A method of rearing fish to reduce the time taken for the development of the ovary

Abstract

The application discloses a breeding method for shortening the ovary development time of fish, and relates to the technical field of aquaculture.The application exhibits significant advantages in shortening the ovary development time of fish through the synergistic application of earthworm additive type stage feed and precise light regulation;as a natural high-protein feed source, earthworms contain natural growth hormone analogs and three types of stage feed, which can be accurately matched to activate the expression of key genes of sexual development of fry.Combined with the regulation of the hypothalamus-pituitary-gonadal axis by a specific light cycle, the ovary development time of fish can be shortened by 30%-40% compared with the traditional breeding method.

Description

Technical Field

[0001] This invention relates to the field of aquaculture technology, specifically to a cultivation method for shortening the ovarian development time of fish. Background Technology

[0002] In aquaculture, the long ovarian development cycle in fish is a key issue restricting reproductive efficiency and farming profitability. Traditional methods, such as natural selection, take many years and are significantly limited by genetic background. While hormone injections (such as HCG and LHRHa) can accelerate gonadal maturation, they have drawbacks such as complex operation, high cost, risk of drug residues, and potential interference with the fish's endocrine system.

[0003] The limitations of existing technologies are mainly reflected in the following aspects: Insufficient efficiency of single regulatory methods: Relying solely on hormones or environmental regulation makes it difficult to precisely accelerate ovarian development. For example, while *Amberjack* can mature earlier through comprehensive regulation of water temperature and light, continuous monitoring of the gonadal index (GSI) and serum sex hormone levels is required, making the operation cumbersome and the results unstable. Limited application of gene regulation technology: Although somatic cell gene transfer technology (such as follicle-stimulating hormone carriers) can induce early ovarian development in *Amberjack* with an induction efficiency of 85%, it requires specialized laboratory conditions and complex operations, making it difficult to promote in large-scale aquaculture. Damaging and lagging nature of monitoring technologies: Traditional dissection or surgical egg retrieval methods can lead to the death or injury of parent fish, while non-invasive technologies such as MRI can dynamically monitor ovarian development, but the equipment is expensive and difficult to popularize. Insufficient application of multi-factor synergistic effects: The synergistic mechanism of temperature and light regulation, nutritional fortification, and gene expression has not yet been systematically elucidated. For example, in the breeding of turbot broodstock, although the synergistic effect of water temperature (12~14℃), light intensity (17~19 hours), and lecithin supplementation is significant, there is a lack of precise control schemes for different developmental stages. Studies on grouper show that the combined use of IGF-1 and hCG can synergistically promote ovarian maturation, but further research is needed to optimize its time window and dosage. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a cultivation method for shortening the ovarian development time of fish.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A method for shortening the ovarian development time in fish is provided, comprising the following steps: S1: Place 1-month-old fish fry in water at 18~25℃ and feed them powdered feed containing 10%~15% freeze-dried earthworm fermentation liquid for 25~35 days; S2: Increase the proportion of freeze-dried earthworm fermentation liquid in the powdered feed, feed the feed with 15%~25% freeze-dried earthworm fermentation liquid, and irradiate with 455nm blue light for 8 hours a day for 40~50 days. S3: Feed a mixture of powdered feed containing 10%~15% freeze-dried earthworm fermentation liquid and pelleted feed containing earthworm compound fermented soybean meal; the ratio of powdered feed to mixed feed in the mixed feed is 7:3; and continue to feed under 455nm blue light irradiation for 45~65 days, with the blue light irradiation time being 12 hours per day. S4: Feed the animal with pelleted feed containing earthworm-fermented soybean meal and expose it to 625nm red light for 15-20 days. The daily exposure time to red light is 14 hours.

[0006] Furthermore, the preparation method of the earthworm fermentation liquid freeze-dried powder is as follows: after crushing the earthworms, add neutral protease, ferment and hydrolyze for 10 days, filter to obtain fermentation liquid, and freeze-dry the fermentation liquid under vacuum to obtain earthworm fermentation liquid freeze-dried powder; the mass ratio of the added neutral protease to the earthworms is 2~4:150.

[0007] Furthermore, the fish fry feed is prepared by mixing 28 parts silkworm pupa powder, 20 parts soybean meal powder, 18 parts corn flour, 2 parts vegetable oil, 1 part compound vitamins, 0.5 parts compound trace minerals, 0.3 parts sodium carboxymethyl cellulose and 0.1 parts phytase. The powdered feed is obtained by mixing the freeze-dried earthworm fermentation liquid with fish fry feed. The powdered feed needs to be sieved through a 100-mesh screen before feeding.

[0008] Furthermore, the specific method for preparing the pelleted feed of earthworm-fermented soybean meal is as follows: A1: Crush the earthworms, add neutral protease, and ferment for 2-3 days; A2: Mix the fermented earthworms into soybean meal, mix evenly, and then compost for 10 days to obtain earthworm compound fermented soybean meal. A3: Take 10-15 parts of freeze-dried earthworm fermentation liquid powder, 40-47 parts of earthworm compound fermented soybean meal, 18 parts of peeled soybean meal, 15 parts of wheat flour, 4 parts of vegetable oil, 3 parts of phospholipid powder, 1 part of compound vitamins, 1 part of compound trace minerals and 0.1 parts of choline, mix them evenly, and then wet-granulate to obtain pellet feed with a particle size of 2-3 mm.

[0009] Fermenting earthworms with neutral protease releases their endogenous enzymes. The earthworms' endogenous enzymes, together with the neutral protease, ferment soybean meal, allowing more soy isoflavones in the soybean meal to exist in a free state. These free soy isoflavones can be absorbed by fish after ingestion, accelerating gonadal development.

[0010] Furthermore, in step A1, the mass ratio of neutral protease to earthworms is 2-4:150; the mass ratio of fermented earthworms to soybean meal is 8-12:100.

[0011] Furthermore, in step A2, on the third day of composting, Bacillus subtilis is added, mixed evenly, and composting continues.

[0012] When neutral protease is fermented with earthworms, the first three days are the adaptation period for neutral protease. Starting from the fourth day, neutral protease enters the logarithmic growth and stabilization phase. During the logarithmic growth phase, organic acids accumulate rapidly, which leads to premature inactivation of neutral protease. Since soybean meal needs to be fully decomposed, prematurely inactivated neutral protease will prolong the composting time and reduce feed preparation efficiency. Adding Bacillus on the second or third day can effectively balance the pH of the compost pile and prolong the activity of neutral protease. Therefore, the endogenous enzymes, neutral protease, and Bacillus abundant in earthworms can enhance the decomposition of earthworm body walls, earthworm metabolites, and large molecular proteins abundant in soybean meal, and make more of the soy isoflavones in soybean meal exist in a free state.

[0013] Furthermore, the amount of Bacillus added is 0.05~0.08%wt.

[0014] Furthermore, the vegetable oil is at least one of peanut oil, soybean oil, rapeseed oil, and sunflower seed oil.

[0015] Furthermore, the mineral additives include at least one of sodium chloride, cobalt chloride, magnesium sulfate, zinc sulfate, copper sulfate, ferric sulfate, sodium phosphate, potassium phosphate, calcium phosphate, and potassium iodate.

[0016] Furthermore, the vitamin additive includes at least one of vitamin A, vitamin B1, vitamin B2, vitamin B6, vitamin B12, vitamin C, vitamin D, vitamin E, vitamin H, and vitamin K.

[0017] The beneficial effects of this invention are as follows: 1. This invention demonstrates a significant advantage in shortening the ovarian development time of fish through the synergistic application of earthworm-added staged feed and precise light regulation. Earthworms, as a natural high-protein feed source, contain natural growth hormone analogs. The precise ratio of these three staged feeds promotes the release of soybean isoflavones in soybean meal, specifically activating the expression of key genes for fish fry sexual development. Combined with the regulatory effect of specific light cycles on the hypothalamus-pituitary-gonadal axis, the ovarian development time of fish can be shortened by 30% to 40% compared to traditional breeding methods.

[0018] 2. Compared to complex technologies such as gene editing or hormone injection, this method requires no specialized equipment and can achieve precise regulation through feed changes and light parameter settings. Light regulation achieves physiological regulation through non-invasive physical intervention, avoiding the ecological safety controversies surrounding gene editing technology and meeting the standards for pollution-free aquaculture. Attached Figure Description

[0019] Figure 1 This is a comparative anatomical image of the ovary of the Sichuan bream in an embodiment of the present invention. Detailed Implementation

[0020] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0021] This invention uses the Sichuan bream (a species endemic to the upper reaches of the Yangtze River) as an example. Sinibrama taeniatus The parent fish were collected from natural populations in the Yibin section of the Yangtze River. Five pairs of healthy parent fish (female to male ratio of 1:1) with gonadal maturity of stage IV or above and no damage to their body surface were selected for breeding. The specific method was as follows: LRH-A2 (10μg / kg) and DOM (5mg / kg) were used to induce spawning, and fertilized eggs were obtained by dry insemination. After hatching, the fry were fed and cultivated using the method of this invention.

[0022] Example 1: Preparation of Powdered Feed The powdered feed for the experimental fish was prepared using the following method: After washing the fresh live earthworms to remove the soil, crush them. Then, add neutral protease to the earthworms at a mass ratio of 2-4:150, mix well, and carry out fermentation and enzymatic hydrolysis. After 10 days, filter to obtain the fermentation liquid. Vacuum freeze-dry the fermentation liquid to obtain the earthworm fermentation liquid freeze-dried powder.

[0023] Take 28 parts silkworm pupa powder, 20 parts soybean meal powder, 18 parts corn flour, 2 parts vegetable oil, 1 part compound vitamins, 0.5 parts compound trace minerals, 0.3 parts sodium carboxymethyl cellulose and 0.1 parts phytase and mix them to obtain fish fry feed; The prepared freeze-dried earthworm fermentation liquid powder is mixed with fish fry feed at a mass ratio of 10~15:85~90 to obtain a powdered feed containing 10%~15% freeze-dried earthworm fermentation liquid powder.

[0024] The prepared freeze-dried earthworm fermentation liquid powder is mixed with fish fry feed at a mass ratio of 15~25:75~85 to obtain a powdered feed containing 15%~25% freeze-dried earthworm fermentation liquid powder.

[0025] Example 2: Preparation of Pelleted Feed The experimental fish were prepared using the following method: A1: After crushing the earthworms, add neutral protease at a mass ratio of 2-4:150 and ferment for 2-3 days. A2: Add the fermented earthworms from step A1 to soybean meal at a mass ratio of 8~12:100, mix evenly, and then compost for 10 days to obtain earthworm compound fermented soybean meal. During the composting process, in order to avoid the temperature of the compost pile getting too high, the pile is turned over on the 3rd and 6th days. When turning the pile on the 3rd day, Bacillus spores are added to the fermentation pile. The amount of Bacillus spores added is 0.05~0.08%wt of the compost pile. A3: Take 10-15 parts of the freeze-dried earthworm fermentation liquid prepared by the method of Example 1, 40-47 parts of earthworm compound fermented soybean meal, 18 parts of peeled soybean meal, 15 parts of wheat flour, 4 parts of vegetable oil, 3 parts of phospholipid powder, 1 part of compound vitamins, 1 part of compound trace minerals and 0.1 parts of choline, mix them evenly, and then wet granulate to obtain pellet feed with a particle size of 2-3 mm.

[0026] Example 3: Feeding of experimental fish The following method was used to feed the bred 1-month-old Sichuan bream: S1: Place 1-month-old fish fry in water at 18-25℃ and feed them with powdered feed prepared according to the method of Example 1, which contains 10%-15% freeze-dried earthworm fermentation liquid powder, for 25-35 days. The daily feeding amount is 5%-8% of the fish's body weight. Use an automatic feeder to feed them once every 4 hours, and sprinkle the powdered feed evenly on the water surface during feeding to ensure that the fish fry in the water can ingest sufficient feed. S2: Increase the proportion of freeze-dried earthworm fermentation liquid in the powdered feed, feed the fish with powdered feed containing 15%~25% freeze-dried earthworm fermentation liquid, and feed the fish with 6%~9% of their body weight per day; feed the fish every 4 hours and irradiate them with 455nm blue light for 8 hours per day for 40~50 days. S3: Feed a mixture of powdered feed containing 10%~15% freeze-dried earthworm fermentation liquid and pelleted feed containing earthworm compound fermented soybean meal; the ratio of powdered feed to mixed feed in the mixed feed is 7:3; the daily feeding amount is 5%~7% of the fish's body weight; feed once every 4 hours, and continue to feed under 455nm blue light irradiation for 45~65 days, and the daily irradiation time of blue light is 12 hours; S4: Feed the fish with pelleted feed containing earthworm-fermented soybean meal prepared according to the method in Example 2. The daily feeding amount is 3% to 5% of the fish's body weight. Feed once every 8 hours. When feeding, to avoid the bream gathering and competing for food, the pelleted feed is evenly scattered on the water surface. Feed the fish under 625nm red light for 15 to 20 days, with the red light irradiation time being 14 hours per day.

[0027] Three experimental groups were set up, and a control group was also set up. The configuration of the control group is shown in Table 1. Table 1

[0028] After the fourth stage of feeding begins, the bream in the water are photographed daily, and the HRNet model is used to record the three-day average body width and body length data of the bream. When the three-day average body width to body length data of the current day is less than or equal to the three-day average body width to body length data of the previous day, the fourth feeding stage is completed, and the number of feeding days when the fourth feeding stage ends is counted. Simultaneously, the average body width, body length, and weight of the experimental fish were statistically analyzed. The ovarian development level of the fish was evaluated by combining morphological and anatomical data. In this embodiment, only female bream were statistically analyzed, and the results are shown in Table 2 below. Table 2

[0029] As shown in Table 2, the feeding method described in this application can significantly accelerate the ovarian maturation process of Sichuan bream, while promoting its body length and width growth, and increasing the ratio of body width to body length. The ovaries of the Sichuan bream with the largest body width in each group were dissected, and the results of the ovarian dissection are shown below. Figure 1 As shown, by Figure 1 It was found that the ovaries of fish in experimental group 1 were fully developed, and their gonadal index (GSI) was significantly higher than that of the other groups; the ovaries of fish in experimental groups 2 and 3 began to show eggs, indicating that they had entered the vitelline development stage; the ovaries of the other control groups were all in the early stages of development. The results indicate that the feeding method described in this application can meet the conditions of balanced nutrition and reasonable lighting, significantly shorten the ovary development time of fish, and promote better growth performance. Therefore, it can achieve more significant results whether for aquaculture harvesting or breeding broodstock.

Claims

1. A cultivation method for shortening the ovarian development time of Sichuan bream, characterized in that, Includes the following steps: S1: Place 1-month-old Sichuan bream fry in water at 18-25℃ and feed them powdered feed containing 10%-15% freeze-dried earthworm fermentation liquid for 25-35 days; the daily feeding amount is 5%-8% of the body weight of the Sichuan bream, and an automatic feeder is used to feed them once every 4 hours. S2: Increase the proportion of freeze-dried earthworm fermentation liquid in the powdered feed, feed the feed with 15%~25% freeze-dried earthworm fermentation liquid, and irradiate with 455nm blue light for 8 hours a day for 40~50 days; the daily feeding amount is 6%~9% of the body weight of Sichuan bream, and feed once every 4 hours; S3: Feed a mixture of powdered feed containing 10%~15% freeze-dried earthworm fermentation liquid and pelleted feed containing earthworm compound fermented soybean meal; the ratio of powdered feed to mixed feed in the mixed feed is 7:3; continue feeding under 455nm blue light irradiation for 45~65 days, with the blue light irradiation time being 12 hours per day; the daily feeding amount is 5%~7% of the body weight of Sichuan bream, fed once every 4 hours; S4: Feed pelleted feed containing earthworm-fermented soybean meal and irradiate with 625nm red light for 15-20 days, with each day's red light irradiation time being 14 hours; the daily feeding amount is 3%-5% of the body weight of Sichuan bream, and feeding is done every 8 hours.

2. The cultivation method for shortening the ovarian development time of Sichuan bream according to claim 1, characterized in that, The preparation method of the earthworm fermentation liquid freeze-dried powder is as follows: after crushing earthworms, add neutral protease, ferment and hydrolyze for 10 days, filter to obtain fermentation liquid, and freeze-dry the fermentation liquid under vacuum to obtain earthworm fermentation liquid freeze-dried powder; the mass ratio of added neutral protease to earthworms is 2~4:

150.

3. The cultivation method for shortening the ovarian development time of Sichuan bream according to claim 2, characterized in that, The fish fry feed is prepared by mixing 28 parts silkworm pupa powder, 20 parts soybean meal powder, 18 parts corn flour, 2 parts vegetable oil, 1 part compound vitamins, 0.5 parts compound trace minerals, 0.3 parts sodium carboxymethyl cellulose and 0.1 parts phytase. The powdered feed is obtained by mixing the freeze-dried earthworm fermentation liquid with fish fry feed. The powdered feed needs to be sieved through a 100-mesh screen before feeding.

4. The cultivation method for shortening the ovarian development time of Sichuan bream according to claim 1, characterized in that, The specific method for preparing the earthworm-fermented soybean meal pellet feed is as follows: A1: Crush the earthworms, add neutral protease, and ferment for 2-3 days; A2: Mix the fermented earthworms into soybean meal, mix evenly, and then compost for 10 days to obtain earthworm compound fermented soybean meal. A3: Take 10-15 parts of freeze-dried earthworm fermentation liquid powder, 40-47 parts of earthworm compound fermented soybean meal, 18 parts of peeled soybean meal, 15 parts of wheat flour, 4 parts of vegetable oil, 3 parts of phospholipid powder, 1 part of compound vitamins, 1 part of compound trace minerals and 0.1 parts of choline, mix them evenly, and then wet-granulate to obtain pellet feed with a particle size of 2-3 mm.

5. The cultivation method for shortening the ovarian development time of Sichuan bream according to claim 4, characterized in that, In step A1, the mass ratio of neutral protease to earthworms is 2-4:150; in step A2, the mass ratio of fermented earthworms to soybean meal is 8-12:

100.

6. The cultivation method for shortening the ovarian development time of Sichuan bream according to claim 4, characterized in that, In step A2, on the third day of composting, Bacillus spores are added, mixed evenly, and composting continues.

7. The cultivation method for shortening the ovarian development time of Sichuan bream according to claim 6, characterized in that, The amount of Bacillus added is 0.05~0.08%wt.

8. The cultivation method for shortening the ovarian development time of Sichuan bream according to claim 4, characterized in that, The vegetable oil is at least one of peanut oil, soybean oil, rapeseed oil, and sunflower seed oil.

9. The cultivation method for shortening the ovarian development time of Sichuan bream according to claim 3 or 4, characterized in that, The complex trace minerals include at least one of sodium chloride, cobalt chloride, magnesium sulfate, zinc sulfate, copper sulfate, ferric sulfate, sodium phosphate, potassium phosphate, calcium phosphate, and potassium iodate.

10. The cultivation method for shortening the ovarian development time of Sichuan bream according to claim 3 or 4, characterized in that, The multivitamin includes at least one of vitamin A, vitamin B1, vitamin B2, vitamin B6, vitamin B12, vitamin C, vitamin D, vitamin E, vitamin H, and vitamin K.

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