Preparation method of silkworm rich selenium egg

Abstract

This application discloses a method for preparing selenium-enriched eggs from silkworms, belonging to the field of functional poultry egg production technology. The method includes four steps: preparation of nano-selenium mulberry leaves, selenium-enriched silkworm rearing, preparation of silkworm selenoprotein, and feeding and management of laying hens. This application addresses the shortcomings of traditional technologies, such as low selenium utilization, high cost, and significant pollution, through synergistic optimization of the biological chain. It achieves efficient conversion and targeted enrichment of selenium resources, resulting in eggs with a stable selenium content of 36.8±1.9 μg / egg and a selenomethionine content as high as 87.9%, significantly improving the nutritional value and safety of the eggs, making it suitable for industrial production.

Description

Technical Field

[0001] This application belongs to the field of functional poultry egg production technology, and in particular relates to a method for preparing selenium-enriched eggs from silkworms. Background Technology

[0002] Selenium-enriched eggs contain dozens of times more selenium than regular eggs, including free-range eggs, and have lower cholesterol. They are believed to have anti-aging properties, boost immunity, and help prevent angina, myocardial infarction, cerebral thrombosis, and have anti-cancer effects. Selenium's primary function in the body is as an antioxidant; it plays a crucial role in an enzyme that eliminates free radicals. A deficiency may lead to heart disease and a higher risk of cancer.

[0003] Currently, the production of selenium-enriched eggs mainly relies on selenium-fortified feed, but existing technologies face the following key challenges: 1. Limitations of traditional selenium sources: Inorganic selenium addition (e.g., sodium selenite): absorption rate in laying hens is <30%, with most being excreted in feces, causing environmental pollution and posing a high toxicity risk. Long-term intake by laying hens can lead to selenium accumulation in the liver (>5 mg / kg wet weight); Plant-derived organic selenium (e.g., selenium yeast): selenomethionine accounts for only 50-60%, resulting in limited bioavailability, and yeast cultivation requires specialized fermentation equipment, leading to high production costs. 2. Technical bottleneck of unstable selenium forms: Existing processes suffer from the problem that selenium in feed is easily oxidized to ineffective forms (e.g., selenate), with a loss rate >20% after 30 days of storage. The proportion of methylselenocysteine ​​in eggs is too high (>15%), reducing nutritional value. 3. Insufficient industry chain synergy: Byproducts of the silkworm industry, such as silkworm pupae and mulberry branches, are not efficiently utilized, and traditional treatment methods such as landfilling or incineration lead to selenium resource loss. Therefore, developing an efficient, safe, and sustainable selenium bioconversion method is a pressing issue for those skilled in the art. Summary of the Invention

[0004] To overcome the aforementioned deficiencies in the prior art, this application provides a method for preparing selenium-enriched eggs from silkworms.

[0005] To achieve the above-mentioned objectives, this application provides the following technical solution:

[0006] On the one hand, this application provides a method for preparing selenium-enriched eggs from silkworms, comprising the following steps:

[0007] (1) Preparation of nano-selenium mulberry leaves: Spray nano-selenium solution on mulberry trees during the peak leafing period to obtain nano-selenium mulberry leaves;

[0008] (2) Selenium-enriched silkworm breeding: Fifth-instar silkworms were fed with the nano-selenium mulberry leaves to obtain selenium-enriched silkworm pupae;

[0009] (3) Preparation of silkworm selenoprotein: The selenium-enriched silkworm pupae were subjected to gradient cooling enzymatic hydrolysis using a compound enzyme to obtain silkworm selenoprotein;

[0010] (4) Feeding and management of laying hens: During the brooding period, laying hens are fed with basic diet A; during the growing period, laying hens are fed with basic diet B; during the pre-laying period, laying hens are fed with advanced feed A; and during the laying period, laying hens are fed with advanced feed B. The resulting selenium-enriched silkworm eggs are obtained from the laying of eggs.

[0011] In step (4), the components of the basic diet A include corn grits, soybean meal, fish meal, limestone powder, dicalcium phosphate, premixed feed for chicks, and vegetable oil.

[0012] The components of the basic diet B include corn grits, soybean meal, wheat bran, limestone powder, premixed feed for growing chickens, and mushroom residue;

[0013] Both advanced feed A and advanced feed B contain the silkworm selenoprotein.

[0014] Optionally, in step (1), the nano-selenium solution is formulated as follows: per 100L of solution, it contains: 70-80g of red elemental nano-selenium, 250-350g of lignin gum, 45-55g of Gynostemma pentaphyllum saponins, 10-20L of sodium citrate buffer, and deionized water to make up to 100L.

[0015] Preferably, in step (1), the nano-selenium solution is formulated as follows: per 100L of solution, it contains: 75g of red elemental nano-selenium, 300g of lignin gum, 50g of Gynostemma pentaphyllum saponins, 15L of sodium citrate buffer, and deionized water to make up to 100L.

[0016] In this application, the lignin gum added to the above-mentioned nano-selenium solution can form a complex with the red elemental nano-selenium, enhancing the rain erosion resistance of mulberry leaves; the added gypenosides can encapsulate the red elemental nano-selenium, and the triterpenoid skeleton of gypenosides can form a "pinning effect" with the nano-selenium, enhancing the adhesion of the nano-selenium to the leaf surface and promoting the penetration of the nano-selenium; the added sodium citrate buffer can stabilize the pH and prevent the stomata of mulberry leaves from closing due to pH fluctuations.

[0017] Optionally, the red elemental selenium nanoparticles have a particle size of 45–55 nm and a purity of ≥99.9%.

[0018] The pH of the sodium citrate buffer solution is 6.3 to 6.6.

[0019] Preferably, the red elemental selenium nanoparticles have a particle size of 50 nm and a purity of 99.9%.

[0020] The pH of the sodium citrate buffer solution is 6.5.

[0021] Optionally, in step (1), the spraying is foliar spraying;

[0022] The spraying time is from 7:30 a.m. to 9:30 a.m.

[0023] The application rate of the nano-selenium solution is 8-12 L / mu;

[0024] The standard for successful spraying is that the selenium content of the nano-selenium mulberry leaves reaches 14-17 mg / kg.

[0025] Preferably, in step (1), the spraying amount of the nano-selenium solution is 10L / mu.

[0026] Optionally, in step (2), the temperature for raising selenium-enriched silkworms is 25–27°C;

[0027] The nano-selenium mulberry leaves are fed 3-4 times / day;

[0028] The amount of nano-selenium mulberry leaves fed each time is 1 to 1.5 times the total weight of the silkworm.

[0029] Preferably, in step (2), the temperature for raising selenium-enriched silkworms is 26°C;

[0030] The nano-selenium mulberry leaves were fed 4 times / day;

[0031] The amount of nano-selenium mulberry leaves fed each time is 1.3 times the total weight of the silkworm.

[0032] Optionally, in step (2), the standard for qualified feeding is that the hemolymph selenium concentration of 5-year-old silkworms reaches 28-32 μg / mL.

[0033] Optionally, in step (3), the complex enzyme includes cellulase and papain;

[0034] The mass ratio of cellulase to papain is 1:1 to 2;

[0035] The cellulase activity is ≥100,000 U / g;

[0036] The papain activity is ≥200,000 U / g;

[0037] The total amount of cellulase and papain added is 750-850 U per gram of selenium-enriched silkworm pupae.

[0038] Preferably, in step (3), the mass ratio of cellulase to papain is 1:1.5;

[0039] The cellulase activity is 100,000 U / g;

[0040] The papain activity is 200,000 U / g;

[0041] The total amount of cellulase and papain added is 815U per gram of selenium-enriched silkworm pupae.

[0042] Optionally, in step (3), the gradient cooling enzymatic hydrolysis conditions are: 50℃, 2h→45℃, 1h→40℃, 0.5h;

[0043] The pH during the gradient cooling enzymatic hydrolysis process is 5.8–6.2.

[0044] Preferably, in step (3), the pH during the gradient cooling enzymatic hydrolysis process is 6.

[0045] Optionally, in step (4), the basic diet A contains the following components in parts by weight: 60-63 parts corn grits, 25-30 parts soybean meal, 1-5 parts fish meal, 1-2 parts limestone powder, 1-2 parts dicalcium phosphate, 3-5 parts premix for chicks, and 0.1-0.5 parts vegetable oil.

[0046] The basal diet B comprises the following components in parts by weight: 63-66 parts corn grits, 18-22 parts soybean meal, 5-10 parts wheat bran, 2-3 parts limestone powder, 3-5 parts premixed feed for growing chickens, and 0.4-0.6 parts mushroom residue.

[0047] Preferably, in step (4), the basic diet A contains the following components in parts by weight: 62 parts corn grits, 28 parts soybean meal, 3 parts fish meal, 1.2 parts limestone powder, 1.5 parts dicalcium phosphate, 4 parts premixed feed for chicks, and 0.3 parts vegetable oil.

[0048] The basic diet B contains the following components in parts by weight: 65 parts corn grits, 20 parts soybean meal, 8 parts wheat bran, 2.5 parts limestone powder, 4 parts premixed feed for growing chickens, and 0.5 parts mushroom residue.

[0049] Optionally, the particle size of the corn grits is 1.5–2.5 mm;

[0050] The stone powder has a particle size of 0.3–0.8 mm;

[0051] The selenium content of the premixed feed for chicks is 0.08–0.12 mg / kg;

[0052] The vegetable oil is soybean oil;

[0053] The selenium content of the premixed feed for pullets is 0.14–0.16 mg / kg;

[0054] The particle size of the mushroom residue is 0.1–0.4 mm.

[0055] Preferably, the particle size of the corn grits is 2 mm;

[0056] The stone powder has a particle size of 0.7 mm;

[0057] The selenium content of the premixed feed for chicks is 0.1 mg / kg;

[0058] The selenium content of the premixed feed for pullets is 0.15 mg / kg;

[0059] The particle size of the mushroom residue is 0.3 mm.

[0060] Optionally, in step (4), the advanced feed A contains the following components in parts by weight: 60-63 parts corn grits, 20-25 parts soybean meal, 5-7 parts limestone powder, 1.5-2 parts dicalcium phosphate, 0.2-0.32 parts silkworm selenium protein, 1-2 parts mushroom residue, 0.4-0.6 parts soybean oil, and 3-5 parts premixed feed for growing chickens;

[0061] The advanced feed B comprises the following components in parts by weight: 55-60 parts corn grits, 20-25 parts soybean meal, 8-10 parts limestone powder, 1-2 parts dicalcium phosphate, 0.5-0.7 parts silkworm selenium protein, 2-2.5 parts mushroom residue, 1-1.5 parts brewer's yeast residue, 0.4-0.6 parts soybean oil, and 3-5 parts premixed feed for laying hens.

[0062] Preferably, in step (4), the advanced feed A contains the following components in parts by weight: 62 parts corn grits, 22 parts soybean meal, 6 parts limestone powder, 1.8 parts dicalcium phosphate, 0.2-0.32 parts silkworm selenium protein, 1.5 parts mushroom residue, 0.5 parts soybean oil, and 4 parts premixed feed for growing chickens.

[0063] The advanced feed B contains the following components in parts by weight: 58 parts corn grits, 24 parts soybean meal, 8 parts limestone powder, 1.5 parts dicalcium phosphate, 0.6 parts silkworm selenium protein, 2 parts mushroom residue, 1.2 parts brewer's yeast residue, 0.5 parts soybean oil, and 4 parts premixed feed for laying hens.

[0064] Optionally, in the advanced feed A, silkworm selenoprotein is added in a mass fraction gradient of 0.2 parts in week 1 and 0.32 parts in week 2.

[0065] Optionally, the particle size of the corn grits is 1.5–2.5 mm;

[0066] The stone powder has a particle size of 0.3–0.8 mm;

[0067] The particle size of the mushroom residue is 0.1–0.4 mm;

[0068] The selenium content of the brewer's yeast residue is 1.5–2 mg / kg;

[0069] The selenium content of both the pullet-specific premix and the laying hen-specific premix is ​​0.14–0.16 mg / kg.

[0070] Preferably, the particle size of the corn grits is 2 mm;

[0071] The stone powder has a particle size of 0.7 mm;

[0072] The particle size of the mushroom residue is 0.3 mm;

[0073] The selenium content of the brewer's yeast residue is 1.7 mg / kg;

[0074] The selenium content of both the pullet-specific premix and the laying hen-specific premix is ​​0.15 mg / kg.

[0075] In this application, the reason why the feed for the brooding and growing periods does not contain silkworm selenoprotein is that: during the brooding period, the chicken's digestive system is not fully developed (gizzard pH > 4.0), and its ability to break down selenoprotein is insufficient. Some selenium remains in inorganic form, leading to increased selenium accumulation in the liver and potentially causing inhibition of immune organ development; while the core goal of the growing period is bone development and weight control, and the selenium requirement is low, which can be met by the basic diet.

[0076] Optionally, in step (4), the temperature during the feeding and management of laying hens is 18-24℃ and the humidity is 55-65%.

[0077] The lighting conditions during the brooding period are: 23 hours of light, 1 hour of darkness, and a light intensity of 20-30 Lux.

[0078] The light conditions during the growth period are: 12 hours of light, 12 hours of darkness, and a light intensity of 20-30 Lux.

[0079] The lighting conditions for the expected delivery date are: 14 hours of light, 10 hours of darkness, with a light intensity of 20-30 Lux.

[0080] The lighting conditions during the egg-laying period are: 16 hours of light and 8 hours of darkness, with a light intensity of 20–30 Lux.

[0081] Preferably, in step (4), the temperature during the feeding and management of laying hens is 21°C and the humidity is 60%.

[0082] The lighting conditions during the brooding period are: 23 hours of light, 1 hour of darkness, and a light intensity of 25 Lux.

[0083] The light conditions during the growth period are: 12 hours of light, 12 hours of darkness, and a light intensity of 25 Lux.

[0084] The lighting conditions for the expected delivery date are: 14 hours of light, 10 hours of darkness, with a light intensity of 25 Lux.

[0085] The lighting conditions during the egg-laying period are: 16 hours of light, 8 hours of darkness, and a light intensity of 25 Lux.

[0086] Optionally, in step (4), the feeding method during the brooding period is: feeding 6 to 7 times a day, with a daily feeding amount of 12 to 35g / bird;

[0087] The feeding method during the rearing period is as follows: feed 3 to 4 times a day, and feed 65 to 80g per bird per day;

[0088] The feeding method during the expected birthing period is as follows: feed 2 to 3 times a day, and feed 90 to 105g / bird per day;

[0089] The feeding method during the egg-laying period is as follows: feed 2 to 3 times a day, and feed 110 to 125g / bird per day.

[0090] Preferably, in step (4), the feeding method during the brooding period is: feeding 6 times a day, with a daily feeding amount of 30g / bird;

[0091] The feeding method during the rearing period is as follows: feed 3 times a day, with a daily feed amount of 75g / bird;

[0092] The feeding method during the expected birthing period is as follows: feed twice a day, with a daily feed amount of 100g / bird;

[0093] The feeding method during the egg-laying period is as follows: feed twice a day, with a daily feed amount of 115g / bird.

[0094] Compared with the prior art, this application has the following advantages:

[0095] (1) The method for preparing selenium-enriched eggs from silkworms provided in this application uses mulberry leaves modified with nano-selenium to feed silkworms and live silkworms as the carrier for selenium conversion. Through a four-level bioconversion chain of "nano-selenium mulberry leaves → silkworm enrichment → enzymatic conversion → feeding to laying hens", the conversion and targeted enrichment of selenium resources are realized. The selenium content of the eggs obtained is stable at 36.8±1.9μg / egg (national standard selenium-enriched eggs ≥20μg / egg), and the proportion of selenomethionine is as high as 87.9%, which significantly improves the nutritional value and safety of the eggs.

[0096] (2) This application utilizes agricultural by-products such as silkworm pupae and mushroom residue to reduce the cost of selenium additives. At the same time, it constructs a closed-loop system of "mulberry garden → breeding → fertilizer" to enable the recycling of selenium resources and reduce the environmental burden.

[0097] (3) The present application develops a gradient cooling enzymatic hydrolysis process and a dynamic gradient selenium supplementation technology, which can retain the activity of selenoproteins, ensure the stability of selenium form, and, combined with other feed components, increase the egg production rate of laying hens to 94.5% and reduce the broken egg rate to 1.2%, which is suitable for large-scale industrial production. Detailed Implementation

[0098] The present application is further illustrated below with reference to specific embodiments. The following descriptions are merely a few embodiments of the present application and are not intended to limit the present application in any way. Although the present application discloses preferred embodiments as follows, they are not intended to limit the present application. Any modifications or variations made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

[0099] Unless otherwise specified, the raw materials used in the embodiments of this application are all purchased commercially and used directly without any special treatment.

[0100] Unless otherwise specified, the analytical methods in the embodiments all adopt conventional instrument or equipment settings and conventional analytical methods.

[0101] Example 1

[0102] I. Experimental Location and Conditions

[0103] Location: Zongxi Town, Xunyang City, Ankang City, Shaanxi Province

[0104] Climate characteristics: average annual temperature of 15.4℃, annual precipitation of 755mm, mulberry tree growing season of ≥240 days, which meets the needs of multi-batch silkworm breeding.

[0105] Variety selection:

[0106] Mulberry trees: “Shaanxi Mulberry 305” (a selenium-tolerant variety, purchased from Shaanxi Hongshengrui Agricultural and Forestry Technology Co., Ltd.), planted at a spacing of 3m×1.5m.

[0107] Domestic silkworm: "Shaanxi No. 3" (5th instar weight ≥4.5g / silkworm, purchased from the Sericulture and Silk Research Institute of Northwest A&F University).

[0108] Laying hens: Hy-Line Brown laying hens (1-day-old chicks, purchased from Ningxia Xiaoming Agricultural and Animal Husbandry Co., Ltd.).

[0109] II. Specific Implementation Steps

[0110] 1. Preparation of nano-selenium mulberry leaves

[0111] (1) Spray solution formula (100L): 75g of red elemental nano-selenium (50nm, 99.9%, purchased from Xi'an Qiyue Biotechnology Co., Ltd.), 300g of lignin gum (purchased from Shanghai Sudaoweiye Technology Co., Ltd.), 50g of Gynostemma pentaphyllum saponins (purchased from Shaanxi Fuerbang Biotechnology Co., Ltd.), 15L of 0.1M sodium citrate buffer (pH 6.5, purchased from Shanghai Shangbao Biotechnology Co., Ltd.), and deionized water to make up to 100L.

[0112] Preparation of spray solution: First, dry mix red elemental nano-selenium with Gynostemma pentaphyllum saponins (1:1), then dissolve in lignin gum, then add sodium citrate buffer and deionized water, mix well to obtain nano-selenium solution.

[0113] (2) Spraying operation:

[0114] Time: 07:30-09:30 on May 10, 2023 (peak foliage season for mulberry trees)

[0115] Method: Drone aerial spraying (atomized particle size 40μm, pressure 3bar)

[0116] Dosage: 10L / mu. After spraying the nano selenium solution for 7 days, the selenium content of mulberry leaves reached 15.7±1.2mg / kg (dried basis), thus obtaining nano selenium mulberry leaves.

[0117] 2. Selenium-enriched silkworm farming

[0118] (1) Feeding management:

[0119] Temperature: 26±0.5℃ (Ground source heat pump control)

[0120] Feeding: Feed the silkworms with nano-selenium mulberry leaves 4 times a day (06:00 / 11:00 / 16:00 / 21:00). The amount of feed given each time is equal to the total weight of the silkworms × 1.3. The total consumption of selenium mulberry leaves during the 5th instar is 38 kg per 10,000 silkworms.

[0121] (2) Quality control:

[0122] Selenium concentration in hemolymph: 29.3±1.2μg / mL (colloidal gold test strip rapid test, purchased from Shaanxi Selenium Valley Biotechnology, product model SX-Se-Rapid).

[0123] The qualified selenium content of silkworm pupae is 62.5±2.1μg / g (detected by atomic fluorescence spectrometry (AFS)).

[0124] 3. Preparation of silkworm selenoprotein

[0125] (1) Enzymatic hydrolysis process:

[0126] Compound enzyme: cellulase (purchased from Hebei Jiuyu Biotechnology Co., Ltd., enzyme activity 100,000 U / g): papain (purchased from Nanning Pangbo Bioengineering Co., Ltd., enzyme activity 200,000 U / g) = 1:1.5 (mass ratio)

[0127] Total amount of compound enzyme added: 815 U / g silkworm pupae

[0128] (2) Enzymatic hydrolysis conditions (gradient cooling enzymatic hydrolysis): 50℃ (2h) → 45℃ (1h) → 40℃ (0.5h), pH 6.

[0129] (3) Product indicators:

[0130] The degree of hydrolysis of selenoproteins was 48.7%, and 88.3% had a molecular weight <3000 Da (HPLC analysis).

[0131] Selenium content 480±15mg / kg (organic selenium accounts for 88.6%).

[0132] 4. Feeding Management of Laying Hens

[0133] (1) Brooding period (1-42 days old):

[0134] Feed formulation (by weight parts): 62 parts corn grits (2mm particle size, purchased from Wenshang County Zhongcheng Grain Industry Co., Ltd.), 28 parts soybean meal (purchased from Shandong Xinlongkai Chemical Co., Ltd.), 3 parts fish meal (purchased from Tianjin Haiwei International Trade Co., Ltd.), 1.2 parts limestone powder (0.7mm particle size, purchased from Shijiazhuang Weijia Mineral Products Co., Ltd.), 1.5 parts dicalcium phosphate (purchased from Shaanxi Yuanyou Biotechnology Co., Ltd.), 4 parts premixed feed for chicks (selenium content 0.1mg / kg, purchased from Anhui Yiyuan Agricultural and Animal Husbandry Technology Co., Ltd.), and 0.3 parts soybean oil (purchased from Jinan Longze Chemical Co., Ltd.).

[0135] Mixing process: First, put corn grits, soybean meal, fish meal, and dicalcium phosphate into the mixer and dry mix for 3 minutes. Then, add chick-specific premix, limestone powder, and soybean oil and mix for 15 minutes.

[0136] Feeding method: Feed 6 times a day (06:00 / 8:30 / 11:00 / 13:30 / 16:00 / 18:30), with a daily feed amount of 30g / bird, and free access to water during the period.

[0137] Lighting control: 23 hours of light, 1 hour of darkness, LED supplemental lighting (intensity of 25 Lux, spectrum: 4000K cool white light).

[0138] (2) Growing period (43-105 days old):

[0139] Feed formulation (by weight): 65 parts corn grits, 20 parts soybean meal, 8 parts wheat bran (wheat bran, purchased from Shandong Huachen Biotechnology Co., Ltd.), 2.5 parts limestone powder, 4 parts premixed feed for growing chickens (selenium content 0.15mg / kg, purchased from Anhui Yiyuan Agricultural and Animal Husbandry Technology Co., Ltd.), and 0.5 parts mushroom residue (enoki mushroom residue, particle size 0.3mm, purchased from Dezhou Fubang Agricultural Development Co., Ltd.).

[0140] Mixing process: First, put corn grits, soybean meal, and wheat bran into the mixer and dry mix for 3 minutes. Then, add chicken premix, stone powder, and mushroom residue and mix for 15 minutes.

[0141] Feeding method: Feed 3 times a day (06:30 / 12:00 / 18:00), with a daily feed amount of 75g / bird, and free access to water during the period.

[0142] Lighting control: 12 hours of light, 12 hours of darkness, LED supplemental lighting (intensity of 25 Lux, spectrum: 4000K cool white light).

[0143] (3) Expected delivery date (106-120 days of age)

[0144] Feed formulation (by weight parts): 62 parts corn grits, 22 parts soybean meal, 6 parts limestone powder, 1.8 parts dicalcium phosphate, silkworm selenium protein added in a gradient of 0.2 parts in week 1 and 0.32 parts in week 2, 1.5 parts mushroom residue, 0.5 parts soybean oil, and 4 parts premixed feed for growing chickens.

[0145] Mixing process: First, premix silkworm selenium protein with mushroom residue for 3 minutes, then add corn residue, soybean meal, and dicalcium phosphate, dry mix for 3 minutes, and finally add chicken-specific premix, limestone powder, and soybean oil and mix for 10 minutes.

[0146] Feeding method: Feed twice a day (7:00 / 15:00), with a daily feed amount of 100g / bird, and free access to water during the period.

[0147] Lighting control: 14 hours of light, 10 hours of darkness, LED supplemental lighting (intensity of 25 Lux, spectrum: 4000K cool white light).

[0148] (4) Laying period (121 days old - culling)

[0149] Feed formula (by weight parts): 58 parts corn grits, 24 parts soybean meal, 8 parts limestone powder, 1.5 parts dicalcium phosphate, 0.6 parts silkworm selenoprotein, 2 parts mushroom residue, 1.2 parts brewer's yeast residue (selenium content 1.7 mg / kg, purchased from China Resources Snow Breweries Xi'an Branch), 0.5 parts soybean oil, and 4 parts laying hen premix (selenium content 0.15 mg / kg, purchased from Anhui Yiyuan Agricultural and Animal Husbandry Technology Co., Ltd.).

[0150] Mixing process: First, premix silkworm selenium protein with mushroom residue and brewer's yeast residue for 3 minutes, then add corn residue, soybean meal, and dicalcium phosphate, dry mix for 3 minutes, and finally add laying hen premix, limestone powder, and soybean oil and mix for 10 minutes.

[0151] Feeding method: Feed twice a day (7:00 / 15:00), with a daily feed amount of 115g / bird, and free access to water during the period.

[0152] Lighting control: 16 hours of light, 8 hours of darkness, LED supplemental lighting (intensity of 25 Lux, spectrum: 4000K cool white light).

[0153] (5) Other parameter control: temperature 21℃, humidity 60% (atomized humidification in winter), ammonia concentration <10ppm.

[0154] Comparative Example 1

[0155] The only difference from Example 1 is that the mulberry leaves were not sprayed with nano-selenium solution.

[0156] Comparative Example 2

[0157] The only difference from Example 1 is that the addition of silkworm selenium protein to the feed is removed during the pre-laying and laying periods of laying hens.

[0158] Experimental Example 1

[0159] Laying hens were fed the methods described in Example 1, Comparative Example 1, and Comparative Example 2, respectively, and the eggs they laid were tested. The results are shown in Table 1.

[0160] Table 1 Results of Egg Index Testing

[0161]

[0162] As shown in Table 1, compared with the comparative example, the eggs obtained in Example 1 of this application have a higher selenium content and better nutritional value, meeting the selenium-enriched egg standard of ≥20μg / egg. Furthermore, the high proportion of selenomethionine indicates that the selenium in the eggs of this application exists mainly in an organic form, ensuring good safety and making it easier for the human body to absorb and utilize. In addition, the feeding program of this application can effectively reduce the egg breakage rate and increase the egg production rate and average egg weight, resulting in higher egg quality.

[0163] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing selenium-enriched eggs from silkworms, characterized in that, Includes the following steps: (1) Preparation of nano-selenium mulberry leaves: During the peak leafing period of mulberry trees, a nano-selenium solution is sprayed to obtain nano-selenium mulberry leaves. The formula of the nano-selenium solution is as follows: per 100L of solution, it contains: 70-80g of red elemental nano-selenium, 250-350g of lignin gum, 45-55g of Gynostemma pentaphyllum saponins, 10-20L of sodium citrate buffer, and deionized water to make up to 100L; the particle size of the red elemental nano-selenium is 45-55nm, and the purity is ≥99.9%; the pH of the sodium citrate buffer is 6.3-6.6; the spraying is foliar spraying; the spraying time is 7:30-9:30 am; the spraying amount of the nano-selenium solution is 8-12L / mu; the standard for completion of spraying is that the selenium content of the nano-selenium mulberry leaves reaches 14-17mg / kg; (2) Selenium-enriched silkworm rearing: Fifth-instar silkworms were fed with the nano-selenium mulberry leaves to obtain selenium-enriched silkworm pupae. The temperature for selenium-enriched silkworm rearing was 25-27℃. The nano-selenium mulberry leaves were fed 3-4 times / day. The amount of nano-selenium mulberry leaves fed each time was 1-1.5 times the total weight of the silkworms. The standard for qualified feeding was that the hemolymph selenium concentration of the fifth-instar silkworms reached 28-32 μg / mL. (3) Preparation of silkworm selenoprotein: The selenium-enriched silkworm pupae were subjected to gradient cooling enzymatic hydrolysis using a compound enzyme to obtain silkworm selenoprotein. The compound enzyme included cellulase and papain. The mass ratio of cellulase to papain was 1:1~2. The enzyme activity of cellulase was ≥100000U / g. The enzyme activity of papain was ≥200000U / g. The total amount of cellulase and papain added was 750~850U per gram of selenium-enriched silkworm pupae. The gradient cooling enzymatic hydrolysis conditions were: 50℃, 2h→45℃, 1h→40℃, 0.5h. The pH during the gradient cooling enzymatic hydrolysis process was 5.8~6.

2. (4) Feeding management of laying hens: During the brooding period, laying hens are fed with basic diet A; during the growing period, laying hens are fed with basic diet B; during the pre-laying period, laying hens are fed with advanced feed A; and during the laying period, laying hens are fed with advanced feed B. The resulting selenium-enriched silkworm eggs are obtained from the laying of eggs. In step (4), the components of the basic diet A include corn grits, soybean meal, fish meal, limestone powder, dicalcium phosphate, premixed feed for chicks, and vegetable oil. The components of the basic diet B include corn grits, soybean meal, wheat bran, limestone powder, premixed feed for growing chickens, and mushroom residue; Both advanced feed A and advanced feed B contain the silkworm selenoprotein.

2. The method for preparing selenium-enriched silkworm eggs according to claim 1, characterized in that, In step (4), the basic diet A contains the following components in parts by weight: 60-63 parts corn grits, 25-30 parts soybean meal, 1-5 parts fish meal, 1-2 parts limestone powder, 1-2 parts dicalcium phosphate, 3-5 parts premix for chicks, and 0.1-0.5 parts vegetable oil. The basic diet B contains the following components in parts by weight: 63-66 parts corn grits, 18-22 parts soybean meal, 5-10 parts wheat bran, 2-3 parts limestone powder, 3-5 parts premix for growing chickens, and 0.4-0.6 parts mushroom residue. The corn grits have a particle size of 1.5~2.5mm; The stone powder has a particle size of 0.3~0.8mm; The selenium content of the premixed feed for chicks is 0.08~0.12 mg / kg; The vegetable oil is soybean oil; The selenium content of the premixed feed for pullets is 0.14~0.16 mg / kg; The particle size of the mushroom residue is 0.1~0.4mm.

3. The method for preparing selenium-enriched silkworm eggs according to claim 1, characterized in that, In step (4), the advanced feed A contains the following components in parts by weight: 60-63 parts corn grits, 20-25 parts soybean meal, 5-7 parts limestone powder, 1.5-2 parts dicalcium phosphate, 0.2-0.32 parts silkworm selenium protein, 1-2 parts mushroom residue, 0.4-0.6 parts soybean oil, and 3-5 parts premixed feed for growing chickens; The advanced feed B contains the following components in parts by weight: 55-60 parts corn grits, 20-25 parts soybean meal, 8-10 parts limestone powder, 1-2 parts dicalcium phosphate, 0.5-0.7 parts silkworm selenium protein, 2-2.5 parts mushroom residue, 1-1.5 parts brewer's yeast residue, 0.4-0.6 parts soybean oil, and 3-5 parts premix for laying hens. In the advanced feed A, silkworm selenoprotein was added in a gradient of 0.2 parts per unit weight in the first week and 0.32 parts per unit weight in the second week. The corn grits have a particle size of 1.5~2.5mm; The stone powder has a particle size of 0.3~0.8mm; The particle size of the mushroom residue is 0.1~0.4mm; The selenium content of the brewer's yeast residue is 1.5~2 mg / kg; The selenium content of both the pullet-specific premix and the laying hen-specific premix is ​​0.14~0.16 mg / kg.

4. The method for preparing selenium-enriched silkworm eggs according to claim 1, characterized in that, In step (4), the temperature during the feeding and management of laying hens is 18~24℃, and the humidity is 55~65%; The lighting conditions during the brooding period are: 23 hours of light, 1 hour of darkness, and a light intensity of 20-30 Lux. The light conditions during the growth period are: 12 hours of light, 12 hours of darkness, and a light intensity of 20-30 Lux. The lighting conditions for the expected delivery date are: 14 hours of light, 10 hours of darkness, with a light intensity of 20-30 Lux. The lighting conditions during the egg-laying period are: 16 hours of light, 8 hours of darkness, and a light intensity of 20-30 Lux. In step (4), the feeding method during the brooding period is: feeding 6 to 7 times a day, with a daily feeding amount of 12 to 35g / bird; The feeding method during the rearing period is as follows: feed 3-4 times a day, and feed 65-80g / bird per day; The feeding method during the expected birthing period is as follows: feed 2-3 times a day, and feed 90-105g / bird per day; During the egg-laying period, the feeding method is as follows: feed 2-3 times a day, and feed 110-125g / bird per day.

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