Detoxification biological bait as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of aquaculture disease prevention and control, and particularly relates to detoxified biological bait as well as a preparation method and application thereof. The detoxified biological bait is formed by mixing biological bait, water and an acidic sterilization compound; wherein the biological bait is at least one of nereis, artemia, rotifer or oyster; the acidic sterilization compound is formed by mixing organic acid and acidic calcium sulfate. When the detoxified biological bait is used for feeding prawns and fishes, not only can the number of pathogens in the biological bait be obviously reduced, but also the density of vibrios in hepatopancreas of the prawns and intestinal tracts of the fishes and the shrimps can be reduced, the growth of the fishes and the shrimps and the gonad development of parents are promoted, the propagation of the pathogens is reduced, and the survival rate of fish and shrimp larvae is increased. Compared with a single agent, the sterilization compound has the advantages that the sterilization capability is higher, the concentration of the sterilization agent is reduced, the damage to nutrient substances is smaller, and the application and popularization value is higher.

Description

Technical Field

[0001] The invention belongs to the technical field of aquaculture disease prevention and control, and specifically relates to a detoxified biological bait and a preparation method and application thereof. Background Art

[0002] Aquaculture is an important pillar industry of fisheries. Driven by the progress of breeding technology and the development of seed and seed propagation technology, marine fish and shrimp farming has also developed rapidly, and the current annual output has exceeded 3.5 million tons. In recent years, due to the influence of factors such as the transmission of pathogens through cross-border transportation of aquatic products, pollution of the breeding environment and increased breeding density, farmed fish and shrimp diseases have frequently occurred, resulting in annual economic losses of more than 10 billion yuan. Marine farmed animal pathogens include bacteria, fungi, viruses and parasites, among which vibrio disease and viral disease are the most serious. There are many ways for viruses and vibrio pathogens to spread, and oral transmission through biological bait is one of the important ways of transmission. In the field of aquatic seed production, the annual consumption of biological baits such as sandworms, oysters, and squids used for parent maturation in coastal fish and shrimp nurseries is about 6,000 tons. These biological baits are all from the wild environment or pond farming. If they are not purified, they will carry various pathogens. If they are used directly as bait, they will bring risks to downstream seedling and aquaculture industries.

[0003] In recent years, the outbreaks of acute hepatopancreatic necrosis disease (AHPND) and vitreous seedling disease, which have caused huge losses to the industry, are related to the shrimp parents eating bait organisms infected with Vibrio pathogens. Studies have shown that healthy shrimp parents can horizontally transmit pathogens to their offspring shrimp fry by eating bait infected with Vibrio pathogens, causing diseases during the breeding process; similarly, the white spot virus (WSSV), which has caused great harm to shrimp farming worldwide, is also mainly transmitted horizontally through the mouth. Therefore, it is of great significance to explore the purification technology of pathogens in biological baits and block the horizontal transmission of pathogens to prevent the outbreak of major diseases in aquaculture.

[0004] To eliminate pathogens carried by bait, traditional methods mostly use treatments such as antibiotic soaking, heating or potassium permanganate soaking. Excessive use of antibiotics will damage the ecological environment of water bodies, induce the production of drug-resistant strains of pathogens, endanger the intestinal health of aquatic animals, lead to decreased growth and immune function of farmed animals, and affect the vitality of reproductive cells of farmed animals. If heat inactivation or oxidation treatment is used, the nutrients in biological bait will be destroyed and the nutritional value of feed will be reduced. Therefore, there is an urgent need to develop safe and effective new sterilization methods to replace products. Summary of the invention

[0005] The purpose of the present invention is to provide a detoxified biological bait and a preparation method and application thereof, so as to overcome the shortcomings of the prior art. The present invention can significantly reduce the number of pathogens in the biological bait and reduce the damage to the nutritional components in the biological bait; feeding the detoxified biological bait to shrimps and fish can not only reduce the density of Vibrio in the hepatopancreas of shrimps and the intestines of fishes and shrimps, but also promote the growth of fishes and shrimps and the gonad development of parents, reduce the spread of pathogens, and improve the survival rate of fish and shrimp larvae, and has application and promotion value.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] In a first aspect, the present invention provides a detoxified biological bait, which is composed of biological bait, water and an acidic bactericidal compound; wherein the biological bait is at least one of lugworms, artemia, rotifers or oysters;

[0008] The acidic bactericidal compound consists of organic acid and acidic calcium sulfate.

[0009] In some other embodiments, the organic acid is at least one of sorbic acid, benzoic acid, dehydroacetic acid, citric acid, malic acid, formic acid, acetic acid, propionic acid or lactic acid.

[0010] In some other embodiments, the organic acid is citric acid or lactic acid;

[0011] Preferably, the citric acid is a saturated aqueous solution of citric acid.

[0012] In some other embodiments, the mass ratio of the biological bait to water is 1:(2-3);

[0013] The mass ratio of water to the acidic bactericidal compound is (500-1000):1;

[0014] The mass ratio of the organic acid to the acidic calcium sulfate is 1:1 to 1:3.

[0015] In a second aspect, the present invention provides a method for preparing the detoxified biological bait according to the first aspect, comprising the following steps:

[0016] (1) mixing an organic acid with acidic calcium sulfate to prepare an acidic bactericidal compound;

[0017] (2) mixing the acidic bactericidal compound with water to obtain a detoxifying solution, and adding the biological bait to the detoxifying solution to perform a detoxifying treatment;

[0018] (3) After the detoxification treatment, the biological bait is taken out from the detoxification solution and rinsed with sterilized seawater to obtain the detoxified biological bait.

[0019] In some other embodiments, in step (2), the detoxification treatment time is 0.5-3h;

[0020] Or, in step (3), the number of times of seawater washing is 2-3 times.

[0021] In a third aspect, the present invention provides a bait for aquaculture, comprising a combination feed and the detoxified biological bait described in the first aspect;

[0022] The combined feed is sterilized shrimp granular feed or sterilized shrimp flakes.

[0023] In some other embodiments, the mixing mass ratio of the detoxified biological bait and the mixed feed is (3:1):1.

[0024] In a fourth aspect, the present invention provides a use of the detoxified biological bait described in the first aspect or the aquaculture bait described in the third aspect in aquaculture.

[0025] In some other embodiments, the invention is used in the broodstock cultivation, maturation acceleration and fry culture of marine shrimp and fish.

[0026] Beneficial effects of the present invention:

[0027] (1) The acidic bactericidal compound prepared by compounding an organic acid with acidic calcium sulfate (ACS) has a synergistically enhanced bactericidal effect, and has a lower bactericidal concentration, less environmental impact, and better safety than single organic acid and ACS.

[0028] (2) The present invention uses biological bait treated with an acidic bactericidal compound to effectively kill pathogenic organisms (bacteria and viruses) in biological bait and aquatic animals; seawater has a weak alkalinity, and washing and detoxifying biological bait with seawater can effectively remove residual acidic bactericidal compounds, thereby reducing the acidic damage to farmed animals after feeding.

[0029] (3) The present invention uses detoxified biological bait for feeding shrimp and fish, which can not only significantly reduce the number of pathogens in the biological bait, but also reduce the density of Vibrio in the hepatopancreas of shrimp and the intestines of fish and shrimp, promote the growth of fish and shrimp and the gonadal development of the parents, reduce the spread of pathogens, and improve the survival rate of fish and shrimp larvae.

[0030] (4) The acidic bactericidal complex treatment group of the present invention showed significant advantages in maintaining the nutritional components of sandworms, especially in the retention of total protein, total fat, cholesterol and vitamin E, which were close to the control group, and were superior to other disinfectant treatments, and had greater application and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0032] Figure 1 is the percentage of mature female shrimps after the broodstock are fed with the processed biological bait in Example 2 of the present invention;

[0033] Figure 2 The average daily maturity rate of female shrimps in Example 2 of the present invention within 2 weeks of feeding the treated biological bait to the broodstock;

[0034] Figure 3 is the gonad index of female shrimp at the end of the experiment in Example 2 of the present invention;

[0035] Figure 4 is the average daily mating rate of mature female shrimp during the experiment in Example 2 of the present invention;

[0036] Figure 5 is the number of eggs laid per day by mature female shrimp during the experiment in Example 2 of the present invention;

[0037] Figure 6 It is the survival rate of the larvae of the experimental group and the control group during the 2 experimental periods in the embodiment of the present invention when they develop to the zoea stage I. DETAILED DESCRIPTION

[0038] Example 1

[0039] Effect of acidic bactericidal compound on killing Vibrio in biological baits of lugworm, oyster, rotifer and Artemia

[0040] 1. Materials and Methods

[0041] 1.1 Experimental materials: lactic acid (purity 90.0%), citric acid (purity 99.5%); acidic calcium sulfate (ACS) stock solution produced by Mionix, USA.

[0042] Vannamei broodstock: 100 SPF female broodstock, average body length (17.5±0.5) cm, 100 SPF male broodstock, average body length (15.5±0.3) cm. The shrimps were tested to be free of white spot syndrome virus (WSSV) and Decapod iridescent virus 1 (DIV1). The shrimps were cultured in natural seawater treated with bleaching powder, with the water temperature controlled at (26±0.3)℃, salinity 32, and light 500lux.

[0043] Vannamei shrimp larvae: 5 million zoeae stage II larvae and 5 million mysid stage III larvae, all of which are SPF level and do not carry common shrimp viruses and Vibrio.

[0044] Biological bait: sandworms, oysters, Artemia, rotifers, collected from the mudflats of Taoluo Town, Donggang District, Rizhao City. Testing showed that sandworms carried shrimp iris virus, as well as Vibrio alginolyticus and Vibrio harveyi, oysters carried Vibrio splendens and Vibrio vulnificus, Artemia carried shrimp white spot virus and Vibrio parahaemolyticus, and rotifers carried Vibrio harveyi.

[0045] Formulated feed for broodstock: shrimp feed produced by Tongwei Co., Ltd.

[0046] Feed for juveniles: high-temperature sterilized shrimp chips, purchased from Boshan Biotechnology Industry (Zhanjiang) Co., Ltd.

[0047] 1.2 Preparation of acidic bactericidal compound:

[0048] Take 100g of pure lactic acid and 100g of saturated aqueous solution of citric acid respectively, add 100g of ACS respectively, to prepare A acidic bactericidal complex solution and B acidic bactericidal complex solution; similarly, take 100g of lactic acid stock solution and 100g of saturated citric acid aqueous solution respectively, add 300g of ACS respectively, to prepare C acidic bactericidal complex solution and D acidic bactericidal complex solution.

[0049] 1.3 Detoxification method of four biological baits (negworm, Artemia, rotifer, oyster): Take 5 portions of fresh negworm, Artemia, rotifer, and oyster, 100 g each, add seawater and four sterilization compound solutions A, B, C, and D according to the method in Table 1 below, set a blank treatment group, and use sterilization instead of drugs;

[0050] 1.4 After treating for 0.5 h, rinse with sterile seawater twice, 1 min each time, and set aside.

[0051] Table 1 Concentration ratio and time of four biological bait detoxification drugs

[0052]

[0053] Note: * indicates no acid bactericidal compound is added

[0054] 1.5 Feeding: The experiment set up 20 groups, and the shrimp broodstock and larvae group settings and feeding methods of each group were carried out according to the method in Table 2. The management of cultured broodstock was carried out according to the normal management method of vannamei broodstock, and the feeding of cultivated mysid shrimp larvae was carried out according to the normal management method of shrimp larvae. The blank broodstock group was fed with untreated nereids and oysters, and the blank zoea II larvae group and the blank mysid shrimp III larvae group were fed with untreated zoea and mysid shrimp larvae, respectively. Each group was set up with 3 parallels. The feeding experiment of broodstock was 5 days, and the feeding time of shrimp larvae was 3 days.

[0055] Table 2 Feed composition and feeding method of experimental broodstock and larvae

[0056]

[0057] 1.5 Detection of Vibrio load in bait organisms before and after treatment

[0058] Randomly select 5 nereids, 5 oysters, 10 g of rotifers, and 10 g of Artemia from each of the detoxified samples of nereids, oysters, rotifers, and Artemia, wash them three times in sterile seawater to remove the attachments on their body surfaces, then take out sterile gauze to absorb the moisture on the body surfaces, weigh them accurately, and homogenize them respectively. Take 10 mL of the homogenate and dilute it 10 times with sterile PBS buffer. 2 , 10 3 , 10 4 , 10 5 Times, take 0.1mL of the dilution and spread it on TCBS medium, repeat 3 plates for each dilution concentration, place the plate in a 28℃ incubator for 24h, distinguish different colonies according to their morphology, size, color and other characteristics and number them, count different colonies and total number respectively, and calculate the number of Vibrio in different biological baits. Use bacterial universal primers for 16SrDNA PCR amplification, sequencing and molecular identification.

[0059] 1.6 Detection of Vibrio load after shrimp ingestion of bait organisms

[0060] After 5 days of broodstock culture, the intestines and hepatopancreas of 5 experimental shrimps were taken and accurately weighed. After homogenization with sterile PBS, the homogenate was diluted 10 times with sterile PBS buffer. 2 , 10 3 , 10 4 , 10 5 0.1 mL of the dilution was spread on TCBS medium, and each dilution concentration was repeated 3 times. The plates were placed in a 28°C incubator for 24 hours. Different colonies were distinguished and numbered according to their morphology, size, color and other characteristics, and the number of different colonies and the total number were counted. 16SrDNA PCR amplification, sequencing and molecular identification were performed using bacterial universal primers.

[0061] After 3 days of culture, 500 zoeae and mysid larvae were taken from each group and homogenized with sterile PBS. The homogenate was diluted 10% with sterile PBS buffer. 2 , 10 3 , 10 4 , 10 50.1 mL of the dilution was spread on TCBS medium, and each dilution concentration was repeated 3 times. The plates were placed in a 28°C incubator for 24 hours. Different colonies were distinguished and numbered according to their morphology, size, color and other characteristics, and the number of different colonies and the total number were counted. 16SrDNA PCR amplification, sequencing and molecular identification were performed using bacterial universal primers.

[0062] 1.7 Virus Detection

[0063] The gill filaments and hepatopancreas tissues of 5 parent shrimps after 5 days of feeding and 50 larvae of zoeae (entering the healthy shrimp stage) and mysid shrimp (entering the juvenile shrimp stage) after 3 days of feeding were taken and used for the detection of WSSV and DIV1 in shrimps with 95% ethanol. The detection method of WSSV refers to OIE (2019), and the detection method of DIV1 refers to Qiu et al. (2017).

[0064] Office international des epizooties. Manual of diagnostic tests for aquatic animals[M]. Paris: OIE, 2019.

[0065] Qiu L,Chen MM,Wan XY,et al.Characterization of a new member ofiridoviridae,shrimp hemocyte iridescent virus(SHIV),found in white leg shrimp(Litopenaeus vannamei)[J].Scientific Reports,2017,7(1):11834.

[0066] 1.8 Comparison of bactericidal effects between acid complex and single acid solution

[0067] Take 100g of lactic acid stock solution and 100g of citric acid saturated aqueous solution, add 100g of ACS respectively, and prepare A acidic bactericidal complex and B acidic bactericidal complex solution; similarly, take 100g of lactic acid stock solution and 100g of saturated citric acid aqueous solution, add 300g of ACS respectively, and prepare C acidic bactericidal complex and D acidic bactericidal complex solution; then take lactic acid stock solution, citric acid saturated aqueous solution and ACS solution as single acid bactericidal solution, design bactericidal experiment according to the bactericidal concentration in Table 6, and the test bacteria are Vibrio harveyi, Vibrio alginolyticus, and Vibrio parahaemolyticus respectively. Test method: Use PBS as dilution solution, prepare 100mL of bactericidal solution according to the concentration gradient in Table 6, and then add live test bacteria to a concentration of 10 4CFU / mL, mix well and incubate at room temperature for 3 hours, then take 100 μL of each plate to coat TCBS plate, incubate at 28°C for 24 hours, and count the number of bacteria.

[0068] 2. Results

[0069] 2.1 Vibrio load in four biological baits after treatment with four acidic bactericidal compounds

[0070] The detection of Vibrio in wild neris, oysters, rotifers and Artemia after being soaked in four acidic bactericidal composite solutions of A, B, C and D is shown in Table 3. It can be seen that except for the control group, no Vibrio was detected in other treatment groups. This shows that the four acidic bactericidal composites of A, B, C and D have good bactericidal effects on Vibrio in the four biological baits.

[0071] Table 3 Detection of Vibrio in four biological baits after being treated with different acidic bactericidal compounds

[0072]

[0073]

[0074] 2. Detection of Vibrio load in shrimp broodstock and larvae after feeding on different biological baits

[0075] The treated nephrites and oysters were fed to broodstock, and the treated rotifers and artemia were fed to shrimp larvae. The number of Vibrio in the intestines, hepatopancreas and shrimp larvae of broodstock is shown in Table 4. It can be seen that after the nephrites carrying Vibrio alginolyticus and Vibrio harveyi were fed to shrimp, the above two Vibrio were not detected in the shrimp intestines and hepatopancreas, while in the blank control group, they were detected in the shrimp hepatopancreas and intestines; similarly, after the oysters carrying Vibrio brillius and Vibrio vulnificus were fed to shrimp, the above two Vibrio were not detected in the shrimp intestines and hepatopancreas, while in the blank control group, Vibrio brillius and Vibrio vulnificus were detected in the shrimp hepatopancreas and intestines. When the rotifers carrying Vibrio harveyi and the artemia carrying Vibrio parahaemolyticus were fed to shrimp larvae, it can be seen that the corresponding bacteria were detected in the shrimp larvae, while after the treated bait was fed to the larvae of fleas and mysid shrimp, the corresponding bacteria were not detected in the larvae of both stages. It shows that the two acidic bactericidal compounds at various concentrations have a killing effect on the bacteria in the biological bait.

[0076] Table 4 Detection of Vibrio in the intestines, hepatopancreas, zoea and mysid larvae of prawns fed with feed treated with different acidic bactericidal compounds

[0077]

[0078]

[0079]

[0080] 3. Detection of WSSV and DIV1 in shrimp broodstock and larvae after feeding on different biological baits. The treated nereids and oysters were fed to broodstock, and the treated rotifers and Artemia were fed to larvae. The detection results of WSSV and DIV1 in the intestines, hepatopancreas and larvae of broodstock are shown in Table 5. It can be seen that after the treated nereids carrying DIV1 were fed to shrimp, no virus was detected in their hepatopancreas and gill tissues; after the Artemia carrying WSSV was fed to mysid shrimp larvae, no WSSV was detected in their bodies, while DIV1 was detected in the tissues of the control group broodstock that fed on untreated nereids. Similarly, WSSV was detected in the mysid shrimp larvae that fed on untreated Artemia carrying WSSV. This shows that each acidic compound treatment group can kill the shrimp virus WSSV and DIV1.

[0081] Table 5 Detection results of WSSV and DIV1 in gill filaments and hepatopancreas, zoea and mysid larvae of prawns after feeding on the baits of each group

[0082]

[0083]

[0084] Note: “-” represents negative, “+” represents positive

[0085] 4. Comparison of the effects of acidic bactericidal complex and single acidic bactericidal solution

[0086] The bactericidal effects of single acidic bactericidal solution and acidic bactericidal composite solution on Vibrio harveyi, Vibrio alginolyticus and Vibrio parahaemolyticus are shown in Table 6. It can be seen that the effective bactericidal concentrations of the four acidic bactericidal composites A, B, C and D are lower than 0.4 g / L, while in the single acidic bactericidal solution, the effective concentrations of lactic acid and citric acid are 1.2 g / L, and the bactericidal concentration of ACS is 1.0 g / L, which are higher than any consistent composite bactericidal solution.

[0087] Table 6 Comparison of the effects of acidic bactericidal complex and single acidic bactericidal solution

[0088]

[0089]

[0090] Note: “+++” means the number of colonies is greater than 50 / plate; “++” means the number of colonies is 10-50 / plate; “+” means the number of colonies is 0-10 / plate; “-” means the number of colonies is 0 / plate

[0091] 3. Conclusion

[0092] (1) The acidic bactericidal complexes with different concentrations were used to treat the biological baits, such as nereidia, oysters, rotifers and Artemia, and had a good killing effect on the Vibrio in their bodies;

[0093] (2) After being treated with the acidic compound, the Vibrio in the biological bait is no longer infectious;

[0094] (3) The acidic bactericidal complexes with different concentrations were used to treat the biological baits, such as nereidia, oysters, rotifers and Artemia, and had a good killing effect on the shrimp viruses in them;

[0095] (4) The effect of acidic bactericidal complexes in different concentrations is better than that of a single acid.

[0096] Example 2

[0097] Effects of feeding live nereids and oysters treated with acidic bactericidal compound to prawn broodstock on gonadal and larval development

[0098] 1. Materials and Methods

[0099] 1.1 Vannamei shrimp broodstock: 150 SPF female broodstock, average body length (18.3±0.7) cm, 200 SPF male broodstock, average body length (15.9±0.5) cm. The shrimp were cultured in natural seawater treated with bleaching powder, with water temperature controlled at (27±0.3)℃, salinity 32, and light 500lux-700lux.

[0100] 1.2 Bait and its processing method: Collect live sandworms and fresh oysters sold in the market, treat them with 1:1000 acidic complex (the preparation method refers to the acidic complex in Example 1) for 3 hours, then rinse with sterilized seawater for 3 times and feed them, and use them immediately after processing.

[0101] 1.3 Experimental grouping: The experiment was divided into two groups, namely the experimental group fed with inactivated bait and the control group fed with non-inactivated lugworms and oysters. Each group had three parallel groups, with 50 male shrimps and 50 female shrimps in each parallel group, and the females were raised separately.

[0102] 1.4 Broodstock management method: Before maturation, female broodstock have their single eyestalks removed and are fed 15% of their body weight per day. The ratio of lugworms to oysters in the feed is 4:1. They are fed 5 meals a day. The experimental group is fed lugworms and oysters treated with acidic complexes, and the control group is fed untreated lugworms and oysters.

[0103] 1.5 Parent shrimp mating and larvae hatching: After 20 days of enhanced feeding, select female shrimps with mature gonads and put them into the male shrimp pond for mating. After the production, the larvae are collected for hatching. After the larvae are collected, they are placed in the larvae breeding pond for breeding.

[0104] 1.6 Statistics on the gonad maturity rate, gonad index and larval metamorphosis rate of female broodstock: The gonad maturity rate of female broodstock for 2 weeks was continuously counted, and the average daily maturity rate was calculated. At the end of the experiment, the gonad index of mature female broodstock was counted; at the same time, the mating rate, spawning number and survival rate of nauplii metamorphosing into zoea stage I were counted for broodstock that matured within 2 weeks.

[0105] 2. Results

[0106] 2.1 Daily gonadal maturation rate of female broodstock

[0107] After the broodstock were fortified with lugworms and oysters for 20 days, the daily maturity ratio of gonads in the experimental group and the control group was calculated. The results are shown in Figure 1 , the average maturity rate of the statistical number is 2w Figure 2 It can be seen that after feeding the nephrites and oysters treated with acidic bactericidal complex, the sexual maturity rate of the gonads of the broodstock tended to increase compared with the control group, but the difference in the average daily maturity rate of the broodstock between the experimental group and the control group was not significant. After the biological bait nephrites and oysters were treated, they had no effect on the gonad development of the broodstock of shrimp.

[0108] 2.2 Gonadal index of female broodstock

[0109] After the broodstock were fortified with lugworms and oysters for 20 days, the gonadal index of the broodstock in the experimental group and the control group was statistically analyzed after the end of the experiment. The results are shown in Figure 3 It can be seen that after feeding with lugworms and oysters treated with acidic bactericidal complex, the gonad index of broodstock was significantly higher than that of the control group (P<0.05), indicating that the treated biological bait not only does not affect the gonad development of shrimp, but also can enhance the gonad index of female shrimp.

[0110] 2.3 Daily average mating rate of mature broodstock

[0111] After the broodstock were fed with enhanced feeding of lugworms and oysters for 20 days, the daily mating rates of the broodstock in the experimental group and the control group were counted. The average daily mating rates within 2 weeks are shown in Table 1. Figure 4 It can be seen that after feeding with sandworms and oysters treated with acidic bactericidal complex, the mating rate of broodstock was significantly higher than that of the control group.

[0112] 2.4 Average number of eggs laid by female shrimp per day

[0113] After the broodstock were fortified with lugworms and oysters for 20 days, the number of eggs laid by the broodstock in the experimental group and the control group was counted. Figure 5 It can be seen that after feeding the lugworms and oysters treated with the acidic bactericidal complex, the daily number of eggs laid by the broodstock increased compared with the control group, indicating that the biological bait lugworms and oysters, after being treated, have an enhancing effect on the number of eggs laid by the broodstock of shrimp.

[0114] 2.5 Survival rate from nauplii to zoea

[0115] After the broodstock were fortified with lugworms and oysters for 20 days, the average daily survival rate of the larvae from the experimental group and the control group from metamorphosis to the zoeae stage I was calculated. Figure 6 It can be seen that after the broodstock were fed with lugworms and oysters treated with acidic bactericidal complex, the survival rate of the larvae from the nauplii to the zoeae stage I was higher than that of the control group, indicating that the biological bait lugworms and oysters, after being treated, not only did not have an adverse effect on the quality of the reproductive cells of the broodstock, but also had a promoting effect on the development of the larvae.

[0116] Based on the above implementation methods, it can be seen that (1) after the biological baits lugworms and oysters are processed, they have no effect on the gonad development of prawn broodstock; (2) the processed baits lugworms and oysters can enhance the gonad index of female prawns and improve the mating rate of prawn broodstock; (3) after the biological baits lugworms and oysters are processed, they have an enhancing effect on the number of eggs laid by prawn broodstock. (4) after the biological baits lugworms and oysters are processed, they will have a promoting effect on the development of larvae.

[0117] Example 3

[0118] Analysis of nutritional components of living nereids treated with acidic bactericidal compound

[0119] The cultivation of prawn broodstock requires rich nutrients in the bait, especially protein, fatty acids, cholesterol and vitamin E, to ensure the development of gonads. Bait organisms such as nereids are rich in various nutrients that promote the development of gonads of prawns. Therefore, this embodiment uses nereids to measure the loss of nutrients after being treated with an acidic bactericidal compound to evaluate the effect of the acidic bactericidal compound on the biological bait.

[0120] 1. Materials and Methods

[0121] 1.1 Nereids: The species was Perineuridae bicolor, collected from the mudflats of Taoluo Town, Donggang District, Rizhao City, with an average body weight of (2.1±0.6) g. They were cultured in clean seawater for 2 days before the experiment.

[0122] 1.2 Experimental grouping and treatment method for sandworms: The experiment was divided into 5 groups, including lactic acid, citric acid, ACS, acidic bactericidal complex and blank control group. Lactic acid stock solution, citric acid saturated aqueous solution and ACS solution were used as single acid bactericidal solution control group. The acidic bactericidal complex solution was prepared according to the preparation method of the acidic complex in Example 1. The three single bactericidal solutions and the acidic bactericidal complex were diluted 1000 times with water to prepare 500mL of bactericidal working solution. 200g of sandworms were taken and placed in the four bactericidal solutions for 3 hours, and then rinsed with sterilized seawater for 3 times for use. The sandworms in the blank control group were only rinsed with sterilized seawater 3 times, and 3 parallels were set for each group.

[0123] 1.3 Effect of acidic bactericidal compound treatment on nutritional components of nereids: Nereids rinsed with seawater were taken, the body surface was dried with absorbent paper, weighed and homogenized in an ice bath for analysis of total protein, total fat, cholesterol and vitamin E. Protein and cholesterol were determined using a total protein detection kit (Sangon Biotechnology Co., Ltd.) and a cholesterol detection kit (Nanjing Jiancheng Bioengineering Research Institute), respectively. The total fat detection method was based on GB 5009.6-2016, and vitamin E was based on GB5009.82-2016.

[0124] 2. Results

[0125] 2.1 Effects of citric acid, lactic acid, CAS and acidic bactericidal complex treatment on the nutritional components of live nereids

[0126] After the nereid was treated with citric acid, lactic acid, CAS and acidic bactericidal compound, the changes in the content of total protein, total fat, cholesterol and vitamin E in the body were analyzed. The results are shown in Table 7. It can be seen that after being treated with different bactericidal substances, the total protein content of the nereid treated with the acidic bactericidal compound was 12.9g / 100g, which was slightly lower than the control group (13.5g / 100g), but significantly higher than the citric acid, lactic acid and ACS treatment groups (12.3-12.6g / 100g) (P < 0.05). This shows that the acidic bactericidal compound treatment can better maintain the protein content of nereid, and compared with other disinfectants, it has the least effect on protein.

[0127] In terms of total fat content, the acidic bactericidal compound treatment group was 1.6 g / 100 g, which was lower than the control group (2.1 g / 100 g), but significantly higher than the other disinfectant treatment groups (P < 0.05), especially the ACS and citric acid treatment groups (0.9-1.0 g / 100 g). This means that the acidic bactericidal compound can effectively retain the fat content in the lugworm, showing its advantage in maintaining fat nutrition.

[0128] The cholesterol content of the acidic bactericidal compound treatment group was 0.91g / 100g, which was comparable to the control group (0.93g / 100g), but significantly higher than the citric acid and ACS treatment groups (0.80-0.86g / 100g) (P < 0.05). This shows that the acidic bactericidal compound can have a significant advantage in maintaining the cholesterol level of nereids and better retain cholesterol, and the difference is not significant compared with the control group.

[0129] The vitamin E content of the acidic bactericidal complex was 9.8×10 -4 g / 100g, second only to the control group (10.5×10 -4 g / 100g, but significantly higher than those treated with citric acid and ACS (5.8-6.2×10 -4g / 100g)(P<0.05). This indicates that the acidic bactericidal complex treatment can greatly retain the content of vitamin E, showing an excellent effect in the retention of antioxidant nutrients.

[0130] Table 7 The content of nutrients in the body of sandworms after being treated with 4 kinds of disinfectants

[0131]

[0132] Note: Different superscript letters in the same row indicate significant differences (P<0.05).

[0133] The above shows that the acidic bactericidal complex treatment group showed significant advantages in maintaining the nutritional components of sandworms, especially in the retention of total protein, total fat, cholesterol and vitamin E, which were close to the control group, and were superior to other disinfectant treatments, and had more application and promotion value.

[0134] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A detoxified biological bait, characterized in that: It is composed of biological bait, water and an acidic bactericidal compound; wherein the biological bait is at least one of lugworm, artemia, rotifer or oyster; The acidic bactericidal compound consists of organic acid and acidic calcium sulfate.

2. The detoxified biological bait according to claim 1, characterized in that: The organic acid is at least one of sorbic acid, benzoic acid, dehydroacetic acid, citric acid, malic acid, formic acid, acetic acid, propionic acid or lactic acid.

3. The detoxified biological bait as claimed in claim 1, characterized in that: The organic acid is citric acid or lactic acid; Preferably, the citric acid is a saturated aqueous solution of citric acid.

4. The detoxified biological bait according to claim 1, characterized in that: The mass ratio of the biological bait to water is 1:(2-3); The mass ratio of water to the acidic bactericidal compound is (500-1000):1; The mass ratio of the organic acid to the acidic calcium sulfate is 1:1 to 1:

3.

5. A method for preparing the detoxified biological bait according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) mixing an organic acid with acidic calcium sulfate to prepare an acidic bactericidal compound; (2) mixing the acidic bactericidal compound with water to obtain a detoxifying solution, and adding the biological bait to the detoxifying solution to perform a detoxifying treatment; (3) After the detoxification treatment, the biological bait is taken out from the detoxification solution and rinsed with sterilized seawater to obtain the detoxified biological bait.

6. The method for preparing the detoxified biological bait according to claim 5, characterized in that: In step (2), the detoxification treatment time is 0.5-3h; Or, in step (3), the number of times of seawater washing is 2-3 times.

7. A bait for aquaculture, characterized in that: Comprising a combination feed and the detoxified biological bait according to any one of claims 1 to 4; The combined feed is sterilized shrimp granular feed or sterilized shrimp flakes.

8. The aquaculture bait according to claim 7, characterized in that: The mixing mass ratio of the detoxified biological bait and the matched feed is (3:1):

1.

9. Use of the detoxified biological bait according to any one of claims 1 to 4 or the aquaculture bait according to claim 7 or 8 in aquaculture.

10. The use according to claim 9, characterized in that: Application in broodstock cultivation, maturation acceleration or rearing of juvenile shrimp and fish in marine aquaculture.

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