eggs and krill degradation products or diets containing shark eggs and low phytin soy peptide were fed than shark eggs alone. Furthermore, the highest survival rate was obtained when shark eggs, krill degradation products and low phytin soy peptide were added.
[0025]
The average total length of the larvae at the start of feeding was 6.65 ± 0.26 mm. The average total length of each test group 10 days after feeding was 8.25 ± 0.56 mm for feed 1, 8.53 ± 0.66 mm for feed 2, 8.88 ± 0.64 mm for feed 3, and 8.97 ± 0.55 mm for feed 4. The feeding effect was recognized for all the feeds, and the overall length was significantly increased (p <0.01) as compared to the time of the start of feeding. The feed containing shark eggs and krill degradation product and the feed containing shark eggs and low phytin soy peptide significantly increased the total length compared to shark eggs alone (p <0.01). Furthermore, when the shark egg, krill decomposition product and low phytin soy peptide were blended, the full-length elongation was shown.
[0026]
Body height was measured to evaluate the body shape of eel larvae. Typical leptocephalus has a high body height and a large body height / body length ratio. The average height of the larvae at the start of feeding was 0.65 ± 0.05 mm. The average height of each test group 10 days after feeding was 0.82 ± 0.08 mm for feed 1, 0.85 ± 0.10 mm for feed 2, 0.95 ± 0.11 mm for feed 3, and 0.97 ± 0.11 mm for feed 4. Feeding effects were observed for all feeds, and the body height was significantly higher (p <0.01) than at the start of feeding. When the feed containing shark eggs and krill degradation product was fed, the body height was significantly higher than when shark eggs alone or shark eggs and soybean peptides were added (p <0.01). Furthermore, when the shark egg, soybean peptide, and krill degradation product were blended, the body height was the highest.
[0027]
The body height / length (%) of each test plot was 9.79 ± 0.48% at the start of the test, 9.91 ± 0.68% for feed 1, 9.91 ± 0.67% for feed 2, 10.75 ± 0.83% for feed 3, and 10.78 ± for feed 4. It was 0.92%. It was shown that the feeding of the feed containing the krill degradation product was significantly increased in terms of the height / length ratio (p <0.01).
From the above results, it was confirmed that the eel larvae were significantly grown by the combination of the fish egg component and the krill degradation product, the low phytin soy peptide or a combination thereof.
[0028]
[Table 2]
[0029]
Example 2
Test for confirming growth by the difference in egg components Larvae hatched from fertilized eggs obtained by artificial ripening and formed eyes and mouth organs and became feedable were used 8 days after hatching. Eel larvae were housed in 20 L acrylic tanks. The breeding water temperature was 21.5 ° C.
The test plot was divided into 5 feeds that were fed shark egg powder, low phytic soy peptide, and krill degradation product, and chicken egg powder, low phytic soy peptide, krill degradation product, and ω-3 high-purified fish oil (DHA content) 46%) was fed. Table 3 shows the feed composition. The feed feeding method was the same as in Example 1.
[0030]
[Table 3]
[0031]
So far, eel larvae have not been observed to grow except for feed containing shark eggs. However, the larvae showed good food intake and grew well even with feed 6 containing no shark egg powder. Comparison of the average total length on day 28 after hatching revealed that feed 5 was 9.85 ± 0.70 mm and feed 6 was 9.43 ± 0.89 mm (FIG. 5). The total length of the longest individual 28 days after hatching was 10.9 mm for feed 5 and 11.0 mm for feed 6.
[0032]
According to Tanaka et al. Using shark egg powder-based feed [Non-Patent Document 1 (H. Tanaka, H. Kagawa, H. Ohta, Aquqculture 201 (2001) 51-60)], larvae obtained by artificial insemination are It has grown to 10.6mm 25 days after hatching. From the results of this test, the feed 6 containing chicken egg powder, krill degradation product, low phytin soy peptide and fish oil also showed growth comparable to the growth of feed 5 which is a feed containing shark eggs.
[0033]
In the feed of the present invention, many individuals exceeding 10 mm were observed 28 days after hatching, and the feed containing chicken egg powder, krill degradation product, low phytic soy peptide and fish oil can be sufficiently comparable to shark egg powder-based feed Was confirmed.
[0034]
Example 3
Test for confirmation of metamorphosis to glass eel We used larvae 8 days after hatching, which hatched from fertilized eggs obtained by artificial ripening and formed eyes and mouth organs and became feedable. Eel larvae were housed in 20 L acrylic tanks. The breeding water temperature was 21.5 ° C. Table 4 shows the feed composition. The shark egg liquid egg has a water content of 50%. Feed 7 was fed until 18 days after hatching, and feed 8 was fed from 19 days after hatching.
[0035]
[Table 4]
[0036]
As a result, the larvae grow smoothly, reach a total length of 50-60 mm about 7-9 months after hatching, start transformation from Leptocephalus to white eel, and about 2 to 2 except for individuals whose bodies are curved during transformation It was confirmed that the whole length was shortened by 2 to 8% in 3 weeks and transformed into glass eel (FIGS. 6 and 7).
[0037]
【The invention's effect】
According to the present invention, it has become possible to provide an excellent eel larvae feed that can grow eel larvae to glass eels.
[Brief description of the drawings]
FIG. 1 shows a shark egg feeding group (feed 1), a shark egg + low phytin soybean peptide group (feed 2), a shark egg + krill degradation product group (feed 3), and a shark egg + low phytin soybean peptide in Example 1. + Survival rate comparison of krill degradation product section (feed 4).
FIG. 2 shows a shark egg feeding group (feed 1), a shark egg + low phytin soybean peptide group (feed 2), a shark egg + krill degradation product group (feed 3), and a shark egg + low phytin soybean peptide in Example 1. + Comparison of the total length (mm) of the krill decomposition product group (feed 4).
FIG. 3 shows a shark egg feeding group (feed 1), a shark egg + low phytin soybean peptide group (feed 2), a shark egg + krill degradation product group (feed 3), and a shark egg + low phytin soybean peptide in Example 1. + Comparison of body height (mm) of the krill decomposition product group (feed 4).
4 shows a shark egg feeding group (feed 1), a shark egg + low phytin soybean peptide group (feed 2), a shark egg + krill degradation product group (feed 3), and a shark egg + low phytin soybean peptide in Example 1. FIG. + Comparison of body height / full length (%) of the krill decomposition product group (feed 4).
5 shows the total length (mm) of shark egg powder + low phytic soy peptide + krill degradation product (feed 5) and chicken egg powder + low phytic soy peptide + krill degradation product + fish oil division (feed 6) in Example 2. FIG. ) Transition comparison.
FIG. 6 shows growth and transformation of larvae in Example 3.
7 shows an example of metamorphosis of larvae in Example 3. FIG. Same individuals from 248,254,262 days after hatching from above.

Claims (9)

An eel larvae feed for growing eel larvae containing a krill degradation product and / or a phytic acid-reduced soybean peptide to a glass eel . The feed for eel larvae for growing the eel larvae of Claim 1 to a glass eel , wherein the krill degradation product is a krill degradation product using a krill endogenous enzyme for degradation treatment. The feed for eel larvae for growing the eel larvae of Claim 1 or 2 to a glass eel , wherein the krill decomposition product is further heat-denatured. The feed for eel larvae for growing the eel larvae of Claim 1, 2 or 3 to a glass eel , wherein the soybean peptide subjected to phytic acid reduction treatment is obtained by allowing protease and phytase to act on soybean protein. The feed for eel larvae for growing the eel larvae of any one of claims 1 to 4 to glass eels, wherein the phytic acid-reduced soybean peptide has a phytic acid content of 1% or less of the soybean peptide. Furthermore, the feed for eel larvae for growing the eel larva of any one of Claim 1 thru | or 5 to a glass eel which mix | blended the egg component of a living body . The feed for eel larvae for growing the eel larvae of Claim 6 to a glass eel, wherein the egg component is derived from fish eggs or chicken eggs. Furthermore, the feed for eel larvae for growing the eel larvae in any one of Claim 1 thru | or 7 containing a highly unsaturated fatty acid containing fat into a glass eel . Claims 1 to 8 eels seedlings a glass eel Grown with eel larvae feed for growing up glass eel one of eel larvae.