Composition for promoting gonad maturation of wild sal-family large yellow croaker and application thereof

Abstract

The invention discloses a composition for promoting gonad maturation of wild sal-family large yellow croakers and application of the composition, and belongs to the technical field of aquaculture. Through scientific proportioning of gonadotropin releasing hormone (GnRH) or analogues, polypeptide gonadotropin (FSH, LH) and auxiliary hormone (dopamine receptor antagonist), multi-target activation of an endocrine system of wild parent fish is realized, and synchronous maturation of gonads is promoted. Meanwhile, culture environment parameters such as illumination period, water temperature and salinity are optimized, an ecological environment suitable for sexual maturity is built, stress is reduced, the health of the parent fish is guaranteed, efficient, synchronous and safe sexual maturity of the parent fish is achieved, the breeding efficiency and the fry quality are remarkably improved, an artificial breeding technology of the Pseudosciaena crocea of the sal family is promoted to stride towards the scientization, standardization and industrialization direction, and the economic benefit is increased. And sustainable development of marine fishery resource protection and culture industry is promoted.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aquaculture, and particularly relates to a composition for promoting gonadal maturation of wild Lutjanus Russelii and application thereof. BACKGROUND

[0002] Wild Lutjanus Russelii is a marine aquaculture species with high economic value and ecological importance in China's coastal waters. As a high-quality marine fishery resource, the efficient artificial breeding of wild parent fish is of great strategic significance for the sustainable utilization of resources and the upgrading and transformation of the aquaculture industry. At present, artificial breeding technology plays a key role in protecting resources and meeting market demand, but traditional methods of promoting sexual maturation and artificial induction have many technical bottlenecks and deficiencies. Existing induction techniques mostly use single gonadotropin or synthetic hormones, and the types of hormones are single and the dosage and injection timing lack scientific and precise optimization, making it difficult to fully activate the hypothalamic-pituitary-gonadal axis of parent fish, resulting in asynchronous sexual maturation, affecting the fertilization rate and stability of embryo development.

[0003] Therefore, there is an urgent need to develop a sexual maturation and artificial induction scheme to achieve efficient, synchronous and safe sexual maturation of parent fish, significantly improve breeding efficiency and fry quality, promote the scientific, standardized and industrialization of artificial breeding technology of Lutjanus Russelii, and promote the sustainable development of marine fishery resources protection and aquaculture industry. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a composition for promoting gonadal maturation of wild Lutjanus Russelii, which can activate multiple targets in the endocrine system of wild parent fish through scientific proportioning and promote synchronous gonadal maturation.

[0005] Another purpose of the present application is to provide the application of the composition in artificial induction of wild Lutjanus Russelii.

[0006] Another purpose of the present application is to provide an artificial induction method for wild Lutjanus Russelii.

[0007] In order to achieve the above-mentioned purposes, the present application provides the following technical solutions: The present application provides a composition for promoting gonadal maturation of wild Lutjanus Russelii, which comprises component one and component two. The component one comprises 0.2-0.5 mu g of gonadotropin-releasing hormone or its analogues and 0.5-1.0 mg of dopamine receptor antagonists per kg of body weight of wild Lutjanus Russelii female fish; and the component two comprises 0.1-0.3 IU of follicle-stimulating hormone and luteinizing hormone mixture. The component one comprises 0.2-0.5 μg of gonadotropin-releasing hormone or its analog and 0.5-1.0 mg of dopamine receptor antagonist; and the component two comprises 0.1-0.15 IU of follicle-stimulating hormone and luteinizing hormone mixture.

[0008] Preferably, the activity unit ratio of the follicle-stimulating hormone to the luteinizing hormone is (2-1):1.

[0009] The application further provides a use of the composition in artificial spawning of wild Pseudosciaena crocea.

[0010] The application further provides an artificial spawning method of wild Pseudosciaena crocea, which comprises injecting the composition into wild Pseudosciaena crocea parent fish.

[0011] Preferably, the injection method comprises injecting the component one into wild Pseudosciaena crocea parent fish by intramuscular injection, and 70-74 h after the injection, injecting the component two into wild Pseudosciaena crocea parent fish by intramuscular injection.

[0012] Preferably, the injection of the component one is performed in the morning to the morning period.

[0013] Preferably, the injection of the component two is performed when the ovary of the female fish develops to the IV stage and the egg diameter reaches ≥0.95 mm; 70-74 h after the injection of the component one, if the sperm of the male fish is stable, the semen is milky white, and the sperm motility is ≥80%, the injection of the component two can be omitted; if the sperm motility of the male fish is <80%, and / or the semen density and the sperm amount are insufficient, the injection of the component two is performed.

[0014] Preferably, the breeding environment of the wild Pseudosciaena crocea parent fish is regulated, and the artificial spawning method further comprises controlling the light period to be 14-16 h of light and 8-10 h of dark per day, and the light intensity gradually changes within 10-20 min; the light intensity is 200-300 lux, the color temperature is 5000 K; the temperature is 26-28℃; and the water flow rate is 0.05-0.10 m / s.

[0015] Preferably, the breeding water quality condition of the wild Pseudosciaena crocea parent fish is regulated, and the artificial spawning method further comprises maintaining the salinity at 30±1 ppt, keeping the dissolved oxygen at more than 6.5 mg / L, controlling the ammonia nitrogen concentration to be less than 0.1 mg / L, keeping the nitrite concentration to be less than 0.02 mg / L, and maintaining the pH value to be 7.8-8.3.

[0016] Preferably, the artificial spawning method further comprises monitoring the health of the parent fish.

[0017] Preferably, the method of monitoring comprises: periodically collecting blood samples, determining the plasma gonadotropin-releasing hormone, follicle-stimulating hormone, luteinizing hormone, serum total protein, white blood cell count and oxidative stress indicators, and evaluating the immune function and stress state of the brood fish; monitoring the feeding frequency, swimming speed and behavior pattern of the brood fish, and identifying abnormal behaviors such as food refusal, floating head and abnormal swimming The present application has the following advantages: The present application realizes multi-target activation of the endocrine system of wild brood fish by scientifically proportioning gonadotropin-releasing hormone (GnRH) or analogs, polypeptide gonadotropin (FSH, LH) and auxiliary hormones (dopamine receptor antagonists), promotes synchronous maturation of gonads, optimizes the parameters of the breeding environment such as light cycle, water temperature and salinity, creates an ecological environment suitable for maturation, reduces stress, ensures the health of brood fish, realizes efficient, synchronous and safe maturation of brood fish, significantly improves the breeding efficiency and fry quality, promotes the scientific, standardized and industrialization of artificial breeding technology of Naozhou group Pseudosciaena crocea, and promotes the sustainable development of marine fishery resources protection and aquaculture industry. DETAILED DESCRIPTION

[0018] The present application provides a composition for promoting the maturation of gonads of wild Naozhou group Pseudosciaena crocea, which comprises component one and component two. In terms of the body weight of 1 kg of wild Naozhou group Pseudosciaena crocea female fish, the component one comprises 0.2-0.5 μg of gonadotropin-releasing hormone or analogs and 0.5-1.0 mg of dopamine receptor antagonists; and the component two comprises 0.1-0.3 IU of a mixture of follicle-stimulating hormone and luteinizing hormone. In terms of the body weight of 1 kg of wild Naozhou group Pseudosciaena crocea male fish, the component one comprises 0.2-0.5 μg of gonadotropin-releasing hormone or analogs and 0.5-1.0 mg of dopamine receptor antagonists; and the component two comprises 0.1-0.15 IU of a mixture of follicle-stimulating hormone and luteinizing hormone.

[0019] In the present application, the dose of gonadotropin-releasing hormone (GnRH) or analogs in the component one is preferably controlled at 0.2-0.5 μg / kg of body weight, further preferably at 0.3-0.4 μg / kg of body weight, and more preferably at 0.35 μg / kg of body weight. At this dose, the activity of GnRH hormone can be stabilized, and the hypothalamic-pituitary-gonadal axis can be effectively activated.

[0020] In the present application, the kind of dopamine receptor antagonist can be selected according to actual needs, and in some embodiments, domperidone (DOM) or metoclopramide HCl (MET) is preferably included. The dosage of the dopamine receptor antagonist is preferably controlled at 0.5-1.0 mg / kg of body weight, further preferably at 0.7-0.9 mg / kg of body weight, and more preferably at 0.8 mg / kg of body weight. The dopamine receptor antagonist can relieve the inhibition of dopamine on the release of gonadotropin, enhance the stimulating effect of hormones, and promote the synchronization of sexual maturation of parent fish and significantly improve the reproductive performance.

[0021] In the present application, the activity unit ratio of follicle-stimulating hormone (FSH) to luteinizing hormone (LH) is preferably (2-1):1, and more preferably 1.5:1.

[0022] In the present application, the dosage of the mixture of follicle-stimulating hormone and luteinizing hormone for female fish is preferably 0.1-0.3 IU / kg of body weight, further preferably 0.15-0.25 IU / kg of body weight, and more preferably 0.2 IU / kg of body weight. The dosage of the mixture of follicle-stimulating hormone and luteinizing hormone for male fish is preferably 0.1-0.15 IU / kg of body weight, further preferably 0.125-0.15 IU / kg, and more preferably 0.15 IU / kg of body weight.

[0023] The present application realizes efficient induction of sexual maturation of wild Lutjanus Russelii parent fish of Lutjanus Russelii by regulating the hormone formula and dosage.

[0024] The present application also provides a use of the composition in artificial spawning of wild Lutjanus Russelii.

[0025] The present application also provides an artificial spawning method of wild Lutjanus Russelii, which comprises injecting the composition into wild Lutjanus Russelii parent fish.

[0026] In the present application, before injection, the wild Lutjanus Russelii parent fish is preferably artificially domesticated for 7-10 days, and then subjected to nutritional enhancement for 30-45 days, and then injected; the method of nutritional enhancement preferably comprises nutritional enhancement with fresh miscellaneous fish, squid or sandworm. During artificial domestication and nutritional enhancement, the parent fish is preferably bred in an environment with water temperature of 26-28℃, salinity of 30±2 ppt, 14-16 h of bright light: 8-10 h of dark light, and 10-20 min of dawn and dusk transition. Preferably, when the female fish is in the III stage or the transition stage of III-IV, the male fish has the ability to ejaculate or is close to the ejaculation stage, and the injection is performed.

[0027] In the present application, the injection method preferably comprises: injecting component one into wild Lutjanus Russellii brood fish by intramuscular injection, and 70-74 hours after injection, injecting component two into wild Lutjanus Russellii brood fish by intramuscular injection.

[0028] In the present application, the injection of component one is preferably performed in the morning to the morning period, and in some embodiments, is preferably performed in the period of 7:00-11:00. After injection, the behavior response and body temperature change of the brood fish are closely monitored to ensure that no obvious stress symptoms occur, and the safety and comfort of the brood fish are ensured. The first injection can activate the hypothalamic-pituitary-gonadal axis and relieve dopamine inhibition.

[0029] In the present application, component two is preferably injected 70-74 hours after the injection of component one, further preferably 71-73 hours, and more preferably 72 hours. Within the time window of 70-74 hours after the injection of component one, the second injection time is flexibly adjusted according to the hormone level and reproductive behavior of the brood fish. In some embodiments, component two is preferably injected when the oocyte of the female fish develops to stage IV and the egg diameter reaches ≥0.95 mm; if the sperm of the male fish is stable, the semen is milky white, and the sperm motility is ≥80%, component two can not be injected; if the sperm motility of the male fish is <80%, and / or the semen density and sperm output are insufficient, component two is injected to promote the proliferation of spermatogonia and the maturation of sperm, thereby improving the quality and synchronization of sperm.

[0030] In the present application, the whole injection process focuses on high matching with the physiological rhythm of the brood fish, and is performed in the morning to the morning period, which is beneficial to the optimal absorption of hormones and reduces the stress caused by changes in the external environment, thereby improving the stability and success rate of the induced spawning effect. The program combines precise dose control and dynamic monitoring to maximize the use of hormone action, while ensuring the health and reproductive quality of the brood fish.

[0031] In the present application, the artificial induced spawning method preferably further comprises regulating the breeding environment of the wild Lutjanus Russelii brood fish, which comprises: controlling the light period to be 14-16 hours of light and 8-10 hours of darkness per day, and the light gradual change process is completed within 10-20 minutes; light intensity is 200-300 lux, color temperature is 5000K; temperature is 26-28℃; water flow rate is 0.05-0.10 m / s.

[0032] In the present application, by regulating the light period, light intensity and color temperature, the natural sunlight conditions are simulated to avoid the sudden change of light intensity causing stress response in the brood fish. The light gradual change process is completed within 10-20 minutes to achieve smooth transition of the morning and evening light, and further relieve the light stress.

[0033] In the present application, the water temperature is preferably precisely adjusted by an automatic heating and cooling system, and is preferably maintained within the range of 26-28 DEG C, with an intraday temperature difference controlled to not more than ±0.5 DEG C, so as to ensure the physiological functions of the parent fish to be stable.

[0034] ELISA detection shows that, when the water temperature is increased from 24 DEG C to 27 DEG C, the FSH level in the plasma of the wild Lutjanus Russii is increased by 32%, and the LH is increased by 28%; under the light intensity of 500 lux or above, the parent fish exhibits the behaviors of jumping and feeding reduction, and the present application can significantly reduce the stress hormones by using the light intensity of 200-300 lux and gradually changing light, so as to maintain the stability of the circadian rhythm and improve the gonadal synchronization rate by 22%. Under the strong water flow, the energy consumption of the parent fish is increased, and the growth rate of the gonadal index (GSI) is decreased by 17%; and the low flow of 5-10 cm / s is helpful to the blood perfusion of the ovary and the accumulation of the yolk.

[0035] In the present application, the artificial induced spawning method preferably further comprises regulating the water quality conditions for the parent fish of the wild Lutjanus Russii, including: maintaining the salinity at 30±1 ppt, keeping the dissolved oxygen at more than 6.5 mg / L, controlling the ammonia nitrogen concentration to be less than 0.1 mg / L, keeping the nitrite to be less than 0.02 mg / L, and maintaining the pH value to be 7.8-8.3.

[0036] During the high metabolism period of the wild Lutjanus Russii, the oxygen demand is increased, and when the dissolved oxygen is less than 6, the LH secretion is significantly inhibited; after the dissolved oxygen is increased to 6.5 mg / L, the gonadal development synchronization rate is increased by about 12%.

[0037] In the present application, by regularly detecting the key water quality indexes, cooperating with the oxygenation and high-efficiency water quality purification device, the water environment is ensured to be excellent, and the influence of the environmental stress on the health and sexual maturity of the parent fish is greatly reduced, so as to provide a good auxiliary condition for the hormone regulation, and improve the success rate of the artificial induced spawning and the breeding quality of the parent fish.

[0038] In the present application, the artificial induced spawning method preferably further comprises monitoring the health of the parent fish, and the monitoring method preferably comprises: regularly collecting blood samples, measuring the levels of key hormones such as gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH) in the plasma, and evaluating the immune function and stress state of the parent fish in combination with the total serum protein, white blood cell count and oxidative stress indexes (such as malondialdehyde content and superoxide dismutase activity) in the blood. A high-definition camera and an intelligent video behavior analysis system are used to monitor the feeding frequency, swimming speed and behavior mode of the parent fish all day long, and automatically identify abnormal behaviors such as food refusal, floating head and abnormal swimming and timely alarm, so as to assist the breeding personnel to take intervention measures quickly.

[0039] The application provides a comprehensive technical scheme for promoting sexual maturation and artificial delivery, which integrates precise hormone regulation, environmental multi-factor optimization and monitoring management, realizes efficient, synchronous and safe sexual maturation of parent fish, significantly improves the breeding efficiency and seedling quality, promotes the scientific, standardized and industrialized development of artificial breeding technology of Pseudosciaena crocea in Naozhou ethnic group, and promotes the sustainable development of marine fishery resources protection and aquaculture industry.

[0040] The technical solutions provided by the application will be described in detail below in combination with the embodiments, but they should not be understood as limiting the protection scope of the application.

[0041] In the following examples, all are conventional methods unless otherwise specified.

[0042] In the following examples, the materials and reagents used, unless otherwise specified, can be obtained from commercial channels.

[0043] Example 1 A composition for promoting the maturation of the gonads of wild Pseudosciaena crocea in Naozhou ethnic group, the composition consisting of component one and component two; In terms of the body weight of 1 kg of wild Pseudosciaena crocea female fish, the component one is gonadotropin-releasing hormone 0.35 μg and dopamine receptor antagonist 0.8 mg; the component two is follicle-stimulating hormone and luteinizing hormone mixture 0.2 IU, and the activity unit ratio of the follicle-stimulating hormone and luteinizing hormone is 1.5:1.

[0044] In terms of the body weight of 1 kg of wild Pseudosciaena crocea male fish, the component one is gonadotropin-releasing hormone 0.35 μg and dopamine receptor antagonist 0.8 mg; the component two is follicle-stimulating hormone and luteinizing hormone mixture 0.15 IU, and the activity unit ratio of the follicle-stimulating hormone and luteinizing hormone is 1.5:1.

[0045] Example 2 A composition for promoting the maturation of the gonads of wild Pseudosciaena crocea in Naozhou ethnic group, the composition consisting of component one and component two; In terms of the body weight of 1 kg of wild Pseudosciaena crocea female fish, the component one is gonadotropin-releasing hormone 0.5 μg and dopamine receptor antagonist 1 mg; the component two is follicle-stimulating hormone and luteinizing hormone mixture 0.15 IU, and the activity unit ratio of the follicle-stimulating hormone and luteinizing hormone is 1:1.

[0046] In terms of the body weight of 1 kg of wild Pseudosciaena crocea male fish, the component one is gonadotropin-releasing hormone 0.5 μg and dopamine receptor antagonist 1 mg; the component two is follicle-stimulating hormone and luteinizing hormone mixture 0.1 IU, and the activity unit ratio of the follicle-stimulating hormone and luteinizing hormone is 1:1.

[0047] Example 3 A composition for promoting gonadal maturation of wild Lutjanus Russelii, the composition consists of component one and component two; The component one is gonadotropin-releasing hormone 0.2 μg and dopamine receptor antagonist 0.5 mg per 1 kg body weight of wild Lutjanus Russelii female fish; the component two is follicle-stimulating hormone and luteinizing hormone mixture 0.3 IU, the activity unit ratio of follicle-stimulating hormone and luteinizing hormone is 2:1.

[0048] The component one is gonadotropin-releasing hormone 0.2 μg and dopamine receptor antagonist 0.5 mg per 1 kg body weight of wild Lutjanus Russelii male fish; the component two is follicle-stimulating hormone and luteinizing hormone mixture 0.125 IU, the activity unit ratio of follicle-stimulating hormone and luteinizing hormone is 2:1.

[0049] Example 4 A method for artificial induced spawning of wild Lutjanus Russelii, the steps of the method are as follows: 1. Hormone injection procedure: in the morning from 7:00 to 11:00, gonadotropin-releasing hormone (GnRH) and dopamine receptor antagonist are injected by intramuscular injection, the dose of GnRH is controlled at 0.35 μg / kg body weight, the dose of dopamine receptor antagonist is 0.8 mg / kg body weight, after injection, the behavior response and body temperature change of the parent fish are closely monitored to ensure that there is no obvious stress symptoms, and the safety and comfort of the parent fish are ensured. 72 hours later, female fish are injected with follicle-stimulating hormone (FSH) and luteinizing hormone (LH) mixture by intramuscular injection, the dose is set at 0.2 IU / kg body weight, if the male fish naturally ejaculates stably, the semen is normal and the sperm motility is ≥80%, and meets the needs of insemination, the male fish can not be injected with component two; if the sperm motility of the male fish is <80% and / or the semen density and ejaculate volume are insufficient, FSH and LH mixture is injected by intramuscular injection, the dose is set at 0.15 IU / kg, to promote the maturation and synchronous development of the gonads.

[0050] 2. Environmental optimization: The photoperiod is set to 14-16 hours of bright light and 8-10 hours of darkness per day, with light intensity strictly controlled within the range of 200-300 lux, and color temperature maintained at about 5000K to simulate natural sunlight conditions and avoid sudden changes in light intensity that could cause stress in the brood fish. The light gradient process is controlled to be completed within 10-20 minutes to achieve a smooth transition between morning and evening light, further reducing light stress. Water temperature is precisely adjusted by an automatic heating and cooling system to maintain a range of 26-28°C, with a daily temperature difference of no more than ±0.5°C, ensuring stable physiological functions of the brood fish. Salinity is maintained at 30±1 ppt. In terms of water quality, key indicators are regularly monitored, with dissolved oxygen maintained above 6.5 mg / L, ammonia nitrogen concentration controlled below 0.1 mg / L, nitrite below 0.02 mg / L, and pH maintained between 7.8 and 8.3. Combined with oxygenation and high-efficiency water purification devices, the water environment is kept in excellent condition, greatly reducing the impact of environmental stress on the health and sexual maturation of the brood fish.

[0051] 3. Brood fish health monitoring: Regular blood sampling is performed, and enzyme-linked immunosorbent assay (ELISA) is used to accurately measure key hormone levels in plasma, such as gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH). In combination with serum total protein, white blood cell count, and oxidative stress indicators (such as malondialdehyde content and superoxide dismutase activity) in the blood, the immune function and stress state of the brood fish are evaluated. High-definition cameras and intelligent video behavior analysis systems are used to monitor the brood fish's feeding frequency, swimming speed, and behavior patterns around the clock. Abnormal behaviors such as refusal to eat, floating head, and abnormal swimming are automatically identified and timely warned to assist the breeding staff in taking prompt intervention measures.

[0052] Example 5 A method for artificially inducing spawning of wild Lutjanus bohar, which differs from Example 4 in that the composition for promoting gonadal maturation of wild Lutjanus bohar of Example 2 is used for injection.

[0053] Example 6 A method for artificially inducing spawning of wild Lutjanus bohar, which differs from Example 4 in that the composition for promoting gonadal maturation of wild Lutjanus bohar of Example 3 is used for injection.

[0054] Comparative Example 1 A method for artificially inducing spawning of wild Lutjanus bohar, which differs from Example 4 in that traditional human chorionic gonadotropin (HCG) single hormone injection is used, with a single injection and an injection dose of 1200 IU / kg, and conventional environmental management (no light control, temperature fluctuation within 2°C).

[0055] Test Example 1 Wild Pseudosciaena kowalevitschi hybrids were randomly divided into two groups, each group with 30 individuals, including 15 females and 15 males. The artificial induced spawning was carried out according to the method of Example 4 (dopamine receptor antagonist selection domperidone (DOM)) and Comparative Example 1, respectively. The results are shown in Table 1.

[0056] Table 1 Gonadal development of broodstock under different artificial induced spawning methods

[0057] Significant effect of gonadal synchronous maturation: After using the hormone combination (GnRH+FSH / LH+dopamine antagonist) and the staged injection procedure of the application, the proportion of individuals with gonadal development reaching stage IV-V was 88.7%, which was significantly higher than 58.3% of the control group. This shows that the hormone combination can effectively activate the hypothalamic-pituitary-gonadal axis (HPG axis) and achieve the synchronization of gonadal development.

[0058] Significant improvement in fertilization rate and hatching rate: The fertilization rate increased by about 28%, and the hatching rate increased by 32%, showing that the synergistic effect of hormone regulation and environmental optimization significantly improved the quality of gametes and the stability of embryonic development.

[0059] Significant increase in endocrine levels: The levels of GnRH, FSH, and LH were significantly higher than those of the control group (P<0.05), proving that the hormone injection scheme effectively promotes the secretion of reproductive hormones.

[0060] Reduced stress and enhanced immune function: MDA decreased significantly (-34.9%), and the activities of SOD and GSH-Px increased by 32% and 27%, respectively, indicating that environmental optimization (light, water temperature, salinity, and dissolved oxygen control) significantly alleviates oxidative stress and improves antioxidant and immune levels.

[0061] Behavior monitoring results show reduced stress and increased vitality: Abnormal swimming rate decreased by 58%, and feeding frequency increased by 40%, indicating that the behavior of broodstock is stable, and the energy metabolism and feeding state are good.

[0062] Survival rate and reproductive efficiency improved: The final survival rate of broodstock was 93.5%, higher than 81.2% of the control group, indicating that the comprehensive method has obvious technical effects in ensuring health and improving reproductive safety.

[0063] Test Example 2 1. Experimental design: (1) Test object and conditions Wild L. crocea parent fish 84 tails (48 tails of female fish, 36 tails of male fish), body weight 0.4-0.6 kg, domestication qualified, average divided into 3 groups, 28 tails in each group (16 tails of female fish, 12 tails of male fish). The breeding conditions (consistent in each group) are as follows: water temperature 26.5±0.3℃, salinity 30±1 ppt, DO≥6.5 mg / L, pH 7.9-8.2; 14L:10D light cycle, 10-20 min gradual change in morning and evening; ammonia nitrogen≤0.05 mg / L, nitrite≤0.02 mg / L.

[0064] (2) Group and drug regimen Group A: male and female fish are injected with LHRH-A2 on the back muscle, the injection dose of male fish is 1 μg / kg, and the injection dose of female fish is 2 μg / kg, and the injection is once; Group B: artificial induced spawning mixed hormone is composed of chorionic gonadotropin 2000 IU / mL, luteinizing hormone releasing hormone analogue No. 2 300 μg / mL and maleic acid diethylstilbestrol 15 mg / mL, the injection dose of female fish is 2 mL / kg, and the injection dose of male fish is halved, and the injection is once; Group C: injection is performed in the manner of Table 2 Table 2 Injection dose of female fish and male fish in group C

[0065] The injection time of group A and group B is the same as the first injection time of group C.

[0066] 2. Experimental results Table 3 Gonadal development of parent fish in different hormone combinations

[0067] As can be seen from the results in Table 3, compared with group A and group B, the injection regimen of the present application can significantly improve the synchronous maturation rate, fertilization rate and hatching rate of wild L. crocea parent fish, reduce the deformity rate of fry, reduce the MDA content, improve the SOD content, and realize efficient induction of sexual maturation of wild L. crocea parent fish.

[0068] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the technical field, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A composition for promoting gonadal maturation in wild large yellow croaker (Cyprinus naanensis), characterized in that, The composition comprises component one and component two; Based on the body weight of 1 kg of wild female large yellow croaker from Naozhou, component one includes 0.2-0.5 μg of gonadotropin-releasing hormone or its analogue and 0.5-1.0 mg of dopamine receptor antagonist; component two includes 0.1-0.3 IU of a mixture of follicle-stimulating hormone and luteinizing hormone. Based on the weight of 1 kg of wild male large yellow croaker from Naozhou, component one includes 0.2-0.5 μg of gonadotropin-releasing hormone or its analogues and 0.5-1.0 mg of dopamine receptor antagonist; component two includes 0.1-0.15 IU of a mixture of follicle-stimulating hormone and luteinizing hormone.

2. The composition according to claim 1, characterized in that, The ratio of the active units of follicle-stimulating hormone to luteinizing hormone is (2~1):

1.

3. The use of the composition according to any one of claims 1 to 2 in the artificial spawning of wild large yellow croaker.

4. A method for artificially inducing spawning in wild large yellow croaker (Cyprinus naanensis), characterized in that, The artificial spawning method comprises: injecting wild-caught large yellow croaker parent fish with the composition described in any one of claims 1 to 2.

5. The method for artificial labor induction according to claim 4, characterized in that, The injection method includes: injecting component one into wild Naozhou grouper broodstock via intramuscular injection, and injecting component two into wild Naozhou grouper broodstock via intramuscular injection 70-74 hours after injection.

6. The method for artificial labor induction according to claim 5, characterized in that, The injection of component one is performed in the morning to forenoon period.

7. The method for artificial labor induction according to claim 5, characterized in that, When the female fish's ovary develops to stage IV and the egg diameter reaches ≥0.95mm, inject component two. If the male fish's natural ejaculation is stable, the semen is milky white, and the sperm motility is ≥80% 70-74 hours after the injection of component one, the injection of component two is not necessary. If the male fish's sperm motility is <80%, and / or the semen density and ejaculation volume are insufficient, the injection of component two should be performed.

8. The method for artificial labor induction according to claim 4, characterized in that, The artificial spawning method also includes regulating the breeding environment of wild large yellow croaker broodstock, including: controlling the light cycle to 14-16 hours of bright light and 8-10 hours of dim light per day, with the light transition process completed within 10-20 minutes; light intensity of 200-300 lux, color temperature of 5000K; temperature of 26-28℃; and water flow rate of 0.05-0.10 m / s.

9. The method for artificial labor induction according to claim 4, characterized in that, The artificial spawning method also includes regulating the aquaculture water quality conditions of wild Naozhou large yellow croaker broodstock, including: maintaining salinity at 30±1ppt, dissolved oxygen at 6.5mg / L or higher, ammonia nitrogen concentration at 0.1mg / L or lower, nitrite at 0.02mg / L or lower, and pH at 7.8~8.

3.

10. The method for artificial labor induction according to claim 4, characterized in that, The artificial spawning method also includes monitoring the health of the parent fish.

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