Application of potassium magnesium sulfate slow-release salt in aquatic product culture, aquatic product feed and fish culture method

Abstract

The invention provides application of potassium magnesium sulfate slow-release salt in aquatic product culture, aquatic product feed and a fish culture method, and relates to the technical field of culture. The invention provides application of potassium magnesium sulfate slow-release salt in aquatic product culture. According to the invention, the potassium magnesium sulfate slow-release salt is added into the aquatic product feed as an osmoregulation auxiliary factor, so that the absorptivity of K < + > and Mg < 2 + > by intestinal tracts can be promoted, and the ion regulation energy consumption is reduced; the Na < + > / K < + >-ATP enzyme activity of gill tissue can be maintained, ion unbalance caused by low salt is reduced, the functions of gill and hepatopancreas are maintained, and tissue structure damage is reduced. The potassium magnesium sulfate slow-release salt is used as the aquatic product feed additive and is rich in potassium and magnesium mineral substances, under the low-salinity (for example, the salinity is 2-5) breeding condition, when the aquatic product feed is fed in fry breeding, the body weight and the body length of fry are obviously increased, the growth performance is high, and the weight gain rate and the feed efficiency of fish can be obviously improved.

Description

Technical Field

[0001] The present invention relates to the field of aquaculture technology, and in particular to application of potassium magnesium sulfate slow-release salt in aquaculture, aquatic product feed and a fish farming method. Background Art

[0002] The channel catfish (Ictalurus punctatus), commonly known as the American catfish, belongs to the phylum Chordata, class Actinopterygii, order Siluriformes, family Ictaluridae, and genus Ictalurus. It boasts rapid growth, strong adaptability, high feed conversion rate, and good disease resistance, making it a key freshwater aquaculture species in my country. Its aquaculture scale has continued to expand, and it has become a major freshwater aquaculture species in my country, particularly in Hubei, Guangdong, and Jiangsu. The channel catfish is a eurythermal fish, surviving naturally in water temperatures between 0 and 35°C, with an optimal growth temperature of 25 to 30°C. In recent years, as traditional aquaculture methods (such as pond culture) have faced challenges such as deteriorating water quality, increased disease, and rising costs, channel catfish aquaculture methods have been continuously optimized, such as the promotion of recirculating aquaculture (RAS) and integrated rice-fish farming. However, in a low-salt environment, spotted catfish are prone to problems such as slow growth, decreased immunity, and high incidence of diseases. Summary of the Invention

[0003] In view of this, the present invention aims to provide the use of potassium magnesium sulfate slow-release salt in aquaculture, aquatic feed, and a fish farming method. Channel catfish cultured using aquatic feed supplemented with potassium magnesium sulfate slow-release salt have a high survival rate, significantly increased weight and length, and strong immunity.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides application of potassium magnesium sulfate slow-release salt in aquaculture.

[0006] Preferably, the aquatic product includes fish, and the fish includes channel catfish and / or euryhaline fish.

[0007] The present invention also provides an aquatic product feed, comprising a basic feed and potassium magnesium sulfate slow-release salt.

[0008] Preferably, the amount of potassium magnesium sulfate slow-release salt added to aquatic product feed is 1.5-6 kg / t.

[0009] Preferably, the basic feed comprises, in terms of mass percentage, 22-25% fish meal, 18-22% soybean meal, 20-24% high-gluten flour, 6-8% corn gluten meal, 4-6% squid viscera meal, 3-5% shrimp bran, 2-3% fish oil, and 4-6% premix.

[0010] Preferably, the premix composition per kilogram of aquatic product feed includes: vitamin A 10,000-15,000 IU, vitamin D3 2,000-3,000 IU, vitamin E 30-50 IU, vitamin K3 2-4 mg, thiamine 5-8 mg, riboflavin 6-9 mg, vitamin B6 8-12 mg, pantothenic acid 20-25 mg, niacin 35-45 mg, folic acid 0.8-1.2 mg, vitamin B12 0.2-0.3 mg, choline 500-700 mg, minerals: manganese 50-70 mg, iron 200-250 mg, zinc 70-90 mg, copper 25-35 mg, iodine 0.4-0.6 mg, selenium 0.3-0.4 mg, cobalt 0.7-0.9 mg.

[0011] Preferably, the nutritional indicators of the aquatic product feed, calculated in percentage by mass of dry matter, include: crude protein 38-42%, crude fat 6-7.5%, calcium 1.8-2.2%, phosphorus 1.2-1.6%, potassium 0.9-1.1%, magnesium 0.2-0.3%, and potassium magnesium sulfate slow-release salt 300-600 mg / kg.

[0012] The present invention also provides a fish breeding method, comprising the following steps: placing fish fry in a body of light salt water and feeding the aquatic product feed described in the above technical solution for breeding.

[0013] Preferably, the physical and chemical indicators of the light salt water body include: salinity 2-5, dissolved oxygen content ≥6 mg / L, pH value 7.5-8.2, water temperature 28-32°C, and ammonia nitrogen content ≤0.03 mg / L.

[0014] Preferably, the breeding is staged breeding; the staged breeding includes sequentially carrying out first stage breeding, second stage breeding and third stage breeding;

[0015] The first stage of breeding lasts from day 1 to day 30, with a daily feeding amount of aquatic feed being 8-10% of body weight and a feeding frequency of 3-5 times per day;

[0016] The second stage of breeding lasts from day 31 to day 60, with a daily feeding amount of aquatic product feed being 6-8% of body weight and a feeding frequency of 2-4 times per day;

[0017] The third stage of breeding is from day 61 to day 90, the daily feeding amount of aquatic product feed is 4-6% of body weight, and the feeding frequency is 1-3 times per day.

[0018] The present invention adopts potassium magnesium sulfate slow-release salt as osmotic adjustment auxiliary factor, which can enhance the intestinal absorption efficiency of aquatic products to potassium and magnesium, maintain gill tissue Na + / K + -ATPase activity, reducing ion imbalance caused by low salt.

[0019] The present invention uses potassium magnesium sulfate slow-release salt as an osmotic adjustment auxiliary factor added to aquatic product feed, which can promote the intestinal tract to K + Mg 2+ The absorption rate can reduce the energy consumption of ion regulation; it can also maintain the Na + / K + -ATPase activity, reduces ion imbalance caused by low salt, maintains gill and hepatopancreas function, and reduces tissue structure damage.

[0020] The aquatic feed provided by the present invention includes a basic feed and a slow-release potassium magnesium sulfate salt. Using the aquatic feed provided by the present invention for aquaculture can optimize the utilization rate of aquatic feed, reduce the feed coefficient, and reduce nitrogen and phosphorus emissions; it also saves aquaculture costs and eliminates the need for frequent water ion adjustments.

[0021] The present invention uses potassium magnesium sulfate slow-release salt as an aquatic product feed additive, which is rich in potassium and magnesium minerals. Under low salinity (for example, a salinity of 2 to 5) breeding conditions, the aquatic product feed is fed in fry breeding, and the weight and body length of the fry are significantly increased, the growth performance is high, the immunity is strong, and the weight gain rate and feed efficiency of the fish can be significantly improved. As shown in the test results of the embodiment, the fish breeding method provided by the present invention can achieve a weight gain rate of 805.0 to 111.0% for channel catfish, a survival rate of 93.5 to 98.6%, a feed coefficient of 1.15 to 1.32, and significantly improved muscle quality. The present invention solves the problems of slow growth of aquatic products in low-salinity breeding, and has significant economic and ecological benefits. DETAILED DESCRIPTION

[0022] The present invention provides the use of a slow-release potassium magnesium sulfate salt in aquaculture. In the present invention, the aquatic product preferably includes fish, including channel catfish and / or euryhaline fish. In the present invention, the euryhaline fish preferably includes one or more of mullet, pike, barramundi, seabass, and yellowfin seabream.

[0023] The present invention adopts potassium magnesium sulfate slow-release salt as osmotic adjustment auxiliary factor, which can enhance the intestinal absorption efficiency of aquatic products to potassium and magnesium, maintain gill tissue Na + / K +-ATPase activity, reducing ion imbalance caused by low salt.

[0024] The present invention also provides an aquatic product feed, comprising a basic feed and potassium magnesium sulfate slow-release salt.

[0025] In the present invention, the addition amount of the potassium magnesium sulfate slow-release salt in the aquatic product feed is preferably 1.5 to 6 kg / t, specifically 1.5 kg / t, 2 kg / t, 2.5 kg / t, 3 kg / t, 3.5 kg / t, 4 kg / t, 4.5 kg / t, 5 kg / t, 5.5 kg / t or 6 kg / t. The present invention uses potassium magnesium sulfate slow-release salt as an osmotic adjustment auxiliary factor added to aquatic product feed, which can promote the intestinal absorption of K + Mg 2+ The absorption rate can reduce the energy consumption of ion regulation; it can also maintain the Na + / K + -ATPase activity, reduces ion imbalance caused by low salt, maintains gill and hepatopancreas function, and reduces tissue structure damage.

[0026] In the present invention, the basic feed preferably comprises, by weight percentage: 22-25% fish meal, specifically 22%, 22.5%, 23%, 23.5%, 24%, 24.5% or 25%; 18-22% soybean meal, specifically 18%, 18.5%, 19%, 19.5%, 20%, 20.5%, 21%, 21.5% or 22%; 20-24% high-gluten flour, specifically 20%, 20.5%, 21%, 21.5%, 22%, 22.5%, 23%, 23.5% or 24%; Corn gluten meal 6-8%, which may be specifically 6%, 6.5%, 7%, 7.5% or 8%; squid viscera meal 4-6%, which may be specifically 4%, 4.5%, 5%, 5.5% or 6%; shrimp bran 3-5%, which may be specifically 3%, 3.5%, 4%, 4.5% or 5%; fish oil 2-3%, which may be specifically 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9% or 3%; premix 4-6%, which may be specifically 4%, 4.5%, 5%, 5.5% or 6%. In the present invention, fish meal provides high-quality animal protein and essential amino acids; soybean meal provides a plant protein source, reducing feed costs; high-gluten flour is carbohydrate, providing energy; corn gluten meal can enhance the feed adhesion of aquatic product feed; squid viscera powder serves as an attractant to increase the feed intake rate of aquatic products; shrimp bran supplements chitin; fish oil provides ω-3 fatty acids, enhancing immunity; and premix serves as vitamins, minerals and functional additives.

[0027] In the present invention, the premix composition in each kilogram of aquatic product feed preferably includes: vitamin A 10000-15000 IU, which can be specifically 10000 IU, 11000 IU, 12000 IU, 13000 IU, 14000 IU or 15000 IU; vitamin D3 2000-3000 IU, which can be specifically 2000 IU, 2200 IU, 2500 IU, 2800 IU or 3000 IU; vitamin E 30-50 IU, specifically 30 IU, 35 IU, 40 IU, 45 IU or 50 IU; Vitamin K 32-4 mg, specifically 2 mg, 2.5 mg, 3 mg, 3.5 mg or 4 mg; Thiamine 5-8 mg, specifically 5 mg, 6 mg, 7 mg or 8 mg; Riboflavin 6-9 mg, specifically 6 mg, 7 mg, 8 mg or 9 mg; Vitamin B6 8-12 mg, specifically 8 mg, 9 mg, 10 mg, 11 mg or 12 mg; Pantothenic acid 2 0-25mg, specifically 20mg, 21mg, 22mg, 23mg, 24mg or 25mg; niacin 35-45mg, specifically 35mg, 38mg, 40mg, 42mg or 45mg; folic acid 0.8-1.2mg, specifically 0.8mg, 0.9mg, 1mg, 1.1mg or 1.2mg; vitamin B12 0.2-0.3mg, specifically 0.2mg, 0.22mg, 0.25mg, 0.28mg or 0.3mg Choline 500-700mg, specifically 500mg, 550mg, 600mg, 650mg or 700mg; Minerals: Manganese 50-70mg, specifically 50mg, 55mg, 60mg, 65mg or 70mg; Iron 200-250mg, specifically 210mg, 220mg, 230mg, 240mg or 250mg; Zinc 70-90mg, specifically 70mg, 75mg, 80mg, 85mg or 90mg; Copper 25- 35mg, which may be specifically 25mg, 28mg, 30mg, 32mg or 35mg; iodine 0.4-0.6mg, which may be specifically 0.4mg, 0.45mg, 0.5mg, 0.55mg or 0.6mg; selenium 0.3-0.4mg, which may be specifically 0.3mg, 0.32mg, 0.35mg, 0.38mg or 0.4mg; cobalt 0.7-0.9mg, which may be specifically 0.7mg, 0.75mg, 0.8mg, 0.85mg or 0.9mg.

[0028] In the present invention, the premix composition in each kilogram of aquatic product feed more preferably includes: vitamin A 12000 IU, vitamin D3 2500 IU, vitamin E 40 IU, vitamin K33 mg, thiamine 6 mg, riboflavin 7 mg, vitamin B6 10 mg, pantothenic acid 22 mg, niacin 40 mg, folic acid 1 mg, vitamin B12 0.25 mg, choline 600 mg, minerals: manganese 60 mg, iron 220 mg, zinc 80 mg, copper 30 mg, iodine 0.5 mg, selenium 0.35 mg, and cobalt 0.8 mg.

[0029] In the present invention, the nutritional indicators of the aquatic product feed, calculated in percentage by mass of dry matter, include: crude protein 38-42%, which can be specifically 38%, 38.5%, 39%, 39.5%, 40%, 40.5%, 41%, 41.5% or 42%; crude fat 6-7.5%, which can be specifically 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2% or 7.5%; calcium 1.8-2.2%, which can be specifically 1.8%, 1.9%, 2%, 2.1% or 2.2%; phosphorus 1.2-1.6%, which can be specifically 1. 2%, 1.3%, 1.4%, 1.5% or 1.6%; Potassium 0.9-1.1%, specifically 0.9%, 0.95%, 1%, 1.05% or 1.1%; Magnesium 0.2-0.3%, specifically 0.2%, 0.22%, 0.25%, 0.28% or 0.3%; Potassium magnesium sulfate sustained-release salt 300-600mg / kg, specifically 300mg / kg, 350mg / kg, 400mg / kg, 450mg / kg, 500mg / kg, 550mg / kg or 600mg / kg.

[0030] By adopting the aquatic product feed provided by the present invention to cultivate aquatic products, the utilization rate of the aquatic product feed can be optimized, the feed coefficient can be reduced, and nitrogen and phosphorus emissions can be reduced; the cultivation cost can be saved, and there is no need to frequently adjust water ions.

[0031] The present invention also provides a fish breeding method, comprising the following steps: placing fish fry in a body of light salt water and feeding the aquatic product feed described in the above technical solution for breeding.

[0032] In the present invention, the physical and chemical indicators of the brackish water body preferably include: salinity 2 to 5, which can be specifically 2, 2.5, 3, 3.5, 4, 4.5 or 5; dissolved oxygen content ≥ 6 mg / L, more preferably 6 to 8 mg / L; pH value 7.5 to 8.2, which can be specifically 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1 or 8.2; water temperature 28 to 32°C, which can be specifically 28°C, 29°C, 30°C, 31°C or 32°C; ammonia nitrogen content ≤ 0.03 mg / L.

[0033] In the present invention, the breeding is preferably staged breeding; the staged breeding preferably includes first-stage breeding, second-stage breeding and third-stage breeding in sequence. In the present invention, the time of the first-stage breeding is preferably 1 to 30 days, and the daily feeding amount of aquatic product feed is 8 to 10% of body weight, which can be specifically 8%, 8.5%, 9%, 9.5% or 10%; the feeding frequency is preferably 3 to 5 times / day, more preferably 4 times / day; the first-stage breeding can promote the feeding of young fish and adapt to the low-salt environment. In the present invention, the time of the second-stage breeding is preferably 31 to 60 days; the daily feeding amount of aquatic product feed is preferably 6 to 8% of body weight, which can be specifically 6%, 6.5%, 7%, 7.5% or 8%; the feeding frequency is preferably 2 to 4 times / day, more preferably 3 times / day; the second-stage breeding can maximize weight gain and reduce feed waste. In the present invention, the third stage of breeding is from day 61 to day 90; the daily feeding amount of aquatic product feed is preferably 4-6% of body weight, which can be specifically 4%, 4.5%, 5%, 5.5% or 6%; the feeding frequency is preferably 1-3 times / day, more preferably 2 times / day; the third stage of breeding can improve muscle firmness and control feed conversion rate. In the present invention, the water K is monitored every 3 days during the breeding process. + Mg 2+ concentration, maintain K + 80~120mg / L, Mg 2+ 40~60mg / L, calculate the difference between the water volume and the target concentration, and then supplement K with KCl + The KCl is preferably used in the form of a KCl aqueous solution, wherein the mass concentration of the KCl aqueous solution is 8-12%, specifically 8%, 9%, 10%, 11% or 12%; Mg 2+ It is supplemented by MgSO4·7H2O (magnesium sulfate heptahydrate), and the MgSO4·7H2O is preferably used in the form of a MgSO4·7H2O aqueous solution. The mass concentration of the MgSO4·7H2O aqueous solution is preferably 18-22%, and can be specifically 18%, 19%, 20%, 21% or 22%.

[0034] The invention uses potassium magnesium sulfate slow-release salt as an aquatic product feed additive, which is rich in potassium and magnesium minerals. Under low salinity (for example, a salinity of 2 to 5) breeding conditions, the aquatic product feed is fed to fry breeding, and the weight and body length of the fry are significantly increased, the growth performance is high, the immunity is strong, and the weight gain rate, feed efficiency and stress resistance of the fish are significantly improved.

[0035] To further illustrate the present invention, the application of the potassium magnesium sulfate slow-release salt in aquaculture, aquatic feed and fish farming method provided by the present invention are described in detail below in conjunction with the examples, but they should not be understood as limiting the scope of protection of the present invention.

[0036] In the following examples, potassium magnesium sulfate sustained-release salt was purchased from Qinghai Yuhong Biotechnology Co., Ltd.

[0037] Example 1

[0038] Salinity 3 aquaculture test

[0039] Aquatic product feed: basic feed and potassium magnesium sulfate slow-release salt 3kg / t; calculated by mass percentage, the basic feed includes: fish meal 24%, soybean meal 20%, high-gluten flour 22%, corn gluten meal 7%, squid viscera meal 5%, shrimp bran 4%, fish oil 2.5%, premix 5%.

[0040] The composition of the premix in each kilogram of aquatic feed: Vitamin A 12000IU, Vitamin D3 2500 IU, Vitamin E 40IU, Vitamin K 33mg, Thiamine 6mg, Riboflavin 7mg, Vitamin B6 10mg, Pantothenic acid 22mg, Niacin 40mg, Folic acid 1mg, Vitamin B12 0.25mg, Choline 600mg, Minerals: Manganese 60mg, Iron 220mg, Zinc 80mg, Copper 30mg, Iodine 0.5mg, Selenium 0.35mg, Cobalt 0.8mg.

[0041] Nutritional indicators (dry matter basis): crude protein 38-42%, crude fat 6-7.5%, calcium 1.8-2.2%, phosphorus 1.2-1.6%, potassium 0.9-1.1%, magnesium 0.2-0.3%, potassium magnesium sulfate sustained-release salt 300 mg / kg.

[0042] Breeding conditions: salinity 3, water temperature 30±1℃, dissolved oxygen 7.2mg / L, pH=8.0. Monitor water K every 3 days. + Mg 2+ concentration, maintain K + 80~120mg / L, Mg 2+ 40~60mg / L.

[0043] The spotted catfish fry are placed in a body of light salt water and fed with aquatic product feed in stages for breeding; wherein, the first stage of breeding: from the 1st to the 30th day, the daily feeding amount of aquatic product feed is 9% of the body weight, and the feeding frequency is 4 times / day; the second stage of breeding: from the 31st to the 60th day, the daily feeding amount of aquatic product feed is 7% of the body weight, and the feeding frequency is 3 times / day; the third stage of breeding: from the 61st to the 90th day, the daily feeding amount of aquatic product feed is 5% of the body weight, and the feeding frequency is 2 times / day.

[0044] Example 2

[0045] Salinity 3 aquaculture test

[0046] The only difference from Example 1 is that the addition amount of potassium magnesium sulfate slow-release salt is 4 kg / t.

[0047] Example 3

[0048] Salinity 4 aquaculture test

[0049] The only difference from Example 1 is that the salinity in the culture conditions is 4.

[0050] Example 4

[0051] Salinity 4 aquaculture test

[0052] The only difference from Example 1 is that the salinity in the aquaculture conditions is 4, and the amount of potassium magnesium sulfate slow-release salt added is 4 kg / t.

[0053] Example 5

[0054] Salinity 5 aquaculture test

[0055] The only difference from Example 1 is that the salinity in the culture conditions is 5.

[0056] Example 6

[0057] Salinity 5 aquaculture test

[0058] The only difference from Example 1 is that the salinity in the culture conditions is 5 and the amount of potassium magnesium sulfate slow-release salt added is 4 kg / t.

[0059] Example 7

[0060] Salinity 5 aquaculture test

[0061] The only difference from Example 1 is that the salinity in the culture conditions is 5, and the amount of potassium magnesium sulfate slow-release salt added is 5 kg / t.

[0062] Feed formula: potassium magnesium sulfate sustained-release salt 5kg / ton, other formulas are the same as those in Example 1.

[0063] The breeding results of Examples 1 to 7 are shown in Table 1, and the values ​​are mean ± standard deviation.

[0064] Table 1 Breeding results of Examples 1 to 7

[0065] Example Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Initial body weight / g 8.0±0.3 8.0±0.3 8.0±0.3 8.0±0.3 8.0±0.3 8.0±0.3 8.0±0.3 Final body weight / g 78.5±3.2 82.6±3.8 85.2±4.1 88.9±4.5 92.3±4.8 96.8±5.2 72.4±3.6 Weight gain rate / % 881.3 932.5 965 1011.3 1053.8 1110 805 Survival rate / % 95.2±1.5 96.8±1.2 97.1±0.9 97.8±0.8 98.2±0.7 98.6±0.6 93.5±1.8 Feed coefficient 1.28±0.12 1.25±0.10 1.23±0.11 1.20±0.09 1.18±0.08 1.15±0.07 1.32±0.15 Fatness 2.15±0.12 2.33±0.31 2.53±0.63 2.65±0.28 2.82±0.42 2.85±0.41 2.01±0.39 Food intake rate / % 2.32±0.14 2.62±0.42 2.74±0.52 2.79±0.63 2.83±0.25 2.92±0.59 2.26±0.93 Initial body length / cm 5.8±0.2 5.8±0.2 5.8±0.2 5.8±0.2 5.8±0.2 5.8±0.2 5.8±0.2 Terminal length of body / cm 17.8±0.8 18.2±0.9 18.6±1.0 19.0±1.1 19.5±1.2 20.0±1.3 16.5±0.7 90-day growth / cm 12.0±0.6 12.4±0.7 12.8±0.8 13.2±0.9 13.7±1.0 14.2±1.1 10.7±0.5

[0066] As shown in Table 1, after 90 days of breeding, the final body weight of channel catfish was 72.4-96.8 g, the weight gain rate was 805.0-111.0%, the survival rate was 93.5-98.6%, the feed coefficient was 1.15-1.32, the fatness was 2.01-2.85, the feeding rate was 2.26-2.92%, and the body length was 16.25-20.0 cm.

[0067] In summary, the fish farming method provided by the present invention has the following advantages:

[0068] (1) Synergistic mechanism: The present invention promotes ion absorption and reduces metabolic energy consumption by adding potassium sulfate magnesium slow-release salt. Potassium sulfate magnesium slow-release salt promotes the intestinal absorption of channel catfish by K + Mg 2+ The absorption of ions reduces the energy consumption of ion regulation; maintains the function of gills and hepatopancreas, and reduces tissue structure damage.

[0069] (2) Environmental protection and economy: Optimize the utilization rate of aquatic product feed, reduce feed coefficient, and reduce nitrogen and phosphorus emissions; save breeding costs and do not need to frequently adjust water ions.

[0070] (3) Improved product quality of spotted catfish: The fatness and body length of spotted catfish have increased significantly, the muscle firmness has improved, the product specifications have been standardized, and the growth has been uniform, which meets the needs of the high-end aquatic product market.

[0071] The present invention adds slow-release potassium magnesium sulfate to aquatic feed and adopts a three-stage aquaculture strategy. Under salinity conditions of 2-5 and water temperature of 28-32°C, by precisely controlling the feeding amount and frequency, and combining it with optimized water quality parameter management, it can achieve a weight gain rate of 805.0-111.0%, a survival rate of 93.5-98.6%, a feed conversion factor of 1.15-1.32, and significantly improved muscle quality. This invention solves the problem of slow growth of aquatic products in low-salinity aquaculture and has significant economic and ecological benefits.

[0072] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. Application of potassium magnesium sulfate slow-release salt in aquaculture.

2. The use according to claim 1, characterized in that The aquatic product includes fish, and the fish includes channel catfish and / or euryhaline fish.

3. A kind of aquatic product feed, comprising basic feed and potassium magnesium sulfate slow-release salt.

4. The aquatic product feed according to claim 3, characterized in that: The amount of potassium magnesium sulfate slow-release salt added to aquatic product feed is 1.5-6 kg / t.

5. The aquatic product feed according to claim 3, characterized in that: Calculated by mass percentage, the basic feed includes: 22-25% fish meal, 18-22% soybean meal, 20-24% high-gluten flour, 6-8% corn gluten meal, 4-6% squid viscera powder, 3-5% shrimp bran, 2-3% fish oil, and 4-6% premix.

6. The aquatic product feed according to claim 5, characterized in that: The composition of the premix in each kilogram of aquatic feed includes: vitamin A 10,000-15,000 IU, vitamin D3 2,000-3,000 IU, vitamin E 30-50 IU, vitamin K3 2-4 mg, thiamine 5-8 mg, riboflavin 6-9 mg, vitamin B6 8-12 mg, pantothenic acid 20-25 mg, niacin 35-45 mg, folic acid 0.8-1.2 mg, vitamin B12 0.2-0.3 mg, choline 500-700 mg, minerals: manganese 50-70 mg, iron 200-250 mg, zinc 70-90 mg, copper 25-35 mg, iodine 0.4-0.6 mg, selenium 0.3-0.4 mg, cobalt 0.7-0.9 mg.

7. The aquatic feed according to any one of claims 3 to 6, characterized in that: Calculated by the mass percentage of dry matter, the nutritional indicators of the aquatic product feed include: crude protein 38-42%, crude fat 6-7.5%, calcium 1.8-2.2%, phosphorus 1.2-1.6%, potassium 0.9-1.1%, magnesium 0.2-0.3%, and potassium magnesium sulfate slow-release salt 300-600 mg / kg.

8. A fish farming method comprising the following steps: The fry are placed in a body of light salt water and fed with the aquatic product feed according to any one of claims 3 to 7 for breeding.

9. The breeding method according to claim 8, characterized in that: The physical and chemical indicators of the brackish water body include: salinity 2-5, dissolved oxygen content ≥6 mg / L, pH value 7.5-8.2, water temperature 28-32°C, and ammonia nitrogen content ≤0.03 mg / L.

10. The breeding method according to claim 8 or 9, characterized in that: The breeding is staged breeding; the staged breeding includes sequentially carrying out the first stage breeding, the second stage breeding and the third stage breeding; The first stage of breeding lasts from day 1 to day 30, with a daily feeding amount of aquatic feed being 8-10% of body weight and a feeding frequency of 3-5 times per day; The second stage of breeding lasts from day 31 to day 60, with a daily feeding amount of aquatic product feed being 6-8% of body weight and a feeding frequency of 2-4 times per day; The third stage of breeding is from day 61 to day 90, the daily feeding amount of aquatic product feed is 4-6% of body weight, and the feeding frequency is 1-3 times per day.