U.S. patent application number 15/545326 was filed with the patent office on 2018-01-04 for micro-encapsulated aquaculture feed.
The applicant listed for this patent is SHIN NIPPON BIOMEDICAL LABORATORIES, LTD.. Invention is credited to Yutaka KAWAKAMI, Ryoichi NAGATA.
Application Number | 20180000122 15/545326 |
Document ID | / |
Family ID | 56417220 |
Filed Date | 2018-01-04 |
United States Patent
Application |
20180000122 |
Kind Code |
A1 |
NAGATA; Ryoichi ; et
al. |
January 4, 2018 |
MICRO-ENCAPSULATED AQUACULTURE FEED
Abstract
To provide a feed that does not pollute rearing water, improves
the immunity activity of leptocephalus larvae, is capable of
directly feeding eel leptocephalus, and is capable of effectively
inducing the growth of said larvae into glass eels. This
micro-encapsulated aquaculture feed includes: an oil phase 11
having an oil-soluble nutrient component; a water phase 13 which is
present inside the oil phase 11, and which includes a water-soluble
nutrient component; and a film 15 which includes the oil phase 11
and the water phase 13. The water-soluble nutrient component
includes at least one hydrolysate from among hydrolysates of amino
acids, oligopeptides, and proteins.
Inventors: |
NAGATA; Ryoichi;
(Kagoshima-shi, Kagoshima, JP) ; KAWAKAMI; Yutaka;
(Kagoshima-shi, Kagoshima, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHIN NIPPON BIOMEDICAL LABORATORIES, LTD. |
Kagoshima-shi, Kagoshima |
|
JP |
|
|
Family ID: |
56417220 |
Appl. No.: |
15/545326 |
Filed: |
January 22, 2016 |
PCT Filed: |
January 22, 2016 |
PCT NO: |
PCT/JP2016/051879 |
371 Date: |
August 23, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A23J 3/346 20130101;
A23K 20/142 20160501; A23J 3/341 20130101; A23K 50/80 20160501;
A23K 20/163 20160501; A23K 40/30 20160501; Y02A 40/818 20180101;
A23K 20/00 20160501; A23K 20/158 20160501; A23K 50/60 20160501;
A23K 20/147 20160501 |
International
Class: |
A23K 20/147 20060101
A23K020/147; A23K 50/80 20060101 A23K050/80; A23K 40/30 20060101
A23K040/30; A23J 3/34 20060101 A23J003/34; A23K 20/163 20060101
A23K020/163 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2015 |
JP |
2015-011860 |
Claims
1. Microencapsulated feed for aquaculture, comprising: an oil phase
(11) having an oil-soluble nutrient component; an aqueous phase
(13) that is present in the oil phase (11) and contains a
water-soluble nutrient component; and a coating (15) containing the
oil phase (11) and the aqueous phase (13), wherein the
water-soluble nutrient component contains any one or more of amino
acids, oligopeptides, and protein hydrolysates.
2. The feed for aquaculture according to claim 1, wherein the
water-soluble nutrient component further comprises saccharides
selected from any one or more of monosaccharides, oligosaccharides,
and polysaccharides.
3. The feed for aquaculture according to claim 1, which is feed for
leptocephalus larvae of eels, that is used for growing
leptocephalus larvae of eels up to glass eels.
4. The feed for aquaculture according to claim 1, wherein the
water-soluble nutrient component comprises a protein hydrolysate,
and the protein hydrolysate is obtained by hydrolyzing a protein
source containing either or both of a vegetable protein and an
animal protein, using a proteolytic enzyme, a hydrochloric acid, or
hot water.
5. The feed for aquaculture according to claim 1, wherein the
water-soluble nutrient component comprises a protein hydrolysate,
and the protein hydrolysate contains any one or more of soybean
enzyme-treated proteins, fish and shellfish autolyzed extracts,
fishmeal enzyme-treated decomposition extracts and fish meat hot
water-treated decomposition extracts.
6. The feed for aquaculture according to claim 1, wherein the
coating (15) is a biodegradable polymer film.
7. The feed for aquaculture according to claim 1, further
comprising an immunostimulator.
8. The feed for aquaculture according to claim 7, wherein the
immunostimulator comprises any one or more of lactic acid bacteria,
yeasts, aspergillus oryzae, hay bacillus, Bacillus subtilis var
natto, intestinal bacteria derived from adult fish intestines of
fish of the order Anguilliformes, intestinal bacteria derived from
glass eel intestines of fish of the order Anguilliformes, and
intestinal bacteria derived from leptocephalus larva intestines of
fish of the order Anguilliformes.
Description
TECHNICAL FIELD
[0001] The present invention relates to feed for aquaculture. More
specifically, the present invention relates to feed for aquaculture
capable of effectively growing leptocephalus larvae of eels up to
glass eels. The present invention relates to biotechnologically and
immunologically improved feed for aquaculture.
BACKGROUND ART
[0002] JP H11-253111 A (the following Patent Literature 1 (JP
2909536 B2)) discloses an eel bait prepared by suspending shark egg
powder in seawater. JP 2005-13116 A (the following Patent
Literature 2 (JP 4530248 B2)) discloses an eel bait containing a
krill decomposition product or a soybean peptide with reduced
phytic acid. The bait disclosed in JP 2005-13116 A (the following
Patent Literature 2) also basically contains shark eggs. JP
2011-239695 A (the following Patent Literature 3) discloses eel
larvae feed containing Lampridae fish egg contents. JP 2011-239696
A (the following Patent Literature 4) discloses eel larvae feed
containing fish egg contents with reduced protease activity.
[0003] JP H11-56257 A (the following Patent Document 5) discloses a
bait for feed organism of eel fry prepared by microencapsulating
nutrients containing .beta.-carotene. JP H11-56257 A (the following
Patent Document 5) produces a microencapsulated bait for feed
organism of eel fry containing .beta.-carotene by stirring and
emulsifying .beta.-carotene, gelatin, gum arabic and fish oil
(paragraphs [0008], [0009] and [0013]).
[0004] JP 2012-505193 A (the following Patent Document 6) discloses
an immunostimulator containing a microencapsulated cytokine. JP
2012-505193 A (the following Patent Document 6) obtains
microcapsules containing yeast expressing cytokines using
malodextrin and a protective polymer (paragraph [0060]).
[0005] JP H10-327770 A (the following Patent Document 7) discloses
microcapsules for feed in which an aqueous phase containing a
water-soluble nutrient component is present in an oil phase
containing an oil-soluble nutrient component, including
microcapsules coated with a biodegradable polymer film. This
microcapsule is a W/O/W type emulsion.
CITATION LIST
Patent Literature
[0006] Patent Literature 1: JP H11-253111 A
[0007] Patent Literature 2: JP 2005-13116 A
[0008] Patent Literature 3: JP 2011-239695 A
[0009] Patent Literature 4: JP 2011-239696 A
[0010] Patent Literature 5: JP H11-56257 A
[0011] Patent Literature 6: JP 2012-505193 A
[0012] Patent Literature 7: JP H10-327770 A
SUMMARY OF INVENTION
Technical Problem
[0013] As described in Patent Literatures 1 to 4, feed based on
shark eggs or Lampridae fish eggs has been used for growing
leptocephalus larvae corresponding to the larval stage of Japanese
eel (Anguilla japonica) on a small scale. However, feed based on
fish eggs is in the form of paste, thus is dispersed in water.
Therefore, when feed based on fish eggs is administered to a
large-scale culturing water tank, there is a problem that not only
bait efficiency is poor but also water in the culture tank is
contaminated. For this reason, a bait that does not deteriorate
water quality even when culturing eels or the like on a large scale
has been desired.
[0014] Therefore, a bait using microcapsules has been developed as
described in Patent Literature 5 above. However, these were not
necessarily able to prevent deterioration of water quality, and in
particular, it was impossible to effectively grow leptocephalus
larvae of eels up to glass eels. In particular, the microcapsule of
Patent Literature 5 is a so-called W/O type, and there is a problem
that only oil-soluble nutrient component can be contained as a
nutrient component. For this reason, the microcapsule feed in
Patent Literature 5 is feed for bait organisms, that is, mainly
intended for use as enrichments for bait organisms commonly used in
seed production of fish culture, like rotifers such as Brachionus
plicatilis, a brine shrimp, etc. Further, Patent Literature 5 uses
a hardly digestible polymeric substance such as gelatin or gum
arabic to obtain microcapsules. Since the microcapsules in Patent
Literature 5 are as small as 1 to 20 .mu.m, there is a possibility
that larval fish prey directly. However, larval fish with weak
digestive function (for example, leptocephalus larvae) cannot
completely digest this bait, thus there is a problem that utility
value as feed for larval fish is very low.
[0015] Patent Literature 6 describes a product obtained by
encapsulating a suspension containing a cytokine-expressing yeast
by a spray drying method. The product of Patent Literature 6 is
primarily intended to certainly orally administer cytokines to fish
culture, so a bait is separately required. That is, the product of
Patent Literature 6 is to be mixed into fish culture feed and
thrown.
[0016] An object of the present invention is to provide feed that
does not contaminate raising water and enhances the immune activity
of leptocephalus larvae, can be directly thrown to eel
leptocephalus, and can effectively grow the eel leptocephalus up to
glass eels.
Solution to Problem
[0017] The present invention is basically based on the finding in
an example that microencapsulated feed for aquaculture in which an
aqueous phase containing a water-soluble nutrient component is
present in an oil phase containing an oil-soluble nutrient
component is feed for aquaculture suitable also for mass culture,
without contaminating water quality.
[0018] In addition, the present invention is based on the finding
that, by containing an immunostimulator for stimulating immune
activity, leptocephalus larvae of eels, which were difficult to
grow up to glass eels, can grow extremely efficiently up to glass
eels.
[0019] That is, a first aspect of the present invention relates to
microencapsulated feed for aquaculture 17. The feed for aquaculture
is microencapsulated feed for aquaculture containing an oil phase
11 having an oil-soluble nutrient component, an aqueous phase 13
that is present in the oil phase 11 and contains a water-soluble
nutrient component, and a coating 15 containing the oil phase 11
and the aqueous phase 13. Moreover, the water-soluble nutrient
component includes any one or more of amino acids, oligopeptides,
and protein hydrolysates. The water-soluble nutrient component may
further contain saccharides selected from any one or more of
monosaccharides, oligosaccharides, and polysaccharides.
[0020] Preferred feed for aquaculture of the present invention is
feed for leptocephalus larvae of eels that is used for growing
leptocephalus larvae of eels up to glass eels.
[0021] Preferred feed for aquaculture of the present invention is
one in which the water-soluble nutrient component contains a
protein hydrolysate, and the protein hydrolysate is obtained by
hydrolyzing a protein source containing either or both of a
vegetable protein and an animal protein, using a proteolytic
enzyme, a hydrochloric acid, or hot water.
[0022] Preferred feed for aquaculture of the present invention is
one in which the water-soluble nutrient component contains a
protein hydrolysate, and the protein hydrolysate contains any one
or more of soybean enzyme-treated proteins, fish and shellfish
autolyzed extracts, fishmeal enzyme-treated decomposition extracts,
and fish meat hot water-treated decomposition extracts.
[0023] Preferred feed for aquaculture of the present invention is
one in which the coating 15 is a biodegradable polymer film.
[0024] Preferred feed for aquaculture of the present invention
further contains an immunostimulator. Examples of the
immunostimulator are any one or more of lactic acid bacteria,
yeasts, aspergillus oryzae, hay bacillus, Bacillus subtilis var
natto, intestinal bacteria derived from adult fish intestines of
fish of the order Anguilliformes, intestinal bacteria derived from
glass eel intestines of fish of the order Anguilliformes, and
intestinal bacteria derived from leptocephalus larva intestines of
fish of the order Anguilliformes. By using feed for aquaculture
containing these immunostimulators, it is possible to effectively
produce leptocephalus larvae of eels, which have been
conventionally thought to be difficult to produce, up to glass
eels.
Advantageous Effects of Invention
[0025] That is, according to the present invention, since nutrients
are microencapsulated, it is possible to provide feed for
aquaculture which does not degrade (deteriorate) water quality even
when culturing fish on a large scale, unlike a pasty fish egg bait.
Further, according to the present invention, it is possible to
provide feed for aquaculture capable of effectively growing larval
fish which is relatively difficult to produce seedlings, such as
being able to enhance the immune activity of leptocephalus larvae
and effectively grow to glass eels.
BRIEF DESCRIPTION OF DRAWINGS
[0026] FIG. 1 is a conceptual diagram of the feed for aquaculture
of the present invention.
[0027] FIG. 2 is a conceptual diagram of a manufacturing process in
Example 1.
[0028] FIG. 3 is a photograph replacing the drawing when the
microcapsules obtained in examples are dispersed in distilled
water.
DESCRIPTION OF EMBODIMENTS
[0029] Hereinafter, modes for carrying out the present invention
will be described using the drawings. The present invention is not
limited to the embodiments and examples described below, but also
includes those appropriately modified within the scope obvious to
those skilled in the art, based on the following embodiments.
[0030] The first aspect of the present invention relates to
microencapsulated feed for aquaculture. Microencapsulation means to
adjust feed such as baits to a size which is easy for aquatic
organisms to prey and the like. The microencapsulated feed for
aquaculture may have any shape such as spherical shape, pellet
shape, and elliptical shape, and the average maximum diameter is,
for example, 1 nm or more and 1000 .mu.m or less, and may be 100 nm
or more and 500 .mu.m or less, 1 .mu.m or more and 200 .mu.m or
less, or 5 .mu.m or more and 100 .mu.m or less. Particularly, when
the feed for aquaculture of the present invention is used as feed
for larval eels, a particle size of 1 to 200 .mu.m is preferable.
The feed for larval eels is feed for growing leptocephalus larvae
to glass eels. The Japanese eels lay eggs near a water depth of
about 200 meters in the spawning ground area, and the fertilized
eggs hatch with gradually decreasing water depth, and become larva
shaped like a leafy leaf called leptocephalus. When this
leptocephalus grows and reaches the maximum elongation stage (6 cm
or more), it undergoes metamorphosis, transforming from a flat body
to a cylindrical body, and is said to be an almost transparent
glass eel at a total length of about 6 cm.
[0031] Feed for Aquaculture
[0032] Feed for aquaculture means, for example, feed given as bait
or nutrients to aquatic organisms (aquatic animals). Feed for
aquaculture can be used as feed given to fish and shellfish in the
aquaculture industry, and can also be used as feed for aquarium
fish or a ground bait for fishing. The feed for aquaculture of the
present invention may be administered alone as bait or nutrients,
or may be administered mixed with other feed.
[0033] As described above, the fish targeted by the feed for
aquaculture of the present invention is not particularly limited,
but the feed for aquaculture of the present invention can be
preferably used for fish of the order Anguilliformes and
particularly preferably used for larval fish (leptocephalus larvae)
of the fish of the order Anguilliformes. Examples of such fish of
the order Anguilliformes include Japanese eel (Anguilla japonica),
European eel (A. anguilla), American eel (A. rostorata), giant
mottled eel (A. marmorata), New Guinean eel (A. bicolor pacifica),
Indonesian eel (A. bicolor bicolor), Mozambican eel (A.
mossambica), Australian eel (A. australis australis), Australian
freshwater eel (A. australis schmidtii), Australian long-finned eel
(A. reinhardtii), Cerebus eel (A. celebesensis), Polynesian
long-finned eel (A. megastoma), Pacific short-finned eel (A.
obscura), New Guinean alpine eel (A. interioris), Indian mottled
eel (A. nebulosa), New Zealand long-finned eel (A. diffenbachii),
Luzon eel (A. luzonensis), Bengali eel (A. bengalensis
bengalensis), African eel (A. bengalensis labiata), continental
freshwater eel (A. breviceps), continental eel (A. nigricans),
Indonesian long-finned eel (A. malgumora), and the like. Other fish
of the order Anguilliformes include common Japanese conger (Conger,
myriaster), beach conger (C. japonica), Ariosoma meeki, Gnathophis
nystromi nystoromi, Synaphobranchus kaupii, moray (Gymnothorax
kidako), conger pike (Muraenesox cinereus), and pike eel
(Muraenesox bagio).
[0034] The larval fish of the order Anguilliformes described in the
present invention refers to the stage from the hatched larval fish
to glass eels through the leptocephalus larvae. Fry of fish of the
order Anguilliformes refers to the stage in which a glass eel has
grown in both internal and external shapes, and the stage called
"Kuroko" in which a black pigment has been deposited in the
external shape.
[0035] FIG. 1 is a conceptual diagram of the feed for aquaculture
of the present invention. As shown in FIG. 1, the feed for
aquaculture contains an oil phase 11 having an oil-soluble nutrient
component; an aqueous phase 13 that is present in the oil phase 11
and contains a water-soluble nutrient component; and a coating 15
containing the oil phase 11 and the aqueous phase 13 therein. In
the feed for aquaculture of the present invention, it is not
necessary for the oil phase 11 and the aqueous phase 13 to be
completely separated, and all or a part of them may be in a mixed
state. In particular, the aqueous phase may be dispersed in the oil
phase.
[0036] The oil phase 11 may include, for example, one or both of
animal oils and vegetable oils. Examples of the animal oils are
oils extracted from fish eggs, fish oils, bird eggs (eg., chicken
eggs), mammals and birds, and animal oils derived from fats and
oils-producing bacteria. Examples of the vegetable oils are soybean
oil and corn oil.
[0037] Examples of the oil-soluble nutrient component are various
animal fats and oils, vegetable fats and oils, and fatty acids
extracted and purified from them. The oil-soluble nutrient
components include oil-soluble components as well as fat-soluble
components. Other examples of the oil-soluble nutrient component
are oil-soluble vitamins (such as vitamins A, D, E) and carotenoids
such as .beta.-cryptoxanthin. Besides those contained in the above
animal oils and vegetable oils, oil-soluble vitamins themselves may
be separately added to these oil-soluble vitamins. Also, other
examples of the oil-soluble nutrient component are DHA and EPA. The
concentration of the oil-soluble nutrient component is, for
example, 5 to 30 wt %, and preferably 10 to 20 wt %, of the
oil-soluble liquid.
[0038] The aqueous phase 13 contains a water-soluble nutrient
component. Examples of the water-soluble nutrient component are any
one or more of saccharides, amino acids, oligopeptides, protein
hydrolysates, water-soluble vitamins, pantothenic acid, and
nicotinic acid. Examples of the saccharides are monosaccharides,
oligosaccharides, and polysaccharides. Specific examples of the
saccharides are glucose, 1,5-anhydro-D-fructose, maltose, and
trehalose. Leptocephalus larvae are low in digestive ability, thus
saccharides composed of small molecules such as monosaccharides and
disaccharides are preferable as the saccharides. In addition, since
the feed of the present invention is microencapsulated feed having
a structure of W/O/W, it is possible to effectively store
saccharides composed of small molecules and ingest it to
leptocephalus larvae.
[0039] An example of the amino acid is essential amino acids. An
oligopeptide is a peptide formed by binding 2 to several hundred
(e.g., 300) amino acids. An example of the protein hydrolysate is a
hydrolysate using a protein source containing either or both of a
vegetable protein and an animal protein using a proteolytic enzyme,
hydrochloric acid, or hot water. The protein hydrolysate may be,
for example, any one or more of soybean enzyme-treated proteins,
fish and shellfish autolyzed extracts, fishmeal enzyme-treated
decomposition extracts, and fish meat hot water-treated
decomposition extracts.
[0040] An example of the vegetable protein is a soybean protein.
Examples of the animal proteins are fish and shellfish extracts and
zooplankton extracts. The soybean enzyme-treated protein is a
soybean protein subjected to enzyme treatment. An example of the
enzyme is a protease (proteolytic enzyme). That is, the soybean
enzyme-treated protein is obtained by reducing the molecular weight
of soybean protein with enzyme.
[0041] The fish and shellfish autolyzed extract is an extract
extracted from fish and shellfish decomposed by autolysis. An
example of a fish and shellfish autolyzed extraction method is
described, for example, in JP 3268657 B2. The fish and shellfish
autolyzed extraction method may decompose by a digestive enzyme
contained in fish and shellfish itself, and decomposition may be
promoted by, if necessary, adding an acid or hot water, and if
necessary, acting a protease, shredding the fish and shellfish
itself into mince, or by stirring. Examples of the fish and
shellfish are anchovy, sardines, squid, and hill. The fish and
shellfish autolyzed extract contains a lot of low molecular weight
compounds such as amino acids. It is preferable that the fish and
shellfish autolyzed extract is an extraction of water-soluble parts
from fish and shellfish decomposed by autolysis. That is, fish and
shellfish contain hard tissues such as bones and exoskeleton, and
when a hard tissue is mixed in even a little bit, the digestive
system of leptocephalus larvae that incorporate it will be damaged.
For this reason, the fish and shellfish autolyzed extract that
extracts water-soluble parts of decomposition products can be
preferably incorporated even the leptocephalus larvae with weak
digestive system.
[0042] The fishmeal enzyme-treated decomposition extract is an
extract of one obtained by decomposing a powdery product of fish
and shellfish by powder enzyme treatment. The method of enzyme
treatment is described, for example, in JP 3408958 B2. In this
method, fish and shellfish are treated with a proteolytic enzyme
under stirring to obtain an emulsified composition. This emulsified
composition is formed from a liquid phase containing a
water-soluble amino acid, oligopeptide and vitamin, and
water-soluble mineral components such as salts, and a solid phase
including a fat and oil containing a water-insoluble highly
unsaturated fatty acid and a protein having a molecular weight of
20,000 to 100,000. The emulsified composition is subjected to
solid-liquid separation, and the liquid portion may be extracted as
a fishmeal enzyme-treated decomposition extract. Other examples of
the enzyme treatment are those described in JP 4804003 B2.
[0043] Fish meat hot water-treated decomposition extract is a
method of treating fish meat with hot water under pressure to
decompose the fish meat to obtain an extract. This hot water may
properly contain a proteolytic enzyme. Specific example of
hydrothermal treatment is disclosed in WO 2002/036802 A.
[0044] Specific examples of the protein hydrolyzate are soybean
peptides, fish and shellfish extracts, yeast extracts, and
phytoplankton extracts. Examples of the water-soluble vitamins are
vitamins B1, B2, B6, and C. Vitamin C is preferable because it also
functions as an antioxidant. An example of the concentration of the
water-soluble nutrient component is 1 mg/ml to 500 mg/ml and
preferably 2 mg/ml to 100 mg/ml, and may be 3 mg/ml to 100 mg/ml in
the aqueous solution. An example of the solution is a buffer, and
an example of the buffer is a phosphate buffer. Other examples of
the solution are pure water, volume heavy water, saline, and
physiological saline.
[0045] Example of the weight ratio of the aqueous phase 13 to the
oil phase 11 is 1:10 to 10:1, and may be 1:5 to 5:1, or 1:3 to 3:1.
Example of the weight ratio of the water-soluble nutrient component
to the oil-soluble nutrient component is 1:10 to 10:1, and may be
1:5 to 5:1, or 1:3 to 3:1. Example of the weight ratio of the
saccharides to the amino acid source (amino acid, oligopeptide,
protein hydrolysate) is 1:10 to 10:1, and may be 1:5 to 5:1, or 1:3
to 3:1.
[0046] The microcapsule feed of the present invention is formed by
being coated with the coating of biodegradable polymer as the wall
material, in the state where the aqueous phase as described above
is present in the oil phase. Examples of the biodegradable polymers
used for the coating of the feed for aquaculture of the present
invention are polysaccharide polymers such as cellulose,
polypeptides, nucleic acids, aliphatic polyesters, and gelatin.
Examples of the polysaccharide polymers are cellulose and
polylactic acid polymers, among which polylactic acid polymers are
preferred. The number average molecular weight of these polymers is
1,600 or more and 460,000 or less, preferably 80,000 or more and
160,000 or less, and may be 140,000 or more and 160,000 or less. In
particular, when the feed for aquaculture of the present invention
is administered to leptocephalus larvae, the number average
molecular weight of the polymer is preferably from 80,000 to
100,000. The thickness of the coating of the feed for aquaculture
of the present invention is, for example, 1 nm or more and 1 .mu.m
or less, and may be 1 .mu.m or more and 50 .mu.m or less, and is
preferably 10 nm or more and 10 .mu.m or less.
[0047] In the microcapsule feed of the present invention, various
substances may be added to the above aqueous phase or oil phase, or
to the inside of the coating not mixed with the aqueous phase or
oil phase. Examples of such additives are algal components such as
spirulina, dried spirulina, spirulina extract, chlorella, dried
chlorella, and chlorella extract. The algal component is contained,
for example, in an amount of 0.1 wt % or more and 10 wt % or less,
and may be contained in an amount of 0.5 wt % or more and 5 wt %,
in the microcapsule feed.
[0048] Preferred feed for aquaculture of the present invention
further contains an immunostimulator. Examples of the
immunostimulator are any one or more of lactic acid bacteria,
yeasts, aspergillus oryzae, hay bacillus, Bacillus subtilis var
natto, intestinal bacteria derived from adult fish intestines of
fish of the order Anguilliformes, intestinal bacteria derived from
glass eel intestines of fish of the order Anguilliformes, and
intestinal bacteria derived from leptocephalus larva intestines of
fish of the order Anguilliformes. By using feed for aquaculture
containing these immunostimulators, it is possible to effectively
produce leptocephalus larvae of fish of the order Anguilliformes,
which have been conventionally thought to be difficult to produce,
up to glass eels. The immunostimulator is contained, for example,
in an amount of 0.1 wt % or more and 10 w t% or less, and may be
contained in an amount of 0.5 wt % or more and 5 wt %, in the
microcapsule feed. As the intestinal bacteria derived from adult
fish intestines of fish of the order Anguilliformes, intestinal
bacteria derived from glass eel intestines of fish of the order
Anguilliformes, and intestinal bacteria derived from leptocephalus
larva intestines of fish of the order Anguilliformes, for example,
intestinal bacteria taken from the intestines of healthy adult fish
of fish of the order Anguilliformes, glass eel of fish of the order
Anguilliformes and leptocephalus of fish of the order
Anguilliformes, and those obtained by culturing the taken
intestinal bacteria can be used. In addition, these may use, for
example, bacteria taken after dissolving feces of healthy adult
fish of fish of the order Anguilliformes, glass eel of fish of the
order Anguilliformes and leptocephalus of fish of the order
Anguilliformes, and those obtained by culturing the taken
bacteria.
[0049] Method for Producing Feed for Aquaculture
[0050] The present invention also provides a method for producing
the microencapsulated feed for aquaculture of the present
invention.
[0051] The feed for aquaculture of the present invention can be
produced by properly adopting the means used for encapsulation. The
manufacturing process which is the basis of the feed for
aquaculture of the present invention is, for example, as
follows.
[0052] The manufacturing process includes a primary emulsification
step, a secondary emulsification step, and an evaporation step.
Next, each step will be described in detail.
[0053] Primary Emulsification Step
[0054] The primary emulsification step is a step of adding an
aqueous solution (internal aqueous phase) of a water-soluble
nutrient component to an oily solution (organic phase) in which a
biodegradable polymer is dissolved in a (volatile) organic solvent
as an oil-soluble nutrient component and a wall material polymer
and stirring the mixture to adjust a W/O type emulsion.
[0055] Examples of the organic solvents are volatile organic
solutions such as alkyl halides, arylalkyls, and ethers. Preferred
examples of the solution of the oil-soluble liquid are
dichloroethane, chloroform, toluene and dimethyl ether which are
low-boiling organic solvents, among which dichloroethane is
preferred. In the primary emulsification step, in addition to the
above components, the element used in a known emulsification step
may be appropriately added. For example, in the primary
emulsification step, a suitable emulsion stabilizer may be blended.
Examples of such emulsion stabilizers include various surfactants,
water-soluble resins, water-soluble polysaccharides and the like
generally used for emulsion adjustment, such as span-type
surfactants like sorbitan monoate. The amount of the surfactant is,
for example, 0.5 to 5 wt % of the oil-soluble liquid, and may be 1
to 3 wt % or 1 to 2 wt %.
[0056] In the primary emulsification step, an aqueous solution is
obtained by putting the water-soluble nutrient component to a
suitable solution. At that time, a protective material polymer is
added for protecting the water-soluble nutrient component including
bacteria. Examples of the protective material polymer include
water-soluble polymeric polysaccharides like alginates and
chitosan, and polyvinyl alcohols. Sodium alginate is particularly
preferred. The water-soluble concentration in the case of using
sodium alginate is preferably 0.5 to 5 wt %, and when it is too
high, the dispersion stability of the W/O type emulsion is lowered
and aggregation tends to occur.
[0057] Then, a W/O type emulsion can be obtained by using an
emulsifying machine (homogenizer), or gradually injecting an
aqueous solution into the prepared oily solution while stirring.
The ratio (volume ratio) of the aqueous solution to the oily
solution is, for example, 1:1 to 1:10, and may be 1:2 to 1:10, or
1:2 to 1:5. The primary emulsification step is preferably carried
out under ice cooling, and the temperature of the oily solution is,
for example, -15.degree. C. to 4.degree. C., and may be -10.degree.
C. to 0.degree. C. The stirring speed is, for example, 1,000 to
10,000 rpm, and preferably 3,000 to 5,000 rpm. Stirring may be
performed by ultrasonic vibration. The stirring time is, for
example, from 10 minutes or more to 1 hour or less, and may be from
10 to 20 minutes.
[0058] Secondary Emulsification Step
[0059] The secondary emulsification step is a step of adding the
W/O type emulsion obtained in the above primary emulsification step
to an aqueous solution (external aqueous phase: second aqueous
solution) different from one used in the primary emulsification
step, and stirring the mixture to adjust a W/O/W type emulsion.
[0060] The second aqueous solution is preferably a solution
containing a coating material or a dispersion stabilizer. Examples
of the second aqueous solution are pure water, distilled water, and
physiological saline. This second aqueous solution (external
aqueous phase) is an aqueous solution of a water-soluble dispersion
stabilizer. Examples of the water-soluble dispersion stabilizer
include sodium polyacrylate, polyacrylamide, polyethylene imine,
polyethylene oxide, polyvinyl pyrrolidone, and the like. Polyvinyl
alcohol is particularly preferred. It is also recommended to
include at least tricalcium phosphate for suppressing aggregation
of droplet particles. Distilled water is used to adjust an aqueous
solution of about 1 to 30 wt %, and particularly preferably 2 to 10
wt %.
[0061] The secondary emulsification step is preferably carried out
at a slower stirring speed and in a shorter time than in the
primary emulsification step. That is, a W/O type emulsion may be
added to and mixed with an aqueous phase to be an external aqueous
phase at ordinary temperature, and by continuing at a stirring
speed of 300 to 1000 rpm for about 3 to 10 minutes, drop
coalescence of the internal aqueous phase is carried out in each
particle of the W/O type emulsion droplet that is a dispersed
phase. By this droplet coalescence, the W/O type emulsion droplet
is added to a droplet of a structure in which the inner single
aqueous phase is covered with the outer organic phase.
[0062] Evaporation Step
[0063] The evaporation step is a step of evaporating the organic
solvent from the W/O/W type emulsion obtained in the secondary
emulsification step, thereby forming microcapsules including the
aqueous phase containing the water-soluble nutrient component in
the oil phase containing the oil-soluble nutrient component.
[0064] After the above droplet coalescence, one or both of warming
and decompression is performed under stirring, in order to
volatilize and remove the low-boiling organic solution of the
organic phase by in-liquid drying. It is recommended to
simultaneously perform warming and decompression from the viewpoint
of processing efficiency. This evaporation step performs gentle
stirring while warming to a temperature slightly higher than the
boiling point of the volatile solution. When the low-boiling
organic solvent of the organic phase is mainly composed of
dichloroethane, the maximum achieving temperature is about
35.degree. C. and the maximum pressure reduction is about 300 hPa,
in in-liquid drying which simultaneously performs warming and
decompression.
[0065] The stirring speed in in-liquid drying is preferably about
100 to 1000 rpm, and the step time is preferably 1 to 24 hours, and
particularly preferably 3 to 10 hours. It is preferable that the
obtained microcapsules are filtered and dried and then
cryopreserved, or filtered and then stored in an aqueous phase.
[0066] In each of the above steps, necessary nutrient components
and immunostimulators may be appropriately mixed.
[0067] Aquaculture Method Using Feed for Aquaculture
[0068] The present invention also provides a culture method using
the microencapsulated feed for aquaculture of the present
invention.
[0069] As a method for culturing fish and shellfish, a known method
may be appropriately adopted. Particularly, when culturing eel fry,
for example, the apparatus disclosed in JP 2013-236598 A may be
used. This apparatus is an apparatus for raising eels which raises
eels under atmospheric pressure to induce sexual maturation.
Moreover, this apparatus includes a water tank for storing raising
water and eels, a water supply unit for supplying raising water to
the water tank, a drainage water unit for discharging the raising
water from the water tank, and a unit for adjusting the
concentration of dissolved oxygen in the raising water.
[0070] When raising eel larvae using the feed of the present
invention, it is preferable to directly put the above feed in a
water tank for raising eel larvae and feed it in the precipitated
or dispersed state. When circulating water in a raising water tank,
it is preferable to stop or intermittent the water flow while
feeding, in order to suppress the loss of bait in the drainage. It
is preferable to feed so that the feed always remains and does not
run short, and feed it from 1 to 5 separate times per day.
Example 1
[0071] Hereinafter, the present invention will be specifically
described with reference to examples. The present invention is not
limited by the examples, and those appropriately adopting known
methods are also included in the present invention. Microcapsules
suitable as feed of cultured larval fish were produced according to
the above-described production method of microcapsules, using the
following compositions and conditions. FIG. 2 is a conceptual
diagram of a manufacturing process in Example 1.
[0072] Adjustment of Internal Aqueous Phase
[0073] 36 ml of a phosphate buffer solution was added to and mixed
with soybean enzyme-treated protein (manufactured by FUJI OIL CO.,
LTD.) and maltose, so as to be 20 mg/ml and 1 mg/ml, respectively,
1 ml of krill enzyme-treated decomposition extracting solution was
further added, and 1 wt % sodium alginate was further added to
adjust an internal aqueous phase.
[0074] Adjustment of Organic Phase
[0075] 15 wt % Feed oil (manufactured by SANSHO BUSSAN CO.,LTD.), 5
wt % polylactic acid polymer (average molecular weight 100,000) and
1.5 wt % sorbitan monooleate were added to and mixed with 108 ml of
dichloroethane to adjust an organic phase.
[0076] Adjustment of External Aqueous Phase
[0077] 4 wt % of polyvinyl alcohol and 0.3 wt % of tricalcium
phosphate were added to and mixed with 680 ml of distilled water to
adjust an external aqueous phase.
[0078] The internal aqueous phase was added and mixed while
stirring the organic phase under ice cooling at 5000 rpm for 10
minutes to adjust a W/O type emulsion, and the W/O type emulsion
was added to the external aqueous phase under stirring at ordinary
temperature (20.degree. C.) to adjust a W/O/W emulsion, followed by
stirring at 150 rpm for 30 minutes at atmospheric pressure.
Thereby, droplets in the internal aqueous phase in the dispersed
W/O type emulsion droplet are united, then the resulting droplets
were subjected to in-liquid drying treatment at a liquid
temperature of 35.degree. C. for 6 hours under an atmospheric
pressure of 300 hPa, the produced microcapsules were separated by
filtration, washed with 0.1 molar concentration of hydrochloric
acid aqueous solution to remove the tricalcium phosphate, and
further washed with distilled water, to recover the
microcapsules.
[0079] The particle size of the microcapsules obtained using the
above operating conditions and compositions was measured with a
laser diffraction type particle size distribution apparatus, and
found to have a particle diameter of 5 to 20 .mu.m.
Example 2
[0080] Capsule feed was prepared in the same manner as in Example
1, except that 1 ml of a commercially available enzyme that
activates microorganisms (LOVE Ibusuki) added with Bacillus
subtilis var natto, dry yeast and lactic acid bacteria was added to
the internal aqueous phase solution.
Example 3
[0081] Capsule feed was prepared in the same manner as in Example
1, except that 1 g of fine powder of satsuma orange dried peel
containing a large amount of .beta.-cryptoxanthin was added as a
base to the phosphate buffer solution, the mixture was stirred at a
low speed for 10 minutes, followed by centrifugation at 100 rpm for
5 minutes, and 1 ml of the obtained supernatant was added to the
internal aqueous phase solution.
Example 4
[0082] Capsule feed was prepared in the same manner as in Example
1, except that spiny dogfish eggs were used instead of the feed oil
in Example 1.
Example 5
[0083] Capsule feed was prepared in the same manner as in Example
1, except that 1 ml of spirulina extract was added to the internal
aqueous phase solution.
Example 6
[0084] Capsule feed was prepared in the same manner as in Example
1, except that 1,5-anhydro-D-fructose was used instead of
maltose.
Comparative Example 1
[0085] A bait was prepared using the method disclosed in JP
H11-56257 (Patent Literature 3). More specifically,
.beta.-carotene, gelatin and fish oil were stirred and emulsified
to produce microencapsulated bait of eel fry containing
.beta.-carotene (feed of Comparative Example 1).
Example 7
[0086] Using the feed of Examples 1 to 6 and Comparative Example 1,
20 each of 7-day-old leptocephalus larvae were stored in a 100
ml-small glass container, and a feeding test of the above samples
was conducted. With each feed, contents were found in the
alimentary canal of larvae, and feeding was confirmed.
Example 8
[0087] Using the feed of Examples 1 to 6 and Comparative Example 1,
200 each of 7-day-old leptocephalus larvae were stored in a 5
1-bowl shaped water tank, and a survival test using the above
samples was performed. With the eel fry bait (Comparative Example
1) disclosed in JP H11-56257 (Patent Literature 5), the survival
rate remarkably decreased after the start of the test, but with the
feed of the present invention, the survival rate showed a result
equivalent to the feed for larvae mainly consisting of shark eggs
so far. Further, in the feed of the present invention, the water
quality in the water tank was maintained.
Example 9
[0088] Adjustment of Aqueous Phase
[0089] 16 g of soybean peptide and 1 g of sodium alginate were
added to 80 ml of distilled water to adjust an aqueous phase.
[0090] Adjustment of Oil Phase
[0091] 1.3 g of span 80 ((Z)-9-octadecenoic acid) was mixed to 130
g of rapeseed oil to adjust an organic phase.
[0092] Adjustment of Added Layer W/O
[0093] 30 g of rapeseed oil, 0.3 g of Span 80, 10 ml of distilled
water and 0.7 g of calcium chloride were mixed to adjust the added
layer W/O.
[0094] The aqueous phase was added and mixed for 10 minutes while
stirring the oil phase at 25.degree. C. at 200 rpm, to adjust a W/O
type emulsion. Added layer W/O was added and mixed for 5 minutes
while stirring this W/O type emulsion at 25.degree. C. at 500 rpm.
Further, it was stirred at 25.degree. C. at 200 rpm to accelerate
the polymerization reaction for 45 minutes. Filtration was
performed to collect 20 g of microcapsules. 20 g of distilled water
was added to and dispersed in 20 g of the collected microcapsules,
and a photograph was taken. The obtained photograph is shown in
FIG. 3. That is, FIG. 3 is a photograph replacing the drawing when
the microcapsules obtained in Examples are dispersed in distilled
water.
INDUSTRIAL APPLICABILITY
[0095] The present invention can be utilized particularly in the
fisheries industry.
REFERENCE SIGNS LIST
[0096] 11 Oil phase [0097] 13 Aqueous phase [0098] 15 Coating
[0099] 17 Feed for aquaculture
* * * * *