Application of capsaicin in grass carp against hypoxia stress

Abstract

The application discloses application of capsaicin in resistance of grass carp to hypoxia stress and belongs to the technical field of agricultural breeding. In view of problems that red blood cell function of the grass carp is damaged, liver and gill tissues are damaged and the like under hypoxia stress, the application adds trace capsaicin in grass carp feed, optimizes a feed formula, relieves the decrease of the number of red blood cells and the increase of fragility of the grass carp in the later growth period caused by hypoxia stress, relieves liver damage, reduces the mortality of the grass carp in a hypoxic environment, reduces breeding risk, has the characteristics of green safety, low cost and remarkable economic benefits, and is suitable for large-scale grass carp breeding industry.

Description

Technical Field

[0001] This invention belongs to the field of agricultural aquaculture technology, specifically relating to the application of capsaicin in grass carp resisting hypoxia stress. Background Technology

[0002] Grass carp is an important economically farmed fish species in my country, ranking first in both domestic and global production and cultivation volume for many consecutive years. As one of the "four major freshwater fish" (a group of four major freshwater fish species in China), it is rich in nutrients, has a high feed conversion ratio, and is a common fish on people's tables. Grass carp is characterized by rapid growth, a wide range of feed sources, and high yield. Intensive and high-density aquaculture has become the main farming method in the aquaculture industry today. Under this method, hypoxia stress has become one of the most common forms of environmental stress. At the same time, my country experiences frequent extreme weather events. Sudden weather changes can cause rapid and massive mortality of green plants and algae in aquatic bodies, leading to a sharp drop in dissolved oxygen and causing hypoxia stress. Under normal circumstances, fish in water with suitable dissolved oxygen concentrations have a large feed intake, high feed conversion rate, and rapid growth rate. Under hypoxia stress, the feed intake and feed conversion efficiency of fish decrease significantly, and growth slows down. Compared to other fish species, grass carp are more sensitive to hypoxia environments. For example, when dissolved oxygen levels are below 2.72 mg / L, their growth rate decreases by 98%. Large grass carp have high oxygen consumption, making them particularly vulnerable to hypoxic stress. Prolonged exposure to low oxygen levels can lead to metabolic disorders and weakened immunity, causing disease outbreaks, especially under high temperatures or deteriorating water quality, resulting in significantly increased mortality. Under hypoxic stress, the gills, as the primary respiratory organ of fish, are the first to be affected, while the liver, as the most important metabolic organ, is also impacted. Therefore, improving the resistance of fish to hypoxic stress and alleviating gill and liver damage is urgently needed. Summary of the Invention

[0003] In view of the above-mentioned prior art, the present invention provides an application of capsaicin in grass carp to resist hypoxia stress, which solves the problem that grass carp have low resistance to hypoxia stress when the dissolved oxygen content in the water is low.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is to provide an application of capsaicin in grass carp resisting hypoxia stress.

[0005] Furthermore, capsaicin was added as an additive to grass carp feed for grass carp feeding.

[0006] Furthermore, the amount of capsaicin added is 0.00006% or 0.00012% of the grass carp feed mass.

[0007] Furthermore, the grass carp feed with added capsaicin comprises the following components in parts by weight: 2.5-3.5 parts fish meal, 2.5-3.5 parts rapeseed meal, 13-15 parts soybean meal, 21.5-22.5 parts dephenolized cottonseed protein, 26-30 parts α-starch, 17-17.1 parts wheat flour, 2.5-2.7 parts fish oil, 1.3-1.5 parts soybean oil, 1.2-1.7 parts calcium dihydrogen phosphate, 1.99988 or 1.99994 parts microcrystalline cellulose, 0.00006 or 0.00012 parts capsaicin, 0.015 parts hydroxyanisole, 0.22 parts L-threonine, and 5 parts compound premix.

[0008] Furthermore, the grass carp feed with added capsaicin comprises the following components in parts by weight: 3 parts fish meal, 3 parts rapeseed meal, 14 parts soybean meal, 22.15 parts dephenolized cottonseed protein, 28 parts α-starch, 17.085 parts wheat flour, 2.650 parts fish oil, 1.380 parts soybean oil, 1.5 parts calcium dihydrogen phosphate, 1.99988 parts microcrystalline cellulose, 0.00012 parts capsaicin, 0.015 parts hydroxyanisole, 0.22 parts L-threonine, and 5 parts compound premix.

[0009] Furthermore, the method for preparing grass carp feed with added capsaicin is as follows: crush the feed ingredients until they all pass through a 40-mesh sieve, then mix them evenly according to the mass proportions to form particles with a diameter of 2 mm and a length of 3 mm. After air-drying at room temperature, the grass carp feed with added capsaicin is obtained.

[0010] The beneficial effects of this invention are as follows: By adding a specific amount of capsaicin to grass carp feed, this invention effectively improves the stress resistance of grass carp under low-oxygen conditions; capsaicin can completely alleviate the decrease in red blood cell count and increase in fragility caused by low oxygen, maintain the stability of red blood cell function, significantly reduce the negative impact of low oxygen stress on the liver of grass carp, and inhibit the abnormal increase in the activities of alanine aminotransferase (GPT), aspartate aminotransferase (GOT), and lactate dehydrogenase (LDH) in serum. Capsaicin effectively reduces hepatocyte damage caused by low oxygen stress; by alleviating the decrease in red blood cell count and increase in fragility in grass carp during the later stages of growth caused by low oxygen stress, this invention can alleviate liver damage, significantly reduce breeding costs and increase yield, and has broad industrial application value. Moreover, as a natural active ingredient, capsaicin is used in extremely low amounts, with no risk of drug residues, and meets the requirements of ecological aquaculture and food safety. Attached Figure Description

[0011] Figure 1 The diagram shows the gill appearance and histological structure of the fish in the basal diet-noroxic group in Example 2; Figure 2 This is a diagram showing the gill appearance and tissue structure of the fish in the basal diet-hypoxia group in Example 2; Figure 3 This is a diagram showing the gill appearance and tissue structure of fish in the diet-hypoxia group of the present invention in Example 2. Detailed Implementation

[0012] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0013] Example 1 One hundred and eighty healthy grass carp with an average weight of 317 g were selected and randomly divided into two treatment groups: a control group and a capsaicin-added group. Each group was treated in three replicates, with 30 fish per replicate. The fish were fed a basal diet and the grass carp feed with capsaicin added according to the present invention, respectively.

[0014] The basic feed consists of the following components in parts by weight: 3 parts fish meal, 3 parts rapeseed meal, 14 parts soybean meal, 22.15 parts dephenolized cottonseed protein, 28 parts α-starch, 17.085 parts wheat flour, 2.650 parts fish oil, 1.380 parts soybean oil, 1.5 parts calcium dihydrogen phosphate, 2 parts microcrystalline cellulose, 0.015 parts hydroxyanisole, 0.22 parts L-threonine, and 5 parts compound premix. Grass carp feed with added capsaicin consists of the following components in parts by weight: 3 parts fish meal, 3 parts rapeseed meal, 14 parts soybean meal, 22.15 parts dephenolized cottonseed protein, 28 parts α-starch, 17.085 parts wheat flour, 2.650 parts fish oil, 1.380 parts soybean oil, 1.5 parts calcium dihydrogen phosphate, 1.99988 parts microcrystalline cellulose, 0.00012 parts capsaicin, 0.015 parts hydroxyanisole, 0.22 parts L-threonine, and 5 parts compound premix.

[0015] The preparation methods for both the basic feed and the grass carp feed with added capsaicin are as follows: crush the feed ingredients until they all pass through a 40-mesh sieve, then mix them evenly according to the mass proportions, make them into pellets with a diameter of 2mm and a length of 3mm, and air-dry them at room temperature.

[0016] The rearing method in this embodiment was as follows: Grass carp were reared in (2.0 m × 2.0 m × 2.0 m) net cages for 63 days. They were fed four times daily at 7:00, 11:00, 15:00, and 19:00. After each feeding, the uneaten feed was collected, dried, and weighed ten minutes later to calculate feed intake (FI). The health status of the grass carp was observed daily. During the experiment, the water temperature and pH were maintained at 25.8 ± 2.1℃ and 7.5 ± 0.2, respectively, and dissolved oxygen was maintained at ≥ 6 mg / L. After the rearing experiment, feeding was stopped for 24 hours, and the fish were anesthetized with ethyl aminobenzoate. The fish were then weighed per cage.

[0017] The experimental results are shown in Table 1. After feeding grass carp with the feed containing capsaicin of this invention, the final weight increased by 14%, feed intake increased by 3%, feed utilization rate increased by 15%, and weight gain rate increased by 19%. This indicates that capsaicin can significantly promote grass carp feeding, improve feed conversion efficiency, and promote grass carp growth.

[0018] Table 1. Effects of capsaicin on the growth performance of grass carp project Basic feed group Feed group of the present invention Average initial weight (g / tail) 317.11±0.84 317.22±0.69 Average final weight (g / tail) 1164.67±61.34 1325.67±179.89 Average feed intake (g / tail) 1269.13±13.21 1304.61±39.17 Feed efficiency 0.67±0.04 0.77±0.12 Weight gain rate (%) 267.30±19.90 317.98±57.53 Example 2 Effects of capsaicin on the ability of grass carp to resist hypoxia stress: Based on Example 1, the experiment was continued. 24 fish were selected from each treatment (12 in the hypoxia group and 12 in the normoxic group). The dissolved oxygen in the normoxic group was ≥6 mg / L, and the dissolved oxygen in the hypoxia group was 1 mg / L. The dissolved oxygen concentration in the water was monitored using a YSI dissolved oxygen meter. The experiment lasted for 96 hours.

[0019] After the hypoxia test, grass carp blood was centrifuged for 10 minutes and the supernatant (i.e., blood sample) was collected to measure hematological parameters. After blood collection, each treated fish was slaughtered, and the gills and liver were separated. Enzyme activity samples, molecular samples, HE section samples, and transmission electron microscopy samples were collected respectively.

[0020] The effects of hypoxia on erythrocyte-related indicators in grass carp are shown in Table 2. Hypoxia stress led to a decrease in erythrocyte count and a significant increase in minimum and maximum erythrocyte fragility. Compared with the normoxic diet group (NN), the basal diet-hypoxia group (NH) showed an increase of 12% and 31% in minimum and maximum erythrocyte fragility, respectively. However, the addition of capsaicin to the diet-hypoxia group (capsaicin-H) of this invention completely alleviated the decrease in erythrocyte count and the increase in erythrocyte fragility caused by hypoxia, indicating that capsaicin can alleviate the decrease in erythrocyte count and the increase in erythrocyte fragility in grass carp during the later stages of growth caused by hypoxia stress.

[0021] Table 2. Effects of capsaicin on blood erythrocyte-related parameters in grass carp during the later stages of growth under hypoxic stress.

[0022] Serum aspartate aminotransferase (AST), alanine aminotransferase (GPT), and lactate dehydrogenase (LDH) activities are key indicators of hepatocyte damage. When hepatocytes are damaged, their permeability changes, and large amounts of GOT, GPT, and LDH are transported from hepatocytes into the serum, leading to increased serum activity. Table 3 shows the changes in relevant serum indicators of grass carp in each treatment group. The data in the table show that hypoxia stress significantly increased serum GOT, GPT, and LDH. Compared with the basal diet-noroxic group (NN), the increases in serum GOT, GPT, and LDH in the basal diet-hypoxia group (NH) were 15%, 29%, and 14%, respectively. However, the addition of capsaicin to the diet-hypoxia group (capsaicin-H) of this invention completely alleviated the increase in serum GOT, GPT, and LDH caused by hypoxia, indicating that capsaicin can alleviate liver damage in grass carp during the later growth stages caused by hypoxia stress.

[0023] Table 3. Effects of capsaicin on serum-related indicators of grass carp during the later stages of growth under hypoxic stress.

[0024] Gills are important respiratory organs in fish, playing a crucial role in regulating hypoxic stress responses. When fish are exposed to prolonged hypoxic conditions, the gill tissue structure is damaged. In this embodiment, the gill and hematoxylin and eosin (HE) sections of fish from the basal diet-noroxic group, the basal diet-hypoxia group, and the diet of this invention-hypoxia group are shown below. Figures 1-3 As shown, the gills of fish in the basal diet-noroxic group were rosy, while the gills of fish in the basal diet-hypoxia group were black, caused by insufficient oxygen. The diet of the present invention with added capsaicin in the hypoxia group completely alleviated the symptom of black gill color. HE results showed that, compared with the basal diet-noroxic group, the gill lamellae of the fish in the basal diet-hypoxia group showed severe respiratory epithelial cell detachment, disappearance or even necrosis, gill lamellae were curved, and gill structure was severely damaged. However, the diet of the present invention-hypoxia group could completely alleviate the gill oxygenation and appearance abnormalities caused by hypoxia.

[0025] Although specific embodiments of the present invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. Application of capsaicin in the preparation of grass carp feed resistant to hypoxia stress, wherein capsaicin is added as an additive to grass carp feed for feeding grass carp; wherein the amount of capsaicin added is 0.00012% of the mass of grass carp feed.

2. The application according to claim 1, characterized in that, The grass carp feed with added capsaicin comprises the following components in parts by weight: 3 parts fish meal, 3 parts rapeseed meal, 14 parts soybean meal, 22.15 parts dephenolized cottonseed protein, 28 parts α-starch, 17.085 parts wheat flour, 2.650 parts fish oil, 1.380 parts soybean oil, 1.5 parts calcium dihydrogen phosphate, 1.99988 parts microcrystalline cellulose, 0.00012 parts capsaicin, 0.015 parts hydroxyanisole, 0.22 parts L-threonine, and 5 parts compound premix.

3. The application according to claim 1, characterized in that, The method for preparing the grass carp feed with added capsaicin is as follows: crush the feed ingredients until they all pass through a 40-mesh sieve, then mix them evenly according to the mass proportions to make granules with a diameter of 2mm and a length of 3mm, and air-dry them at room temperature to obtain the grass carp feed with added capsaicin.

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