Method for promoting the fattening and synchronous molting of empty crab

Abstract

The present application belongs to the technical field of aquaculture, and particularly relates to a method for promoting the fattening and synchronous molting of empty-shell crabs. The method comprises three core steps of screening and temporary rearing, implementing a starvation-re-feeding cycle, and molting period management: empty-shell crabs with a body weight of 80-120 g and a fullness degree of less than 0.22 g / cm 3 are selected and placed in an indoor factory circulating water system with specific water quality parameters for temporary rearing and adaptability treatment; the empty-shell crabs after temporary rearing are subjected to 3-5 cycles of starvation-re-feeding, each cycle comprising a 2-3 day starvation period, a 2 day ladder re-feeding period, and a 1 day full re-feeding period; after molting signs are monitored, the environmental parameters are adjusted and calcium, magnesium and phosphorus substances are added. The present application significantly improves the fattening efficiency and molting synchronization rate of empty-shell crabs, reduces the cost of aquaculture, and has extremely high practical value by precisely regulating the feeding mode and the aquaculture environment.

Description

Technical Field

[0001] This invention belongs to the field of aquaculture technology, specifically relating to a method for promoting the fattening and simultaneous molting of empty-shell crabs. Background Technology

[0002] Empty-shell crabs are a common and unusual group in crab farming. They typically refer to crabs that, after molting, have underdeveloped muscles, gonads, and other tissues due to insufficient nutrient reserves, environmental stress, or physiological imbalances, resulting in a fullness of less than 0.22 g / cm³. The formation of these empty-shell crabs is mainly related to three factors: First, excessive energy consumption during molting; if nutrient accumulation is insufficient before molting, it is difficult to quickly replenish the body's needs after molting, easily leading to an empty shell. Second, fluctuations in the farming environment, such as sudden changes in water temperature, insufficient dissolved oxygen, or water pollution, can interfere with the crabs' feeding and metabolism, hindering nutrient absorption. Third, improper feeding methods, such as continuous overfeeding or a monotonous diet, can reduce the crabs' digestive and absorption efficiency, leading to impaired nutrient conversion.

[0003] From the current industry perspective, the incidence of empty-shell crabs in mainstream farmed crab species such as swimming crabs and mud crabs can reach 15%-30%. These crabs not only grow slowly and have disordered molting rhythms, but are also more susceptible to pathogens due to their weak constitution, resulting in a mortality rate more than 40% higher than normal crabs. This causes hundreds of millions of yuan in economic losses to my country's crab farming industry every year. However, empty-shell crabs are not without value. They still possess the potential for normal growth and molting. Through scientific regulation, their plumpness can be rapidly improved, transforming them into high-quality marketable crabs. Furthermore, if synchronized molting can be achieved, high-value-added soft-shell crab products can be developed based on the soft-shell state after molting, significantly improving farming efficiency.

[0004] Currently, the processing technologies for empty-shell crabs mainly fall into two categories: one is fattening and improvement technology, the mainstream method of which is to continuously feed high-protein feed (such as miscellaneous fish, shrimp paste, etc.) supplemented by water quality regulation. However, this model has significant drawbacks—continuous feeding easily leads to a decrease in the crabs' appetite, with feed utilization rate less than 60%. The remaining feed, after decaying, will also exacerbate the accumulation of ammonia nitrogen and nitrite, causing water quality deterioration; moreover, there is a lack of means to regulate the molting rhythm, with the synchronization rate of molting in the group being less than 30%, and the fattening cycle lasting 45-60 days. The other category is soft-shell crab preparation technology, which is mostly achieved through artificial induction of molting. Common methods include temperature stimulation, adding molting hormones, or adjusting salinity. However, these methods often ignore the nutritional basis of empty-shell crabs, and after induction, molting failure or death during the soft-shell period is common, with a success rate of only about 50%, and the product has poor taste and nutritional quality. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for promoting the fattening and simultaneous molting of empty-shell crabs. This method achieves the dual goals of rapid fattening and simultaneous molting of empty-shell crabs through scientific screening and temporary rearing, precise feeding cycle control, and targeted molting period management.

[0006] The first objective of this invention is to provide a method for promoting the fattening and simultaneous molting of empty-shell crabs.

[0007] The second aspect of the present invention aims to provide an application of the method of the first aspect of the present invention.

[0008] To achieve the above-mentioned objectives of this invention, the technical solution adopted by this invention is as follows:

[0009] A first aspect of the present invention provides a method for promoting the fattening and simultaneous molting of empty-shell crabs, comprising the following steps:

[0010] S1. Select empty-shell crabs;

[0011] S2. Implement a starvation-refeeding cycle: Implement an intermittent feeding cycle for the temporarily held empty-shell crabs. Each cycle includes:

[0012] 1) Hunger period: Stop feeding for 2-3 days;

[0013] 2) Step-by-step refeeding period: Immediately after the hunger period, feed is started. This period lasts for 2 days, and the amount of feed is increased day by day.

[0014] 3) Sufficient refeeding period: This period lasts for 1 day immediately following the stepped refeeding period;

[0015] S3. Molting period management: During the breeding process, monitor the signs of molting in empty-shell crabs and adjust the breeding environment parameters in the early stage of molting.

[0016] In some embodiments of the present invention, in S1, the weight of the empty-shell crab is 80-120g; and its condition factor is less than 0.22 g / cm³. 3 Among them, empty-shell crabs weighing 80-120 grams are in the transitional stage from sub-adult to adult, possessing strong growth and molting potential. Crabs in this weight range have vigorous metabolism and high efficiency in nutrient absorption and conversion, making them the optimal starting size for fattening. Furthermore, crabs with a condition factor below 0.22 g / cm³ are not considered optimal. 3 This is the core criterion for identifying "empty-shell crabs." This indicator directly reflects the nutritional accumulation status of the crab's body. A value below this indicates that the crab's muscles, hepatopancreas, gonads, and other tissues are underdeveloped, leaving a huge potential for fattening.

[0017] In some embodiments of the present invention, in S1, the empty-shell crab is a healthy, disease-free, and vigorous empty-shell crab. Diseased or weak crabs have poor responsiveness to environmental regulation and feeding patterns, and are prone to death in subsequent breeding, which increases breeding costs and management difficulty; therefore, through precise screening, it can be ensured that the breeding targets have a good growth foundation and fattening potential, thereby improving the breeding success rate from the source and avoiding ineffective investment.

[0018] In some embodiments of the present invention, the species of the empty-shell crab include swimming crab and mud crab.

[0019] In some embodiments of the present invention, S1 further includes the step of placing empty-shell crabs in an indoor industrialized circulating water system for temporary acclimatization treatment.

[0020] Indoor, factory-style recirculating aquaculture systems can eliminate the influence of fluctuations in parameters such as water temperature and salinity in the natural environment, enabling precise and controllable aquaculture environments. Meanwhile, empty-shell crabs, newly removed from their original habitat, are prone to stress responses due to sudden environmental changes, manifesting as cessation of feeding and abnormal activity. Temporary acclimatization treatment allows them to gradually adapt to the new environment, reducing stress damage. Therefore, this treatment provides a stable environmental foundation for subsequent precision breeding, minimizing the interference of environmental stress on the physiological state of empty-shell crabs and ensuring the effective implementation of subsequent feeding and management measures.

[0021] In some embodiments of the present invention, the water quality parameters of the indoor factory-style circulating water system are: salinity 7-8‰, pH 7.8-8.2, water temperature 22-28℃, dissolved oxygen 4.0-5.5 mg / L, ammonia nitrogen <0.2 mg / L, and nitrite <0.05 mg / L.

[0022] The optimal salinity range is 7-8‰, which is considered a brackish water environment. This range promotes the stability of the osmotic pressure regulation system of empty-shell crabs, reduces energy consumption, and enhances the activity of digestive enzymes. A pH range of 7.8-8.2 is considered a slightly alkaline environment, meeting the acid-base balance requirements of crab blood and maintaining normal respiratory and metabolic functions. A water temperature of 22-28℃ is the optimal temperature range for crab growth, where feeding rate, metabolic rate, and nutrient conversion efficiency are at their peak. Dissolved oxygen ≥4.0 mg / L meets the aerobic respiration requirements of empty-shell crabs, preventing reduced feeding and growth stagnation due to oxygen deficiency. Ammonia nitrogen <0.2 mg / L and nitrite <0.05 mg / L are important because these two substances are toxic to crabs; low concentrations prevent damage to gill tissue and decreased immunity, ensuring the crabs' health. By controlling these parameters, the most suitable water quality environment for the temporary rearing of empty-shell crabs can be created, ensuring their physiological recovery and adaptation, and laying the foundation for subsequent fattening.

[0023] In some embodiments of the present invention, the temporary acclimatization treatment specifically includes:

[0024] 1) Starve the empty-shell crabs for 2-3 days;

[0025] 2) Feed the animal normally for 1-2 days;

[0026] 3) During this period, individuals that do not feed or have low feed intake are removed, and empty-shell crabs that feed normally are retained for subsequent breeding.

[0027] Since empty-shell crabs may have irregular feeding habits during selection and transportation, starvation treatment can clear residual food from their digestive tract, preventing intestinal contamination from putrefaction. It also stimulates the crabs' feeding center, increasing their appetite and feeding activity. Therefore, starvation treatment cleanses the digestive tract, activates feeding desire, and creates conditions for the absorption and utilization of feed during subsequent normal feeding. Individuals that do not feed or feed very little may have underlying diseases, extreme weakness, or poor adaptability to new environments. These individuals are unlikely to achieve the goals of fattening and synchronous molting in subsequent breeding and are prone to becoming sources of disease transmission. Therefore, culling can further optimize the breeding population, ensuring that the remaining individuals all have good feeding and growth capabilities, improving overall breeding results, and reducing breeding risks.

[0028] In some embodiments of the present invention, in S2, the starvation-refeeding cycle is repeated 3 to 5 times.

[0029] In some embodiments of the present invention, in S2, starvation for 2-3 days can put the digestive tract of the empty-shell crab in a "window" state. At this time, the excitability of its feeding center is enhanced, and its sensitivity to bait is increased. At the same time, the crab body will reduce its basal metabolic rate, concentrating energy consumption on maintaining core physiological functions. After feeding, it can more efficiently convert the nutrients of the bait into its own tissues. Therefore, this stage can maximize the stimulation of the empty-shell crab's feeding desire, preparing for efficient feeding during subsequent tiered feeding and sufficient feeding, and reducing bait waste.

[0030] In some embodiments of the present invention, in S2, the feeding amount on the first day of the stepped refeeding period is 4~7wt%, and the feeding amount on the second day is 6~8wt%.

[0031] In some embodiments of the present invention, the stepped refeeding period involves feeding twice a day; on the morning of the first day (7:00-8:00), the feeding amount is 4wt%-5wt% of the body weight of the empty-shell crabs, and on the evening of the first day (18:00-19:00), the feeding amount is 6wt%-7wt% of the body weight of the empty-shell crabs; on the morning of the second day (7:00-8:00), the feeding amount is 6wt%-7wt% of the body weight of the empty-shell crabs, and on the evening of the second day (18:00-19:00), the feeding amount is 7wt%-8wt% of the body weight of the empty-shell crabs.

[0032] Because the digestive system of crabs has not fully recovered after starvation, feeding them large amounts immediately can easily lead to indigestion, excessive intestinal burden, and even enteritis. Feeding them twice a day (once in the morning and once in the evening) aligns with their nocturnal habits, as their feeding needs are higher in the evening than in the morning, thus improving feed intake. Furthermore, the lower feeding amount on the first day allows their digestive system, which has just resumed feeding, to slowly adapt to the digestive process, preventing functional disorders. Gradually increasing the feeding amount on the second day follows the pattern of simultaneous improvement in the crab's appetite and digestive capacity. The higher feeding amount in the evening is because crabs are more active and have higher metabolic demands and stronger feeding capacity in the evening. Therefore, this feeding setting achieves a precise match between feed amount and the digestive capacity of empty-shell crabs, meeting their nutritional needs while minimizing feed residue and water pollution, and maximizing feed utilization.

[0033] In some embodiments of the present invention, in S2, the feeding amount during the sufficient refeeding period is 10~14wt%.

[0034] During the full feeding period, feed twice a day; that is, feed 10wt%-12wt% of the empty shell crab's body weight in the morning (7:00-8:00) and 12wt%-14wt% of the empty shell crab's body weight in the evening (18:00-19:00).

[0035] After two days of tiered feeding, the digestive function of the empty-shell crabs has fully recovered, and their appetite is at its peak. Sufficient feeding at this time can fully meet their nutritional needs, utilizing the compensatory growth effect to rapidly convert proteins and fats in the feed into muscle, gonads, and other tissues, thus achieving nutrient accumulation. Simultaneously, maintaining the feed and the frequency of two feedings ensures consistency in the feeding pattern and reduces stress. Therefore, this stage allows the crabs to rapidly accumulate the nutrients needed for fattening, shortening the fattening cycle. Furthermore, a uniform feeding intensity ensures that the nutrient accumulation progress of the entire group is more consistent. In addition, the 10-14 wt% feeding amount is far higher than the conventional feeding level and is designed based on the compensatory growth needs after starvation-tiered feeding. At this time, the crabs' nutrient conversion efficiency is highest, and the excess feed can be fully utilized. Meanwhile, the higher feeding amount in the evening is in line with the biological characteristics of crabs being active at night and feeding vigorously, which can ensure that the bait is consumed efficiently and avoid waste. Therefore, this feeding amount setting can achieve rapid and efficient accumulation of nutrients, significantly improve the plumpness of empty-shell crabs, and lay the foundation for the energy reserves required for molting.

[0036] In some embodiments of the present invention, in S2, the empty-shell crabs are raised in an indoor factory-style recirculating water system, and the breeding conditions are the same as in S1.

[0037] In some embodiments of the present invention, in S1 and S2, the bait includes razor clams, mussels, hard clams, blood clams, and snails. Taking razor clams as an example, their recommended weight is 7-10g / clam.

[0038] Razor clams, mussels, hard clams, blood clams, and snails are rich in protein, unsaturated fatty acids, and various minerals. Their nutritional composition is highly compatible with the natural diet of crabs, making them easily digestible and absorbable by empty-shell crabs, quickly replenishing their energy and nutrients. Furthermore, razor clams, weighing 7-10g each, are a suitable size for easy consumption and chewing by empty-shell crabs, reducing feed waste. In addition, "normal feeding" refers to providing sufficient but not excessive feed, allowing the crabs to gradually resume their feeding rhythm. Therefore, this feeding stage replenishes the basic nutrients of empty-shell crabs, helping them recover their strength and feeding function, while also improving feed utilization through the selection of feed type and size.

[0039] In some embodiments of the present invention, in S3, monitoring signs of molting in empty-shell crabs refers to: reduced or stopped feeding, reduced activity or prolonged resting, darkening of the abdominal carapace, and abdominal bulging. Specifically, crabs stop feeding in the early stages of molting, concentrating their energy on the shedding of the old carapace and the formation of the new one; reduced activity is to avoid excessive energy consumption due to exercise and to reduce the risk of injury; darkening of the abdominal carapace is due to increased pigment deposition in the carapace, preparing for molting; and abdominal bulging is a manifestation of the new shell developing under the old shell, causing the abdomen to swell. These are all typical physiological and behavioral characteristics in the early stages of molting.

[0040] In some embodiments of the present invention, in S3, the aquaculture environment parameters include a water temperature of 28-30℃ and dissolved oxygen of 6.0-7.5 mg / L. Raising the water temperature to 28-30℃ can accelerate the metabolic rate of crabs, promote the calcification and growth of the new shell, and shorten the molting cycle. Simultaneously, the respiratory intensity of crabs increases significantly during molting, leading to a higher demand for dissolved oxygen. Increasing the dissolved oxygen to ≥6.0 mg / L can meet their high-intensity respiratory needs and prevent molting interruption or death due to hypoxia. Therefore, adjusting these parameters can provide suitable environmental conditions for molting, improve the molting success rate, shorten the molting duration, and reduce mortality during the molting period.

[0041] In some embodiments of the present invention, step S3 further includes the step of adding mineral components; said mineral components include calcium gluconate, magnesium sulfate, and calcium dihydrogen phosphate.

[0042] In some embodiments of the present invention, the concentration of calcium gluconate in the water is 1.0-2.2 g / m³. 3 The concentration of magnesium sulfate in water is 0.4-1.2 g / m³. 3 The concentration of calcium dihydrogen phosphate in water is 0.05-0.14 g / m³. 3 .

[0043] In some embodiments of the present invention, the concentration of calcium gluconate in the water is 1.0-1.4 g / m³. 3 The concentration of magnesium sulfate in water is 0.4-0.7 g / m³. 3 The concentration of calcium dihydrogen phosphate in water is 0.05-0.08 g / m³. 3 .

[0044] In some embodiments of the present invention, the concentration of calcium gluconate in the water is 1.12-1.34 g / m³. 3 The concentration of magnesium sulfate in water is 0.51-0.61 g / m³. 3 The concentration of calcium dihydrogen phosphate in water is 0.06-0.07 g / m³. 3 .

[0045] In some embodiments of the present invention, bone meal is used as a source of calcium dihydrogen phosphate.

[0046] Calcium is a core component in the formation of a crab's new shell. Calcium gluconate, as an organic calcium source, is easily absorbed and utilized by the crab, quickly replenishing the calcium needed for molting. Magnesium promotes calcium absorption and deposition, enhancing the hardness and toughness of the new shell. Phosphorus participates in the synthesis of calcium phosphate in the shell, and calcium dihydrogen phosphate, as a phosphorus source, also provides other trace elements. The synergistic effect of these three substances ensures rapid development and calcification of the new shell. Therefore, adding these substances provides sufficient mineral nutrition for the molting process, promotes the formation and hardening of the new shell, avoids problems such as molting difficulties and soft shell disease caused by insufficient minerals, and ensures a smooth molting process.

[0047] A second aspect of the present invention provides the application of the method of the first aspect of the present invention in steps 1) to 3):

[0048] 1) Promote the fattening of empty-shell crabs;

[0049] 2) Synchronize the molting cycle of empty-shell crabs;

[0050] 3) Increase the economic value of empty-shell crabs.

[0051] The beneficial effects of this invention are:

[0052] 1) High fattening efficiency: This invention adopts a hunger-refeeding cycle mode, which enhances the appetite of empty-shell crabs through hunger stimulation. The step-by-step increase in feeding amount, combined with sufficient feeding, not only avoids feed waste, but also promotes the rapid accumulation of nutrients in the crab body, significantly improving the fatness. Compared with the traditional continuous feeding mode, the fattening cycle is shortened by 20%-30%.

[0053] 2) High molting synchronization rate: By precisely controlling the feeding rhythm and environmental parameters and mineral supplementation during the molting period, the physiological state of empty-shell crabs tends to be consistent, and the molting synchronization rate can reach more than 85%, which solves the problems of scattered molting and difficult management in traditional farming.

[0054] 3) Low breeding cost: Using shellfish such as razor clams as feed, which are widely available and have high nutritional value, combined with a scientific feeding mode, the feed utilization rate is increased by more than 15%; at the same time, the indoor factory-style circulating water system reduces water pollution and disease incidence, further reducing breeding costs.

[0055] 4) High practicality: The method of this invention has clear steps, and each parameter is well-defined and easy to control. It is suitable for large-scale factory farming, easy to promote and apply, and can effectively improve the economic benefits of empty-shell crab farming. Attached Figure Description

[0056] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0057] Figure 1 The images show the results of the empty-shell crabs in the experimental group before and after fattening. A, B, C, and D represent photos of empty-shell crabs before the experiment, and A1, B1, C1, and D1 represent photos of empty-shell crabs after the experiment.

[0058] Figure 2 The images show the results of fattening empty-shell crabs in the control group. a, b, c, and d represent photos of empty-shell crabs in the control group before the experiment, while a1, b1, c1, and d1 represent photos of empty-shell crabs in the control group after the experiment.

[0059] Figure 3 The figures show the dissection results of empty-shell crabs before and after the experiment in the experimental group. E is the dissection diagram of the experimental group before the experiment, and E1 is the dissection diagram of the experimental group after the experiment.

[0060] Figure 4 The figures show the dissection results of empty-shell crabs before and after the control group experiment. e is the dissection diagram before the control group experiment, and e1 is the dissection diagram after the control group experiment. Detailed Implementation

[0061] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0062] Example 1: Screening and Temporary Holding of Empty-Shell Crabs

[0063] Experimental design: A group of "suspected empty-shell crabs" (400 crabs in total, randomly divided into experimental group and control group, 200 crabs in each group) was selected from a crab sales company in Zhanjiang (mainly mud crabs and swimming crabs) after preliminary screening.

[0064] The experimental group strictly screened target empty-shell crabs (weight 80-120 grams, plumpness <0.22 g / cm³, healthy) according to the method of this invention, and carried out temporary acclimatization treatment (indoor factory-style circulating water system, water quality parameters: salinity 7-8‰, pH 7.8-8.2, water temperature 22-28℃, dissolved oxygen ≥4.0 mg / L, ammonia nitrogen <0.2 mg / L, nitrite <0.05 mg / L).

[0065] The control group used conventional screening methods (selecting only individuals weighing 80-120 grams, without limiting condition or excluding those with low feed intake) and traditional temporary rearing procedures (natural water temperature environment, temporary rearing in ordinary cement ponds, without targeted water quality control). The screening process and post-rearing population status data were recorded for both groups.

[0066] The specific operating procedure for the experimental group is as follows:

[0067] 1. Screening: Based on body weight 80-120 grams and body fat percentage <0.22 g / cm². 3 (Fatness = weight (g) / nail width (cm)³ × 0.6) and health (no lesions, normal vitality, active feeding) criteria for screening.

[0068] 2. Temporary holding treatment: First, starve the animals for 2-3 days (stop feeding), then feed them normally for 1-2 days (the bait is razor clams, size 7-10g / each, feeding amount 3%-5%). During this period, remove individuals that do not feed or whose feeding amount is less than 50% of the group average.

[0069] 3. Temporary holding environment: Indoor factory-style circulating water system, with water quality parameters controlled as follows: salinity 7-8‰, pH 7.8-8.2, water temperature 22-28℃, dissolved oxygen ≥4.0 mg / L, ammonia nitrogen <0.2 mg / L, and nitrite <0.05 mg / L.

[0070] The specific operating procedure for the control group is as follows:

[0071] 1. Selection: Only crabs weighing 80-120 grams are selected (no restriction on plumpness, plumpness range includes ≥0.22 g / cm³). 3 (individuals).

[0072] 2. Temporary holding treatment: No starvation treatment is performed. Feed the animals directly with ordinary food (minced fish meat, 5%-8% of the total feed), and do not remove individuals with low feeding.

[0073] 3. Temporary holding environment: natural water temperature pond (15-30℃), no water quality parameter control (ammonia nitrogen <1.0 mg / L, nitrite <0.1 mg / L).

[0074] The data records are shown in Table 1.

[0075] Table 1

[0076]

[0077] Results analysis:

[0078] 1. Screening efficiency: After rigorous screening, only 64% (128 crabs) in the experimental group met the standard for empty-shell crabs (plumpness <0.22 g / cm³). 3 The control group, which did not restrict condition factor, included 90% (180 animals) of its population (including a large number with condition factor ≥0.22 g / cm²). 3 The non-empty-shell crabs) indicate that this invention precisely selects and identifies empty-shell crab populations that truly need fattening, thus avoiding ineffective investment.

[0079] 2. Adaptability to temporary rearing: The experimental group underwent a starvation-normal feeding process, with the removal of individuals exhibiting low feeding levels. Ultimately, 115 healthy, normally feeding empty-shell crabs (57.5% of the initial population) remained. After temporary rearing, their average condition factor was only 0.19 ± 0.02 g / cm³. 3 (Significantly below the fattening target), and no deaths were observed; the average condition rating of the control group after temporary rearing was 0.24 ± 0.04 g / cm³. 3 (Some individuals were no longer empty shell crabs), but the survival rate was only 97.1% (5 died), and the failure to remove individuals with low feeding intake may lead to higher risks in subsequent breeding.

[0080] 3. Environment and cost: The indoor factory-style circulating water system in the experimental group achieved precise water quality control (dissolved oxygen ≥ 4.0 mg / L, ammonia nitrogen < 0.2 mg / L), while the water quality in the natural pond in the control group fluctuated greatly (ammonia nitrogen may be > 1.0 mg / L), which easily led to diseases in long-term aquaculture. The experimental group laid the foundation for efficient fattening in the future through early screening and precise treatment, which is in line with the beneficial effect of "reducing aquaculture costs" of this invention.

[0081] Example 2: Starvation-Refeeding Cycle in Empty-Shell Crabs

[0082] Experimental Design: 115 empty-shell crabs (experimental group) and 170 empty-shell crabs (control group) after temporary rearing in Example 1 were selected and treated with different feeding methods. The experimental group underwent a four-cycle "starvation-step feeding-full feeding" cycle (each cycle lasting 5 days: 2 days of starvation + 2 days of step feeding + 1 day of full feeding), with the feeding amount set according to the method in this example (see Table 2). The control group adopted the traditional continuous feeding method (daily feeding of mixed fish paste, with a feeding amount of 3%-5% of the crab's body weight, and no starvation period). Growth indicators and survival rates of both groups at each stage were recorded.

[0083] Table 2 Feeding amount for each stage of the experimental group (based on crab body weight percentage)

[0084]

[0085] The experimental group's operating procedure is as follows:

[0086] 1. Feeding plan: 4 cycles (20 days), each cycle includes:

[0087] (1) Hunger period: Stop feeding for 2 days (day 1-2 / cycle).

[0088] (2) Step-by-step refeeding period: Day 3-4 / cycle, feed twice a day (7:00-8:00 and 18:00-19:00), and the amount of feed increases day by day (4%-5% in the morning / 6%-7% in the evening on the 3rd day; 6%-7% in the morning / 7%-8% in the evening on the 4th day).

[0089] (3) Sufficient feeding period: Day 5 / cycle, feed twice a day (10%-12% in the morning / 12%-14% in the evening).

[0090] (4) Bait: Razor clams (7-10g / each).

[0091] 2. Environmental parameters: Indoor factory-style circulating water system, water quality is the same as in Example 1.

[0092] The procedure for the control group is as follows:

[0093] 1. Feeding plan: Continuously feed mixed fish paste (feeding amount 3%-5% of body weight), with no hunger period, feed twice a day (7:00-8:00 in the morning and 18:00-19:00 in the evening).

[0094] 2. Environmental parameters: Ordinary pond (natural water temperature 15-30℃, dissolved oxygen 3-5 mg / L, ammonia nitrogen 0.1-1.0 mg / L).

[0095] The results are shown in Table 3. Figures 1-4 As shown.

[0096] Table 3 Comparison of growth indicators between the two groups after 20 days (n=experimental group 115 n=170 n=170 n=115 ...

[0097]

[0098] Figure 1 , 2 The results before and after the experiment were compared for the experimental group and the control group, respectively. Figure 3 , 4 The images show the dissection results of empty-shell crabs before and after the experiment in the experimental and control groups, respectively. Compared with the control group, the experimental group showed a significant improvement in the fattening rate of the empty-shell crabs.

[0099] Results analysis:

[0100] This experiment compared the 20-day rearing conditions of an experimental group (fed razor clams using the "starvation-step refeeding-full refeeding" cycle of this invention) and a control group (fed traditional continuous mixed fish paste, without a starvation period) to comprehensively demonstrate the impact of different feeding methods on the growth and survival of empty-shell crabs. In terms of the two key growth indicators, average weight and average condition factor, the experimental group showed a significant advantage. The average weight of the experimental group increased to 125.3±10.1 g, an increase of 20.1% from the initial value, while the average weight of the control group increased to 114.2±9.8 g, with a growth rate of only 5.2%, meaning the experimental group was 11.1% higher than the control group. Regarding average condition factor, the experimental group reached 0.32±0.03 g / cm³. 3 The increase was 12%, compared to 0.27 ± 0.03 g / cm³ in the control group. 3 The growth rate was 3%, with the experimental group showing a 5% increase compared to the control group. Furthermore, the fattening success rate of the experimental group (≥0.25) reached 92.04% (104 crabs), significantly higher than the control group's 43.9% (65 crabs), a difference of 48.14%. This fully demonstrates that the unique feeding mode of this invention, through hunger stimulation and step-by-step increasing feeding, effectively activates the compensatory growth mechanism of empty-shell crabs, greatly promoting nutrient accumulation and physical development, and significantly improving fattening efficiency—a feat unmatched by traditional continuous feeding methods.

[0101] The feeding rate data further revealed the differences between the two feeding modes. The feeding rate of the experimental group reached 98.5%, while that of the control group was only 82.3%, with the experimental group being 16.2% higher than the control group. The razor clams used as bait in the experimental group had a nutritional composition that highly matched the natural diet of crabs, and their size was suitable for easy feeding and chewing by empty-shell crabs. At the same time, the stepped feeding amount and frequency set according to the method of this invention, as well as the reasonable setting of the hunger period, kept the excitability of the feeding center of the empty-shell crabs continuously maintained, and their appetite and digestive ability gradually increased during the feeding process. In contrast, the control group was continuously fed with mixed fish paste, which not only had poor palatability but also lacked hunger stimulation, leading to a gradual decrease in the feeding enthusiasm of the empty-shell crabs, and the feeding rate was significantly lower than that of the experimental group. This indicates that a reasonable feeding mode and high-quality bait selection are crucial for improving the feeding effect of empty-shell crabs.

[0102] Mortality data demonstrate the impact of different feeding methods on the survival of empty-shell crabs. The mortality rate in the experimental group was 1.74% (2 crabs), while the mortality rate in the control group was 12.9% (22 crabs), with the experimental group being 11.16% lower than the control group. The experimental group was cultured in an indoor, factory-style recirculating aquaculture system, where water quality parameters were stable, providing a favorable living environment for the crabs. The precise feeding method also avoided digestive problems and water pollution caused by overfeeding or improper feeding. In contrast, the control group was cultured in ordinary ponds, where natural water temperature fluctuated greatly, dissolved oxygen content was low, and the levels of harmful substances such as ammonia nitrogen and nitrite were relatively high. The unstable water environment, coupled with continuous feeding of miscellaneous fish paste, easily led to water quality deterioration, increasing stress and disease risk in the empty-shell crabs, thus resulting in a higher mortality rate. This indicates that the present invention, by optimizing the culture environment and feeding method, effectively reduced the mortality risk of empty-shell crabs and improved the safety and stability of culture.

[0103] The comparison of fattening achievement rates highlights the advantages of the feeding model of this invention in improving the overall quality of empty-shell crabs. The experimental group's high fattening achievement rate of 92.04% means that most empty-shell crabs reached a high level of plumpness, possessing the potential to become high-quality marketable crabs. The group's nutrient accumulation progress was highly consistent, facilitating subsequent unified management and sales. In contrast, the control group's fattening achievement rate was only 43.9%, with most empty-shell crabs failing to reach the ideal plumpness level. The group exhibited severe differentiation, making efficient unified fattening and development difficult. This further proves that this invention, through scientific feeding cycles and precise parameter control, can maintain good synchronicity and consistency in the growth of empty-shell crab populations, providing a strong guarantee for improving aquaculture efficiency and product quality.

[0104] As shown in Table 3, the "hunger-step refeeding-sufficient refeeding" cyclical model adopted in this invention exhibits significant advantages in terms of fattening efficiency, feeding effect, survival rate, and the rate of achieving the target fattening level for empty-shell crabs. Compared with the traditional continuous feeding model, this invention not only significantly improves the growth rate and fattening level of empty-shell crabs but also increases the feeding rate and reduces the mortality rate, resulting in a healthier and more uniform empty-shell crab population, laying a solid foundation for subsequent molting and aquaculture management. These data fully verify the effectiveness and practicality of the method of this invention, and are highly consistent with the beneficial effects described in the invention patent, possessing significant value for promotion and application.

[0105] Example 3: Molting Period Management

[0106] Experimental design: 104 empty-shell crabs (experimental group, condition factor ≥ 0.25 g / cm³) from the experimental group after reaching the fattening standard were selected from Example 2. 3 65 empty-shell crabs (control group, condition factor ≥ 0.25 g / cm³) were fattened and compared with the control group. 3The fish were treated according to different molting management methods. After monitoring molting signs, the environmental parameters (water temperature 28-30℃, dissolved oxygen ≥6.0 mg / L) were adjusted, and calcium magnesium phosphate (calcium gluconate 1.23 g / m³) was added to the experimental group. 3 Magnesium sulfate 0.56 g / m 3 Bone meal 0.065 g / m 3 The control group maintained only the standard aquaculture environment (water temperature 20-26℃, dissolved oxygen 4-5 mg / L), without any added minerals. Molting success rate, synchronization rate, and soft-shell crab survival rate were recorded for both groups. Molting rate and survival number of empty-shell crabs were tallied 5-7 days after culture.

[0107] The experimental group's operating procedure is as follows:

[0108] 1. Molting Management: Monitor for signs of molting (reduced / ceasing feeding, decreased activity / restlessness, darkening of the plastron, and abdominal bulging). Once confirmed, adjust the environment: raise the water temperature to 28-30℃, ensure dissolved oxygen is ≥6.0 mg / L; supplement minerals: add calcium gluconate 1.12-1.34g / m³. 3 Magnesium sulfate 0.51-0.61 g / m 3 Bone meal 0.06-0.07g / m 3 (This example uses an intermediate value).

[0109] 2. Environmental parameters: Indoor factory-style circulating water system, water quality is the same as in Example 1.

[0110] The procedure for the control group is as follows:

[0111] 1. Molting Management: No active monitoring is required. Maintain normal water temperature (20-26℃) and dissolved oxygen (4-5 mg / L). No minerals are added.

[0112] 2. Environmental parameters: Ordinary cement pool.

[0113] The experimental data are shown in Table 4.

[0114] Table 4 Comparison of molting management effects between the two groups (n=experimental group 104 animals, control group 65 animals)

[0115]

[0116] Results analysis:

[0117] This experiment focused on the management of empty-shell crabs during the molting period, comparing the molting success rate, synchronization rate, and survival rate of soft-shell crabs between the experimental group (using the molting management method of this invention) and the control group (using a traditional conventional breeding environment). The experimental group achieved a remarkable molting success rate of 93.2% (97 crabs successfully molted), while the control group only achieved 55.4% (36 crabs successfully molted). The experimental group precisely monitored molting signs and promptly adjusted environmental parameters after confirming that the empty-shell crabs had entered the pre-molting stage, raising the water temperature to 28-30℃ and dissolved oxygen to ≥6.0 mg / L, while also adding calcium gluconate, magnesium sulfate, and bone meal. The suitable water temperature accelerated the crabs' metabolic rate, promoted the calcification and growth of the new shell, and shortened the molting cycle; sufficient dissolved oxygen met the crabs' high respiratory demands during molting, preventing molting interruption or death due to oxygen deficiency; and the synergistic effect of calcium, magnesium, and phosphorus provided sufficient mineral nutrition for the molting process, ensuring rapid development and calcification of the new shell. In contrast, the control group maintained normal water temperature (20-26℃), dissolved oxygen (4-5 mg / L), and no minerals were added. These environmental conditions failed to meet the molting requirements of the empty-shell crabs, resulting in a low molting success rate. This clearly demonstrates that the present invention, through precise control of environmental parameters and supplementation of minerals, can significantly improve the molting success rate of empty-shell crabs.

[0118] The comparison of molting synchronization rates also demonstrates the advantages of this invention. The experimental group achieved a molting synchronization rate of 91.7% (89 crabs molted within 48 hours), while the control group only achieved 47.2% (17 crabs molted within 48 hours). Through monitoring molting signs and targeted environmental control, the experimental group achieved a more uniform physiological state among the empty-shell crabs, prompting most to enter the molting stage within a similar timeframe. This high synchronization rate is crucial for large-scale farming, facilitating unified management and operation by farmers and improving farming efficiency. In contrast, the control group, lacking effective intervention in the molting process, experienced dispersed molting times, making centralized management difficult and increasing the difficulty and cost of farming. This indicates that the molting period management method of this invention can effectively solve the problems of dispersed molting and management difficulties in traditional farming, achieving efficient and synchronized molting of empty-shell crabs.

[0119] The survival rate data for soft-shell crabs further highlights the advantages of this invention. The survival rate of the experimental group reached 98.9% (96 out of 97 crabs survived), while the control group only achieved 77.8% (28 out of 36 crabs survived). During molting, the experimental group benefited from suitable environmental conditions and sufficient mineral nutrition, which promoted the rapid formation and hardening of the new shell, enhancing the soft-shell crabs' resistance and survival ability. Simultaneously, stable water quality and a high dissolved oxygen environment also aided in the recovery and growth of soft-shell crabs after molting. In contrast, the control group, due to unfavorable environmental conditions, was more susceptible to external environmental influences after molting, such as oxygen deficiency and water pollution, resulting in a lower survival rate. This demonstrates that the molting period management method of this invention can significantly improve the survival rate of soft-shell crabs, reduce aquaculture risks, and bring higher economic benefits to farmers.

[0120] Based on the data in Table 4, this invention demonstrates significant effectiveness in managing the molting period of empty-shell crabs. By precisely monitoring molting signs, adjusting environmental parameters, and adding calcium, magnesium, and phosphorus, this invention significantly improves the molting success rate and synchronization rate of empty-shell crabs, as well as the survival rate of soft-shell crabs. It solves the problems of difficult molting management, high mortality rate of soft-shell crabs, and low farming efficiency in traditional aquaculture. These data align with the beneficial effects of this invention, verifying its scientific validity and practicality. It possesses significant promotional value and application prospects, and can bring significant economic and social benefits to the crab farming industry.

[0121] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for promoting the fattening and simultaneous molting of empty-shell crabs, comprising the following steps: S1. Select empty-shell crabs; The empty-shell crabs weighed 80-120g; their condition factor was less than 0.22g / cm². 3 ; S2. Implement a starvation-refeeding cycle: Implement an intermittent feeding cycle for empty-shell crabs, each cycle including: 1) Hunger period: Stop feeding for 2-3 days; 2) Step-by-step refeeding period: Immediately after the hunger period, feed is started. This period lasts for 2 days, and the amount of feed is increased day by day. 3) Sufficient refeeding period: This period lasts for 1 day immediately following the stepped refeeding period; The feeding amount on the first day of the stepped refeeding period is 4-7 wt%, and the feeding amount on the second day is 6-8 wt%. The feeding amount during the sufficient refeeding period is 10~14 wt%; The starvation-refeeding cycle is repeated 3 to 5 times. S3. Molting period management: During the breeding process, monitor the signs of molting in empty-shell crabs and adjust the breeding environment parameters in the early stage of molting.

2. The method according to claim 1, characterized in that: S1 also includes the step of temporarily acclimatizing empty-shell crabs by placing them in an indoor factory-style circulating water system.

3. The method according to claim 1, characterized in that: In S3, the aquaculture environment parameters include a water temperature of 28-30℃ and dissolved oxygen of 6.0-7.5 mg / L.

4. The method according to claim 3, characterized in that: S3 also includes the step of adding mineral components; The mineral components include calcium gluconate, magnesium sulfate, and calcium dihydrogen phosphate.

5. The method according to claim 4, characterized in that: The concentration of calcium gluconate in the water is 1.0-2.2 g / m³. 3 ; The concentration of magnesium sulfate in the water is 0.4-1.2 g / m³. 3 ; The concentration of the calcium dihydrogen phosphate in the water is 0.05-0.14 g / m³. 3 .

6. The application of the method according to any one of claims 1 to 5 in steps 1) to 3): 1) Promote the fattening of empty-shell crabs; 2) Synchronize the molting cycle of empty-shell crabs; 3) Increase the economic value of empty-shell crabs.

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