A nutrition-program-based compound feed capable of ensuring the health of aquatic fry, and a preparation method and application thereof

Abstract

The application discloses a nutrition-programmed feed for guaranteeing the health of aquatic fry and a preparation method and application thereof. The feed is composed of white fish meal, casein, animal protein powder, plant protein powder, fat, dextrin, vitamin premix, calcium dihydrogen phosphate, mineral premix, composite phagostimulant and sodium alginate. The application first converts the nutrition-programming theory into an industrialized systematic solution. Through a two-stage feeding strategy, the composite phagostimulant is used to quickly complete the domestication of artificial feed and establish a healthy foundation in the opening period, and the programming effect is consolidated and the metabolic adaptability is improved in the growth period. The breeding test shows that the feed and the application method can simultaneously solve the industry pain points of carnivorous aquatic fry, such as "not willing to eat, weak digestion, and many diseases", significantly improve the survival rate, growth performance and disease resistance of the fry, protect the liver and intestinal health, and achieve remarkable effects on various aquatic fry such as sturgeon, swamp eel and Chinese soft-shelled turtle.

Description

Technical Field

[0001] This application relates to the field of aquaculture feed technology, specifically to a compound feed based on nutritional programming that can ensure the health of aquatic seedlings, its preparation method, and its application. Background Technology

[0002] Seedlings are the cornerstone of the sustainable development of aquaculture. In recent years, with the improvement of people's living standards and the upgrading of the consumer market, high-value carnivorous aquatic products such as largemouth bass, sturgeon, eel, and Chinese soft-shelled turtle have not only enjoyed strong market demand but have also become key species for promoting the quality and efficiency of the industry. However, during their seedling cultivation stage, the following three factors have affected the healthy development of the industry, making it the most vulnerable and deadliest link in the entire aquaculture cycle.

[0003] First, seedlings have unique feeding habits, making them difficult to domesticate with artificial feed. In their natural environment, carnivorous aquatic seedlings feed on live prey, and their feeding behavior is strongly dependent on the dynamic stimulation and specific chemical signals of live prey. They generally exhibit strong wariness, low start-up rate, and long domestication period when faced with static, monotonous artificial feeds, resulting in uneven feeding and significant individual differences.

[0004] Secondly, their digestive and immune systems are underdeveloped, leading to frequent disease outbreaks. During the seedling stage, their intestinal structure is simple, digestive enzyme secretion is insufficient, and their intestinal flora is not yet stable. This limits their ability to digest and absorb complex artificial feeds, easily causing indigestion and intestinal stress. Simultaneously, their congenitally low immunity makes them vulnerable to environmental stresses (such as temperature fluctuations, transportation, and separation) and pathogens (such as Aeromonas and Vibrio), making them highly susceptible to enteritis, hepatopancreatic necrosis, and skin rot, resulting in large-scale mortality.

[0005] Third, nutritional needs are highly phased, and traditional feeds cannot respond precisely. The early life stage of seedlings, the transition from the "yolk stage" (when they rely entirely on endogenous yolk nutrition) to the "start-of-life stage" (when they actively consume exogenous feed), is a critical and vulnerable developmental juncture. During this process, their digestive organs (such as the liver, pancreas, and intestines) undergo rapid differentiation and maturation, and their metabolic mechanisms and feeding behaviors undergo fundamental changes. During rapid growth and development, the physiological state and nutritional needs of seedlings change dramatically at different stages (such as the start-of-life stage, intestinal transition period, and rapid skeletal growth period).

[0006] Under natural conditions, carnivorous fish fry feed on animal-based food during their initial feeding stage, such as cladocerans, copepods, and mosquito larvae. During their growth period, they consume live food such as fish and shrimp. However, under artificial breeding conditions, most carnivorous fish feed on formulated feeds during their growth period. These feeds inevitably contain some plant-based ingredients. Because plant-based ingredients have problems such as protein imbalance, high levels of toxic and harmful substances, and high carbohydrate content, carnivorous fish cannot utilize them well and may experience effects such as liver and intestinal damage, which have a negative impact on the physiological health of the fry.

[0007] Traditional theories of aquatic fry feed formulation are still primarily based on classical animal nutrition, aiming to meet the static nutrient requirements of fry during their growth stage. However, this theory overlooks two core aspects: first, there are qualitative differences between fry and adult fish in terms of digestive organ development and metabolic mechanisms (e.g., fry have more fragile intestines and less developed digestive enzyme systems). As mentioned earlier, the fry stage is dynamic, and these changes can be rapid; second, developmental plasticity, i.e., the "programmed" influence of early nutrition on the long-term health and metabolic trajectory of the organism. Therefore, traditional theories treat fry as "miniature adult fish," failing to provide precise nutritional interventions for key physiological "windows," resulting in a series of long-term problems such as insufficient release of growth potential, increased risk of physiological defects, and incomplete formation of immune memory. Against this backdrop, developing a compound feed that can provide comprehensive and balanced nutrition and precisely respond to the physiological characteristics of fry has become crucial to overcoming the limitations of traditional aquaculture models.

[0008] In recent years, the theory of "programmed nutrition" has provided a new solution to the above problems. This theory posits that during critical or sensitive developmental windows in early animal life (such as the gonadal development stage of parents or the initial feeding stage of larvae), specific nutritional interventions can have long-term or even lifelong "programmed" effects on their body structure, metabolic patterns, and physiological functions. Existing research has validated the feasibility of this theory in aquatic animals. For example, by using plant protein sources or implementing high-glucose stimulation during specific window periods, the feed utilization capacity and metabolic pathways of fish in later stages can be programmed (Izquierdo et al., 2015; Gong et al., 2015).

[0009] However, existing technological solutions have significant limitations. On the one hand, studies generally show high species specificity, meaning that "different species require completely different programmed strategies." For example, using plant-based ingredients in the broodstock feed of golden-headed seabream improves offspring's utilization of plant-based feed (Izquierdo et al., 2015; Turkmen et al., 2017), while similar strategies are not effective in yellow catfish (Li Haijie, 2021) and largemouth bass (Kwasek et al., 2021); early high-sugar stimulation in Siberian sturgeon induces abnormal sugar metabolism and inhibits growth (Kwasek et al., 2021). This specificity leads to fragmented and uncommon technological solutions, greatly increasing the complexity and cost of product development. On the other hand, existing research mostly remains at the level of "mechanism exploration" and "phenomenon verification." The intervention methods used (such as short-term extreme diets and yolk injection) cannot be directly applied to large-scale, economical aquaculture production, nor have they been integrated into a complete and industrializable product system.

[0010] Therefore, there is an urgent need in this field for a solution that can overcome species limitations, transform nutritional programming theory into an industrially implementable product solution, and systematically address the issues of feeding attraction, health, and precision nutrition in the breeding process of carnivorous aquatic seedlings. Summary of the Invention

[0011] In view of this, the purpose of this application is to provide a compound feed based on nutritional programming that can ensure the health of aquatic seedlings, as well as its preparation method and application. This compound feed, through the phased and modular formulation of compound palatability enhancers, functional health-promoting ingredients, and basic nutrients, forms a two-stage feeding program. This allows the feed to not only meet basic growth needs but also proactively adapt to the specific physiological needs of seedlings at different developmental windows. Using the feed and its systematic application scheme of this application can simultaneously solve the core pain points of various high-value carnivorous aquatic seedlings, such as "refusal to eat, weak digestion, and frequent diseases," significantly improving seedling survival rate, uniformity, and later disease resistance. This realizes the universality and industrial application of nutritional programming theory in various carnivorous aquatic seedlings.

[0012] To achieve the above objectives, this application provides the following technical solution:

[0013] In the first aspect, this application provides a formulated feed based on a nutritional program that can ensure the health of aquatic seedlings, comprising the following components by weight: 30-60 parts white fish meal, 5-10 parts casein, 0-20 parts animal protein powder, 5-30 parts plant protein powder, 2-8 parts fat, 2-15 parts dextrin, 0.1-0.5 parts vitamin premix, 0.5-3 parts calcium dihydrogen phosphate, 0.5-2 parts mineral premix, 2-8 parts compound attractant, and 0-5 parts sodium alginate.

[0014] In some embodiments, the nutritionally programmed compound feed for ensuring the health of aquatic seedlings comprises, by weight, the following components: 45-60 parts white fish meal, 6-8 parts casein, 3-8 parts animal protein powder, 5-20 parts plant protein powder, 3-6 parts fat, 8-10 parts dextrin, 0.25-0.5 parts vitamin premix, 1.5-2.5 parts calcium dihydrogen phosphate, 1.2-1.8 parts mineral premix, 3-6 parts compound attractant, and 2-4 parts sodium alginate.

[0015] In some preferred embodiments, the nutritionally programmed compound feed for ensuring the health of aquatic seedlings comprises, by weight, the following components: 42.5 parts white fish meal, 6.5 parts casein, 11.8 parts animal protein powder, 10.4 parts plant protein powder, 6.3 parts fat, 10.3 parts dextrin, 1.1 parts vitamin premix, 1.5 parts calcium dihydrogen phosphate, 1 part mineral premix, 6 parts compound attractant, and 2.6 parts sodium alginate.

[0016] In some preferred embodiments, the nutritionally programmed compound feed for ensuring the health of aquatic seedlings comprises, by weight, the following components: 35 parts white fish meal, 5.5 parts casein, 14.8 parts animal protein powder, 16.4 parts plant protein powder, 6.3 parts fat, 13.2 parts dextrin, 1.5 parts vitamin premix, 1.5 parts calcium dihydrogen phosphate, 1.3 parts mineral premix, 2.5 parts compound attractant, and 2 parts sodium alginate.

[0017] In some preferred embodiments, the nutritionally programmed compound feed for ensuring the health of aquatic seedlings comprises, by weight, the following components: 45.5 parts white fish meal, 5.6 parts casein, 11.8 parts animal protein powder, 10.6 parts plant protein powder, 4 parts fat, 7.5 parts dextrin, 1.3 parts vitamin premix, 1.5 parts calcium dihydrogen phosphate, 1.2 parts mineral premix, 7.5 parts compound attractant, and 3.5 parts sodium alginate.

[0018] In some preferred embodiments, the nutritionally programmed compound feed for ensuring the health of aquatic seedlings comprises, by weight, the following components: 40 parts white fish meal, 6.5 parts casein, 10.8 parts animal protein powder, 12.8 parts plant protein powder, 6.3 parts fat, 13.2 parts dextrin, 1.2 parts vitamin premix, 1.8 parts calcium dihydrogen phosphate, 1.3 parts mineral premix, 4 parts compound attractant, and 2.1 parts sodium alginate.

[0019] In some preferred embodiments, the nutritionally programmed compound feed for ensuring the health of aquatic seedlings comprises, by weight, the following components: 50 parts white fish meal, 5 parts casein, 13 parts animal protein powder, 12.5 parts plant protein powder, 2 parts fat, 10 parts dextrin, 1 part vitamin premix, 1.5 parts calcium dihydrogen phosphate, 1 part mineral premix, 3 parts compound attractant, and 1 part sodium alginate.

[0020] In some preferred embodiments, the nutritionally programmed compound feed for ensuring the health of aquatic seedlings comprises, by weight, the following components: 43.5 parts white fish meal, 5 parts casein, 15.5 parts animal protein powder, 13.5 parts plant protein powder, 2.5 parts fat, 15 parts dextrin, 0.8 parts vitamin premix, 1.2 parts calcium dihydrogen phosphate, 1 part mineral premix, and 2 parts compound attractant.

[0021] In some embodiments, the animal protein powder, by weight, comprises the following components: 400 parts krill powder, 300 parts tubifex powder, and 300 parts chicken powder.

[0022] In some embodiments, the plant protein powder, by weight, comprises the following components: 500 parts soybean meal and 500 parts cottonseed meal.

[0023] In some embodiments, the fat, by weight, is composed of the following components: 300 parts cod liver oil, 600 parts pork liver oil, and 100 parts lysophosphatidylcholine.

[0024] In some embodiments, the vitamin premix comprises, by weight, the following components: 1.2 parts vitamin B1, 1.2 parts vitamin B2, 0.3 parts calcium pantothenate, 4 parts niacin, 0.02 parts biotin, 0.3 parts vitamin B6, 0.1 parts folic acid, 3 parts inositol, 10 parts vitamin C, 0.3 parts vitamin A, 0.05 parts vitamin D3, 10 parts vitamin E, 0.8 parts vitamin K3, and 984.645 parts Haematococcus pluvialis powder.

[0025] In some embodiments, the mineral premix, by weight, comprises the following components: 3.18 parts ferrous sulfate, 60 parts magnesium sulfate, 0.1 parts aluminum chloride, 1.5 parts calcium iodate, 0.5 parts copper chloride, 0.5 parts manganese sulfate, 1.2 parts cobalt chloride, 1.3 parts zinc sulfate, 0.03 parts sodium selenite, 50 parts sodium chloride, 0.05 parts sodium molybdate, and 881.64 parts zeolite powder.

[0026] In some embodiments, the compound attractant, by weight, comprises the following components: 250 parts glycine, 150 parts mussel extract, 200 parts hawthorn extract, 200 parts astragalus polysaccharide, and 200 parts yeast β-glucan.

[0027] Secondly, this application provides a method for preparing the compound feed described in the first aspect, comprising the following steps:

[0028] (1) Raw material pretreatment: White fish meal, casein, animal protein powder, plant protein powder, dextrin, calcium dihydrogen phosphate and sodium alginate are mixed in the above mass ratio and then ultra-finely pulverized and passed through an 80-120 mesh standard sieve to obtain basic premix.

[0029] (2) Graded premixing: Weigh the compound palatability enhancer, vitamin premix, mineral premix and appropriate amount of basic premix according to the above mass ratio, and premix them step by step. Then add them to the remaining basic premix and continue mixing until the uniformity variation coefficient is ≤5%;

[0030] (3) Conditioning: The homogeneous mixture obtained in step (2) is fed into a conditioner and saturated steam at 85-95 ℃ is introduced for conditioning for 30-60 seconds;

[0031] (4) Granulation and post-maturation: The conditioned material is fed into the granulator and pressed or crushed into particles of the required diameter according to the target seedling specifications; then the wet particles are fed into the post-maturation unit and maintained at a temperature of 75-90 ℃ for 10-20 minutes.

[0032] (5) Drying: Transfer the post-matured pelleted feed into a dryer and dry it with a low-temperature airflow of no more than 60 °C to reduce the moisture content of the pellets to below 10% and then cool it to room temperature;

[0033] (6) Liquid component spraying: Weigh the fat component according to the above mass ratio and mix it evenly. Use a vacuum spraying device to spray it evenly onto the surface and internal micropores of the cooled pellet feed to make finished pellet feed.

[0034] In some embodiments, in step (4), the feed is made into pellets with a diameter of 0.1-2.0 mm according to the seedling specifications; in step (6), a vacuum spraying device is used for spraying.

[0035] Thirdly, this application provides a method for applying the compound feed described in the first aspect, the method comprising two stages of feeding:

[0036] The first stage is the initial feeding period, during which the compound feed described in the first aspect is fed 1-8 times a day or every other day, with a daily feeding rate of 3%-80% of body weight, for 14-28 days.

[0037] The second stage is the growth period, during which the feed described in the first part is fed 1-4 times a day, with a daily feeding rate of 1%-30% of body weight, for 28-72 days.

[0038] In the above method, in the first stage, compound attractants in the feed are used to induce seedlings to feed and complete the domestication of artificial feed. At the same time, a healthy foundation is established during the window period of the seedlings' digestive and immune systems, and the adaptability of seedlings to plant protein sources and carbohydrates is improved. In the second stage, after the seedlings' feeding habits are formed, the seedlings' metabolic system is adapted to more economical raw materials, and the effects of the previous programmed feeding are consolidated.

[0039] In some embodiments, at the end of the second stage, a smooth transition to general commercial compound feed is achieved through mixed feeding; the mixed feeding refers to feeding the compound feed and general commercial compound feed together in gradually adjusted proportions.

[0040] Compared with the prior art, this application has at least the following beneficial effects:

[0041] 1. For the first time, the cutting-edge theory of "programmed nutrition" has been successfully transformed into a universally applicable and industrially scalable systematic solution. It combines a unique compound appetite stimulant (integrating appetite stimulation, digestion enhancement, and immune enhancement) with a phased and precise application strategy to simultaneously solve the core pain points of the industry for various high-value carnivorous aquatic seedlings, such as "refusal to eat, weak digestion, and frequent diseases."

[0042] 2. Breeding trials have shown that the feed and application method described in this application can strongly induce seedlings to feed, rapidly complete artificial feed acclimatization, significantly improve seedling survival rate, final weight and uniformity, enhance resistance to pathogens, and effectively reduce damage to the liver and intestines caused by plant-based raw materials. Furthermore, this early nutritional intervention has a profound and positive impact on the long-term health and metabolic trajectory of seedlings, maintaining significantly better growth performance and disease resistance even after subsequent feeding entirely with commercial feed.

[0043] 3. The preparation process provided in this application is based on a mature industrial process, with controllable costs and easy large-scale production; the two-stage application method simplifies the process, transforming complex theories into clear and operable breeding procedures, which can significantly improve the survival rate, uniformity, and feed adaptability of seedlings in the later stage, realizing the efficient transformation from advanced concepts to significant benefits, and has outstanding practical value and promotion prospects. Attached Figure Description

[0044] Figure 1 A slice of sturgeon liver tissue provided in an embodiment of this application.

[0045] Figure 2 The first-stage liver and intestinal tissue sections of the eel provided in the embodiments of this application.

[0046] Figure 3 The second-stage liver and intestinal tissue sections of the eel provided in this application embodiment.

[0047] Figure 4 First-time slices of the liver and intestinal tissue of the Chinese soft-shelled turtle provided for embodiments of this application.

[0048] Figure 5 Second-time slices of Chinese soft-shelled turtle liver and intestinal tissue provided for embodiments of this application. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0050] The materials used in the following embodiments are not limited to those listed below, and other similar materials may be used instead. Unless otherwise specified, the instruments shall be used under conventional conditions or as recommended by the manufacturer. Those skilled in the art should have relevant knowledge of the use of conventional materials and instruments.

[0051] In this application, unless the context clearly indicates otherwise, the terms “including,” “comprising,” “containing,” “having,” etc., shall be understood as open-ended and mean “including but not limited to.”

[0052] To better understand this teaching and without limiting its scope, all figures and other numerical values ​​used in the specification and claims to express quantities, percentages, or proportions should, in all cases, be understood to be modified by the term "about." Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​that may be adjusted according to the desired performance. At a minimum, each numerical parameter should be interpreted based on the reported significant figures and by applying common rounding techniques.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the subject matter of this application pertains. Before a detailed description of this application, the following explanations of terminology are provided to better understand this application.

[0054] 1. Mixed feeding: This refers to feeding the compound feed of this application with the general commercial compound feed to be used in the subsequent stage in a certain proportion. The specific transition method is to gradually reduce the proportion of the feed of this application and gradually increase the proportion of the general commercial feed (for example, in the weight ratio of 7:3, 5:5, 3:7, 0:10) so that the digestive and metabolic systems of the seedlings can gradually adapt to the new feed and avoid decreased feed intake, stress response or intestinal discomfort caused by sudden feed change.

[0055] 2. Start-up Period and Growth Period: The "start-up period" refers to the critical developmental window during which seedlings transition from complete reliance on endogenous yolk nutrition to actively consuming exogenous feed. During this time, the seedlings' digestive organs (such as the liver, pancreas, and intestines) are undergoing rapid differentiation and maturation, marking the initial and most crucial stage of nutritional programming. The "growth period" refers to the rapid growth and development stage after the seedlings have completed artificial feed domestication and their feeding habits have been largely established. At this stage, the seedlings' digestive and immune systems tend to stabilize, representing a period of enhanced nutritional programming.

[0056] 3. Coefficient of Variation (CV): This is a commonly used indicator to measure the uniformity of feed mixing. It is calculated as the ratio of the standard deviation to the mean multiplied by 100%. A smaller CV value indicates a more uniform mixture. This application requires a CV of no more than 5%, indicating a high level of uniformity in the mixing of the feed components.

[0057] The following are specific examples:

[0058] Example 1 is applicable to formulated feeds based on nutritional programming that can ensure the health of sturgeon fry and their application.

[0059] 1. Feed formulation

[0060] The formula for sturgeon compound feed is shown in Table 1 below. It is divided into two stages: Stage 1 and Stage 2, and the formula mass ratios for the two stages are different.

[0061] Table 1. Formula for Sturgeon Fry Compound Feed

[0062]

[0063] In Table 1 above, the animal protein powder, per kg, is composed of the following components: 400 g krill powder, 300 g tubifex powder, and 300 g chicken powder; the plant protein powder, per kg, is composed of the following components: 500 g soybean meal and 500 g cottonseed meal.

[0064] The fat, per kg, is composed of the following components: 300 g cod liver oil, 600 g pork liver oil, and 100 g lysophosphatidylcholine;

[0065] The vitamin premix, per kg, consists of the following components: 1.2 g vitamin B1, 1.2 g vitamin B2, 0.3 g calcium pantothenate, 4 g niacin, 0.02 g biotin, 0.3 g vitamin B6, 0.1 g folic acid, 3 g inositol, 10 g vitamin C, 0.3 g vitamin A, 0.05 g vitamin D3, 10 g vitamin E, 0.8 g vitamin K3, and 984.645 g Haematococcus pluvialis powder.

[0066] The mineral premix, per 1 kg, consists of the following components: 3.18 g ferrous sulfate, 60 g magnesium sulfate, 0.1 g aluminum chloride, 1.5 g calcium iodate, 0.5 g copper chloride, 0.5 g manganese sulfate, 1.2 g cobalt chloride, 1.3 g zinc sulfate, 0.03 g sodium selenite, 50 g sodium chloride, 0.05 g sodium molybdate, and 881.64 g zeolite powder.

[0067] The compound attractant, per 1 kg, consists of the following components: 250 g glycine, 150 g mussel extract, 200 g hawthorn extract, 200 g astragalus polysaccharide, and 200 g yeast β-glucan.

[0068] 2. Preparation of compound feed

[0069] (1) Raw material pretreatment

[0070] First, weigh out the white fish meal, casein, animal protein powder, plant protein powder, dextrin, calcium dihydrogen phosphate, and sodium alginate according to the mass percentages in Table 1, put them into a mixer for preliminary mixing, and then pulverize them through an ultra-fine pulverizer so that all solid raw materials pass through an 80-mesh standard sieve to form a basic premix.

[0071] (2) Graded premixing

[0072] Weigh the components such as compound palatability enhancer, vitamin premix, and mineral premix according to the mass percentage in Table 1, and perform step-by-step premixing with an appropriate amount of basic premix. Put the mixture into a mixer containing the basic premix and continue mixing for 5-8 minutes until the coefficient of variation (CV) of the overall mixing uniformity is no greater than 5%.

[0073] (3) Conditioning

[0074] The resulting homogeneous mixture is fed into a conditioner and saturated steam at 85-95°C is introduced. The mixture is conditioned for 30-60 seconds to fully soften the material and gelatinize the starch.

[0075] (4) Granulation and post-maturation

[0076] The conditioned material is fed into a pellet mill. The first stage of feed is made into pellets with a diameter of 0.2-0.3 mm, and the second stage of feed is made into pellets with a diameter of 0.5-1.0 mm. Subsequently, the wet pellets are fed into a post-curing unit and maintained at a temperature of about 90 ℃ for 20 minutes to enhance the starch binding effect.

[0077] (5) Drying

[0078] The post-matured pelleted feed is transferred to a dryer and dried using a low-temperature airflow not exceeding 60°C to reduce the moisture content of the pellets to below 10%, and then cooled to room temperature.

[0079] (6) Liquid component spraying

[0080] Finally, the fat is weighed according to the mass percentage in Table 1 and mixed evenly. Using a vacuum spraying device, it is evenly sprayed onto the surface and internal micropores of the cooled pellet feed to produce finished pellet feed.

[0081] 3. Application methods of compound feed

[0082] The first stage is the "initiation period". Feeding is done 6 times a day, with a daily feeding rate of 20%-60% of body weight. The method is "slow, even, and scattered" to ensure that all individuals eat evenly. The feeding period lasts for 21 days from the start of feeding.

[0083] The second stage is the "growth period". Feeding is adjusted to 3 times a day, with a daily feeding rate of 5%-20% of body weight. The feeding period is 56 days. At the end of the period, the feed can be mixed to smoothly transition to the next stage of general commercial compound feed.

[0084] 4. Breeding Results

[0085] The experimental feeds were divided into Phase 1 and Phase 2 feeds, as well as commercially available branded feeds. The feed label indicated that the commercial feed consisted of white fish meal, krill meal, fish oil, vitamin premix, and mineral premix.

[0086] The experiment used hybrid sturgeon bred at Beijing Jushengyuan Aquaculture Farm. After hatching, the fertilized eggs were transported to the seedling breeding base of Jingzhou Yudu Special Aquatic Products Breeding Company (Jingzhou, Hubei Province). Six breeding tanks (2.5 m in diameter, 2000 L effective volume) with one set of flowing water system were selected, with 1500 fish in each tank. They were divided into two groups: one group was fed the formulated feed prepared in this embodiment (the experimental group), and the other group was fed commercial feed (the control group). Each group had three replicates. Because previous experiments found that feeding entirely with formulated feed caused a small number of experimental fish to not start eating, and the coefficient of variation in body growth was too large, it was necessary to reduce the interference of entirely with formulated feed to ensure survival rate and uniformity. Therefore, feeding began when some experimental fish had finished absorbing their yolk sac at 6 days of age and expelled the thrombus. For 5 days, they were fed tubifex worms plus the first stage feed, gradually reducing the tubifex worms and gradually increasing the formulated feed to achieve a complete transition to formulated feed. From day 6 onwards, they were fed entirely with formulated feed.

[0087] Feeding was divided into two periods. The first period was the nutritional program period, following the above application method. As the fish grew, they needed to be gradually separated and raised according to conventional aquaculture operations. After the aquaculture was completed, livers from the same part of each of the three fish in each tank were randomly selected, placed in 4% paraformaldehyde, and tissue sections were prepared using the HE method. Subsequently, 20 fish were randomly selected and challenged with Aeromonas hydrophila. The survival rate was recorded after 7 days.

[0088] The second period involved feeding the fish entirely with commercial feed to verify the impact of a programmed nutrition method on subsequent fish growth and health. Two hundred uniformly sized experimental fish were selected from each tank and gradually fed commercial formulated feed. The rearing process followed standard procedures; if the density became too high, the feed was gradually increased. Rearing continued for 12 months. After the rearing period, livers from the same location were randomly selected from three fish in each tank and placed in 4% paraformaldehyde for hematologic malignancy (HE) analysis to prepare tissue sections. Then, ten fish were randomly selected from each tank and challenged with Aeromonas hydrophila after the rearing period, and the survival rate was recorded after 7 days. The growth, survival, and challenge survival rates of the sturgeon after the first and second periods are shown in Table 2. Liver tissue condition is shown in [Table 2]. Figure 1 .

[0089] Table 2. Growth performance and survival rate of sturgeon, and survival rate after virus challenge.

[0090]

[0091] Note: Different lowercase letters in the same column of the table indicate significant differences (P<0.05), and the same applies to the following tables.

[0092] As shown in Table 1, regardless of whether it was the first period or the end of the second period, the growth and survival rate of the group fed the earlier example were better than those fed the earlier commercial feed, and there were significant differences in indicators such as final body weight and survival rate after challenge (P < 0.05). Figure 1 It can also be found that, compared with the control group fed with commercial feed, the sturgeon fed with the feed of the example had more intact hepatocytes and less inflammatory cell infiltration at 56 months; while after 12 months, the hepatocytes were more compact, while the control group had more severe hepatocyte vacuolation.

[0093] Example 2 is applicable to formulated feeds based on nutritional programming that can ensure the health of eel fry and their application.

[0094] 1. Feed formulation

[0095] The formula for the compound feed for loach is shown in Table 3 below. It is divided into two stages, Stage 1 and Stage 2, and the formula mass ratios of the two stages are different.

[0096] Table 3 Formula for Compound Feed of Eel Seedlings

[0097]

[0098] In Table 3 above, the formulations of the animal protein powder, plant protein powder, fat, vitamin premix, mineral premix, and compound palatability enhancer are the same as in Example 1.

[0099] 2. Preparation of compound feed

[0100] (1) Raw material pretreatment

[0101] First, weigh out the white fish meal, casein, animal protein powder, plant protein powder, dextrin, calcium dihydrogen phosphate, and sodium alginate according to the mass percentages in Table 3, put them into a mixer for preliminary mixing, and then pulverize them through an ultra-fine pulverizer so that all solid raw materials pass through a 100-mesh standard sieve to form a basic premix.

[0102] (2) Graded premixing

[0103] Weigh the components such as compound palatability enhancer, vitamin premix, and mineral premix according to the mass percentage in Table 3, and perform step-by-step premixing with an appropriate amount of basic premix. Put the mixture into a mixer containing the basic premix and continue mixing for 6 minutes until the coefficient of variation (CV) of the overall mixing uniformity is no greater than 5%.

[0104] (3) Conditioning

[0105] The resulting homogeneous mixture is fed into a conditioner and saturated steam at 90 °C is introduced. The mixture is conditioned for 50 seconds to fully soften the material and gelatinize the starch.

[0106] (4) Granulation and post-maturation

[0107] The conditioned material is fed into a pellet mill. The first stage of feed is made into pellets with a diameter of 1 mm, and the second stage of feed is made into pellets with a diameter of 2 mm. Then, the wet pellets are fed into a post-curing unit and maintained at a temperature of about 90 ℃ for 20 minutes to enhance the starch binding effect.

[0108] (5) Drying

[0109] The post-matured pelleted feed is transferred to a dryer and dried using a low-temperature airflow not exceeding 60°C to reduce the moisture content of the pellets to below 10%, and then cooled to room temperature.

[0110] (6) Liquid component spraying

[0111] Finally, the fat is weighed according to the mass percentage in Table 3 and mixed evenly. Using a vacuum spraying device, it is evenly sprayed onto the surface and internal micropores of the cooled pellet feed to produce finished pellet feed.

[0112] 3. Application methods of compound feed

[0113] The first stage is the "start-of-feeding period," during which the baby is fed four times a day at a rate of 40%-60% of body weight. The feeding period lasts for 28 days, starting from the first feeding.

[0114] The second stage is the "growth period". Feeding is adjusted to 1-2 times a day, with a daily feeding rate of 3%-20% of body weight. The feeding period is 35 days. At the end of the period, the feed can be mixed to smoothly transition to the next stage of general commercial compound feed.

[0115] 4. Breeding Results

[0116] The experimental feeds included Phase 1 and Phase 2 feeds, as well as commercially available branded feeds. The feed label indicated that the commercial feed consisted of white fish meal, earthworm meal, soybean meal, corn gluten meal, fish oil, vitamin premix, and mineral premix.

[0117] The experimental eel fry were self-bred artificial fry from the Yangtze River Fisheries Research Institute (Wuhan, Hubei Province), Chinese Academy of Fishery Sciences. Six rearing tanks (50 cm long, 35 cm wide, and 10 cm deep) were selected from one set of flowing water system, with 500 eels stocked in each tank. The eels were divided into two groups: one group was fed the formulated feed of this embodiment (experimental group), and the other group was fed commercial feed (control group), with three replicates in each group. Feeding began when the experimental eels had partially absorbed their yolk sacs at 6 days of age.

[0118] Feeding was divided into two periods. The first period was the nutritional program period, following the above application method. As the fish grew, they needed to be gradually separated and raised according to conventional aquaculture operations. After the aquaculture was completed, livers from the same part of each of the three fish in each tank were randomly selected, placed in 4% paraformaldehyde, and tissue sections were prepared using the HE method. Subsequently, 20 fish were randomly selected and challenged with Aeromonas hydrophila. The survival rate was recorded after 7 days.

[0119] The second period involved feeding the fish entirely with commercial feed to verify the impact of a programmed nutrition method on subsequent fish growth and health. One hundred uniformly sized experimental fish were selected from each tank and gradually fed commercial formulated feed. The rearing process followed standard procedures; if the density became too high, the feed was gradually increased. Rearing continued for 6 months. After the rearing period, livers from the same location were randomly selected from three fish in each tank and placed in 4% paraformaldehyde for hematologic malignancy (HE) analysis to prepare tissue sections. Then, ten fish were randomly selected from each tank and challenged with Aeromonas hydrophila after the rearing period, and the survival rate was recorded after 7 days. The growth, survival, and challenge survival rates of the eels after the first and second periods are shown in Table 4. The liver and intestinal tissue conditions are shown in Table 5. Figure 2 and Figure 3 .

[0120] Table 4. Growth performance and survival rate of *Eel* and its survival rate after viral challenge.

[0121]

[0122] Note: Different lowercase letters in the same column of the table indicate significant differences (P<0.05), and the same applies to the following tables.

[0123] As shown in Table 4, in both the first and second periods, the growth and survival rates of the group fed with the early-stage feed were better than those fed with the early-stage commercial feed, with significant differences in final body weight and survival rate after virus challenge (P < 0.05). Figure 2 In the study, it was also observed that, compared to the control group fed commercial feed, the eels fed the feed from the example had significantly lower levels of liver congestion and better regularity of intestinal villi. After the second period ended ( Figure 3 In the liver structure, the hepatocytes of the eels fed in the first-period feeding example had more vacuoles, but the hepatocyte membranes were clear and the structure was intact, while the hepatocytes of the control group had blurred boundaries and showed signs of fusion and necrosis, indicating that the eels fed in the first-period feeding example were still healthier than the control group. In the intestinal structure, it was observed that the intestinal villi height of the eels fed in the early-period feeding example was higher than that of the control group, indicating that the positive effect of the feed in the example on the intestinal digestive function of the eels still exists.

[0124] Example 3 applies to formulated feeds based on nutritional programming that can ensure the health of Chinese soft-shelled turtle hatchlings and their applications.

[0125] 1. Feed formulation

[0126] The formula for compound feed for Chinese soft-shelled turtles is shown in Table 5 below. It is divided into two stages, Stage 1 and Stage 2, and the formula mass ratios for the two stages are different.

[0127] Table 5. Formula for Compound Feed of Chinese Soft-shelled Turtle Seedlings

[0128]

[0129] In Table 5 above, the formulations of the animal protein powder, plant protein powder, fat, vitamin premix, mineral premix, and compound palatability enhancer are the same as in Example 1.

[0130] 2. Preparation of compound feed

[0131] (1) Raw material pretreatment

[0132] First, weigh out the white fish meal, casein, animal protein powder, plant protein powder, dextrin, calcium dihydrogen phosphate, and sodium alginate according to the mass percentages in Table 5, put them into a mixer for preliminary mixing, and then pulverize them through an ultra-fine pulverizer so that all solid raw materials pass through an 80-mesh standard sieve to form a basic premix.

[0133] (2) Graded premixing

[0134] Weigh the components such as compound palatability enhancer, vitamin premix, and mineral premix according to the mass percentage in Table 5, and perform step-by-step premixing with an appropriate amount of basic premix. Put the mixture into a mixer containing the basic premix and continue mixing for 8 minutes until the coefficient of variation (CV) of the overall mixing uniformity is no greater than 5%.

[0135] (3) Conditioning

[0136] The resulting homogeneous mixture is fed into a conditioner and saturated steam at 90 °C is introduced. The mixture is conditioned for 50 seconds to fully soften the material and gelatinize the starch.

[0137] (4) Granulation and post-maturation

[0138] The conditioned material is fed into a pellet mill. The first stage of feed is made into pellets with a diameter of 0.1-0.25 mm, and the second stage of feed is made into pellets with a diameter of 0.3-0.4 mm. Subsequently, the wet pellets are fed into a post-curing unit and maintained at a temperature of about 90 ℃ for 20 minutes to enhance the starch binding effect.

[0139] (5) Drying

[0140] The post-matured pelleted feed is transferred to a dryer and dried using a low-temperature airflow not exceeding 60°C to reduce the moisture content of the pellets to below 10%, and then cooled to room temperature.

[0141] (6) Liquid component spraying

[0142] Finally, the fat is weighed according to the mass percentage in Table 5 and mixed evenly. Using a vacuum spraying device, it is evenly sprayed onto the surface and internal micropores of the cooled pellet feed to produce finished pellet feed.

[0143] 3. Application methods of compound feed

[0144] The first stage is the "initiation period". Feeding is done 4 times every other day, with a daily feeding rate of 3%-5% of body weight. The feeding period lasts for 28 days from the start of feeding.

[0145] The second stage is the "growth period". Feeding is adjusted to twice a day, with a daily feeding rate of 1%-3% of body weight. The feeding period is 42 days. At the end of the period, the feed can be mixed to smoothly transition to the next stage of general commercial compound feed.

[0146] 4. Breeding Results

[0147] The experimental feeds included Phase 1 and Phase 2 feeds, as well as a commercially available brand of feed. The feed label indicated that the commercial feed consisted of white fish meal, chicken meal, α-starch, vitamin premix, and mineral premix.

[0148] The Chinese soft-shelled turtle hatchlings used in the experiment were artificially bred by Hubei Hongwang Ecological Agriculture Technology Co., Ltd. (Xiantao, Hubei). Six rearing ponds (200 cm long, 100 cm wide, and 10-30 cm deep) were selected, with 300 turtles placed in each pond. They were divided into two groups: one group was fed the formulated feed of this embodiment (experimental group), and the other group was fed commercial feed (control group), with three replicates in each group. The turtles were placed in the rearing ponds after hatching, and feeding began on the fourth day.

[0149] Feeding was divided into two periods. The first period was the nutritional program period, following the above application method. As the turtles grew, they needed to be gradually separated and raised according to conventional breeding operations. After the breeding was completed, three turtles from each tank were randomly selected, and their livers from the same part were taken and placed in 4% paraformaldehyde. Tissue sections were prepared using the HE method. Then, 20 turtles were randomly selected and challenged with Aeromonas hydrophila. The survival rate was recorded after 10 days.

[0150] The second period involved feeding the turtles entirely with commercial feed to verify the impact of programmed nutrition on their subsequent growth and health. One hundred uniformly sized experimental turtles were selected from each tank and gradually fed commercial formulated feed. The rearing operation followed standard procedures; if the density became too high, the feeding was gradually reduced. Rearing continued for 5 months. After the rearing period, livers from the same location were randomly selected from three turtles in each tank and placed in 4% paraformaldehyde for hematologic malignancy (HE) analysis to prepare tissue sections. Ten turtles were then randomly selected from each pond and challenged with Aeromonas hydrophila after the rearing period. The survival rate was recorded 10 days later. The growth, survival, and challenge survival rates of the Chinese soft-shelled turtles after the first and second periods are shown in Table 6. The liver and intestinal tissue conditions are shown in [Table 6]. Figure 4 and Figure 5 .

[0151] Table 6. Growth performance and survival rate of Chinese soft-shelled turtle seedlings and survival rate after virus challenge.

[0152]

[0153] Note: Different lowercase letters in the same column of the table indicate significant differences (P<0.05).

[0154] As shown in Table 6, in both the first and second periods, the growth and survival rates of the group fed with the earlier-stage feed were better than those fed with the earlier-stage commercial feed, with significant differences in final body weight and survival rate after virus challenge (P < 0.05). Figure 4 In the study, it was found that compared with the control group fed commercial feed, the Chinese soft-shelled turtle hatchlings fed the feed from the example in the first period had less melanin deposition in their livers and a more intact intestinal structure, indicating that the example was better for the health of the hatchlings. Figure 5In the second phase, the hepatocytes of the Chinese soft-shelled turtles all showed vacuolation. However, it was still found that the hepatocyte membranes of the hatchlings fed the example feed in the first phase were clearer and more distinct than those fed the control group feed, and the intestinal villi were also more intact. This indicates that feeding the example feed still has a positive effect on the health of the Chinese soft-shelled turtles.

[0155] The above examples, using sturgeon (Example 1), eel (Example 2), and Chinese soft-shelled turtle (Example 3) as representatives, cover various typical carnivorous aquatic seedlings with different evolutionary positions and different living habits (flow-dwelling, benthic, and amphibious). The results of the aquaculture trials show that:

[0156] At the end of the first period (nutritionally programmed period) of each embodiment, the experimental groups fed with the present application and compound feed were significantly better than the control groups of commercial feed in terms of core indicators such as final average body weight, survival rate and survival rate after challenge (P<0.05); histological observation also confirmed that the liver and intestinal structure of the experimental group seedlings were healthier and more intact.

[0157] More importantly, at the end of the second period in each embodiment (when all seedlings were switched to commercial feed for continued rearing), the seedlings that had previously received the nutritional programmed intervention described in this application still showed significantly better final average body weight, survival rate, and survival rate after challenge than the control group fed commercial feed (P<0.05), and their liver and intestinal histological condition remained superior. This indicates that the nutritional programmed intervention achieved in this application has significant long-term sustainability, and that early nutritional intervention has a profound positive impact on the growth trajectory, metabolic adaptation, and immune memory of the seedlings.

[0158] In summary, the formulated feed based on nutritional programming that can ensure the health of aquatic seedlings, as well as its preparation and application methods, provided in this application, have shown stable and reproducible excellent effects on different carnivorous aquatic seedlings, and have broad species applicability and outstanding industrial application value.

[0159] The present application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present application. The descriptions of the embodiments above are only for the purpose of helping to understand the present application and its core ideas. It should be noted that those skilled in the art can make several improvements and modifications to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A formulated feed based on nutritional programming to ensure the health of aquatic seedlings, characterized in that, By weight, it includes the following components: 30-60 parts white fish meal, 5-10 parts casein, 0-20 parts animal protein powder, 5-30 parts plant protein powder, 2-8 parts fat, 2-15 parts dextrin, 0.1-0.5 parts vitamin premix, 0.5-3 parts calcium dihydrogen phosphate, 0.5-2 parts mineral premix, 2-8 parts compound palatability enhancer, and 0-5 parts sodium alginate.

2. The formulated feed based on nutritional programming to ensure the health of aquatic seedlings according to claim 1, characterized in that, By weight, it includes the following components: 45-60 parts white fish meal, 6-8 parts casein, 3-8 parts animal protein powder, 5-20 parts plant protein powder, 3-6 parts fat, 8-10 parts dextrin, 0.25-0.5 parts vitamin premix, 1.5-2.5 parts calcium dihydrogen phosphate, 1.2-1.8 parts mineral premix, 3-6 parts compound palatability enhancer, and 2-4 parts sodium alginate.

3. The formulated feed based on nutritional programming to ensure the health of aquatic seedlings according to claim 1, characterized in that, Based on parts by mass, its components include at least one of the following (a)-(f): (a) 42.5 parts white fish meal, 6.5 parts casein, 11.8 parts animal protein powder, 10.4 parts plant protein powder, 6.3 parts fat, 10.3 parts dextrin, 1.1 parts vitamin premix, 1.5 parts calcium dihydrogen phosphate, 1 part mineral premix, 6 parts compound attractant, and 2.6 parts sodium alginate; (b) 35 parts white fish meal, 5.5 parts casein, 14.8 parts animal protein powder, 16.4 parts plant protein powder, 6.3 parts fat, 13.2 parts dextrin, 1.5 parts vitamin premix, 1.5 parts calcium dihydrogen phosphate, 1.3 parts mineral premix, 2.5 parts compound palatability enhancer, and 2 parts sodium alginate; (c) 45.5 parts white fish meal, 5.6 parts casein, 11.8 parts animal protein powder, 10.6 parts plant protein powder, 4 parts fat, 7.5 parts dextrin, 1.3 parts vitamin premix, 1.5 parts calcium dihydrogen phosphate, 1.2 parts mineral premix, 7.5 parts compound palatability enhancer, and 3.5 parts sodium alginate; (d) 40 parts white fish meal, 6.5 parts casein, 10.8 parts animal protein powder, 12.8 parts plant protein powder, 6.3 parts fat, 13.2 parts dextrin, 1.2 parts vitamin premix, 1.8 parts calcium dihydrogen phosphate, 1.3 parts mineral premix, 4 parts compound palatability enhancer, and 2.1 parts sodium alginate; (e) 50 parts white fish meal, 5 parts casein, 13 parts animal protein powder, 12.5 parts plant protein powder, 2 parts fat, 10 parts dextrin, 1 part vitamin premix, 1.5 parts calcium dihydrogen phosphate, 1 part mineral premix, 3 parts compound palatability enhancer, and 1 part sodium alginate. (f) 43.5 parts white fish meal, 5 parts casein, 15.5 parts animal protein powder, 13.5 parts plant protein powder, 2.5 parts fat, 15 parts dextrin, 0.8 parts vitamin premix, 1.2 parts calcium dihydrogen phosphate, 1 part mineral premix, and 2 parts compound attractant.

4. The formulated feed based on nutritional programming to ensure the health of aquatic seedlings according to any one of claims 1-3, characterized in that, The animal protein powder, by weight, is composed of the following components: 400 parts krill powder, 300 parts tubifex worm powder, and 300 parts chicken powder; the plant protein powder, by weight, is composed of the following components: 500 parts soybean meal and 500 parts cottonseed meal; the fat, by weight, is composed of the following components: 300 parts cod liver oil, 600 parts pork liver oil, and 100 parts lysophosphatidylcholine.

5. The formulated feed based on nutritional programming to ensure the health of aquatic seedlings according to any one of claims 1-3, characterized in that, The vitamin premix, by weight, comprises the following components: 1.2 parts vitamin B1, 1.2 parts vitamin B2, 0.3 parts calcium pantothenate, 4 parts niacin, 0.02 parts biotin, 0.3 parts vitamin B6, 0.1 parts folic acid, 3 parts inositol, 10 parts vitamin C, 0.3 parts vitamin A, 0.05 parts vitamin D3, 10 parts vitamin E, 0.8 parts vitamin K3, and 984.645 parts Haematococcus pluvialis powder; the mineral premix, by weight, comprises the following components: 3.18 parts ferrous sulfate, 60 parts magnesium sulfate, 0.1 parts aluminum chloride, 1.5 parts calcium iodate, 0.5 parts copper chloride, 0.5 parts manganese sulfate, 1.2 parts cobalt chloride, 1.3 parts zinc sulfate, 0.03 parts sodium selenite, 50 parts sodium chloride, 0.05 parts sodium molybdate, and 881.64 parts zeolite powder.

6. The formulated feed based on nutritional programming to ensure the health of aquatic seedlings according to any one of claims 1-3, characterized in that, The compound attractant, by weight, consists of the following components: 250 parts glycine, 150 parts mussel extract, 200 parts hawthorn extract, 200 parts astragalus polysaccharide, and 200 parts yeast β-glucan.

7. A method for preparing compound feed based on nutritional programming according to any one of claims 1-6 to ensure the health of aquatic seedlings, characterized in that, Includes the following steps: (1) Raw material pretreatment: White fish meal, casein, animal protein powder, plant protein powder, dextrin, calcium dihydrogen phosphate and sodium alginate are mixed in any mass ratio of claims 1-6 and then ultra-finely pulverized and passed through an 80-120 mesh standard sieve to obtain basic premix; (2) Graded premixing: Weigh the compound palatability enhancer, vitamin premix, mineral premix and appropriate amount of basic premix according to any mass ratio in claims 1-6, and premix them in stages. Then add them to the remaining basic premix and continue mixing until the uniformity variation coefficient is ≤5%; (3) Conditioning: The homogeneous mixture obtained in step (2) is fed into a conditioner and saturated steam at 85-95 ℃ is introduced for conditioning for 30-60 seconds; (4) Granulation and post-maturation: The conditioned material is fed into the granulator and pressed or crushed into particles of the required diameter according to the target seedling specifications; then the wet particles are fed into the post-maturation unit and maintained at a temperature of 75-90 ℃ for 10-20 minutes. (5) Drying: Transfer the post-matured pelleted feed into a dryer and dry it with a low-temperature airflow of no more than 60 °C to reduce the moisture content of the pellets to below 10% and then cool it to room temperature; (6) Liquid component spraying: Weigh the fat component according to the above mass ratio and mix it evenly. Use a vacuum spraying device to spray it evenly onto the surface and internal micropores of the cooled pellet feed to make finished pellet feed.

8. The method for preparing compound feed based on nutritional programming to ensure the health of aquatic seedlings according to claim 7, characterized in that, In step (4), the feed is made into pellets with a diameter of 0.1-2.0 mm according to the seedling specifications; in step (6), a vacuum spraying device is used for spraying.

9. A method for using any one of the nutritionally programmed compound feeds according to claims 1-6 to ensure the health of aquatic seedlings, characterized in that, The method involves feeding in two stages: The first stage is the initial feeding period, during which the compound feed described in any of claims 1-6 is fed 1-8 times daily or every other day, with a daily feeding rate of 3%-80% of body weight, for 14-28 days. The second stage is the growth period, during which the feed described in any one of claims 1 is fed 1-4 times a day, with a daily feeding rate of 1%-30% of body weight, for 28-72 days.

10. The method according to claim 9, characterized in that, At the end of the second stage, a smooth transition to general commercial compound feed is achieved through mixed feeding; the mixed feeding refers to feeding the compound feed and general commercial compound feed together in gradually adjusted proportions.

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