Earthworm compound feed for improving body color of pelteobagrus fulvidraco and preparation method thereof

Abstract

The invention discloses an earthworm compound feed for improving the body color of pelteobagrus fulvidraco, and belongs to the technical field of aquatic feed. The feed comprises 40%-65% of earthworm ferment powder, 10%-25% of a plant protein source, 10%-25% of an animal protein source and 10%-20% of a starch energy source. A preparation method of the earthworm ferment powder comprises the following steps: carrying out immersion bath on live earthworms subjected to hunger treatment and a green tea immersion solution for 8-12 hours to obtain an earthworm immersion bath solution; adding phaffia rhodozyma yeast liquid for anaerobic fermentation; performing high-pressure homogenization and wall breaking on the fermentation product, and adding lipase for enzymolysis to obtain earthworm fermentation pulp; and freezing and drying the earthworm fermentation pulp to obtain earthworm fermentation powder with the water content of 18-20%. The feed can effectively improve the body color of the pelteobagrus fulvidraco, improves the commodity value of the pelteobagrus fulvidraco, fully utilizes earthworm resources, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of aquaculture, in particular to the technical field of artificial aquaculture feed, and specifically relates to an earthworm compound feed for improving the body color of yellow catfish and a preparation method thereof. Background Art

[0002] Pelteobagrus fulvidraco is a common small freshwater economic fish in my country. It has no scales on its body and lives a benthic life. During the day, it likes to live on the bottom of slow-flowing waters with rich humus, and swim to the upper layer of the water to feed at night. Its diet is omnivorous and carnivorous.

[0003] Pelteobagrus fulvidraco has a high commercial value due to its golden body color. However, with the continuous expansion of aquaculture scale, high-density and intensive aquaculture models are becoming increasingly popular. As a result, the resistance and disease resistance of farmed Pelteobagrus fulvidraco fish have deteriorated, and disease problems have occurred frequently. In addition, the quality of feed is uneven, and body color fading is common in artificial breeding environments, resulting in "banana fish" with black or golden body color, which brings economic losses to the Pelteobagrus fulvidraco aquaculture industry.

[0004] There are currently two main methods for improving the color of yellow catfish. The first is to add synthetic pigments to the feed, but the long-term use of most synthetic pigments not only increases aquaculture costs but also may cause environmental problems. The second method is to add carotenoids from natural ingredients such as krill meal and spirulina, or some carotene-based natural pigment compound powders to the feed, which undoubtedly significantly increases aquaculture costs.

[0005] Earthworms have a long history as feed and fishing bait. They are commonly used by locals to feed fish, chickens, and ducks. Fresh earthworms attract fish more than other baits. As a high-quality protein feed, large-scale earthworm farming is gradually gaining popularity as a replacement for fish meal and other feeds. However, current methods often use earthworm powder or slurry to add to feed, primarily as a protein source with a limited purpose. Summary of the Invention

[0006] The present invention aims to provide an earthworm compound feed for improving the body color of yellow catfish and a preparation method thereof. The earthworm is used as one of the main raw materials, and the advantages of the raw earthworm are fully utilized. The feed can not only provide a high-quality protein source for yellow catfish and improve its feeding attractant, but also improve the body color of yellow catfish and make it present a golden body color.

[0007] The present invention provides an earthworm compound feed for improving the body color of yellow catfish, which adopts the following technical solutions:

[0008] A compound earthworm feed for improving the body color of yellow catfish comprises the following components: 40% to 65% earthworm fermentation powder, 10% to 25% plant protein source, 10% to 25% animal protein source, and 10% to 20% starch energy source; wherein the earthworm fermentation powder is obtained by the following method:

[0009] Step a: soaking live earthworms in green tea soaking liquid for a period of time to obtain earthworm soaking liquid;

[0010] Step b: adding Phaffia rhodozyma solution to the earthworm bath solution and performing anaerobic fermentation for 72 hours;

[0011] Step c: After the fermentation product is homogenized under high pressure (50 MPa) and broken, 0.1% lipase is added for enzymatic hydrolysis for 2 h to obtain earthworm fermentation slurry;

[0012] Step d: The earthworm fermentation slurry is freeze-dried to obtain earthworm fermentation powder, with the water content controlled at about 18-20%.

[0013] Earthworms are a premium ingredient in fish feed and a source of high-quality protein. Their dry matter contains 60%-70% crude protein, a level far higher than many common plant-based feeds and even higher than some fish meal. Furthermore, earthworms' body walls are primarily composed of muscle, lacking a chitinous shell, making them highly digestible and absorbable by fish, resulting in a high feed conversion rate. Earthworms secrete unique odorants (both in their body fluids and on their surface mucus) that have a strong natural appeal to most carnivorous, omnivorous, and even some herbivorous fish. They can stimulate fish's appetite and significantly increase their feed intake, making them particularly suitable for fish with poor appetite or for training fry to consume artificial feeds.

[0014] However, earthworms have certain limitations when used in fish feed. One limitation is that earthworms contain gamma-formic acid, which has an anesthetic effect. Excessive feeding can cause gastrointestinal paralysis and affect appetite. Therefore, the proportion of earthworm powder added to rabbit feed should not be too high, which limits the widespread use of earthworms as fish feed.

[0015] In the above scheme of the present invention, live earthworms are prepared into earthworm fermentation powder by a specific method. First, the live earthworms are bathed in green tea soaking liquid. This step stimulates the earthworms with the green tea soaking liquid to secrete more body surface mucus and mucopolysaccharides and other components. The earthworms are then fermented with red yeast rice, and then homogenized and crushed, and finally freeze-dried to obtain earthworm fermentation powder.

[0016] After experiments, it was found that the earthworm fermentation powder processed by the above-mentioned specific method can be used in yellow catfish feed. Compared with the existing technology, its usage can be greatly increased, instead of affecting the appetite of yellow catfish. In addition, it has better appetizing properties and significantly improves the weight growth rate. At the same time, it was also found that compared with ordinary compound feeds, the body color of yellow catfish fed with the compound feed configured according to the present invention changed significantly, and the body color became golden yellow. The inventor speculates that the reason why the compound feed of the present invention can improve the body color of yellow catfish may be that when earthworms are exposed to green tea soaking liquid, under the stimulation of the green tea soaking liquid, they synthesize carotenoids to resist oxidative damage and maintain cell membrane stability. The β-carotene produced by stress is converted into canthaxanthin in the subsequent red yeast fermentation, thereby achieving the change in the body color of yellow catfish.

[0017] Therefore, the contact time and concentration of the green tea solution are crucial to the results. Too short a contact time doesn't fully activate the pathways, while too long a contact time depletes the worms' energy. Too low a concentration doesn't provide sufficient stress, while too high a concentration can lead to a sudden increase in the worm's mortality rate. Through optimization, in step a, the immersion time for the live earthworms in the green tea solution is 8-12 hours, and the ratio of green tea to water is 60g-150g / L.

[0018] At the same time, the fermentation conditions of adding rhodozyma also have a great influence on the results, especially the effect of improving the body color. Preferably, in step b, the fermentation temperature is 25°C-30°C and the pH is 6.5-7.0.

[0019] As a preference, in step b, the inoculation amount of Rhodozyma is 10 7 CFU / mL.

[0020] Preferably, in step a, the ratio of live earthworms to green tea soaking liquid is 1:1.

[0021] Preferably, the live earthworms are starved before step a, and the starvation treatment time is at least 24 hours, preferably 24-26 hours.

[0022] Preferably, the green tea infusion is prepared as follows: immerse the green tea in water at a ratio of 60g-150g / 1L, control the temperature at 40°C ± 5°C, and the pressure at 1.8MPa-2.5MPa, overnight with low-speed stirring, for example, at 80-100rpm.

[0023] Preferably, the plant protein source is at least one of soybean meal and rapeseed meal.

[0024] Preferably, the animal protein source is at least one of fish meal and insect meal.

[0025] Preferably, the starch energy source is at least one of corn flour and wheat flour.

[0026] The present invention provides a method for preparing a compound earthworm feed for improving the body color of yellow catfish, comprising the following steps:

[0027] S1..Preparation of earthworm fermentation powder:

[0028] Step a: soaking live earthworms in green tea soaking liquid for a period of time to obtain earthworm soaking liquid;

[0029] Step b: adding Phaffia rhodozyma solution to the earthworm bath solution and performing anaerobic fermentation for 72 hours;

[0030] Step c: After the fermentation product is homogenized under high pressure (50 MPa) and broken, 0.1% lipase is added for enzymatic hydrolysis for 2 h to obtain earthworm fermentation slurry;

[0031] Step d: The earthworm fermentation slurry is freeze-dried to obtain earthworm fermentation powder, with the water content controlled at about 18-20%.

[0032] S2 prepares raw materials according to the following ratio: 40% to 65% earthworm fermentation powder, 10% to 25% plant protein source, 10% to 25% animal protein source, 10% to 20% starch energy source;

[0033] S3. The plant protein source, animal protein source, and starch energy source are mixed, crushed, and sieved to obtain a premix;

[0034] S4. The premix is ​​mixed with earthworm fermentation powder, and the mixture is put into a twin-screw extruder for granulation to obtain a compound feed.

[0035] The beneficial effects of the present invention are:

[0036] 1. The present invention's fermented earthworm powder, processed using a specific method, can be used in yellow catfish feed, significantly increasing its usage without affecting the fish's appetite. The earthworms, treated with green tea soaking liquid and fermented with Phaffia rhodozyma, effectively reduce the anesthetic effects of gamma-formic acid, resolving the issue of limited usage in traditional earthworm feed.

[0037] 2. The earthworm compound feed of the present invention has better food appeal and significantly increases the weight growth rate of yellow catfish. Compared with traditional feed, the compound feed of the present invention contains earthworm fermentation powder processed through a special process. This not only provides rich nutrients but also enhances the palatability of the feed, promoting the food intake and growth rate of yellow catfish.

[0038] 3. Compared to conventional compound feeds, the compound feed prepared according to the present invention significantly changes the body color of yellow catfish, giving it a golden yellow appearance, effectively alleviating the problem of color fading. This is because the specially processed earthworm fermented powder retains a rich source of natural pigments, effectively promoting the formation and maintenance of yellow catfish's color, while being much less expensive than directly adding natural pigment compound powder. DETAILED DESCRIPTION

[0039] The technical solutions of the present invention are described clearly and completely below with the aid of embodiments. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0040] Example 1

[0041] A compound earthworm feed for improving the body color of yellow catfish comprises the following components: 50% earthworm fermentation powder, 15% plant protein source, 15% animal protein source, and 20% starch energy source. The plant protein source is soybean meal, the animal protein source is fish meal, and the starch energy source is corn flour.

[0042] The earthworm fermentation powder is obtained by the following method:

[0043] Before being immersed in the green tea solution, the live earthworms are starved for 24 hours. This starvation treatment involves placing the live earthworms in clean water without any food, allowing them to empty their intestinal contents and reduce impurities in subsequent processing.

[0044] The green tea infusion was prepared as follows: the green tea was immersed in water at a ratio of 100 g / 1 L, the temperature was controlled at 40° C., the pressure was controlled at 2.0 MPa, and the infusion was stirred at a low speed of 90 rpm overnight.

[0045] Step a: Starved live earthworms are mixed with green tea soaking solution at a ratio of 1:2 and soaked for 10 hours to obtain an earthworm soaking solution. During the soaking process, the active ingredients in the green tea soaking solution can fully contact the surface and internal substances of the earthworms, promoting the release of beneficial ingredients.

[0046] Step b: Add red yeast yeast solution to the earthworm bath solution. The inoculation amount of red yeast yeast is 10 7 CFU / mL, fermented under anaerobic conditions for 72 hours. The fermentation temperature was controlled at 28°C and the pH was maintained at 6.8. During the anaerobic fermentation process, Phaffia rhodozyma can break down macromolecules in earthworms, producing a variety of beneficial metabolites while increasing the bioavailability of active substances in the earthworms.

[0047] Step c: The fermentation product is subjected to high-pressure homogenization at 50 MPa, followed by the addition of 0.1% lipase and enzymatic hydrolysis at 37°C for 2 hours to obtain earthworm fermentation slurry. High-pressure homogenization effectively disrupts the earthworm cell wall structure, releasing the cell contents, while the addition of lipase hydrolyzes the earthworm fat, increasing the availability of nutrients.

[0048] Step d: The earthworm fermentation slurry is freeze-dried at -50°C, a vacuum of 10 Pa, and a drying time of 48 hours to obtain earthworm fermentation powder with a moisture content of 19%. The freeze-drying process maximizes the retention of active substances in the earthworm fermentation slurry and prevents nutrient loss due to high temperatures.

[0049] The resulting earthworm fermentation powder is brown in color, has a distinctive aroma, and is fine, uniform, and well-soluble. It is rich in protein, peptides, amino acids, unsaturated fatty acids, as well as various trace elements and bioactive substances, all of which have a significant effect on improving the color of yellow catfish.

[0050] Example 2

[0051] A compound earthworm feed for improving the body color of yellow catfish comprises the following components: 40% earthworm fermentation powder, 25% plant protein source, 25% animal protein source, and 10% starch energy source. The plant protein source is rapeseed meal, the animal protein source is insect meal, and the starch energy source is wheat flour.

[0052] The earthworm fermentation powder is obtained by the following method:

[0053] Before the live earthworms are immersed in the green tea solution, they are starved for 26 hours. During the starvation process, the water is changed regularly to ensure that the earthworms have emptied their intestinal contents.

[0054] The green tea infusion was prepared as follows: the green tea was immersed in water at a ratio of 60 g / 1 L, the temperature was controlled at 35° C., the pressure was controlled at 1.8 MPa, and the infusion was stirred at a low speed of 80 rpm overnight.

[0055] Step a: Mix the starved earthworms with green tea soaking solution at a ratio of 1:3 and soak for 12 hours to obtain an earthworm soaking solution. Maintain the temperature at 25°C and avoid exposure to light during the soaking process.

[0056] Step b: Add red yeast yeast solution to the earthworm bath solution. The inoculation amount of red yeast yeast is 10 7CFU / mL, ferment under anaerobic conditions for 72 hours. The fermentation temperature was controlled at 25°C and the pH was maintained at 6.5. The pH was checked every 24 hours during the fermentation process and adjusted if necessary.

[0057] Step c: The fermentation product was subjected to high-pressure homogenization and cell wall breaking at a pressure of 50 MPa. 0.1% lipase was then added and enzymatically hydrolyzed at 35°C for 2 hours to obtain earthworm fermentation slurry. The pH was maintained at approximately 7.0 during the enzymatic hydrolysis process to ensure optimal lipase activity.

[0058] Step d: freeze-drying the earthworm fermentation slurry at a drying temperature of -45°C, a vacuum degree of 15 Pa, and a drying time of 60 hours to obtain earthworm fermentation powder with a water content controlled at 18%.

[0059] The prepared earthworm fermentation powder is dark brown, has a strong fermentation aroma, and is fine and uniform in powder. It is rich in pigments such as carotenoids and astaxanthin, as well as multiple vitamins and trace elements, which can effectively promote the formation and stabilization of the body color of yellow catfish.

[0060] Example 3

[0061] A compound earthworm feed for improving the color of yellow catfish includes the following components: 65% earthworm fermentation powder, 10% plant protein source, 10% animal protein source, and 15% starch energy source. The plant protein source is a mixture of soybean meal and rapeseed meal in a 1:1 ratio; the animal protein source is a mixture of fish meal and insect meal in a 2:1 ratio; and the starch energy source is a mixture of corn flour and wheat flour in a 1:1 ratio.

[0062] The earthworm fermentation powder is obtained by the following method:

[0063] Before being immersed in the green tea solution, the live earthworms were starved for 25 hours. During the starvation process, the water was changed every 8 hours to ensure that the earthworms had fully emptied their intestinal contents.

[0064] The green tea infusion was prepared as follows: 150g of green tea was mixed with water per liter, and the tea was immersed in water at a temperature of 45°C and a pressure of 2.5 MPa overnight with slow stirring at 100 rpm. A high-concentration green tea infusion contains more tea polyphenols and other active ingredients, which improves the extraction efficiency of beneficial substances from earthworms.

[0065] Step a: Mix starved earthworms with green tea infusion at a 1:1 ratio and soak for 8 hours to create an earthworm soaking solution. Maintain the temperature at 22°C and avoid direct sunlight. Gently stir the mixture every 2 hours to ensure adequate contact.

[0066] Step b: Add red yeast yeast solution to the earthworm bath solution. The inoculation amount of red yeast yeast is 10 7 CFU / mL, fermented under anaerobic conditions for 72 hours. The fermentation temperature was controlled at 30°C and the pH was maintained at 7.0. Anaerobic fermentation tanks were used during the fermentation process to ensure a good anaerobic environment.

[0067] Step c: The fermentation product was subjected to high-pressure homogenization at 50 MPa for three cycles to ensure complete cell disruption. 0.1% lipase was then added and enzymatic hydrolysis was carried out at 40°C for two hours to obtain earthworm fermentation slurry. The pH was maintained at approximately 7.2 during the enzymatic hydrolysis process to ensure optimal lipase activity.

[0068] Step d: freeze-drying the earthworm fermentation slurry at a drying temperature of -55°C, a vacuum degree of 8 Pa, and a drying time of 72 hours to obtain earthworm fermentation powder with a moisture content controlled at 20%.

[0069] Comparative Example 1

[0070] A compound earthworm feed comprises the following components: 50% earthworm powder, 15% plant protein source, 15% animal protein source, and 20% starch energy source, wherein the plant protein source is soybean meal, the animal protein source is fish meal, and the starch energy source is corn flour.

[0071] The preparation method of earthworm powder is as follows: drying living earthworms and grinding them into powder.

[0072] Comparative Example 2

[0073] A compound earthworm feed comprises the following components: 50% earthworm powder, 15% plant protein source, 15% animal protein source, and 20% starch energy source, wherein the plant protein source is soybean meal, the animal protein source is fish meal, and the starch energy source is corn flour.

[0074] The preparation method of earthworm powder is as follows: live earthworms are beaten into pulp, and then freeze-dried and crushed to obtain the pulp.

[0075] Comparative Example 3

[0076] A compound earthworm feed comprises the following components: 50% earthworm fermentation powder, 15% plant protein source, 15% animal protein source, and 20% starch energy source, wherein the plant protein source is soybean meal, the animal protein source is fish meal, and the starch energy source is corn flour.

[0077] The earthworm fermentation powder is obtained by the following method:

[0078] The green tea infusion was replaced with clean water, and the other conditions remained unchanged.

[0079] The compound feeds of the embodiments and comparative examples were used to feed yellow catfish, and the corresponding yellow catfish were tested for relevant test items.

[0080] Breeding conditions:

[0081] Healthy juvenile yellow catfish (initial weight 50±2 g) were fed with the compound feeds of the examples and comparative examples at a feeding rate of 3% body weight / day in a circulating water system (water temperature 25±1° C., dissolved oxygen >6 mg / L) for 2 months.

[0082] Measurement indicators:

[0083] Growth performance: Weight gain rate (%) = (final body weight - initial body weight) / initial body weight × 100%; Feed conversion ratio (FCR) = total feed amount / total weight gain.

[0084] Body color analysis: Take the back skin and measure L* (brightness), a* (redness), and b* (yellowness) with a colorimeter; calculate the golden index: Δb = b 实施例 -b 对比例1 .

[0085] L* (Lightness): Indicates the lightness or darkness of a color, reflecting the overall brightness or darkness of the skin.

[0086] a* (redness): positive values ​​indicate red, negative values ​​indicate green, reflecting the relative amount of red components (possibly derived from hemoglobin, certain carotenoids, etc.) or green components in the skin.

[0087] b* (yellowness): Positive values ​​indicate yellow, negative values ​​indicate blue. This directly quantifies the intensity of the yellow component in the skin. The higher the positive value, the more pronounced the yellow.

[0088] Golden yellow quantitative index: Δb=b 实施例 -b 对比例1 .

[0089] Δb>0: Indicates that the yellowness (yellowness) of the Example group is higher than that of the Comparative Example group. The larger the positive value, the more "yellow".

[0090] Δb<0: Indicates that the yellowness (yellowness) of the Example group is lower than that of the Comparative Example group. The smaller the negative value, the less "yellow" (it may be darker, redder, greener, etc.).

[0091] Pigmentation: The astaxanthin content in muscle was determined by HPLC (mg / kg).

[0092] Incidence of enteritis (%): number of fish tails with enteritis symptoms / total number of fish tails × 100 (dissection observation of intestinal wall congestion / mucus).

[0093] Experimental results:

[0094] Table 1 Body color observed with naked eyes (50th day)

[0095]

[0096]

[0097] Note: Product standard reference: Aquatic product market grading standard (golden yellow > light yellow > grayish yellow > dark brown)

[0098] Table 2. Growth performance and digestibility

[0099]

[0100]

[0101] * indicates p < 0.01 compared with control group 1

[0102] Table 3. Body color improvement effect

[0103]

[0104] * indicates p < 0.01 compared with control group 1

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A compound earthworm feed for improving the body color of yellow catfish, characterized in that: The invention comprises the following components: 40% to 65% of earthworm fermentation powder, 10% to 25% of a plant protein source, 10% to 25% of an animal protein source, and 10% to 20% of a starch energy source; wherein the earthworm fermentation powder is obtained by the following method: Step a: soaking live earthworms in green tea soaking liquid for a period of time to obtain earthworm soaking liquid; Step b: adding Phaffia rhodozyma solution to the earthworm bath solution and performing anaerobic fermentation for 72 hours; Step c: After the fermentation product is homogenized under high pressure (50 MPa), 0.1% lipase is added for enzymatic hydrolysis for 2 h. Obtain earthworm fermentation pulp; Step d: The earthworm fermentation slurry is freeze-dried to obtain earthworm fermentation powder, with the water content controlled at 18-20%.

2. The earthworm compound feed for improving the body color of yellow catfish according to claim 1, characterized in that: Before step a, the live earthworms are starved for at least 24 hours, preferably 24-26 hours.

3. The earthworm compound feed for improving the body color of yellow catfish according to claim 1, characterized in that: The green tea infusion is prepared as follows: immerse the green tea in water at a ratio of 60g-150g / 1L, control the temperature at 40°C ± 5°C, and the pressure at 1.8MPa-2.5MPa, overnight with low-speed stirring, for example, at 80-100rpm.

4. The earthworm compound feed for improving the body color of yellow catfish according to claim 1, characterized in that: In step a, the living earthworms are immersed in the green tea soaking solution for 8-12 hours.

5. The earthworm compound feed for improving the body color of yellow catfish according to claim 1, characterized in that: In step a, the ratio of live earthworms to green tea soaking liquid is 1:1-3.

6. The earthworm compound feed for improving the body color of yellow catfish according to claim 1, characterized in that: In step b, the fermentation temperature is 25° C.-30° C. and the pH is 6.5-7.

0.

7. The earthworm compound feed for improving the body color of yellow catfish according to claim 1, characterized in that: In step b, the inoculation amount of Phaffia rhodozyma is 10 7 CFU / mL.

8. The earthworm compound feed for improving the body color of yellow catfish according to claim 1, characterized in that: The plant protein source is at least one of soybean meal and rapeseed meal.

9. The earthworm compound feed for improving the body color of yellow catfish according to claim 1, characterized in that: The animal protein source is at least one of fish meal and insect meal.

10. The earthworm compound feed for improving the body color of yellow catfish according to claim 1, characterized in that: The starch energy source is at least one of corn flour and wheat flour.

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