Application of Acremonium terricola culture in eel farming

Abstract

The present invention discloses the application of Acremonium terricola culture in eel farming, belonging to the technical field of aquaculture, which is used to improve the weight gain rate of eels. The Acremonium terricola culture is used to improve the intestinal digestive enzyme activity of eels, and the dosage of the Acremonium terricola culture is 0.1-0.3 wt% of the basic formula feed for eels; the weight gain rate of eels is calculated through experiments, blood biochemical and immune indexes are analyzed, and the digestive enzyme activity of the foregut is measured; the results show that after the Acremonium terricola culture is added to the technical formula feed for eels in a small amount, it can significantly increase the weight gain rate of eels. Through experimental verification, the Acremonium terricola culture helps to increase the number of red blood cells, total protein content, complement C4 content, superoxide dismutase content and lysozyme content in the blood of eels, can also reduce the urea nitrogen content in the blood of eels, and helps to improve the intestinal digestive enzyme activity of eels, thereby promoting the growth of eels and increasing the yield.

Description

Technical Field

[0001] The present invention belongs to the technical field of aquaculture, and specifically relates to the application of Acremonium terricola culture in the cultivation of eels. Background Art

[0002] Acremonium terricola is a fungus of the family Geosmithiaceae, which widely exists in the natural environment, commonly found in soil, water bodies, air, and on the surfaces of various animals and plants. It can decompose organic matter, such as plant residues, animal excreta, etc., thus playing an important role in the ecosystem.

[0003] Acremonium terricola culture is a new type of green feed additive prepared by using the solid-liquid double fermentation technology with artificial culture medium from the Acremonium terricola strain isolated from Cordyceps. It contains active ingredients similar to Cordyceps. Through research, it has been shown that Acremonium terricola culture can regulate the immune function of livestock and poultry animals and improve the production performance of mammals, etc., but its application in the cultivation of eels has not been reported. Summary of the Invention

[0004] The purpose of the present invention is to provide the application of Acremonium terricola culture in the cultivation of eels.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] The application of Acremonium terricola culture in the cultivation of eels, wherein the addition amount of Acremonium terricola culture in the feed is 0.1% to 0.3%, which is used to improve the intestinal digestive enzyme activity of eels, enhance the immune function and antioxidant activity of eels, and increase the weight gain rate of eels.

[0007] The feasibility of the application of Acremonium terricola culture in the cultivation of eels is verified through experiments.

[0008] 1. Experimental animals and grouping

[0009] Wild eel seedlings, with a body weight of about 25 g. They are cultured in net cages (2 m × 1.5 m × 1 m), with 100 tails in each cage. The bait is fed at 4% of the eel body weight, once a day (at 5 pm).

[0010] A control group, experimental group 1, and experimental group 2 are set up, and each group contains 3 parallel net cage replicates. The control group is fed with the basic formula feed, and experimental group 1 and experimental group 2 are respectively added with 0.1% and 0.3% of Acremonium terricola culture in the basic formula feed.

[0011] 2. Index Observation: Observe and record the water temperature in the breeding area and whether there are any abnormal situations of eels every day. The test period is 8 weeks (from May 12, 2023 to July 7, 2023). Weigh the whole box at the beginning and end of the test, calculate the average weight of each eel, and conduct a significance analysis on the data of 3 parallel replicates. At the end of the test, randomly select 10 eels from each group, analyze the blood biochemical and immune indexes, and measure the digestive enzyme activity in the foregut.

[0012] Advantages of the present invention:

[0013] After adding a small amount of Geotrichum coccidii culture to the technical formula feed for eels, the weight gain rate of eels can be significantly increased, which is economical, efficient and environmentally friendly. Through experimental verification, Geotrichum coccidii culture helps to increase the number of red blood cells, total protein content, complement C4 content, superoxide dismutase content and lysozyme content in the blood of eels, improve the immune function and antioxidant activity of eels, and can also reduce the urea nitrogen content in the blood of eels, and helps to improve the digestive enzyme activity in the intestine of eels, thereby promoting the growth of eels and increasing the yield. Specific Embodiments

[0014] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0015] Example 1

[0016] Formulating the test

[0017] 1. Test animals and grouping: Prepare 9 cages with specifications of 2m×1.5m×1m, place the cages in an artificial pond, control the water temperature at 18 - 22°C, and aerate and oxygenate every day; select wild eel seedlings with a weight of about 25g, evenly put them into different cages for breeding, and mark them as the control group, test group 1 and test group 2. Each group sets 3 parallel cages and controls the number of wild eel seedlings to be 100.

[0018] 2. Feeding method: The control group is fed with the basic formula feed, the feed fed to the test group 1 is the basic formula feed added with 0.1wt% Geotrichum coccidii culture, and the feed fed to the test group 2 is the basic formula feed added with 0.3wt% Geotrichum coccidii culture; the feeding period is 8 weeks (from May 12, 2023 to July 7, 2023), and it is fed once a day (at 5 pm), and the quality of the feed fed each time is 4% of the total weight of the wild eels in the cage.

[0019] The basic formula feed is selected from commercially available feeds, and the ingredients are shown in Table 1:

[0020] Table 1

[0021] Ingredient Content / % Peruvian steam fish meal 40 Soybean meal 20 Fish oil 2 Shrimp meal 6 Choline 0.5 Monopterus albus premix 1 Calcium dihydrogen phosphate 1.2 α-starch 18

[0022] The Acremonium terricola culture is a product of Hefei Macro-Bioengineering Co., Ltd., with the batch number 20230110. Quality indicators: ergosterol 670 mg / kg, adenosine 432 mg / kg.

[0023] Example 2

[0024] Body weight detection

[0025] After the feeding cycle ended, the total weight of the eels in each net cage was weighed, and the average weight of each eel was calculated. The repeated data of the three parallel net cages in each group were subjected to a significance analysis.

[0026] The results are shown in Table 2:

[0027] Table 2

[0028]

[0029]

[0030] Note: Different letters indicate significant differences between groups (p ≤ 0.05).

[0031] Analysis of the experimental data shows that compared with the control group, the final body weight and weight gain rate of the eels in the two experimental groups were significantly increased, the feed coefficient was significantly decreased, and the survival rate did not change. The experimental results suggest that adding the Acremonium terricola culture can significantly improve the growth performance and feed utilization rate of eels, thereby improving the breeding efficiency. In addition, when comparing Experimental Group 2 (addition amount 0.3%) with Experimental Group 1 (0.1%), the weight gain rate was higher and the feed coefficient was lower, but the difference did not reach a significant level, indicating that in actual production, the addition amount of the Acremonium terricola culture is preferably 0.1%.

[0032] Example 3

[0033] Blood biochemical and immune indicators

[0034] In each group of eels after the feeding cycle in Example 1, 10 eels were randomly selected and fixed. Add 20 μL of 0.1% heparin physiological saline solution to a 0.5 μL EP tube. Vertically and centrally insert a syringe into the caudal vein about 1 cm behind the anus of the eel. When it is felt that the needle touches the spine, gently touch it and slowly draw the syringe. Draw 100 μL of blood samples from each eel; detect the number of red blood cells, total protein content, urea nitrogen content, complement C4 content, superoxide dismutase content, and lysozyme content in the blood samples. The results are shown in Table 3:

[0035] Table 3

[0036] Item Control group Test group 1 Test group 2 <![CDATA[Red blood cells (×10 12 cells / L)]]> <![CDATA[3.28±0.05 a > <![CDATA[5.21±0.06 b > <![CDATA[5.13±0.06 b > Total protein (mg / mL) <![CDATA[41.25±2.21 a > <![CDATA[48.46±3.95 b > <![CDATA[54.77±4.363 b > Urea nitrogen (mmol / L) <![CDATA[3.52±0.41 a > <![CDATA[2.71±0.41 b > <![CDATA[2.48±0.31 b > Complement C4 (g / L) <![CDATA[0.102±0.01 a > <![CDATA[0.135±0.01 b > <![CDATA[0.138±0.01 b > Superoxide dismutase (U / mL) <![CDATA[126.22±8.60 a > <![CDATA[164.19±17.55 b > <![CDATA[177.95±14.25 b > Lysozyme (U / mL) <![CDATA[105.78±5.67 a > <![CDATA[137.43±8.33 b > <![CDATA[145.42±9.10 b >

[0037] Note: Different letters indicate significant differences between groups (p ≤ 0.05).

[0038] As can be seen from Table 3, for the eels fed with the basic formula feed supplemented with Acremonium terricola culture, the number of red blood cells, total protein content, complement C4 content, superoxide dismutase content, and lysozyme content in their blood were all significantly increased, while the urea nitrogen content in the blood of eels in experimental group 1 and experimental group 2 decreased. These results suggest that the addition of Acremonium terricola culture significantly improved the health status of eels, and enhanced their immunity, antioxidant and anti-infection abilities.

[0039] Example 4

[0040] Digestive enzyme activity

[0041] Randomly select 10 eels from each group of eels after the feeding cycle in Example 1. After dissection, take 100 mg of fresh anterior intestine of the eel digestive tract, dry it with filter paper and weigh it, add 10 times its mass of ultrapure water, homogenize it with an electric homogenizer under ice bath conditions, then centrifuge it at 4 °C and 6000 r / min for 10 min, take the supernatant and store it at 4 °C, and measure the enzyme activities of trypsin, amylase and lipase respectively (measurement should be completed within 24 h after preparing the supernatant).

[0042] The determination of trypsin adopts the Folin-phenol reagent colorimetric method with casein as the substrate. The protease activity is defined as the amount of enzyme that hydrolyzes 1 μg of tyrosine per minute at 37 °C with casein as the substrate, and 1 enzyme activity unit is defined as such.

[0043] The determination of amylase adopts the starch-iodine colorimetric method. The amylase activity unit is defined as the amylase in 100 mL of enzyme solution that can completely hydrolyze 10 mg of starch within 30 min at 37 °C, and 1 amylase activity unit is defined as such.

[0044] The determination of lipase adopts the method of detecting the degradation of fat in fresh milk by lipase to measure the lipase activity. Take 3 mL of fresh milk, preheat it at 37 °C for 10 min, add 0.5 mL of the crude enzyme extract, shake and react at 37 °C for 60 min, add 1.5 mL of 95% ethanol to terminate the reaction; add 3 - 4 drops of phenolphthalein reagent to the reaction solution, and titrate it with 0.01 mol / L NaOH solution until the solution turns pink; in the control reaction, add ethanol to fresh milk first to inactivate the enzyme and then add distilled water; the lipase activity is defined as the number of micromoles of NaOH consumed per 1 mg of enzyme protein per 1 min, and 1 lipase activity unit is defined as such.

[0045] The results are shown in Table 4:

[0046] Table 4

[0047] Item Trypsin U / mg Amylase U / mg Lipase U / mg Control group <![CDATA[1183.33±25.78 a > <![CDATA[0.051±0.001 a > <![CDATA[18.43±2.44 a > Test group 1 <![CDATA[1432.35±32.53 b > <![CDATA[0.066±0.002 b > <![CDATA[26.19±3.11 b > Test group 2 <![CDATA[1513.87±40.17 b > <![CDATA[0.068±0.002 b > <![CDATA[24.78±2.51 b >

[0048] Note: Different letters indicate significant differences between groups (p ≤ 0.05).

[0049] As can be seen from Table 4, for the eels fed with the basic formula feed supplemented with Acremonium terricola culture, the activities of trypsin, amylase, and lipase in the anterior intestine of their digestive tract have all increased significantly. The test results suggest that adding Acremonium terricola culture can promote the growth of eels, and the reason may be that Acremonium terricola culture improves the digestive ability of eels.

[0050] It should be noted that in this article, terms such as "including", "comprising", or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such a process, method, article, or device.

[0051] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Application of Acremonium terricola culture in eel farming, characterized in that, The application is used to improve the weight gain rate of eels.

2. Application of Acremonium terricola culture in eel farming, characterized in that, The Acremonium terricola culture is used to improve the intestinal digestive enzyme activity of eels.

3. Application of Acremonium terricola culture in eel farming, characterized in that, The Acremonium terricola culture is used to improve the immune function and antioxidant activity of eels.

4. Use of the acremonium terricola culture according to any one of claims 1 to 3 in the cultivation of eels, characterized in that The addition amount of the Acremonium terricola culture in the feed is 0.1% - 0.3%.

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