A breeding method for improving the heat stress resistance of mandarin fish

Abstract

A breeding method for improving the heat stress resistance of mandarin fish is to breed in a pond, when the water temperature is at a high temperature of 32-35°C, the mandarin fish is fed with heat stress resistance feed once at 6:00 every day, the daily feeding rate of mandarin fish seedlings below 100g is 1.5-2.0%, the daily feeding rate of mandarin fish 100-250g is 1.0-1.5%, and the daily feeding rate of mandarin fish above 250g is less than 1.0%. The present invention adopts physiological and biochemical, histological, nutritional and other research methods to analyze the stress mechanism of high temperature on fish body by reasonable nutritional intervention. Through scientific feeding, the food intake of fish body to feed is increased, the growth of mandarin fish is accelerated, the heat stress resistance of mandarin fish is improved, the liver antioxidant and immune ability of mandarin fish in a high temperature environment is enhanced, and the digestion and absorption capacity of mandarin fish is improved, thereby improving the high temperature survival ability of mandarin fish, and the survival rate reaches 96% in a long-term high temperature environment of 35°C.

Description

Technical Field

[0001] The invention relates to the technical field of fish breeding, and in particular to a breeding method for improving the heat stress resistance of mandarin fish. Background Art

[0002] Fish are aquatic cold-blooded animals, and their growth and reproduction are closely related to the living environment. Ambient temperature is one of the most important environmental factors for fish growth and development, affecting the entire life activities and metabolic processes of fish. Changes in water temperature not only affect fish feeding, feed efficiency, embryonic development and basal metabolism, but also affect fish antioxidant, immune function and sexual differentiation.

[0003] Heat stress refers to the sum of non-specific physiological responses of the body to temperature stimulation under high temperature conditions, which affects the animal's nerves, endocrine system, immunity, blood circulation, digestion, absorption, metabolism, etc. Fish have a certain tolerance to stress. When subjected to mild or short-term stress, the body can quickly recover to normal as the stimulation weakens; however, excessive or prolonged stress will cause the visceral tissues and the body to lose their ability to cope, the internal physiological balance will be broken, and the fish will show pathological conditions such as reduced immune function and inflammatory response, and even worse, death.

[0004] Mandarin fish is a traditional famous fish in my country, commonly known as "Osmanthus fish". It belongs to the order Perciformes, family Serranidae, and genus Siniperca. Its optimal growth water temperature is 22-28℃. In the range of 14~30℃, as the temperature rises, Mandarin fish's food intake increases and its growth rate accelerates; but above 30℃, it will be in a state of heat stress, which affects its feeding and growth.

[0005] As global warming intensifies, many provinces in my country have experienced extreme high temperature climates of varying lengths, especially in Chongqing. In 2022, due to a large-scale, high-intensity, extreme high temperature climate (40-45°C) lasting for more than 20 days, the water temperature in the breeding pond reached 35°C. Under the stress of high water temperature, mandarin fish shows a state of heat stress, and its nerves, endocrine system, immunity, blood circulation, digestion, absorption, metabolism and other aspects are all affected. The digestive glands cannot secrete digestive enzymes normally, appetite decreases, protein, fat and sugar metabolism is disordered, organ tissue structure and function are damaged, antioxidant and immune abilities decrease, poor feeding, closed mouth, vomiting, body surface ulcers, frequent bacterial diseases, conditional outbreaks of infectious spleen and kidney necrosis virus and frog iris virus, and large-scale mandarin fish deaths in ponds. When fish become ill, the healing process is relatively long and has a certain mortality rate. Therefore, the development of a heat stress-resistant feed and breeding method for mandarin fish under high water temperature is a need for industrial development, which can provide an important guarantee for the sustainable and healthy development of the mandarin fish industry. Summary of the invention

[0006] Based on the above technical deficiencies, the present invention aims to provide a breeding method for improving the heat stress resistance of mandarin fish. Through scientific breeding, the fish's feed intake is increased, the growth of mandarin fish is accelerated, and the heat stress resistance of mandarin fish is improved.

[0007] Another object of the present invention is to provide a heat stress resistant mandarin fish feed.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A breeding method for improving the heat stress resistance of mandarin fish, characterized in that: breeding is carried out in a pond, and when the water temperature is suitable for 20-30°C, the mandarin fish is acclimated and fed with ordinary feed, and the mandarin fish is cultivated into large-sized seedlings, and the heat stress resistance feed is fed during the high temperature period of 30-35°C. When the water temperature is at a high temperature of 30-32°C, 20-100g mandarin fish seedlings are flushed with water and fed with heat stress resistance feed, and the daily feeding rate of the feed is 2.0-2.5% of the weight of the mandarin fish, and it is fed twice a day, specifically 60% of the total amount fed at 6:00 and 40% of the total amount fed at 19:00; 100-250g mandarin fish are fed with heat stress resistance feed, and the daily feeding rate of the feed is 1.5-2.0% of the weight of the mandarin fish, and it is fed twice a day, 70% of the total amount fed at 6:00 and 40% of the total amount fed at 19:00. 30% of the total amount; 250-500g mandarin fish are fed with heat stress resistance feed, fed once a day at 6:00, and the daily feeding rate is 1.0-1.5% of the weight of mandarin fish; when the water temperature is at a high temperature of 32-35℃, all sizes of mandarin fish are fed with heat stress resistance feed once a day at 6:00, the daily feeding rate of mandarin fish fry below 100g is 1.5-2.0%, the feeding rate of mandarin fish 100-250g is 1.0-1.5%, and the feeding rate of mandarin fish above 250g is less than 1.0%.

[0010] Furthermore, the heat stress resistant feed is composed of a basic feed and an heat stress resistant additive, wherein the heat stress resistant feed includes perilla leaf powder, sunflower seed protein powder, pumpkin seed protein powder, tilapia scale protein powder, eucalyptus globulus essential oil, and rice protein amino acid chelated zinc.

[0011] Furthermore, the basic feed is white fish meal, red fish meal, chicken meal, gluten powder, cassava starch, mulberry leaf powder, artemisia annua leaf powder, perilla oil, corn oil, soybean oil, mineral and vitamin premix and monocalcium phosphate.

[0012] Furthermore, in terms of mass percentage, the heat stress resistant feed comprises 20-25% white fish meal, 20-25% red fish meal, 20-25% chicken meal, 5-6% gluten powder, 8-12% cassava starch, 3% mulberry leaf powder, 3% artemisia annua leaf powder, 1% perilla oil, 1% corn oil, 1% soybean oil, 2% mineral and vitamin premix and 2% monocalcium phosphate, and 5-6% heat stress resistant additives.

[0013] Furthermore, in terms of mass percentage, the anti-heat stress additive comprises 50% perilla leaf powder, 15-18% sunflower seed protein powder, 15-18% pumpkin seed protein powder, 6-10% tilapia scale protein powder, 5-10% eucalyptus essential oil, and 0.1-0.3% rice protein amino acid chelated zinc, and the mass percentage of 1,8-cineole in the eucalyptus essential oil is 20%.

[0014] Furthermore, during the entire breeding process, ammonia nitrogen is always maintained below 0.5, nitrite is below 0.05, pH is 7.5-8.5, and dissolved oxygen is higher than 5.0 mg / L.

[0015] Most specifically, a method for cultivating mandarin fish to improve its heat stress resistance comprises the following steps:

[0016] It is to set a floating board that occupies 20-30% of the pond area in the middle or side of the pond, plant water spinach, pennywort and other plants, and use net baskets to isolate and grow them independently;

[0017] When the water temperature is high at 30-32℃, 20-100g mandarin fish fry are flushed with water and fed with heat stress resistant feed, the daily feeding rate of the feed is 2.0-2.5% of the weight of the mandarin fish, and they are fed twice a day, specifically 60% of the total feeding amount at 6:00 and 40% of the total feeding amount at 19:00; 100-250g mandarin fish are fed with heat stress resistant feed, the daily feeding rate of the feed is 1.5-2.0% of the weight of the mandarin fish, and they are fed twice a day, 70% of the total feeding amount at 6:00 and 30% of the total feeding amount at 19:00; 250-500g mandarin fish are fed with heat stress resistant feed, fed once a day at 6:00, and the daily feeding rate of the feed is 1.0-1.5% of the weight of the mandarin fish;

[0018] When the water temperature is high at 32-35℃, all sizes of mandarin fish are fed with heat stress resistance feed once a day at 6:00 a.m. The daily feeding rate for mandarin fish fry under 100g is 1.5-2.0%, the feeding rate for mandarin fish 100-250g is 1.0-1.5%, and the feeding rate for mandarin fish over 250g is less than 1.0%;

[0019] The heat stress resistant feed is composed of a basic feed and an anti-heat stress additive. In the heat stress resistant feed, 20-25% of white fish meal, 20-25% of red fish meal, 20-25% of chicken meal, 5-6% of gluten powder, 8-12% of cassava starch, 3% of mulberry leaf powder, 3% of artemisia annua leaf powder, 1% of perilla oil, 1% of corn oil, 1% of soybean oil, 2% of mineral and vitamin premix and 2% of monocalcium phosphate are used to form the basic feed, and the anti-heat stress additive is 5-6%; the anti-heat stress additive is composed of 50% of perilla leaf powder, 15-18% of sunflower seed protein powder, 15-18% of pumpkin seed protein powder, 6-10% of tilapia scale protein powder, 5-10% of eucalyptus globulus essential oil and 0.1-0.3% of rice protein amino acid chelated zinc in the anti-heat stress additive, and the mass percentage of 1,8-cineole in the eucalyptus globulus essential oil is 20%;

[0020] The water quality in the pond is kept below 0.5 for ammonia nitrogen, below 0.05 for sub-salt, 7.5-8.5 for pH, and above 5.0 mg / L for dissolved oxygen. Two waterwheel aerators are set for every 5 mu of pond, placed in the 30-60 degree angle area 10-15m away from the feeding point, and one impeller aerator is set in the middle of the pond to ensure that the aquaculture water is in circulation and operates around the clock.

[0021] A heat stress resistant feed for mandarin fish, characterized in that the feed comprises a basic feed and a heat stress resistant additive, wherein the basic feed consists of white fish meal, red fish meal, chicken meal, gluten protein powder, cassava starch, mulberry leaf powder, artemisia annua leaf powder, perilla oil, corn oil, soybean oil, mineral and vitamin premix and monocalcium phosphate, and the heat stress resistant additive consists of perilla leaf powder, sunflower seed protein powder, pumpkin seed protein powder, tilapia scale protein powder, eucalyptus globulus essential oil and rice protein amino acid chelated zinc.

[0022] Furthermore, in terms of mass percentage, the heat stress resistant feed comprises 20-25% white fish meal, 20-25% red fish meal, 20-25% chicken meal, 5-6% gluten powder, 8-12% cassava starch, 3% mulberry leaf powder, 3% artemisia annua leaf powder, 1% perilla oil, 1% corn oil, 1% soybean oil, 2% mineral and vitamin premix and 2% monocalcium phosphate, and 5-6% heat stress resistant additives.

[0023] Furthermore, in terms of mass percentage, the anti-heat stress additive comprises 50% perilla leaf powder, 15-18% sunflower seed protein powder, 15-18% pumpkin seed protein powder, 6-10% tilapia scale protein powder, 5-10% eucalyptus essential oil, and 0.1-0.3% rice protein amino acid chelated zinc, and the mass percentage of 1,8-cineole in the eucalyptus essential oil is 20%.

[0024] The present invention has the following technical effects:

[0025] The present invention adopts physiological and biochemical, histological, and nutritional research methods to analyze the mechanism of high temperature stress on fish through reasonable nutritional intervention. Through scientific feeding, the fish's feed intake is increased, the growth of mandarin fish is accelerated, the mandarin fish's heat stress resistance is improved, the liver's antioxidant and immune abilities in high temperature environments are enhanced, and the mandarin fish's digestion and absorption abilities are improved, thereby improving the mandarin fish's ability to survive high temperatures, with a survival rate of 96% in a long-term high temperature environment of 35°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : Effects of common feed and heat stress-resistant feed on gastrointestinal tract, liver and spleen histology of mandarin fish (mandarin fish weighing about 100g). DETAILED DESCRIPTION

[0027] The present invention is described in detail below through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above-mentioned contents of the present invention.

[0028] A breeding method for improving the heat stress resistance of mandarin fish comprises the following steps:

[0029] It is to set a floating board that occupies 20-30% of the pond area in the middle or side of the pond, plant water spinach, pennywort and other plants, and use net baskets to isolate and grow them independently;

[0030] When the water temperature is suitable at 20-30℃, acclimate and switch to eating ordinary feed to cultivate mandarin fish into large-sized seedlings. When the water temperature is at a high temperature of 30-32℃, 20-100g mandarin fish seedlings are flushed with water and fed with heat stress resistant feed, the daily feeding rate of the feed is 2.0-2.5% of the weight of the mandarin fish, and fed twice a day, specifically 60% of the total feeding at 6:00 and 40% of the total feeding at 19:00; 100-250g mandarin fish are fed with heat stress resistant feed, the daily feeding rate of the feed is 1.5-2.0% of the weight of the mandarin fish, and fed twice a day, 70% of the total feeding at 6:00 and 30% of the total feeding at 19:00; 250-500g mandarin fish are fed with heat stress resistant feed, fed once a day at 6:00, and the daily feeding rate of the feed is 1.0-1.5% of the weight of the mandarin fish;

[0031] When the water temperature is high at 32-35℃, all sizes of mandarin fish are fed with heat stress resistance feed once a day at 6:00 a.m. The daily feeding rate for mandarin fish fry under 100g is 1.5-2.0%, the feeding rate for mandarin fish 100-250g is 1.0-1.5%, and the feeding rate for mandarin fish over 250g is less than 1.0%;

[0032] The heat stress resistant feed is composed of a basic feed and an anti-heat stress additive. In the heat stress resistant feed, according to mass percentage, 20-25% of white fish meal, 20-25% of red fish meal, 20-25% of chicken meal, 5-6% of gluten powder, 8-12% of cassava starch, 3% of mulberry leaf powder, 3% of artemisia annua leaf powder, 1% of perilla oil, 1% of corn oil, 1% of soybean oil, 2% of mineral and vitamin premix and 2% of monocalcium phosphate form the basic feed, and the anti-heat stress additive is 5-6%; the anti-heat stress additive is composed of 50% of perilla leaf powder, 15-18% of sunflower seed protein powder, 15-18% of pumpkin seed protein powder, 6-10% of tilapia scale protein powder, 5-10% of eucalyptus globulus essential oil and 0.1-0.3% of rice protein amino acid chelated zinc, and the mass percentage of 1,8-cineole in the eucalyptus globulus essential oil is 20%;

[0033] The water quality in the pond is kept below 0.5 for ammonia nitrogen, below 0.05 for sub-salt, 7.5-8.5 for pH, and above 5.0 mg / L for dissolved oxygen. Two waterwheel aerators are set for every 5 mu of pond, placed in the 30-60 degree angle area 10-15m away from the feeding point, and one impeller aerator is set in the middle of the pond to ensure that the aquaculture water is in circulation and operates around the clock.

[0034] The heat stress resistant feed is prepared into pellet feed according to the following method:

[0035] 1. Raw material preparation: prepare the raw materials according to the formula ratio, accurately crush the various raw materials and mix them evenly;

[0036] 2. Conditioning: Add appropriate amount of water and steam to the mixed raw materials to increase the temperature and humidity of the materials, keep the materials under certain conditions for a period of time, and promote the gelatinization of starch;

[0037] 3. Extrusion and puffing: The quenched and tempered material is extruded through the die hole under high temperature and high pressure by an extruder. The volume of the material expands rapidly at the die hole outlet to form a puffed structure;

[0038] 4. Cooling and drying: The extruded hot feed is cooled by a cooling device and further dried to reduce the moisture content;

[0039] 5. Crushing and grading: crush large puffed particles into appropriate sizes and separate particles of different sizes by screening.

[0040] The present invention reduces ammonia nitrogen and nitrite in aquaculture water through scientific feed control and feeding, improves the heat stress resistance of mandarin fish, enhances the antioxidant and immune capabilities of mandarin fish in a high temperature environment, and improves the digestion and absorption capacity of mandarin fish, thereby improving the high temperature survival ability of mandarin fish, and the survival rate reaches 96% in a long-term high temperature environment of 35°C.

[0041] Example 1

[0042] A heat stress resistant mandarin fish feed, the formula of which is as follows:

[0043] The heat stress resistant feed is composed of a basic feed and an anti-heat stress additive. In the heat stress resistant feed, the basic feed is composed of 25% white fish meal, 20% red fish meal, 22% chicken meal, 5% gluten powder, 10% cassava starch, 3% mulberry leaf powder, 3% artemisia leaf powder, 1% perilla oil, 1% corn oil, 1% soybean oil, 2% mineral and vitamin premix and 2% monocalcium phosphate, and the anti-heat stress additive is 5%; the anti-heat stress additive is composed of 50% perilla leaf powder, 17% sunflower seed protein powder, 17% pumpkin seed protein powder, 8% tilapia scale protein powder, 7.9% eucalyptus essential oil and 0.1% rice protein amino acid chelated zinc, and the mass percentage of 1,8 cineole in the eucalyptus essential oil is 20%.

[0044] The eucalyptus globulus essential oil in the heat stress resistant feed of Example 1 was replaced with eucalyptus microphylla essential oil with an equal amount of 1,8 cineole content, and the other step formulas were consistent with Example 1. The feed containing eucalyptus globulus essential oil in the heat stress resistant feed was used as a control, and the mandarin fish was fed at a high temperature of 33°C for 6 weeks. The effects of eucalyptus globulus essential oil and eucalyptus microphylla essential oil on the heat stress resistance of mandarin fish were detected, and some growth performance data results are shown in Table 1.

[0045] Table 1: Effects of eucalyptus globulus essential oil on the growth performance of mandarin fish under high temperature

[0046]

[0047] Note: The superscript * in the same data indicates significant difference among the groups ( P <0.05), the same below

[0048] The active ingredients in Eucalyptus microphylla essential oil and Eucalyptus globulus essential oil are basically the same, but when the two are added to feed as anti-heat stress components, it is found that the addition of Eucalyptus globulus essential oil improves the heat stress resistance of mandarin fish, but after replacing it with Eucalyptus microphylla essential oil, it has no effect at all on improving the heat stress resistance of mandarin fish.

[0049] Heat stress resistance test:

[0050] Ordinary mandarin fish feed was used as reference 1, and the heat stress resistant feed in Example 1 was used as reference 2. The heat stress resistant additive in Example 1 was added to reference 1 and reference 2, respectively, for a total of 4 groups. Mandarin fish weighing about 50 g were cultured at 25° C. (suitable growth temperature) and 33° C. (heat stress temperature) for 6 weeks, and their growth performance, feed coefficient, survival rate, liver and intestine morphology changes and other comprehensive indicators were tested to evaluate the anti-high temperature stress effect and safety.

[0051] The common feed formula in reference group 1 is as follows: high-refined flour 7.09% + cassava starch 8% + soybean concentrated protein 4% + soybean meal (CP46%) 7% + super steam fish meal 6% + high-quality steam fish meal 40% + high-quality chicken meal 20% + soybean oil 3.33% + phospholipid oil 2% + monocalcium phosphate 1.5% + choline chloride 0.2% + betaine 0.3% + lysine 0.3% + DL-methionine 0.1% + VC phosphate 0.1% + mildew inhibitor 0.05% + antioxidant 0.03%.

[0052] The effects of various feeds on the growth performance of mandarin fish are shown in Table 2. Table 2: Effects of feeds on growth performance and feed utilization of mandarin fish

[0053]

[0054] As can be seen from the above table, under suitable water temperature conditions (25℃), the survival rates of mandarin fish fed ordinary feed and basic feed both reached 100%. Under high water temperature (33℃) stress, mandarin fish in the ordinary feed group died with a survival rate of 78.56%, and the survival rate of the basic feed group was 75.80%. Under high water temperature (33℃), the survival rate of the heat stress resistant feed group was 100%, and the effect of the heat stress resistant feed group was significantly higher than that of the ordinary feed group (P<0.05), the weight gain rate increased by 46.93%, and the feed efficiency increased by 17.31%, thereby improving the growth performance and feed efficiency of mandarin fish.

[0055] 2. Influence of gastrointestinal and spleen morphology

[0056] The gastric gland of mandarin fish is a single tubular gland with independent parietal cells and chief cells. The more cells there are, the thicker the muscular membrane is, and the stronger its acid secretion and digestion ability is. The intestinal villi of mandarin fish are branched in a dendrite-like manner, which can greatly increase the digestion and absorption area of ​​the intestinal villus epithelium, which may be a compensatory effect for the short intestine of mandarin fish during the long-term evolution process. The number and height of villi on the intestinal mucosa are closely related to the number of mature cells. The more villi there are and the higher the height is, the more mature cells there are on the villi, the more complete the intestinal development is, and the digestion and absorption function is also enhanced. The experiment found that under the stress of high water temperature (33°C), the thickness of the gastric mucosal layer of the heat stress-resistant feed group was significantly thicker than that of the reference group. In addition, the length of intestinal villi, the number of branched villi, and the density of goblet cells were significantly increased. Structural comparison, and the HE staining section results of spleen tissue showed that compared with the ordinary feed group, the spleen white myelocytes of mandarin fish in the heat stress-resistant feed group increased, such as Figure 1As shown, among which: (a) is the stomach of mandarin fish in the 33℃ normal diet group (40×); (b) is the stomach of mandarin fish in the 33℃ heat stress resistant diet group (40×); (c) is the intestine of mandarin fish in the 33℃ normal diet group (40×); (d) is the intestine of mandarin fish in the 33℃ heat stress resistant diet group (40×); (e) is the liver of mandarin fish in the 33℃ normal diet group (40×); (f) is the liver of mandarin fish in the 33℃ heat stress resistant diet group (40×); (g) is the spleen of mandarin fish in the 33℃ normal diet group (40×); (h) is the spleen of mandarin fish in the 33℃ heat stress resistant diet group (40×); Bar=500 μm.

[0057] 3. The effects of feed on liver function under 33℃ high temperature stress are shown in Table 3.

[0058] Table 3: Effects of diet on liver structure and function of mandarin fish

[0059]

[0060] As shown in the table above, under high water temperature (33°C) stress, the immunoglobulin M (IgM), total antioxidant capacity (T-AOC) and total superoxide dismutase (T-SOD) activity of the liver of mandarin fish in the heat stress-resistant feed group were higher than those in the common feed group (P<0.05), and increased by 24.94%, 18.78% and 17.27% compared with the 33°C common feed group, while malondialdehyde decreased by 13.51%. Effects on liver structure Figure 1 As shown in the figure, it can be seen that the number of vacuolated liver cells and the number of cell nuclei deviation in the ordinary feed group are greater than those in the heat stress resistant feed group, and the arrangement is more loose and the development is poor.

[0061] 4. The effects on gastrointestinal digestion and absorption function are shown in Table 4.

[0062] Table 4: Effects of feed on gastrointestinal digestion and absorption function of mandarin fish

[0063]

[0064] It can be seen from the above that when feeding the common feed to mandarin fish, the high water temperature (33℃) inhibited the gastrointestinal digestion and absorption capacity of mandarin fish. Under the stress of high water temperature (33℃), feeding the heat stress-resistant feed improved the digestion and acid secretion capacity of the stomach of mandarin fish. Compared with the common feed group, the pepsin activity increased by 18.37%, and H +- K +- ATPase activity increased by 15.72%. In addition, the digestive and absorptive capacity of the intestines was also enhanced, and the activities of trypsin, lipase, amylase, Na +- K +- The ATPase activities increased by 15.48%, 14.95%, 18.75% and 20.24% respectively.

[0065] 5. Influence of intestinal microbial composition

[0066] Table 5: Effects of diet on intestinal microorganisms of mandarin fish

[0067]

[0068] As can be seen from the table above, under high water temperature (33°C) stress, the diversity of intestinal microorganisms is lower than that of the suitable water temperature (25°C group). However, in the high temperature group, the diversity of intestinal microorganisms in the 33°C heat stress resistant feed group was better than that in the 33°C ordinary feed group, among which the number of OUT, Ace index, Chao1 index, Simpson index, Shannon index, and PD_whole_tree index increased by 44.94%, 31.48%, 64.24%, 52.94%, 174.8%, and 59.33%, respectively, indicating that the heat stress resistant feed is beneficial to maintaining the health of the intestinal flora.

[0069] 6. Effect of feed on hormone levels

[0070] Table 6: Effects of feed on hormone levels in mandarin fish

[0071]

[0072] As can be seen from the table above, the 33℃ high water temperature group and the 25℃ suitable water temperature group in the common feed group showed a significant increase in cortisol hormone and a significant decrease in heat shock protein 70. Compared with the 33℃ heat stress resistant feed group and the 33℃ common feed group, the cortisol hormone level was 16.07% lower than that of the common group; heat shock protein 70 increased by 63.26%, which reduced high temperature stress and enhanced the heat stress resistance of mandarin fish. Therefore, the heat stress resistant feed for mandarin fish improves the survival rate of mandarin fish by regulating endocrine hormones to cope with the negative physiological effects of high water temperature.

[0073] Example 2

[0074] A heat stress resistant mandarin fish feed, the formula of which is as follows:

[0075] The heat stress resistant feed is composed of a basic feed and an anti-heat stress additive. In the heat stress resistant feed, according to mass percentage, 20% white fish meal, 20% red fish meal, 25% chicken meal, 5-6% gluten powder, 12% cassava starch, 3% mulberry leaf powder, 3% artemisia leaf powder, 1% perilla oil, 1% corn oil, 1% soybean oil, 2% mineral and vitamin premix and 2% monocalcium phosphate constitute the basic feed, and the anti-heat stress additive is 5%; the heat stress additive is composed of 50% perilla leaf powder, 18% sunflower seed protein powder, 15% pumpkin seed protein powder, 7% tilapia scale protein powder, 9.9% eucalyptus essential oil and 0.1% rice protein amino acid chelated zinc, and the mass percentage of 1,8 cineole in the eucalyptus essential oil is 20%.

[0076] Example 3

[0077] A heat stress resistant mandarin fish feed, the formula of which is as follows:

[0078] The heat stress resistant feed is composed of a basic feed and an anti-heat stress additive. In the heat stress resistant feed, according to mass percentage, 23% of white fish meal, 24% of red fish meal, 20% of chicken meal, 6% of gluten powder, 8% of cassava starch, 3% of mulberry leaf powder, 3% of artemisia leaf powder, 1% of perilla oil, 1% of corn oil, 1% of soybean oil, 2% of mineral and vitamin premix and 2% of monocalcium phosphate constitute the basic feed, and the anti-heat stress additive is 6%; the anti-heat stress additive is composed of 50% of perilla leaf powder, 15% of sunflower seed protein powder, 18% of pumpkin seed protein powder, 10% of tilapia scale protein powder, 6.7% of eucalyptus globulus essential oil and 0.3% of rice protein amino acid chelated zinc in the anti-heat stress additive, and the mass percentage of 1,8-cineole in the eucalyptus globulus essential oil is 20%.

[0079] Example 4

[0080] The heat stress resistant feeds and common feeds of Examples 1, 2 and 3 were applied in actual production, the aquaculture water temperature was about 35° C., and the aquaculture was carried out in three ponds for 4 weeks (i.e., three parallels). The aquaculture method for improving the heat stress resistance of mandarin fish comprises the following steps:

[0081] Set up floating boards that take up 20-30% of the pond area in the middle or on the side of the pond, plant water spinach, pennywort and other plants, and use net baskets to isolate them for independent growth;

[0082] When the water temperature is between 20 and 30℃, the fish are acclimated and fed with ordinary feed, and the fish are cultivated into large-sized seedlings. When the water temperature is high at 35℃, all sizes of fish are fed with heat stress-resistant feed once a day at 6:00 a.m. The daily feeding rate for fish seedlings under 100g is 1.5-2.0%, the feeding rate for fish 100-250g is 1.0-1.5%, and the feeding rate for fish over 250g is less than 1.0%;

[0083] The water quality in the pond is kept below 0.5 for ammonia nitrogen, below 0.05 for sub-salt, 7.5-8.5 for pH, and above 5.0 mg / L for dissolved oxygen. Two waterwheel aerators are set for every 5 mu of pond, placed in the 30-60 degree angle area 10-15m away from the feeding point, and one impeller aerator is set in the middle of the pond to ensure that the aquaculture water is in circulation and operates around the clock.

[0084] The effects of feed on the growth performance and feed utilization of mandarin fish were tested by comprehensively evaluating the heat stress resistance and safety of mandarin fish at a culture water temperature of 35°C. The results are shown in Table 7.

[0085] Table 7: Effects of heat stress-resistant diets on growth performance and feed utilization of mandarin fish at 35°C water temperature

[0086]

[0087] As can be seen from the above table, at a high temperature of 35°C, the common feed group died, with a survival rate of 62.2% and a mortality rate of 37.8%, while the heat stress resistant feed group had a survival rate of 96% and a mortality rate of only 4%. From the perspective of the food intake and weight gain rate of mandarin fish, the effect of the heat stress resistant feed group was significantly higher than that of the common feed group. The average food intake and weight gain rate of the tails in Example 1 increased by 21.99% and 65.64% respectively compared with the common feed group (P<0.05). From the perspective of body shape indicators, compared with the common feed group, the fatness and intestinal length ratio of the heat stress resistant feed group increased, while the organ-body ratio, liver-body ratio, and abdominal fat ratio decreased (P<0.05).

Claims

1. A method for cultivating mandarin fish to improve its heat stress resistance, characterized in that: For breeding in ponds, when the water temperature is high at 30-32℃, 20-100g mandarin fish fry are flushed with water and fed with heat stress resistant feed, the daily feeding rate of the feed is 2.0-2.5% of the weight of the mandarin fish, and they are fed twice a day, specifically 60% of the total feeding at 6:00 and 40% of the total feeding at 19:00; 100-250g mandarin fish are fed with heat stress resistant feed, the daily feeding rate of the feed is 1.5-2.0% of the weight of the mandarin fish, and the feed is fed twice a day. Feed twice, 70% of the total amount at 6:00 and 30% of the total amount at 19:00; 250-500g mandarin fish are fed with heat stress resistance feed, once at 6:00 a.m., and the daily feeding rate is 1.0-1.5% of the weight of mandarin fish; when the water temperature is at a high temperature of 32-35℃, all sizes of mandarin fish are fed with heat stress resistance feed once at 6:00 a.m. every day, and the daily feeding rate of mandarin fish fry below 100g is 1.5-2.0%, The feeding rate of mandarin fish weighing 100-250g is 1.0-1.5%, and the feeding rate of mandarin fish weighing more than 250g is lower than 1.0%. The heat stress resistant feed comprises, by mass percentage, 20-25% white fish meal, 20-25% red fish meal, 20-25% chicken meal, 5-6% gluten powder, 8-12% cassava starch, 3% mulberry leaf powder, 3% artemisia annua leaf powder, 1% perilla oil, 1% corn oil, 1% soybean oil, 2% mineral and vitamin premix and 2% monocalcium phosphate, and the heat stress resistant additive is 5-6%. Among the heat stress resistant additive, the perilla leaf powder is 50%, the sunflower seed protein powder is 15-18%, the pumpkin seed protein powder is 15-18%, the tilapia scale protein powder is 6-10%, the eucalyptus globulus essential oil is 5-10%, and the rice protein amino acid chelated zinc is 0.1-0.3%. The mass proportion of 1,8 cineole in the eucalyptus globulus essential oil is 20%.

2. A heat stress resistant mandarin fish feed, characterized in that: The feed comprises a basic feed and an anti-heat stress additive, wherein the basic feed comprises white fish meal, red fish meal, chicken meal, gluten powder, cassava starch, mulberry leaf powder, artemisia annua leaf powder, perilla oil, corn oil, soybean oil, mineral and vitamin premix and monocalcium phosphate, and the anti-heat stress additive comprises perilla leaf powder, sunflower seed protein powder, pumpkin seed protein powder, tilapia scale protein powder, eucalyptus globulus essential oil and rice protein amino acid chelated zinc. In terms of mass percentage, the white fish meal, the red fish meal, the chicken meal and the gluten powder are 20-25%, 20-25%, 20-25% and 5-10% of the feed. 6%, cassava starch is 8-12%, mulberry leaf powder is 3%, artemisia annua leaf powder is 3%, perilla oil is 1%, corn oil is 1%, soybean oil is 1%, mineral and vitamin premix is ​​2%, monocalcium phosphate is 2%, and anti-heat stress additive is 5-6%; among the anti-heat stress additive, perilla leaf powder is 50%, sunflower seed protein powder is 15-18%, pumpkin seed protein powder is 15-18%, tilapia scale protein powder is 6-10%, eucalyptus globulus essential oil is 5-10%, and rice protein amino acid chelated zinc is 0.1-0.3%, and the mass proportion of 1,8 cineole in the eucalyptus globulus essential oil is 20%.

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