Application of xanthan gum in low-fish-meal feed for promoting formation of excrement of scophthalmus maximus and feed

Abstract

The invention relates to an application of xanthan gum in a low-fish-meal feed for promoting formation of excrement of turbots and the feed, and belongs to the technical field of aquaculture feeds, when the low-fish-meal feed for turbots is fed, 0.3% by mass of xanthan gum is added into the low-fish-meal feed for turbots, and the low-fish-meal feed is characterized in that the fish meal content in the feed is 42.00%, and the fish meal content in the low-fish-meal feed is 42.00%. The feed comprises the following components in percentage by mass: 12.00% of soybean meal, 10.00% of dephenolized cottonseed protein, 10.00% of corn protein powder, 17.34% of wheat flour, 0.3% of L-methionine, 4.7% of fish oil, 1% of soybean lecithin, 1.0% of various vitamins, 0.30% of choline chloride, 0.5% of various minerals, 0.5% of monocalcium phosphate, 0.05% of calcium propionate and 0.01% of yttrium oxide. The method can promote the formation of the excrement of the turbot, specifically, the formation rate of the excrement of the turbot is increased, the stability of the excrement of the turbot is enhanced, and the method is suitable for feeding the turbot in a recirculating aquaculture system.

Description

Technical Field

[0001] The invention belongs to the technical field of aquaculture feed, and particularly relates to application of xanthan gum in low-fish meal feed for promoting formation of turbot feces and the feed. Background Art

[0002] Factory farming is a farming model that industrializes traditional fisheries. It uses modern science and technology (including mechanical engineering, biology, water treatment chemistry, etc.) to produce aquatic products in a high-density and intensive manner, ultimately achieving the business goals of high efficiency, low pollution and sustainable development. In recent years, the scale of factory farming in my country has been expanding rapidly, and the expansion of farming scale is also accompanied by an increase in water resource consumption. In aquaculture systems, waste particles in water bodies mainly come from feces discharged by farmed animals, although some of these solids can be removed by microscreens and sedimentation devices. However, this treatment method is only rapid and effective when the particle size of suspended solids is large enough to be captured by the corresponding filtration device. Especially in the recirculating water aquaculture model, the removal efficiency of suspended solids in the water body directly determines the efficiency and stability of the entire aquaculture system. Therefore, improving the feces formation rate of farmed fish and then improving the particle size integrity of feces is a key prerequisite for ensuring efficient recycling of aquaculture water.

[0003] Against the backdrop of a shortage of fish meal resources, plant protein sources have been developed and widely used in aquatic feeds, but excessive addition of plant protein sources can cause some problems. Studies have found that excessive plant ingredients can affect the feed intake rate and digestion efficiency of farmed fish, especially carnivorous fish. The reduction in feed utilization efficiency is not only detrimental to the growth of farmed fish, but also increases the load on the water treatment system, which is not conducive to the healthy and sustainable development of aquaculture. For example, replacing fish meal in feed with soybean meal feed will lead to an increase in the amount of fecal waste and fecal particles of rainbow trout, which are smaller in size and less stable; when more than 30% of fish meal in the feed is replaced by soybean meal, the intestinal tissue morphology of turbot is damaged, inducing enteritis and causing unformed feces; studies on yellowtail kingfish have also found that an increase in the starch content in the feed will reduce the stability of feces, and when the starch content exceeds 6%, it will reduce the digestibility of fat. Under high-density and recirculating aquaculture conditions, the feces produced by farmed fish will be broken into smaller particles by the turbulence in the water body. The accumulation of these small particles in the water body not only hinders the normal operation of the aquaculture system, but the high solid load of the aquaculture water body is also believed to affect the health of farmed fish, especially the fine suspended solids in it may affect the survival of farmed fish by affecting the physiological function of the gills.

[0004] There are relatively few studies on improving the fecal formation of farmed fish. Several existing studies have proposed adding a certain amount of adhesive substances to the feed to increase the fecal formation rate, and to maintain structural stability (i.e., substances that will not be broken down into smaller particles) after a certain shear force and leaching time, which is conducive to collection and processing. However, there is no research on how to improve the problem of fecal non-formation caused by farmed fish feeding low in fish meal feed. Xanthan gum is a natural polysaccharide, and xanthan gum is usually added to food as a stabilizer, thickener and processing aid. Research on aquatic animals is very limited, and the research mainly focuses on the application of feed adhesives. Some studies have reported that adding 2% xanthan gum to feed can increase the water stability of feed and improve the growth performance and feed efficiency of abalone. Studies on sea cucumbers have found that adding a mixture of 5% xanthan gum and 5% carrageenan to feed can increase the water stability of feed, while improving water quality and the growth of sea cucumber fry. Guar gum is a gelatinous galactomannan obtained by grinding the endosperm part of guar beans. The most notable feature of guar gum is that it can be quickly hydrated in a cold water system to obtain a highly viscous solution. Due to the characteristics of guar gum, such as thickening, gelling, stabilization, and binding, it is widely used in various fields such as food, materials, medicine, and environment. There are many studies on guar gum in aquatic animals. For example, adding 0.3% guar gum to high-fat feed can improve the growth performance of largemouth bass, stabilize intestinal flora and liver lipid metabolism, and reduce inflammation and apoptosis. In carp, when the dose of guar gum in the feed exceeds 3%, the growth performance of carp is significantly reduced. When the addition of guar gum is 1%, the length of microvilli in the hind intestine of carp increases. Carrageenan is a high molecular weight sulfated polysaccharide found in the cell wall of red seaweed. As a food hydrocolloid extracted from seaweed, carrageenan has been widely used in the food and cosmetics industry due to its superior gelling and thickening properties. The research direction of carrageenan in aquaculture mainly focuses on its immunostimulatory and adhesive effects. Studies on white shrimp (Penaeus vannamei) have found that adding low levels of carrageenan (up to 1.5%) to shrimp may be beneficial to its microbiota composition and resistance to white spot syndrome virus infection without causing any damage to growth performance and health. In a study on tongue sole, it was found that adding 2% carrageenan as a binder to the feed had an adverse effect on the growth and trypsin content of tongue sole. On brown-spotted grouper, a study found that adding 0.5% κ-carrageenan to the feed could enhance its innate immunity and increase resistance to Vibrio alginolyticus. At present, there are no reports on the research or application of xanthan gum, guar gum or carrageenan in aquatic feed for fish feces formation and stability in water.

[0005] Turbot is the main marine farmed fish in northern my country and also a representative species of factory farming, with important economic value. Under high-density factory farming conditions, the water treatment system is a key link, and the feces formation and stability of farmed fish have an important impact on the operating efficiency of the water treatment system. Therefore, exploring and clarifying the effect of adding xanthan gum to low fish meal feed on the formation and stability of turbot feces is of great significance for improving the operating efficiency of the water treatment system, and even ensuring the health of farmed animals and promoting the healthy and sustainable development of aquaculture. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a low-fishmeal feed which can improve the formation of turbot feces, promote the stability of turbot feces and ensure its normal growth, so as to alleviate the water treatment pressure in the turbot breeding process.

[0007] The present invention is achieved through the following technical solutions:

[0008] The invention discloses an application of xanthan gum in a low-fish meal feed for promoting the formation of turbot feces. The application method comprises adding 0.3% xanthan gum by weight to the low-fish meal feed for turbot. The low-fish meal feed refers to a feed with a fish meal content of 41-43.00%.

[0009] As a preferred technical solution, the other ingredients and mass percentages of the low fish meal turbot feed are: 12.00% soybean meal, 10.00% dephenolized cottonseed protein, 10.00% corn gluten meal, 17.34% wheat flour, 0.3% L-methionine, 4.7% fish oil, 1% soybean lecithin, 1.0% multivitamins, 0.30% choline chloride, 0.5% multiminerals, 0.5% monocalcium phosphate, 0.05% calcium propionate, and 0.01% yttrium trioxide.

[0010] A low-fish meal feed for turbot, the components of the feed and their mass percentages are: 42.00% fish meal, 0.3% xanthan gum, 12.00% soybean meal, 10.00% dephenolized cottonseed protein, 10.00% corn gluten meal, 17.34% wheat flour, 0.3% L-methionine, 4.7% fish oil, 1% soybean lecithin, 1.0% multivitamins, 0.30% choline chloride, 0.5% multiminerals, 0.5% monocalcium phosphate, 0.05% calcium propionate and 0.01% yttrium trioxide.

[0011] The beneficial effects of the present invention compared with the prior art are as follows:

[0012] 1. The present invention can promote the formation of turbot feces, specifically by improving the formation rate of turbot feces and enhancing the stability of turbot feces, and is suitable for feeding turbot cultured in a recirculating aquaculture system without affecting the normal growth and intestinal health of turbot.

[0013] 2. The present invention has the characteristics of being easy to use, having cheap and readily available materials, and having no residue. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram of the morphology of formed feces and diffuse feces. Formed feces (A, B, C) have a smooth "capsule" surface, are long strips in shape, and are large in size. They can maintain their original shape for a long time in water without disintegrating. Dispersed feces (D, E, F) have a rough surface, are small in size, and have irregular shapes. They are easy to disintegrate into smaller particles in water;

[0015] Figure 2 This is a bar graph of fecal formation rate of turbot feces fed with different experimental groups at different times. Error bars represent standard error of the mean (n=3), and different letters indicate significant differences in values ​​(P<0.05);

[0016] Figure 3 This is a bar graph of the fecal particle size distribution of turbot feces fed with different experimental groups in water bodies at different times. Error bars represent the standard error of the mean (n=12), and different letters indicate significant differences in values ​​(P<0.05);

[0017] Figure 4 This is a comparison of the morphological structure of the hindgut tissue, the ratio of intestinal villus circumference, the thickness of the intestinal muscle layer, the ratio of intestine to body, and the ratio of intestine to weight of turbot fed with different experimental groups for 35 days, fish meal group (A and D), low fish meal group (B and E), xanthan gum group (C and F), A, B, C scale bar is 500μm, D, E, F, scale bar is 50μm. Error bars represent the standard error of the mean (n=9), and different letters indicate significant differences in values ​​(P<0.05);

[0018] Figure 5 This is a bar graph of the gene expression levels of inflammatory cytokines in the hind intestine of turbot fed with different experimental groups of feed. Error bars represent the standard error of the mean (n=9), and different letters indicate significant differences in values ​​(P<0.05);

[0019] Figure 6 This is a bar graph of the expression levels of tight junction protein genes in the hind intestine of turbot fed with different experimental groups of feed. Error bars represent the standard error of the mean (n=9), and different letters indicate significant differences in values ​​(P<0.05);

[0020] Figure 7 It is a bar graph of the expression level of apoptosis genes in intestinal cells of turbot fed with different experimental groups of diets. Error bars represent the standard error of the mean (n=9), and different letters indicate significant differences in numbers and values ​​(P<0.05). DETAILED DESCRIPTION

[0021] The preparation and application methods of the present invention are described in detail below by way of examples:

[0022] It is common knowledge in the art that the normal amount of fish meal added to turbot feed is 50-55%. However, due to the shortage of fish meal and its high cost, in the prior art, excessive vegetable protein such as soybean meal is added to replace part of the fish meal, so that the amount of fish meal added is reduced to about 42%. At this time, the turbot feed becomes a low-fish meal feed, but this feed will make turbot feces shapeless or unstable.

[0023] The median particle size DX(50) of the fecal particle parameters: The median particle size means that 50% of the particles in the entire water body are larger than this value, and 50% of the particles are smaller than this value. The smaller the DX(50) value, the more small particles there are in the water body, that is, the higher the degree of fecal dispersion and the worse the stability, and vice versa.

[0024] Example 1

[0025] Firstly, a 35-day breeding experiment was conducted to evaluate the effects of xanthan gum, guar gum and carrageenan on the growth of turbot fry to ensure that adding 0.3% xanthan gum, 0.3% guar gum and 0.3% carrageenan by mass to turbot feed could ensure the normal growth of turbot fry.

[0026] The specific operation method is as follows: 5 kinds of feeds with equal nitrogen and equal fat (crude protein content of 54%, crude fat content of 10.6%) are set, namely fish meal group (fish meal content of 50%), low fish meal group (fish meal content of 42%), and 0.3% by mass of xanthan gum, guar gum and carrageenan are added to the low fish meal group, namely xanthan gum group, guar gum group and carrageenan group. All feed raw materials are ground into fine powder, passed through a 60-mesh sieve, and then fully mixed with fish oil and soybean lecithin, and water is added to form a hard dough. A single-screw feed pelletizer is used to form small particles with a diameter of 2 mm. The prepared feed is dried in a ventilated oven at 60°C for about 12 hours and stored in a refrigerator at -20°C for use. Table 1 lists the formula and crude nutritional composition of the experimental feed.

[0027] Table 1 Experimental feed formula and nutritional composition (% dry matter)

[0028]

[0029]

[0030] Experimental feed formula and chemical composition analysis (% dry matter)

[0031] 1 Purchased from Qingdao Saigelin Bioengineering Co., Ltd. Fish meal (dry matter, %): CP 71.59, CL 11.45; soybean meal (dry matter, %): CP 50.11, CL 3.67; corn gluten meal (dry matter, %): CP 66.70, CL 2.74; dephenolized cottonseed protein (dry matter, %): CP 66.96, CL 2.83; wheat flour (dry matter, %): CP 19.00, CL 4.18.

[0032] 2 Multivitamins (g / kg): purchased from Qingdao Master Biotechnology Co., Ltd. Main ingredients: vitamin A acetate ≥1,140,000IU; vitamin D3 ≥180,000IU; dl-α-tocopheryl acetate ≥7.6g; menadione ≥1.2g; thiamine nitrate ≥0.93g; riboflavin ≥1.35g; pyridoxine hydrochloride ≥1.10g; cyanocobalamin ≥0.0075g; D-calcium pantothenate ≥4.5g; nicotinamide ≥6.75g; folic acid ≥0.465g; D-biotin ≥00475g; L-ascorbic acid-2 phosphate (calculated as L-ascorbic acid) ≥16.7g; inositol ≥10g; moisture ≤10%.

[0033] 3 Multi-mineral (g / kg): purchased from Qingdao Master Biotechnology Co., Ltd. Main ingredients: iron ≥ 37.14g; zinc ≥ 16.43g; manganese ≥ 3.03g; copper ≥ 0.95g; cobalt ≥ 0.1g; selenium ≥ 0.04g; iodine ≥ 0.1g; moisture ≤ 10%.

[0034] 4 was purchased from Ordos Zhongxuan Biochemical Co., Ltd.

[0035] 5 was purchased from Guangrao Liuhe Chemical Co., Ltd.

[0036] 6 Purchased from Fujian Haoyunda Technology Group Co., Ltd.

[0037] A 35-day breeding experiment was carried out using the feed prepared with the above formula. Before the experiment began, all experimental fish were uniformly fed with commercial feed for one week to adapt them to the breeding environment. After the temporary breeding, 375 turbot fry with an initial weight of about 13g were randomly distributed to 15 breeding boxes. Each treatment group was fed with the corresponding feed every day, and the feeding frequency was twice a day (08:00 and 17:00). During the breeding period, the environmental factors were controlled to maintain suitable conditions for the growth of turbot. After the experiment, the effects of different feeds on the growth of turbot fry were measured, and the results are as follows:

[0038] Table 2 Effects of xanthan gum on growth performance and feed utilization of turbot juveniles.

[0039]

[0040] All data were expressed as mean ± standard error.

[0041] As shown in Table 2, there was no significant difference in weight gain rate, feed efficiency and feeding rate of turbot fry in the xanthan gum group, guar gum group and carrageenan group compared with the fish meal group (P>0.05).

[0042] Example 2

[0043] During the breeding experiment, the water and feces of the turbot were sampled on the 21st and 28th days, that is, 7 hours after the first feeding on the 21st and 28th days (at this time, there was feces in the water that could be sampled). After the 35-day breeding experiment, the turbot fry were counted, weighed and sampled. The experimental data obtained were expressed as mean ± standard error, and one-way analysis of variance was performed using SPSS 22.0 analysis software. Different letters indicate significant differences between groups (P<0.05). The results of fecal formation rate are as follows:

[0044] Table 3 Effect of xanthan gum on feces formation rate of turbot juveniles.

[0045]

[0046] All data were expressed as mean ± standard error.

[0047] Depend on Figure 1 It can be seen that the formed feces (A, B, C) discharged by turbot have smooth surface and membrane, and are in the shape of long strips. The diffuse feces (D, E, F) discharged by turbot are granular, irregular in shape, rough on the surface and not membraned.

[0048] From Table 3 and Figure 2 It can be seen that although there was no statistically significant difference, the feces formation rate of the xanthan gum group, guar gum group and carrageenan in the third and fourth weeks was significantly higher than that of the low fish meal group (P>0.05).

[0049] Depend on Figure 3 It can be seen that in the third week, the median particle size DX(50) of the xanthan gum group was significantly higher than that of the low fish meal group (P<0.05); in the fourth week, the DX(50) of the xanthan gum group and the guar gum group were significantly higher than that of the low fish meal group (P<0.05), and the DX(50) of the xanthan gum group was significantly higher than that of the fish meal group (P<0.05).

[0050] Taking all factors into consideration, adding 0.3% xanthan gum by mass to turbot feed can increase the formation rate of turbot feces and keep it stable in the water. Therefore, the intestinal integrity and gene level of the turbot in the fish meal group, xanthan gum group and low fish meal experimental group were tested respectively, and the specific results are as follows:

[0051] Depend on Figure 4 It can be seen that during the 35-day culture period, the intestinal epithelial cells of turbot fry in the three treatment groups were intact, the cell nuclei were located at the base of the cells and arranged neatly; the lamina propria did not show significant widening, and there was no obvious inflammatory cell infiltration in the lamina propria. There was no significant difference in the intestinal villus perimeter ratio and intestinal muscle layer thickness among the treatment groups (P>0.05).

[0052] Depend on Figure 5 It can be seen that the fish meal group and xanthan gum group significantly downregulated the expression level of intestinal pro-inflammatory factor TNF-α compared with the low fish meal group (P<0.05). The expression level of intestinal anti-inflammatory factor IL-22 in the fish meal group and xanthan gum group tended to increase compared with the low fish meal group, but there was no significant difference (P>0.05).

[0053] Depend on Figure 6 It can be seen that the expression level of intestinal tight junction protein Tricellulin in the xanthan gum group was significantly higher than that in the low fish meal group (P<0.05). Although there was no statistically significant difference, the expression levels of JAM-2 and Occludin in the intestine of turbot in the fish meal group and xanthan gum group were higher than those in the low fish meal group (P>0.05).

[0054] Depend on Figure 7 It can be seen that the expression level of intestinal apoptosis factor Caspase-9 in the fish meal group and xanthan gum group was significantly lower than that in the low fish meal group (P<0.05). The expression level of intestinal apoptosis factor BAX in the fish meal group and xanthan gum group showed a downward trend compared with the low fish meal group, but there was no significant difference (P>0.05). The expression level of intestinal apoptosis inhibitor Bcl-2 in the xanthan gum group showed an upward trend compared with the low fish meal group, but there was no significant difference (P>0.05).

[0055] Compared with large-sized turbot, turbot fry has higher requirements for feed nutrients. The above experiments have confirmed that adding 0.3% by weight of xanthan gum to turbot fry can ensure normal growth while stably forming fecal particles. Therefore, this technical solution has also achieved good breeding results in other large-sized turbot.

[0056] Example 3

[0057] In this example, the fish meal content in the turbot feed in Example 1 was adjusted to 41% and 43% respectively, and aquaculture experiments were carried out on turbot of the same specifications, and good aquaculture results were achieved.

[0058] summary

[0059] Although the addition of guar gum and xanthan gum to low fish meal feed can improve the feces formation rate of turbot fry, the effect of these two gums on the stability of feces is not significant from the results of feces particle size distribution; however, the addition of xanthan gum can increase the feces stability while improving the feces formation rate of turbot fry, and can ensure the normal growth of turbot fry. It can be seen that the above invention can improve the formation rate and stability of turbot feces without affecting the normal growth of turbot fry, and has a good improvement effect on the intestinal health of turbot fry, so it has broad development and application prospects.

[0060] The above basic feed formula simulates the commonly used commercial feed formula, and its implementation is only a preferred specific implementation of the present invention, and is not a limitation on the protection scope of the present invention. Under the condition that the normal growth of turbot can be met, the dynamic addition scheme of the present invention can achieve the effect of the present invention. Any dynamic implementation scheme that is equivalently replaced or changed according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention should be included in the protection scope of the present invention.

Claims

1. The application of xanthan gum in low fish meal feed for promoting the formation of turbot feces is characterized in that: The application method is to add 0.3% by mass of xanthan gum into the low fish meal feed for turbot when feeding the turbot, wherein the low fish meal feed refers to the feed with a fish meal content of 41-43.00%.

2. The use of xanthan gum according to claim 1 in a low fish meal feed for promoting the formation of turbot feces, characterized in that: The other ingredients and mass percentages of the low fish meal turbot feed are: 12.00% soybean meal, 10.00% dephenolized cottonseed protein, 10.00% corn gluten meal, 17.34% wheat flour, 0.3% L-methionine, 4.7% fish oil, 1% soybean lecithin, 1.0% multivitamins, 0.30% choline chloride, 0.5% multiminerals, 0.5% monocalcium phosphate, 0.05% calcium propionate and 0.01% yttrium trioxide.

3. A low-fishmeal feed for turbot, characterized in that: The ingredients of the feed and their mass percentages are 42.00% of fish meal, 0.3% of xanthan gum, 12.00% of soybean meal, 10.00% of dephenolized cottonseed protein, 10.00% of corn protein powder, 17.34% of wheat flour, 0.3% of L-methionine, 4.7% of fish oil, 1% of soybean lecithin, 1.0% of multiple vitamins, 0.30% of choline chloride, 0.5% of multiple minerals, 0.05% of calcium propionate, and 0.01% of yttrium trioxide.

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