Functional feed for catfish and preparation method thereof

Abstract

According to the functional feed for catfish and the preparation method of the functional feed, tissue damage can be effectively relieved through the excellent nutritional value and biological activity of the functional feed, the growth speed and the health level of fish can be improved, meanwhile, dependence on marine resources is reduced, the problem of fish meal shortage is relieved, and the growth and immune performance of cultured fish is improved; and the culture benefit is increased.

Description

Technical Field

[0001] The present invention belongs to the fields of aquaculture and feed science, and particularly relates to a functional feed for Silurus meridionalis and a preparation method thereof. Background Art

[0002] Silurus meridionalis is an important freshwater aquaculture variety in China. Its rapid growth, high feeding efficiency, low disease incidence, and good cold resistance make it widely used in aquaculture. However, due to the insufficient supply and high price of fish meal, and the environmental pressure caused by the dependence on marine resources, with the expansion of aquaculture scale, finding efficient and economical alternative protein sources has become a key requirement in the aquaculture industry. Currently, soybean protein has been widely used to partially replace fish meal, but its antinutritional factors may have an adverse impact on the health of fish.

[0003] However, too high a proportion of plant protein sources in fish feed may have various adverse effects on fish liver tissue. The liver is an important organ for fish metabolism, detoxification, protein synthesis, and energy storage. Therefore, the composition and proportion of plant protein in feed are crucial for liver function and health. The digestion and absorption of plant protein sources in fish are more difficult compared to animal proteins. Plant proteins usually contain more dietary fiber and antinutritional factors, and the liver needs to expend more metabolic energy to process these components. When the proportion of plant protein is too high, the metabolic pressure on the liver increases, which may lead to a decline in liver function and even pathological changes such as liver inflammation and hepatocyte damage. Some components in plant proteins may exert oxidative stress on the fish liver. For example, some phytochemicals (such as flavonoids, tannins, etc.) in plant proteins may induce oxidative stress reactions, increase the production of free radicals, thereby damaging the liver cell membrane and leading to liver inflammation and tissue damage. Long-term exposure of the liver to oxidative stress may result in lipid peroxidation, affecting its health and function. In addition, the liver and intestine cooperate closely in fish. Some substances in the intestine (such as plant antinutritional factors) need to be cleared through the metabolism and detoxification of the liver. Too much plant protein source may lead to intestinal health problems (such as intestinal inflammation, malabsorption, etc.), which in turn increase the burden on the liver and further exacerbate liver damage. Therefore, there are currently pathological damages such as liver edema and vacuolization in the culture of Silurus meridionalis under commercial feed feeding, and it is necessary to develop more high-quality and suitable feeds. Summary of the Invention

[0004] In view of the above problems, the present invention provides a functional feed for Silurus meridionalis and a preparation method thereof, with Periplaneta americana powder as the core component. This feed can effectively reduce oxidative damage and inflammatory responses in fish tissues, enhance its antioxidant capacity, improve the diversity of its intestinal microbiota, and at the same time, the application of the present invention can also effectively reduce the breeding cost of Silurus meridionalis and improve the growth performance of Silurus meridionalis to obtain the maximum economic benefits.

[0005] When using the feed of the present invention, the growth rate of Silurus meridionalis Chen is significantly improved. The final body weight FBW (53.86±1.93b%) and weight gain rate WGR (404.07±22.02b%) under the condition of replacing 10% of fish meal with Blattella germanica powder are significantly higher than the final body weight FBW (43.30±1.60a%) and weight gain rate WGR (312.86±32.00a%) without adding Blattella germanica powder, and its feed conversion rate reaches the best (1.02±0.003a). At the 10% replacement ratio, the liver edema of the fish body is significantly reduced, the tissue structures of the fish body liver and intestine are significantly improved, and the infiltration of inflammatory cells is reduced. The MDA levels in serum and liver are significantly decreased, and the antioxidant enzyme activities are significantly enhanced. In terms of intestinal microbiota, the abundances of Bacteroidaceae, Barnesiellaceae, Fusobacteriaceae, unclassified_bacteroidales, and Peptostreptococcaceae in the intestine are significantly increased, and the intestinal flora diversity is significantly enhanced.

[0006] One of the technical solutions of the present invention is to provide a functional feed for Silurus meridionalis Chen. The feed contains 40%-45% of animal protein source by mass, and the animal protein source consists of Blattella germanica powder, fish meal, and chicken meal in a weight ratio of (1.6-5.55):(27.2-35.15):8, and the Blattella germanica powder accounts for 5%-15% of the total mass of Blattella germanica powder and fish meal.

[0007] Furthermore, it also contains 25%-35% of plant protein source by mass and 4%-8% of fat by mass.

[0008] Furthermore, the plant protein source is one or more of fermented soybean meal and corn protein powder.

[0009] Furthermore, it also contains auxiliary components, and the auxiliary components are one or more of calcium dihydrogen phosphate, trace element premix, vitamin premix, L-lysine monohydrochloride, choline chloride, methionine, mannan oligosaccharide, threonine, lysine, and chromium sesquioxide.

[0010] Furthermore, it also includes carbohydrates, and its mass fraction is 20%.

[0011] Furthermore, the mass fraction of the auxiliary components in the feed is 3.5-4.5%.

[0012] The second technical solution of the present invention lies in providing a preparation method of the above-mentioned feed, specifically: mixing and pulverizing animal protein sources, plant protein sources, fats, auxiliary components and carbohydrates, sieving through a 80-mesh sieve, then adding it to a blender for stirring, preparing feed pellets from the stirred feed through commercial granulation equipment, and finally drying it using a dryer at a temperature of 40 - 45 °C for 1.0 - 1.5 hours, and storing it at -20 °C after drying.

[0013] The beneficial effects of the present invention are as follows: The animal-derived feed raw materials added to this feed meet the carnivorous physiological characteristics of Silurus meridionalis, provide sufficient animal protein and some mineral elements, and can effectively improve the survival rate and growth rate of Silurus meridionalis.

[0014] During the breeding process, using the feed with 10% Periplaneta americana powder replacing fish meal as the standard formula to feed Silurus meridionalis can improve the growth performance of Silurus meridionalis, enhance the antioxidant capacity, improve the intestinal microbiota, and relieve tissue damage. Brief Description of the Drawings

[0015] Figure 1 It is a histological section diagram of the liver and intestine of Silurus meridionalis fed for 56 days in Example 1; Figure 2 It is the intestinal trypsin activity and intestinal lipase activity of Silurus meridionalis fed for 56 days in Example 1; Figure 3 It is the serum detection indexes of Silurus meridionalis fed for 56 days in Example 1; Figure 4 It is the liver detection indexes of Silurus meridionalis fed for 56 days in Example 1; Figure 5 It is the α-diversity analysis of Silurus meridionalis fed for 56 days in Example 1; Figure 6 It is the PCA analysis of Silurus meridionalis fed for 56 days in Example 1; Figure 7 It is the intestinal species richness analysis of Silurus meridionalis fed for 56 days in Example 1; Figure 8 It is the functional analysis based on FAPROTAX of Silurus meridionalis fed for 56 days in Example 1; Figure 9 It is the functional analysis based on BugBase of Silurus meridionalis fed for 56 days in Example 1. Detailed Embodiments

[0016] The following embodiments are used to further illustrate the present invention, and their purpose is to illustrate the present invention rather than to limit the scope of the present invention. Unless otherwise specified below, all are in parts by weight and weight percentages.

[0017] The raw materials used in the present invention are all conventional commercially available products unless otherwise specified; the methods used in the present invention are all conventional methods in the art unless otherwise specified.

[0018] The following further illustrates the embodiments of the present invention through multiple examples. [[ID=?]]

[0019] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope protected by the present application.

[0020] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0021] Example 1 Mix and pulverize animal protein sources, plant protein sources, fats, auxiliary components and carbohydrates, sieve them through an 80-mesh sieve, then add them to a blender for stirring, prepare feed pellets from the stirred feed through commercial granulation equipment, and finally use a dryer for drying treatment at a temperature of 40 °C for 1.5 hours, and store at -20 °C after drying.

[0022] The feed formulation is 33.3 wt% fish meal, 3.7 wt% cockroach powder, 20 wt% fermented soybean meal, 20 wt% high-gluten flour, 8 wt% chicken meal, 7.5 wt% corn protein powder, 4 wt% soybean oil, 1.2 wt% calcium dihydrogen phosphate, 0.4 wt% trace element premix, 0.4 wt% vitamin premix, 0.35 wt% L-lysine hydrochloride, 0.3 wt% choline chloride, 0.25 wt% methionine, 0.2 wt% mannan oligosaccharide, 0.15 wt% threonine, 0.15 wt% lysine, 0.1 wt% chromium sesquioxide.

[0023] Example 2 Mix and pulverize animal protein sources, plant protein sources, fats, auxiliary components and carbohydrates, sieve them through an 80-mesh sieve, then add them to a blender for stirring, prepare feed pellets from the stirred feed through commercial granulation equipment, and finally use a dryer for drying treatment at a temperature of 45 °C for 1.0 hour, and store at -20 °C after drying.

[0024] The feed formulation is as follows: fish meal 30.4 wt%, Periplaneta americana powder 1.6 wt%, fermented soybean meal 20 wt%, high-gluten flour 20 wt%, chicken meal 8 wt%, corn protein powder 15 wt%, soybean oil 5.5 wt%, calcium dihydrogen phosphate 1.5 wt%, trace element premix 0.5 wt%, vitamin premix 0.6 wt%, L-lysine hydrochloride 0.35 wt%, choline chloride 0.3 wt%, methionine 0.3 wt%, mannan oligosaccharide 0.2 wt%, threonine 0.2 wt%, lysine 0.15 wt%, chromium(III) oxide 0.1 wt%.

[0025] Example 3 Mix and grind the animal protein source, plant protein source, fat, auxiliary components and carbohydrates, sieve through an 80-mesh sieve, then add them to a blender for stirring. Prepare feed pellets from the stirred feed through commercial pelletizing equipment, and finally dry it using a dryer at a temperature of 44 °C for 1.3 hours, and store it at -20 °C after drying.

[0026] The feed formulation is as follows: fish meal 31.45 wt%, Periplaneta americana powder 5.55 wt%, fermented soybean meal 20 wt%, high-gluten flour 20 wt%, chicken meal 8 wt%, corn protein powder 5 wt%, soybean oil 5.5 wt%, calcium dihydrogen phosphate 1.7 wt%, trace element premix 0.6 wt%, vitamin premix 0.6 wt%, L-lysine hydrochloride 0.35 wt%, choline chloride 0.3 wt%, methionine 0.3 wt%, mannan oligosaccharide 0.2 wt%, threonine 0.2 wt%, lysine 0.15 wt%, chromium(III) oxide 0.1 wt%.

[0027] Example 4 Mix and grind the animal protein source, plant protein source, fat, auxiliary components and carbohydrates, sieve through an 80-mesh sieve, then add them to a blender for stirring. Prepare feed pellets from the stirred feed through commercial pelletizing equipment, and finally dry it using a dryer at a temperature of 45 °C for 1.0 hour, and store it at -20 °C after drying.

[0028] The feed formulation is as follows: fish meal 27.2 wt%, Periplaneta americana powder 4.8 wt%, fermented soybean meal 20 wt%, high-gluten flour 20 wt%, chicken meal 8 wt%, corn protein powder 15 wt%, soybean oil 5.5 wt%, calcium dihydrogen phosphate 1.5 wt%, trace element premix 0.5 wt%, vitamin premix 0.6 wt%, L-lysine hydrochloride 0.35 wt%, choline chloride 0.3 wt%, methionine 0.3 wt%, mannan oligosaccharide 0.2 wt%, threonine 0.2 wt%, lysine 0.15 wt%, chromium(III) oxide 0.1 wt%.

[0029] Example 5 Mix and pulverize animal protein sources, plant protein sources, fats, auxiliary components, and carbohydrates, sieve them through a 80-mesh sieve, then add them to a blender for stirring. Prepare feed pellets from the stirred feed using commercial pelletizing equipment, and finally dry them using a dryer at a temperature of 45 °C for 1.5 hours, and store them at -20 °C after drying.

[0030] The feed formulation is as follows: fish meal 35.15 wt%, cockroach powder 1.85 wt%, fermented soybean meal 20 wt%, high-gluten flour 20 wt%, chicken meal 8 wt%, corn protein powder 5 wt%, soybean oil 5.5 wt%, calcium dihydrogen phosphate 1.7 wt%, trace element premix 0.6 wt%, vitamin premix 0.6 wt%, lysine hydrochloride 0.35 wt%, choline chloride 0.3 wt%, methionine 0.3 wt%, mannan oligosaccharide 0.2 wt%, threonine 0.2 wt%, lysine 0.15 wt%, chromium sesquioxide 0.1 wt%.

[0031] Control Example 1 The difference from Example 1 is that 37 wt% of fish meal is used and cockroach powder is not added.

[0032] Control Example 2 The difference from Example 1 is that 29.6 wt% of fish meal and 7.4 wt% of cockroach powder are used.

[0033] Control Example 3 The difference from Example 1 is that 25.9 wt% of fish meal and 11.1 wt% of cockroach powder are used.

[0034] Transfer 400 juvenile Silurus meridionalis fish (with an average weight of about 7 grams per fish) that have been acclimated to the feed to a recirculating aquaculture system. The system consists of four circular plastic water tanks, each with a capacity of 1500 L, and the water volume in each tank is maintained at 1200 L. After adaptation, randomly allocate 320 healthy fish with an average weight of 10.0 ± 0.1 g to the water tanks, with 80 fish in each tank. In the early stage of the experiment, raise the Silurus meridionalis fish under the above conditions and manually feed commercial feed twice a day at 9:00 and 17:00 until they are almost full, for two consecutive weeks. After that, feed them with the prepared feed for 56 days. During the entire experiment, maintain the water quality by continuous aeration, daily removal of excreta, and changing one-third of the water in the water tank every five days. Keep the water quality parameters as follows: temperature at 27 ± 2 °C, pH value between 6.8 and 7.5, dissolved oxygen level higher than 5.0 mg / L, ammonia nitrogen level lower than 0.1 mg / L, and nitrite level lower than 0.1 mg / L.

[0035] As shown in Table 1, after 8 weeks of feeding, the weight gain of the Silurus meridionalis in Example 1 group was significantly higher than that in the other three groups. The weight gain rate (WGR) and specific growth rate (SGR) of the Silurus meridionalis in Example 1 group were the highest, while those in Comparative Example 3 group were the lowest. The feed conversion rate (FCR) of the Silurus meridionalis in Example 1 group was significantly lower than that in Comparative Example 1 group, and the feed conversion rate (FCR) of the Silurus meridionalis in Comparative Example 1 group was significantly higher than that in Comparative Example 1 group. The condition factor (CF) of the Silurus meridionalis in Comparative Example 3 group was also significantly higher than that in Example 1 group. Compared with Comparative Example 1, the hepatosomatic index (HSI) of the Silurus meridionalis in Comparative Example 3 group increased significantly.

[0036] Table 1 Analysis of the effect of PAP replacing fish meal on the growth performance of Silurus meridionalis As Figure 1 shown, in Comparative Example 1, the liver was edematous and the cell volume increased. The liver edema in Example 1 group was significantly alleviated compared with that in Comparative Example 1. Obvious liver edema also occurred in Comparative Example 2 group and Comparative Example 3 group, the cell volume increased, accompanied by inflammatory infiltration, and the liver damage in Comparative Example 3 group was the most serious. Pathological analysis showed that there was no obvious difference in the intestinal tissue between Comparative Example 1 (control) and Example 1 (PAP-10) group. However, the intestinal villi in Comparative Example 2 (PAP-20) and Comparative Example 3 (PAP-30) groups were significantly elongated and filled the entire intestinal lumen. At the same time, it was observed that the intestinal villi in Comparative Example 3 group became thinner and denser.

[0037] The trypsin and lipase in the intestine of Silurus meridionalis were measured to analyze the effect of PAP on intestinal digestive enzymes. The results showed that the intestinal trypsin activity of the Silurus meridionalis in Example 1 group was significantly higher than that in Comparative Example 1 (2A). However, the intestinal trypsin activities of the Silurus meridionalis in Comparative Example 2 group and Comparative Example 3 group with a higher proportion of PAP replacing fish meal were significantly lower than those in Example 1 group, and even the intestinal trypsin activity in Comparative Example 3 group was significantly lower than that in Comparative Example 1 ( Figure 2 A). There was no significant difference in the intestinal lipase activity between Example 1 group and Comparative Example 1 group of Silurus meridionalis, and those in Comparative Example 2 group and Comparative Example 3 group were lower than that in Comparative Example 1 ( Figure 2 B). The intestinal lipase activity in Comparative Example 3 group was the lowest ( Figure 2 B).

[0038] The changes in the activities of superoxide dismutase (SOD), total antioxidant capacity (T-AOC), malondialdehyde (MDA), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the serum and liver of Silurus meridionalis were detected. The results showed that the serum SOD activity in Example 1 group was significantly higher than that in Comparative Example 1, and the serum SOD activity in Comparative Example 3 group was significantly lower than that in Comparative Example 1 ( Figure 3 A). Similarly, the liver SOD activity was the highest in Example 1 group and the lowest in Comparative Example 3 group ( Figure 4 A). The serum T-AOC in Comparative Example 2 group and Comparative Example 3 group was significantly lower than that in Comparative Example 1 ( Figure 3B). The highest liver T-AOC was observed in the control group 3 ( Figure 4 B). Compared with the control group 1, the MDA levels in the serum and liver of the example 1 group were significantly reduced, but the malondialdehyde level was the highest in the control group 3 ( Figure 3 C). Compared with the control group 1, the serum AST activity of the example 1 group was significantly reduced, while that of the control groups 2 and 3 was significantly increased ( Figure 3 D). Similar results were also observed in the liver of Silurus meridionalis Chen ( Figure 4 D). The ALT activity in the serum of Silurus meridionalis Chen was lower than the detection limit. The liver ALT activity of the control group 3 was significantly higher than that of the control group 1 ( Figure 4 E).

[0039] The changes in the intestinal flora of Silurus meridionalis Chen after replacing fish meal with PAP were analyzed by 16S rDNA high-throughput sequencing. The α-diversity analysis was performed using the Shannon, Simpson, ACE, and Chao1 indices, and the results showed that there were no significant differences in the species richness and diversity of the intestinal flora among the groups of Silurus meridionalis Chen ( Figure 5 ). The PCA analysis showed that the intestinal flora composition of the example 1 group was significantly different from that of the other three groups ( Figure 6 A-C). The species distribution analysis also showed that there were significant differences in the intestinal microbiota at the phylum level between the example 1 group and the other three groups ( Figure 6 D). Similar to the species distribution analysis, the ANOVA showed that the abundance of the intestinal flora in the example 1 group increased significantly ( Figure 7 A). Further comparison at the scientific level found that the abundances of Bacteroidaceae, Pasteurellaceae, Fusobacteriaceae, unclassified Bacteroidaceae, Streptococcaceae, and in the intestine of the example 1 group increased significantly ( Figure 7 B). The functional analysis based on BugBase showed that the anaerobic intestinal flora in the example 1 group increased significantly, mainly due to the increased abundances of Bacteroidaceae, Fusobacteriaceae, and Streptococcaceae ( Figure 8 A and Figure 9 ). The increased abundances of Bacteroidaceae, Fusobacteriaceae, and Streptococcaceae also led to an increase in Contain_Mobile_Elements in the intestine of the example 1 group ( Figure 8 A and Figure 9 ). The functional analysis based on FAPROTAX showed that the fermentation and chemoheterotrophic functions of the intestinal microbiota in the example 1 group were significantly enhanced ( Figure 8 B). Overall, the composition of the intestinal microbiota in the example 1 group of Silurus meridionalis Chen changed significantly.

[0040] The above embodiments have described in detail the structure, features, and effects of the present invention. The above are only the preferred embodiments of the present invention. Any changes made according to the concept of the present invention, or equivalent embodiments modified into equivalent changes, which still do not exceed the scope covered by the specification, shall be within the protection scope of the present invention.

Claims

1. A functional feed for Silurus meridionalis Chen, characterized in that, It contains an animal protein source with a mass ratio of 40% to 45%. The animal protein source consists of Periplaneta americana powder, fish meal, and chicken meal in a weight ratio of (1.6 - 5.55):(27.2 - 35.15):8, and the Periplaneta americana powder accounts for 5 - 15% of the total mass of the Periplaneta americana powder and fish meal.

2. The feed according to claim 1, characterized in that, It also contains a plant protein source with a mass ratio of 25% to 35% and fat with a mass ratio of 4% to 8%.

3. The feed according to claim 1, characterized in that, The plant protein source is one or more of fermented soybean meal and corn gluten meal.

4. The feed according to claim 1, characterized in that, It also contains auxiliary components, which are one or more of calcium dihydrogen phosphate, trace element premix, vitamin premix, L-lysine monohydrochloride, choline chloride, methionine, mannan oligosaccharide, threonine, lysine, chromium trioxide.

5. The feed according to claim 4, characterized in that, The mass ratio of the auxiliary components in the feed is 3.5 - 4.5%.

6. The feed according to claim 1, wherein It also includes carbohydrates with a mass ratio of 20%.

7. A method for preparing a feed according to any one of claims 1-6, characterized in that, Mix and crush the animal protein source, plant protein source, fat, auxiliary components and carbohydrates, sieve them through an 80-mesh sieve, then add them to a blender for stirring. Prepare feed pellets from the stirred feed through commercial pelletizing equipment, and finally dry them using a dryer at a temperature of 40 - 45°C for 1.0 - 1.5 hours, and store them at -20°C after drying.

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