JP2923263B2 - Feed composition for fish culture - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feed composition for aquaculture of fish, and more particularly, to a feed composition for aquaculture of fish for improving productivity in a farm by increasing the immunological activity of cultured fish and the like. About.

[0002]

2. Description of the Related Art In recent years, the depletion of resources has been called out in the field of fisheries, and aquaculture of various fishes has been actively carried out, and certain results have been obtained. However, infectious diseases on fish have become widespread due to contamination of aquaculture water areas, overcrowding for increasing productivity, and propagation of pathogenic bacteria due to increased seed and seedling transportation, thereby significantly impairing aquaculture productivity. To solve this problem,
Administration of drugs such as antibiotics has been mainly performed. However, the use of excess chemicals for edible fish,
Problems such as reduced persistence and the effect due to the emergence of resistant bacteria have arisen, and in recent years, various immunostimulants have been supplied to the market for the purpose of prevention rather than treatment. Examples of these include yeasts, basidiomycetes, polysaccharides derived from seaweed, levamisole, bovine lactoferrin, and peptidoglycan of Bifidobacterium.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a relatively inexpensive immunostimulant for cultured fish which is relatively inexpensive and has an excellent addition effect in order to raise disease-resistant fish in a farm. The purpose is to:

[0004]

In the process of searching for a compound having an immunostimulatory effect on fish, the present inventors found that curdlan, a linear β-1,3-glucan, was extremely effective for that purpose. They have found something and have completed the present invention. That is, it has been known that curdlan has immunostimulating effects such as an antitumor effect and a complement activating effect on mice. However, this is only the case when a mammal is given intraperitoneally in the laboratory, showing how curdlan affects the immune system of fish and also protects against fish infections. There was no information on whether or not. In view of such a situation, the present inventors administered orally to fish in order to introduce curdlan having an immunostimulating effect into the aquaculture industry. It was found that the survival rate in the fish disease challenge test was significantly improved. In addition, curdlan obtained new findings such as improving the phagocytic activity of phagocytes and remarkably activating the complement system.

[0005] The present invention is based on such new knowledge of the present inventors and provides a feed composition for cultured fish, which comprises curdlan. The feed composition of the present invention comprises a feed component and curdlan.
Curdlan is blended at a ratio of 0.5 to 5% by weight,
The curdlan used is preferably a curdlan heated to 60 ° C. or higher in the presence of water.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The card run used in the present invention is as follows.
It is a linear β-1,3-glucan produced by Alcaligenes faecalis and Agrobacterium bacteria. Curdlan was discovered by Harada et al. (1966) and is currently widely used as a food additive, primarily in food applications. Its structure is a homopolymer in which glucose is connected linearly by β-1,3-linkage,
It is said that there is no bond other than the -1,3-bond and no constituent sugar other than glucose. Its properties are insoluble in water and various organic solvents, soluble in alkali, formic acid solution and urea solution, and once heated to around 60 ° C. and further heated to form a heated gel (high set gel),
Further, after heating to around 60 ° C. and cooling, a cooled gel is formed (a low-set gel). In addition, it forms a film and exhibits a moisturizing effect. Thus, a major characteristic of curdlan is that it differs significantly in its physicochemical properties, especially with temperature and temperature history. That is, the molecular structure of the curdlan is greatly different depending on its temperature history.

Thus, the curdlan used may be a commercially available curdlan as it is, or may be a curdlan that has been dispersed in water and heated in advance to cause the curdlan to assume a specific conformation. Good. No particular conditions or special considerations are required for dispersing the curdlan in water, but for curdlan 0.1 to 5 per 100 parts by weight of water.
The weight part is the easiest to handle. Further, the amount of water is determined in consideration of the dosage form of the composition and the like. The heating condition may be 40 ° C. or higher, preferably 60 ° C. or higher, more preferably 70 ° C. or higher. Maximum heating temperature is 15
There is no significant difference in the effect up to 0 ° C, and the range up to 100 ° C is sufficient from the viewpoint of workability. The heating time is not particularly limited, but is usually 30 seconds to 2 seconds.
A desired effect can be obtained by heating for 0 minutes. Although the content of curdlan in the feed composition of the present invention is not particularly limited, it may be 0.05 to 5% by weight based on the total amount of the composition from the viewpoint of handling of the composition and effects. preferable.

[0008] The feed composition for fish culture of the present invention is produced by mixing a feed component with curdlan. The other feed components to be mixed are not particularly limited, and may be any of various feeds usually used for fish farming and mixtures thereof, and the mixing method is not particularly limited. Further, in advance, according to a method known per se, after mixing the feed ingredient and curdlan, a desired dosage form such as powder, granules, pellets or the like may be formed. The known feed for fish culture and curdlan may be mixed and, if necessary, further molded into a composition.
For example, curdlan may be mixed into a powdered feed before molding as one of the raw materials using a commonly used mixer. Then, if necessary, it is molded with an extruder, a pelleter or the like, and a desired feed composition is obtained. In addition, when using a heated curdlan, the curdlan dispersion becomes a gel or paste, so that when it is mixed with the composition, for example, after it is crushed, it is uniformly dispersed in water for forming the feed composition. For example, the mixture is uniformly mixed with the entire feed composition.

The feed composition for aquaculture of fish of the present invention can be used in the same manner as a usual feed composition, and the supply amount of the composition is not particularly limited. Can be given. The feed composition of the present invention can correspond to each type of fish that has been cultured. Examples of fish include
Freshwater fish rainbow trout, carp, goldfish, American catfish,
Saltwater fish such as Atlantic salmon, sockeye salmon, Chinook salmon, cherry salmon, yellowtail, yellowtail, blackfish, eel, tilapia, sweetfish, yamame, amago, brown trout, brown trout, etc.
Flounder, puffer fish, horse mackerel, amberjack and the like.

[0010] In addition, the composition of the present invention is not particularly limited to the target infectious diseases since it exhibits an immunoreactive effect on fish. That is, rhabdovirus, birnavirus, herpesvirus, iridovirus and other viral diseases, nocardiosis, streptococcal disease, pseudomonassis, nodulopathy, fin red disease, bacterial kidney disease, red spot disease,
Eromonas disease, malignant disease, vibrio disease, bacterial gill disease,
Bacterial diseases such as red mouse disease, intestinal sepsis, parakoloosis, edwajellosis, cold water disease, gliding bacterium disease, and columnaris disease, water mold disease, cotton scab disease, fungal granulomatosis, ichthionosis, blanchiomycosis, dermosis It is possible to respond to fungal diseases such as tidiasis and gastric distension from the standpoint of enhancing the defense function of the fish itself. Furthermore, the fish in the curdlan-administered group had better tactile sensation and visual perception in the taste elements (Yasushi Omata, “Deliciousness and Science of Taste, Nikkan Kogyo Shimbun”) compared to the fish in the control group. Admitted. In other words, the fish in the curdlan-administered group had good vitality, muscle stiffness, and were healthy fish. In contrast,
Diseased fish tend to have darker body color and more mucus on the body surface,
Such tendency was not observed in the fish in the curdlan administration group. Furthermore, it was confirmed that the fish in the curdlan-administered group were thicker and easier to cook than the fish in the control group.

[0011]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Example 1 Carp (weight: about 30 g) purchased from a farm in Yatsushiro City, Kumamoto Prefecture was placed in a 60-liter aquarium, each of which was preliminarily reared at a water temperature of 22 to 23 ° C. for one week, and then subjected to an experiment. During the preliminary breeding period, a commercially available mixed feed for carp raising (Japanese mixed feed, No. 6P) was given daily until satiation.

The curdlan-containing feed composition was produced as follows. As shown in Table 1, curdlan (160, 310 or 630 mg) was suspended in 38 ml of deionized water and gelled by heating in a microwave oven. Each gel was made into fine particles by using a mixer, and then 62 g of powdered compound feed for carp culture (Japanese compound feed, No. 6P) was added and mixed, and the mixture was formed into pellets to prepare test feed. The test feed (A, B and C) weighed 9.7 g (carp 1).
Daily dose to 0 fish)
Stored at 20 ° C.

[0013]

[Table 1]

The administration of the test sample was performed as follows. To the carp in each test group, a test feed (equivalent to 2% in terms of combined feed) equivalent to 3.2% of the body weight of the fish was administered five times every other day and twice in the morning and evening. In addition, a compound feed equivalent to 2% of the body weight of the fish was given on the day on which the test feed was not administered and on the control group. The daily curdlan dose was calculated to be 50 mg / kg body weight in feed A section and 1 mg in feed B section.
00 mg / kg body weight and 200 mg / kg body weight in feed C group. Edwardo Sierra Talda used in this experiment
dsiella tarda) NG8104 is a strain isolated from flounder fish. After increasing the pathogenicity of this strain by passing through the fish, it was placed on a heart infusion agar medium (Nissui Pharmaceutical) at 36 ° C., 13 hours and 22 ° C., respectively.
After culturing for 7 hours, 2 × 10 ⁸ CFU / ml and 5 × 10 ⁷ CFU / ml in sterile physiological saline (0.85% NaCl), respectively.
And suspended. Three days after the final administration of the test feed, E. tarda bacteria (2 × 10 ⁸ CFU / 100 g body weight) were inoculated intraperitoneally into carp, and the survival rate 7 days later was determined. For comparison of survival rates, Fisher's exact test was used, and P <0.
At the time of 05, it was considered that there was a significant difference.

FIG. 1 shows the results of an attack test using E. tarda bacteria.
Shown in In the challenge test by E. tarda, the control group (feed D)
Area) had a survival rate of 20%, whereas 50 mg / kg
The administration group (feed A section) was 60%, the 100 mg / kg administration section (feed B section) was 70%, and the 200 mg / kg administration section (feed A section) was 40%. As a result of the test, the 100 mg / kg administration group was significantly higher than the control group. At this time, the activity of head kidney phagocytes was measured. The method and results are described below. Use the above method to add curdlan supplemented feed every other day for 5 days.
The carp was orally administered to the carp, and anesthetized with 2-methylquinoline on the third day after the final administration, and blood was removed from the dorsal aorta, and the head kidney tissue was removed. The head kidney was subjected to ice-cold RPMI-PC medium (RPMI-PC medium containing 10 mM phosphate and 0.31% sodium citrate).
1640, pH 7.4) transferred to a plastic dish (60 mm in diameter) containing 5 ml,
The head kidney was crushed between the sheets to release phagocytic cells. This was transferred to a test tube, and the tissue was further loosened by pipetting with a silicon-treated pipette, followed by centrifugation at 30 × g for 3 minutes to sediment aggregated aggregates of connective tissue and cells.
Sodium citrate free RPM
After washing three times with I medium (RPMI-P), the number of living phagocytes was counted by trypan blue exclusion test and phase contrast microscopic observation, and the cells were suspended in RPMI-P at 1 × 10 ⁷ cells / ml.

On the other hand, baker's yeast (Saccharomyces serevis)
Iae, oriental yeast) (500 mg) was weighed into a 100 ml beaker, and physiological saline (50 ml) was added, followed by boiling for 30 minutes. After filtration with sterile gauze, centrifugation, washing the precipitate several times with physiological saline, PR containing 10% fetal bovine serum (FBS)
The cells were suspended in an MI-P medium at 1 × 10 ⁸ cells / ml. In measuring the phagocytic activity, the suspension of head and kidney phagocytes (1
× 10 ⁷ cells / ml) and yeast suspension (1 × 10 ⁸ cells / ml)
(cells / ml) were mixed in a siliconized test tube and incubated at 25 ° C. for 60 minutes. Then, the test tube was immersed in ice water to stop the poor eating. About 50 μl of this solution was spread on a slide glass, air-dried, and light-stained.
By observing zero or more phagocytes under a microscope, the phagocytosis index (P
I) was determined.

[0017]

(Equation 1)

Mann-Whitney is used to compare the average PI values.
Was determined to be significant when P <0.05. As a result of measuring the phagocytic activity of head and kidney phagocytic cells by orally administering curdlan at 0, 50, 100, and 200 mg / kg body weight every other day to carp every other day, as shown in Table 2, all the administration groups showed As compared with the control group, it showed significantly higher poor food activity.
Among them, the 50 mg / kg group showed an average value 4.9 times that of the control group.

[0019]

[Table 2]

Example 2 Flounder (Japnese Flo) of test fish
under, Pralichthys olivaceus) is a conven bred as a seedling after hatching at the Utsumi Institute of Biological Resources, Fukuyama University
Traditional fish (average weight 3.5 g, average length 5.2 cm, average height 2.2 cm) were used. The curdlan-containing feed composition was produced as follows. As a raw material, 20 g of curdlan was added to 1.88 kg of flatfish feed (Marubeni feed), followed by 0.1 kg of feed oil (RIKEN vitamin) and 0.3 water.
kg were added in this order and the whole was kneaded. The mixing machine is SHIN
-EIPD10-1 was used. Then, a die having a diameter of 5 mm was attached to a disk pelletizer F-5 made by Fuji Paudal, extruded, and cut into a length of 10 mm to obtain a molded body. After that, it was dried in an oven and then steamed to obtain a feed. Instead of curdlan, the same amount of cellulose (trade name: “KC Floc”, Nippon Paper Industries) was used as a control feed. The experiments were maintained on test diets for 49 days. tarda F
E1 (2 × 10 ⁷ cell / ml) is suspended in seawater at 26 ° C.
The fish placed in the net basket was immersed therein for 10 minutes. Thereafter, the animals were returned to the experimental tank and bred without feeding. Every morning after infection
In the afternoon, we checked the infection status and life extension. As a result, as shown in FIG. 2, the life extension after infection was clearly higher in the curdlan-administered group. In the dissection of surviving fish, favorable symptoms were observed in the group to which the curdlan-containing feed composition was administered.

Example 3 As in Example 2, medium-sized flounder fry (average body weight: 60.0 g) was used for a medium period (22 days).
After oral feeding of E. coli, the same procedure as in Example 1 was repeated. Tarda bacteria (3 × 10 ⁷ cells / ml) were artificially infected and the life extension was examined. As shown in FIG. 3, the life extension on day 19 after infection was clearly higher in the group to which the curdlan-containing feed composition was administered.

Example 4 In the same manner as in Example 1, after a short period (13 days) of oral feeding using large flounder, tard
a was artificially infected, and life extension was examined. The feed at this time was prepared as follows. As a raw material, 0.4 kg of curdlan was added to 37.6 kg of flounder feed (Marubeni feed) and mixed. The molding was carried out using an alpha riser α100 as a molding machine, with the tip barrel temperature set at 110 ° C. Die hole diameter is 8
The thing of mmφ was used. Then, it was dried in a dryer for 1 hour to obtain a feed. Instead of curdlan, the same amount of cellulose (trade name: “KC Floc”, Nippon Paper Industries) was used as a control feed. Life extension at 17 days after infection is shown in FIG.
As shown in FIG.
The same results as in the round test were obtained. Although there was little effect on the weight of the main organs after infection, favorable findings were observed in the individual anatomical pathological findings in the group to which the curdlan-containing feed composition was administered.

[0023]

As described above, according to the present invention,
It is possible to provide a novel feed composition for fish farming, which is relatively inexpensive and contains an immunostimulant for cultured fish having an excellent addition effect.

[Brief description of the drawings]

FIG. 1. Oral administration of curdlan-containing feed composition was confirmed by E. coli.
7 is a graph showing the results of testing the effect of carp on the survival rate after tarda fungus attack.

FIG. 2 is a graph showing the relationship between the number of days after infection and the survival rate in the test results in Example 2.

FIG. 3 is a graph showing the relationship between the number of days after infection and the survival rate in the test results in Example 3.

FIG. 4 is a graph showing the relationship between the number of days after infection and the survival rate in the test results in Example 4.

Continuation of the front page (56) References JP-A-6-172217 (JP, A) Yano, T et al: Nippon Suisan Gakkais i, 55, 1818-1819 (1989) (58) Fields investigated (Int. . ^6, DB name) A23K 1/00 - 1/18 BIOSIS (DIALOG )

Claims (3)

(57) [Claims] 1. A feed composition for fish cultivation, comprising curdlan. 2. The curdlan content based on the composition is:
The feed composition for fish culture according to claim 1, wherein the amount is 0.05 to 5% by weight. 3. The method according to claim 1, wherein the curd run is used in the presence of water.
The feed composition for fish culture according to claim 1, which is curdlan heated at 0 ° C or higher.