Breeding method for improving intramuscular fat content of pigs

Abstract

The invention relates to the technical field of pig breeding, in particular to a breeding method for increasing the intramuscular fat content of pigs. Berkshire boars and Meishan pigs are subjected to cross breeding, and offspring is fed with compound feed, the compound feed is prepared from the following components in parts by weight: 6 to 8 parts of compound extract, 2 to 4 parts of sustained release microspheres, 40 to 50 parts of corn, 30 to 40 parts of soybean meal, 20 to 30 parts of bran, 5 to 8 parts of alfalfa meal, 2 to 3 parts of rhizoma phragmitis powder, 4 to 6 parts of fish meal, 0.1 to 0.3 part of amino acid, 0.03 to 0.05 part of vitamin, 0.03 to 0.05 part of ferrous fumarate, 2 to 4 parts of calcium carbonate, 0.01 to 0.02 part of L-ferrous lactate, 0.5 to 0.8 part of beta-carotene and 0.2 to 0.4 part of table salt, the breeding method provided by the invention can effectively improve the intramuscular fat content of pork.

Description

Technical Field

[0001] The invention relates to the technical field of pig breeding, and in particular to a breeding method for increasing the intramuscular fat content of pigs. Background Art

[0002] Pork has fine and soft fibers, less connective tissue, and contains more intramuscular fat. Intramuscular fat (IMF) refers to the fat extracted from pork by the Soxhlet drawer method. It comes from fat cells and muscle cells and is the fat tissue between pig muscle fibers. IMF is one of the key factors affecting meat quality. It also affects the tenderness, water retention, flavor and juiciness of meat. It is a very important indicator for evaluating pork. According to the reference [Lei Shenghui, Wu Haomin, Tu Kefeng, et al. Analysis of data on growth performance, carcass traits and meat quality traits of local breed pigs in Shanghai [J]. Today's Pig Industry, 2021, (05): 90-7.], in 2015, the Shanghai Breeding Pig Testing Center measured the average intramuscular fat content of Meishan pigs to be 3.63%. At present, according to needs, multiple strains have been bred by introducing breeding pigs, but the existing breeding technology often one-sidedly pursues growth performance and lean meat rate and ignores the important indicator of intramuscular fat content. Traditional methods of improving meat quality involve hybridization of Duroc pigs as the father and local pig breeds as the mother. Although the intramuscular fat content of the F1 hybrid generation is increased, the growth rate is slow and the feed conversion rate is poor. Summary of the invention

[0003] In view of the deficiencies of the prior art, the present invention proposes a breeding method for increasing the intramuscular fat content of pigs.

[0004] The present invention is achieved through the following technical solutions: A breeding method for increasing the intramuscular fat content of pigs comprises the following steps: S1: Select healthy Berkshire boars and healthy Meishan sows for breeding; S2: piglets were ear-marked and weighed within 12 hours after birth; S3: After weaning at 28 days old, piglets are moved to a nursery and fed with compound feed, with free access to food and water; S4: After feeding to 30 kg, the pigs are transferred to the fattening house and fed with compound feed, with free access to food and water until they reach 110-120 kg.

[0005] Furthermore, the compound feed comprises the following components in parts by weight: 6-8 parts of compound extract, 2-4 parts of sustained-release microspheres, 40-50 parts of corn, 30-40 parts of soybean meal, 20-30 parts of bran, 5-8 parts of alfalfa powder, 2-3 parts of reed root powder, 4-6 parts of fish meal, 0.1-0.3 parts of amino acids, 0.03-0.05 parts of vitamins, 0.03-0.05 parts of ferrous fumarate, 2-4 parts of calcium carbonate, 0.01-0.02 parts of L-ferrous lactate, 0.5-0.8 parts of β-carotene, and 0.2-0.4 parts of salt.

[0006] Furthermore, the amino acids are composed of lysine, tryptophan, methionine and threonine in a weight ratio of 3:3:2:1.

[0007] Furthermore, the vitamins are composed of vitamin E, vitamin B2, folic acid and niacin in a weight ratio of 4:2:2:3.

[0008] Furthermore, the preparation method of the composite extract comprises the following steps: A1: Inoculate the activated Bacillus subtilis into the seed culture medium at an inoculation rate of 3-5%, and culture at 37°C, 150-200r / min in a shaking incubator for 10-12 h to obtain the seed solution. Inoculate the seed solution into the fermentation medium at an inoculation rate of 8-10%, and culture at 37°C in a shaking incubator for 22-24 h; A2: After the cultivation in step A1 is completed, centrifuge at 8000 rpm for 20 min, collect the precipitate, heat and reflux with 60-75 vol% ethanol solution at 80-90℃ for 2 h, centrifuge at 5000 r / min for 15-20 min, take the supernatant and evaporate it at 80℃ to remove ethanol, add deionized water, centrifuge at 5000 r / min for 10-15 min, and freeze-dry the precipitate at -40℃ to obtain extract I; A3: Dunaliella salina, Isochrysis galbana, Thalassiosira wissensis and Steinernema coniformis in logarithmic growth phase were centrifuged at 5000 rpm for 15-20 min, the precipitates were freeze-dried at -40°C to obtain algae powder, the algae powders of different algae were mixed, 10 times the weight of isopropanol / ethyl acetate mixed solvent was added, heated and extracted at 90-100°C for 5-6 h, centrifuged at 10000 rpm and 4°C for 8-10 min, the supernatant was rotary evaporated at 70-80°C to remove the solvent, and freeze-dried at -40°C to obtain extract II; A4: Dry and grind Polygonatum odoratum, Radix Ophiopogonis, Citrus reticulatae, Radix Aucklandiae and Piper longum, sieve through 80-100 mesh, add 10 times the weight of water, heat at 100℃ for 2-3 h, cool to 80-90℃ and keep for 1-2 h, filter, and simmer the filtrate at 30℃, 10 -3MPa was concentrated under reduced pressure to 20% of the original volume, and then freeze-dried at -40°C to obtain extract III; extracts I, II, and III were mixed evenly to obtain a composite extract.

[0009] Furthermore, in step A1, the Bacillus subtilis is purchased from China General Microbiological Culture Collection Center with the strain number of CGMCC 1.14985.

[0010] Furthermore, in step A1, the seed culture medium is 0.3% beef extract, 1% peptone, 2% glucose, 0.5% NaCl, water is added to 100%, pH 5, sterilized at 112°C for 20 min, and cooled to room temperature.

[0011] Furthermore, in step A1, the fermentation medium is: peptone 10-12 g / L, yeast powder 8-10 g / L, corn flour 10-15 g / L, glucose 10-15 g / L, lactose 4-6 g / L, potassium dihydrogen phosphate 0.5-1 g / L, ammonium sulfate 0.2-0.6 g / L, calcium carbonate 2-4 g / L, the solvent is purified water, the pH value is adjusted to 7-7.5, high temperature sterilization at 112°C for 20 min, and cooled to room temperature.

[0012] Furthermore, in step A2, the ratio of the precipitate to the ethanol solution is 1 g:5 mL.

[0013] Furthermore, in step A2, the volume ratio of the deionized water to the ethanol solution is 5:1.

[0014] Furthermore, in step A3, the mass ratio of the algae powder of Dunaliella salina, Isochrysis galbana, Thalassiosira wissenschiff and Steinernema coniformis after freeze-drying is 2:1:1.5:1.2.

[0015] Furthermore, in step A3, the volume ratio of isopropanol to ethyl acetate in the isopropanol / ethyl acetate mixed solvent is 2:1.

[0016] Furthermore, in step A4, the mass ratio of polygonatum odoratum, ophiopogon japonicus, dried tangerine peel, costusroot and piper longiped is 2:3:1:1:0.8.

[0017] Furthermore, in step A4, the mass ratio of extract I, extract II and extract III is 1:2-2.5:1.5.

[0018] Furthermore, the raw materials for preparing the sustained-release microspheres include the following components in parts by weight: 10-15 parts of ethyl cellulose, 1.5-2.5 parts of glycyrrhizic acid, 2-3 parts of ammonium bicarbonate, 2-3 parts of magnesium chloride, and 4-6 parts of sodium alginate.

[0019] Furthermore, the method for preparing the sustained-release microspheres comprises the following steps: B1: Add ethyl cellulose and glycyrrhizic acid to dichloromethane and mix well. Stir at 200-300 rpm for 30-40 min. Add 0.1 g / mL ammonium bicarbonate aqueous solution and homogenize at 4000-5000 rpm for 3-5 min. Add dropwise to 2 wt% polyvinyl alcohol aqueous solution and stir at 400-500 rpm for 1-1.5 h. B2: After stirring in step B1, 10 -3 MPa, stirred at 60°C to volatilize the dichloromethane, centrifuged at 5000 rpm for 15-20 min, washed the precipitate with 2wt% acetic acid solution, anhydrous ethanol and distilled water, and dried in vacuum at 60-70°C to obtain modified microspheres; B3: The modified microspheres obtained in step B2 were mixed with 0.1 g / mL magnesium chloride solution, stirred at 40°C and 400-500 rpm for 1 h, centrifuged at 5000 rpm for 15-20 min, washed with deionized water, vacuum dried at 60-70°C, added to 0.02 g / mL sodium alginate aqueous solution, 0.1 mol / L calcium chloride solution was added dropwise, stirred at 200-300 rpm for 1-2 h, filtered, washed with deionized water, and vacuum dried at 40-50°C to obtain sustained-release microspheres.

[0020] Furthermore, in step B1, the mass concentration of the ethyl cellulose in dichloromethane is 20 mg / mL.

[0021] Furthermore, in step B3, the volume ratio of the calcium chloride solution to the sodium alginate aqueous solution is 1:5.

[0022] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a breeding method for increasing the intramuscular fat content of pigs, using Berkshire boars as the father and Meishan pigs as the mother, and the hybridized Bamei pig offspring has a higher intramuscular fat content, which is better than Berkshire and Meishan pigs, and the growth performance is improved. The present invention uses microorganisms, algae and Chinese medicine extracts to cooperate with each other and add them to feed, which can synergistically increase the intramuscular fat content of Bamei pigs and effectively improve the meat quality. The composite extract contains multiple nutrients and is easy to be absorbed and utilized. The present invention prepares sustained-release microspheres, which have a sustained-release effect, can release organic acids and magnesium ions, are beneficial to the health of the digestive tract, and can effectively resist bacteria. Glycyrrhizic acid is cross-linked with ethyl cellulose through hydrogen bonds and loaded on ethyl cellulose. The modified microspheres are prepared by the emulsified solvent volatilization method. The microspheres have a microporous structure and are loaded with carboxyl-containing compounds, which can coordinate with metal ions and load metal ions. The porous structure of the microspheres and the carboxyl groups of the organic acid work together to efficiently and stably load metal ions. Then, sodium alginate is used to wrap the outer layer to enhance the antibacterial effect, reduce the diarrhea rate, enhance the dispersibility of the microspheres, and enhance the sustained-release effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a scanning electron microscope image of the sustained-release microspheres described in Example 1 of the present invention; Figure 2 The meat quality test of the Bamei pig of the present invention; Figure 3 The average daily weight gain of the Bamei pigs described in Example 1 and Comparative Examples 1-4 of the present invention; Figure 4 It is the diarrhea incidence rate of the Bamei pigs described in Example 1 of the present invention and Comparative Examples 1-4. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. It should be noted that, unless otherwise specified, the chemical reagents involved in the present invention are purchased through commercial channels.

[0026] Embodiment 1: A breeding method for increasing the intramuscular fat content of pigs, comprising the following steps: S1: Select 9 healthy Berkshire boars and 6 healthy Meishan sows for breeding; S2: piglets were ear-marked and weighed within 12 hours after birth; S3: After weaning at 28 days old, piglets are moved to a nursery and fed with compound feed, with free access to food and water; S4: After feeding to 30 kg, the pigs are transferred to the fattening house and fed with compound feed, with free access to food and water until they reach 120 kg.

[0027] The compound feed includes the following components in parts by weight: 8 parts of compound extract, 4 parts of sustained-release microspheres, 50 parts of corn, 40 parts of soybean meal, 30 parts of bran, 8 parts of alfalfa powder, 3 parts of reed root powder, 6 parts of fish meal, 0.3 parts of amino acids, 0.05 parts of vitamins, 0.05 parts of ferrous fumarate, 4 parts of calcium carbonate, 0.02 parts of L-ferrous lactate, 0.8 parts of beta-carotene and 0.4 parts of salt.

[0028] The amino acids are composed of lysine, tryptophan, methionine and threonine in a weight ratio of 3:3:2:1; the vitamins are composed of vitamin E, vitamin B2, folic acid and niacin in a weight ratio of 4:2:2:3.

[0029] The preparation method of the composite extract comprises the following steps: A1: Inoculate the activated Bacillus subtilis into the seed culture medium with an inoculation amount of 5%, and culture it in a shaking incubator at 37℃ and 200 r / min for 12 h to obtain the seed solution. Inoculate the seed solution into the fermentation medium with an inoculation amount of 10%, and culture it in a shaking incubator at 37℃ for 24 h. The seed culture medium is 0.3% beef extract, 1% peptone, 2% glucose, and 0.5% NaCl. Add water to 100%, pH 5, sterilize it at 112℃ for 20 min, and cool it to room temperature. The fermentation medium is: 12 g / L peptone, 10 g / L yeast powder, 15 g / L corn flour, 15 g / L glucose, 6 g / L lactose, 1 g / L potassium dihydrogen phosphate, 0.6 g / L ammonium sulfate, and 4 g / L calcium carbonate. The solvent is purified water. Adjust the pH value to 7.5, sterilize it at 112℃ for 20 min, and cool it to room temperature. A2: After the cultivation in step A1 is completed, centrifuge at 8000 rpm for 20 min, collect the precipitate, and extract it with 75 vol% ethanol solution by heating and refluxing at 90℃ for 2 h. The ratio of precipitate to ethanol solution is 1 g:5 mL. Centrifuge at 5000 r / min for 20 min. Take the supernatant and evaporate it at 80℃ to remove ethanol. Add deionized water. The volume ratio of deionized water to ethanol solution is 5:1. Centrifuge at 5000 r / min for 15 min. The precipitate is freeze-dried at -40℃ to obtain extract I. A3: Dunaliella salina, Isochrysis galbana, Thalassiosira wissenii and Steinernema coniformis in logarithmic growth phase were centrifuged at 5000 rpm for 20 min, the precipitates were freeze-dried at -40°C to obtain algae powder, the algae powders of different algae were mixed, the mass ratio of Dunaliella salina, Isochrysis galbana, Thalassiosira wissenii and Steinernema coniformis after freeze-drying was 2:1:1.5:1.2, 10 times the weight of isopropanol / ethyl acetate (v / v=2:1) ​​mixed solvent was added, heated and extracted at 100°C for 6 h, centrifuged at 10000 rpm and 4°C for 10 min, the supernatant was rotary evaporated at 80°C to remove the solvent, and freeze-dried at -40°C to obtain extract II; A4: Dry and grind Polygonatum odoratum, Radix Ophiopogonis, Pericarpium Citri Reticulatae, Radix Aucklandiae and Radix Piperis Piper at a mass ratio of 2:3:1:1:0.8, pass through a 100-mesh sieve, add 10 times the weight of water, heat at 100℃ for 3 h, cool to 90℃ and maintain for 2 h, filter, and condense the filtrate at 30℃, 10 -3 MPa was concentrated under reduced pressure to 20% of the original volume, and then freeze-dried at -40°C to obtain extract III; extracts I, II, and III were mixed uniformly at a mass ratio of 1:2.5:1.5 to obtain a composite extract.

[0030] The raw materials for preparing the sustained-release microspheres include the following components in parts by weight: 15 parts of ethyl cellulose, 2.5 parts of glycyrrhizic acid, 3 parts of ammonium bicarbonate, 3 parts of magnesium chloride, and 6 parts of sodium alginate.

[0031] The method for preparing sustained-release microspheres comprises the following steps: B1: Add ethyl cellulose and glycyrrhizic acid to dichloromethane and mix well. The mass concentration of ethyl cellulose in dichloromethane is 20 mg / mL. Stir at 300 rpm for 40 min. Add 0.1 g / mL ammonium bicarbonate aqueous solution and homogenize at 5000 rpm for 5 min. Add dropwise to 2 wt% polyvinyl alcohol aqueous solution and stir at 500 rpm for 1.5 h. B2: After stirring in step B1, 10 -3 MPa, stirred at 60°C to volatilize the dichloromethane, centrifuged at 5000 rpm for 20 min, washed the precipitate with 2 wt% acetic acid solution, anhydrous ethanol and distilled water, and dried under vacuum at 70°C to obtain modified microspheres; B3: The modified microspheres obtained in step B2 were mixed with 0.1 g / mL magnesium chloride solution, stirred at 40°C and 500 rpm for 1 h, centrifuged at 5000 rpm for 20 min, washed with deionized water to obtain the precipitate, dried under vacuum at 70°C, added into 0.02 g / mL sodium alginate aqueous solution, and 0.1 mol / L calcium chloride solution was added dropwise, the volume ratio of calcium chloride solution to sodium alginate aqueous solution was 1:5, stirred at 300 rpm for 2 h, filtered, washed with deionized water, and dried under vacuum at 50°C to obtain sustained-release microspheres.

[0032] Embodiment 2: A breeding method for increasing the intramuscular fat content of pigs, comprising the following steps: S1: Select 9 healthy Berkshire boars and 6 healthy Meishan sows for breeding; S2: piglets were ear-marked and weighed within 12 hours after birth; S3: After weaning at 28 days old, piglets are moved to a nursery and fed with compound feed, with free access to food and water; S4: After feeding to 30 kg, the pigs are transferred to the fattening house and fed with compound feed, with free access to food and water until they reach 110 kg.

[0033] The compound feed includes the following components in parts by weight: 6 parts of compound extract, 2 parts of sustained-release microspheres, 40 parts of corn, 30 parts of soybean meal, 20 parts of bran, 5 parts of alfalfa powder, 2 parts of reed root powder, 4 parts of fish meal, 0.1 parts of amino acids, 0.03 parts of vitamins, 0.03 parts of ferrous fumarate, 2 parts of calcium carbonate, 0.01 parts of L-ferrous lactate, 0.5 parts of beta-carotene and 0.2 parts of salt.

[0034] The amino acids are composed of lysine, tryptophan, methionine and threonine in a weight ratio of 3:3:2:1; the vitamins are composed of vitamin E, vitamin B2, folic acid and niacin in a weight ratio of 4:2:2:3.

[0035] The preparation method of the composite extract comprises the following steps: A1: Inoculate the activated Bacillus subtilis into the seed culture medium with an inoculation amount of 3%, and culture it in a shaking incubator at 37℃ and 150 r / min for 10 h to obtain the seed solution. Inoculate the seed solution into the fermentation medium with an inoculation amount of 8%, and culture it in a shaking incubator at 37℃ for 22 h. The seed culture medium is 0.3% beef extract, 1% peptone, 2% glucose, and 0.5% NaCl. Add water to 100%, pH 5, sterilize it at 112℃ for 20 min, and cool it to room temperature. The fermentation medium is: 10 g / L peptone, 8 g / L yeast powder, 10 g / L corn flour, 10 g / L glucose, 4 g / L lactose, 0.5 g / L potassium dihydrogen phosphate, 0.2 g / L ammonium sulfate, and 2 g / L calcium carbonate. The solvent is purified water. Adjust the pH value to 7, sterilize it at 112℃ for 20 min, and cool it to room temperature. A2: After the cultivation in step A1 is completed, centrifuge at 8000 rpm for 20 min, collect the precipitate, and extract it with 60 vol% ethanol solution by heating and refluxing at 80℃ for 2 h. The ratio of precipitate to ethanol solution is 1 g:5 mL. Centrifuge at 5000 r / min for 15 min. Take the supernatant and evaporate it at 80℃ to remove ethanol. Add deionized water. The volume ratio of deionized water to ethanol solution is 5:1. Centrifuge at 5000 r / min for 10 min. Freeze-dry the precipitate at -40℃ to obtain extract I. A3: Dunaliella salina, Isochrysis galbana, Thalassiosira wissenii and Steinernema coniformis in logarithmic growth phase were centrifuged at 5000 rpm for 15 min, the precipitates were freeze-dried at -40°C to obtain algae powder, the algae powders of different algae were mixed, the mass ratio of Dunaliella salina, Isochrysis galbana, Thalassiosira wissenii and Steinernema coniformis after freeze-drying was 2:1:1.5:1.2, 10 times the weight of isopropanol / ethyl acetate (v / v=2:1) ​​mixed solvent was added, the mixture was heated and extracted at 90°C for 5 h, centrifuged at 10000 rpm and 4°C for 8 min, the supernatant was rotary evaporated at 70°C to remove the solvent, and freeze-dried at -40°C to obtain extract II; A4: Dry and grind Polygonatum odoratum, Radix Ophiopogonis, Pericarpium Citri Reticulatae, Radix Aucklandiae and Radix Piperis Piper at a mass ratio of 2:3:1:1:0.8, pass through an 80-mesh sieve, add 10 times the weight of water, heat at 100℃ for 2 h, cool to 80℃ and hold for 1 h, filter, and condense the filtrate at 30℃, 10 -3 MPa was concentrated under reduced pressure to 20% of the original volume, and then freeze-dried at -40°C to obtain extract III; extracts I, II, and III were mixed uniformly in a mass ratio of 1:2:1.5 to obtain a composite extract.

[0036] The raw materials for preparing the sustained-release microspheres include the following components in parts by weight: 10 parts of ethyl cellulose, 1.5 parts of glycyrrhizic acid, 2 parts of ammonium bicarbonate, 2 parts of magnesium chloride, and 4 parts of sodium alginate.

[0037] The method for preparing sustained-release microspheres comprises the following steps: B1: Add ethyl cellulose and glycyrrhizic acid into dichloromethane and mix well. The mass concentration of ethyl cellulose in dichloromethane is 20 mg / mL. Stir at 200 rpm for 30 min. Add 0.1 g / mL ammonium bicarbonate aqueous solution and homogenize at 4000 rpm for 3 min. Add dropwise into 2 wt% polyvinyl alcohol aqueous solution and stir at 400 rpm for 1 h. B2: After stirring in step B1, 10 -3 MPa, stirred at 60°C to volatilize the dichloromethane, centrifuged at 5000 rpm for 15 min, washed the precipitate with 2 wt% acetic acid solution, anhydrous ethanol and distilled water, and dried under vacuum at 60°C to obtain modified microspheres; B3: The modified microspheres obtained in step B2 were mixed with 0.1 g / mL magnesium chloride solution, stirred at 40°C and 400 rpm for 1 h, centrifuged at 5000 rpm for 15 min, washed with deionized water to obtain the precipitate, dried under vacuum at 60°C, added into 0.02 g / mL sodium alginate aqueous solution, and 0.1 mol / L calcium chloride solution was added dropwise, the volume ratio of calcium chloride solution to sodium alginate aqueous solution was 1:5, stirred at 200 rpm for 1 h, filtered, the filter cake was washed with deionized water, and dried under vacuum at 40°C to obtain sustained-release microspheres.

[0038] Embodiment 3: A breeding method for increasing the intramuscular fat content of pigs, comprising the following steps: S1: Select 9 healthy Berkshire boars and 6 healthy Meishan sows for breeding; S2: piglets were ear-marked and weighed within 12 hours after birth; S3: After weaning at 28 days old, piglets are moved to a nursery and fed with compound feed, with free access to food and water; S4: After reaching 30 kg, the pigs are transferred to the fattening house and fed with compound feed, with free access to food and water until they reach 115 kg.

[0039] The compound feed includes the following components in parts by weight: 7 parts of compound extract, 3 parts of sustained-release microspheres, 45 parts of corn, 35 parts of soybean meal, 25 parts of bran, 6 parts of alfalfa powder, 2.5 parts of reed root powder, 5 parts of fish meal, 0.2 parts of amino acids, 0.04 parts of vitamins, 0.04 parts of ferrous fumarate, 3 parts of calcium carbonate, 0.015 parts of L-ferrous lactate, 0.6 parts of beta-carotene and 0.3 parts of salt.

[0040] The amino acids are composed of lysine, tryptophan, methionine and threonine in a weight ratio of 3:3:2:1; the vitamins are composed of vitamin E, vitamin B2, folic acid and niacin in a weight ratio of 4:2:2:3.

[0041] The preparation method of the composite extract comprises the following steps: A1: Inoculate the activated Bacillus subtilis into the seed culture medium with an inoculation amount of 4%, and culture it in a shaking incubator at 37℃ and 180 r / min for 11 h to obtain the seed solution. Inoculate the seed solution into the fermentation medium with an inoculation amount of 9%, and culture it in a shaking incubator at 37℃ for 23 h. The seed culture medium is 0.3% beef extract, 1% peptone, 2% glucose, and 0.5% NaCl. Add water to 100%, pH 5, sterilize it at 112℃ for 20 min, and cool it to room temperature. The fermentation medium is: 11 g / L peptone, 9 g / L yeast powder, 12 g / L corn flour, 12 g / L glucose, 5 g / L lactose, 0.8 g / L potassium dihydrogen phosphate, 0.4 g / L ammonium sulfate, and 3 g / L calcium carbonate. The solvent is purified water. Adjust the pH value to 7.2, sterilize it at 112℃ for 20 min, and cool it to room temperature. A2: After the cultivation in step A1 is completed, centrifuge at 8000 rpm for 20 min, collect the precipitate, and extract it with 70 vol% ethanol solution by heating and refluxing at 85℃ for 2 h. The ratio of precipitate to ethanol solution is 1 g:5 mL. Centrifuge at 5000 r / min for 18 min. Take the supernatant and evaporate it at 80℃ to remove ethanol. Add deionized water. The volume ratio of deionized water to ethanol solution is 5:1. Centrifuge at 5000 r / min for 12 min. Freeze-dry the precipitate at -40℃ to obtain extract I. A3: Dunaliella salina, Isochrysis galbana, Thalassiosira wissenii and Steinernema coniformis in logarithmic growth phase were centrifuged at 5000 rpm for 18 min, the precipitates were freeze-dried at -40°C to obtain algae powder, the algae powders of different algae were mixed, the mass ratio of Dunaliella salina, Isochrysis galbana, Thalassiosira wissenii and Steinernema coniformis after freeze-drying was 2:1:1.5:1.2, 10 times the weight of isopropanol / ethyl acetate (v / v=2:1) ​​mixed solvent was added, heated and extracted at 95°C for 5.5 h, centrifuged at 10000 rpm and 4°C for 9 min, the supernatant was rotary evaporated at 75°C to remove the solvent, and freeze-dried at -40°C to obtain extract II; A4: Dry and grind Polygonatum odoratum, Radix Ophiopogonis, Pericarpium Citri Reticulatae, Radix Aucklandiae and Radix Piperis Piper at a mass ratio of 2:3:1:1:0.8, pass through a 90-mesh sieve, add 10 times the weight of water, heat at 100℃ for 2.5 h, cool to 85℃ and maintain for 1.5 h, filter, and condense the filtrate at 30℃, 10 -3 MPa was concentrated under reduced pressure to 20% of the original volume, and then freeze-dried at -40°C to obtain extract III; extracts I, II, and III were mixed uniformly in a mass ratio of 1:2.2:1.5 to obtain a composite extract.

[0042] The raw materials for preparing the sustained-release microspheres include the following components in parts by weight: 12 parts of ethyl cellulose, 2 parts of glycyrrhizic acid, 2.5 parts of ammonium bicarbonate, 2.5 parts of magnesium chloride, and 5 parts of sodium alginate.

[0043] The method for preparing sustained-release microspheres comprises the following steps: B1: Add ethyl cellulose and glycyrrhizic acid to dichloromethane and mix well. The mass concentration of ethyl cellulose in dichloromethane is 20 mg / mL. Stir at 250 rpm for 35 min. Add 0.1 g / mL ammonium bicarbonate aqueous solution and homogenize at 4500 rpm for 4 min. Add dropwise to 2 wt% polyvinyl alcohol aqueous solution and stir at 450 rpm for 1.2 h. B2: After stirring in step B1, 10 -3 MPa, stirred at 60°C to volatilize the dichloromethane, centrifuged at 5000 rpm for 18 min, washed the precipitate with 2 wt% acetic acid solution, anhydrous ethanol and distilled water, and dried under vacuum at 65°C to obtain modified microspheres; B3: The modified microspheres obtained in step B2 were mixed with 0.1 g / mL magnesium chloride solution, stirred at 40°C and 450 rpm for 1 h, centrifuged at 5000 rpm for 18 min, washed with deionized water, dried in vacuum at 65°C, added into 0.02 g / mL sodium alginate aqueous solution, and 0.1 mol / L calcium chloride solution was added dropwise, the volume ratio of calcium chloride solution to sodium alginate aqueous solution was 1:5, stirred at 250 rpm for 1.5 h, filtered, washed with deionized water, and dried in vacuum at 45°C to obtain sustained-release microspheres.

[0044] The only difference between Comparative Example 1 and Example 1 is that Extract I is not added.

[0045] The only difference between Comparative Example 2 and Example 1 is that no extract II is added.

[0046] The only difference between Comparative Example 3 and Example 1 is that no extract III is added.

[0047] The only difference between Comparative Example 4 and Example 1 is that glycyrrhizic acid is not added.

[0048] Experimental Example 1: The sustained-release microspheres prepared in Example 1 were dispersed in deionized water, observed and photographed using a scanning electron microscope. The results are as follows: Figure 1 As shown, the sustained-release microspheres are uniformly spherical, with a relatively smooth surface, good dispersibility, and are not easy to agglomerate.

[0049] Experimental Example 2: Berkshire, Meishan and Berkshire×Meishan hybrid piglets were raised according to the method of Example 1, and slaughtered after fattening. The longissimus dorsi muscle was taken after slaughter to test the intramuscular fat content and shear force of the pork. The results are as follows: Figure 2 shown.

[0050] Figure 2 The results showed that the intramuscular fat content of Bamei pigs was significantly higher than that of Berkshire and Meishan pigs, and the shear force was significantly lower than that of Berkshire and Meishan pigs, indicating that the hybrid combination of Berkshire as the father and Meishan pig as the mother can significantly increase the intramuscular fat content and increase the tenderness of pork.

[0051] Experimental Example 3: After fattening, the animals of Examples 1-3 and Comparative Examples 1-4 were slaughtered and fasted for 24 hours before slaughter. After slaughter, the longissimus dorsi muscle was taken out and the meat quality performance was tested. The results are shown in Table 1.

[0052] Table 1:

[0053] The results in Table 1 show that the intramuscular fat content and marbling score of Examples 1-3 are higher than those of Comparative Examples 1-4, indicating that the breeding method of the present invention can effectively increase the intramuscular fat content of pigs and improve meat quality.

[0054] Experimental Example 4: In the first 50 days of feeding of Example 1 and Comparative Examples 1-4, the incidence of diarrhea was determined, and the average daily weight gain (fasting weight) from 30 kg to 90 kg was calculated. The results are as follows Figure 3 and Figure 4 shown.

[0055] Figure 3 and Figure 4 The results showed that the average daily weight gain of the Example 1 group was higher than that of the Comparative Examples 1-4, and the incidence of diarrhea was lower than that of the Comparative Examples 1-4, indicating that the compound feed of the present invention can promote the growth of piglets and reduce the incidence of diarrhea in piglets, and the breeding method of the present invention has a good effect.

[0056] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A breeding method for increasing the intramuscular fat content of pigs, characterized in that: The following steps are involved: S1: Select healthy Berkshire boars and healthy Meishan sows for breeding; S2: piglets were ear-marked and weighed within 12 hours after birth; S3: After weaning at 28 days old, piglets are moved to a nursery and fed with compound feed, with free access to food and water; S4: After reaching 30 kg, the animals are transferred to the fattening house and fed with compound feed, with free access to food and water until they reach 110-120 kg. The compound feed comprises the following components in parts by weight: 6-8 parts of compound extract, 2-4 parts of slow-release microspheres, 40-50 parts of corn, 30-40 parts of soybean meal, 20-30 parts of bran, 5-8 parts of alfalfa powder, 2-3 parts of reed root powder, 4-6 parts of fish meal, 0.1-0.3 parts of amino acids, 0.03-0.05 parts of vitamins, 0.03-0.05 parts of ferrous fumarate, 2-4 parts of calcium carbonate, 0.01-0.02 parts of L-ferrous lactate, 0.5-0.8 parts of beta-carotene, and 0.2-0.4 parts of salt; The amino acids are composed of lysine, tryptophan, methionine and threonine in a weight ratio of 3:3:2:1; the vitamins are composed of vitamin E, vitamin B2, folic acid and niacin in a weight ratio of 4:2:2:3; The preparation method of the composite extract comprises the following steps: A1: Inoculate activated Bacillus subtilis into a seed culture medium, culture on a shaking table to obtain a seed solution, inoculate the seed solution into a fermentation medium, and culture on a shaking table; A2: After the cultivation in step A1 is completed, centrifuge, collect the precipitate, extract with ethanol solution by heating and refluxing, centrifuge, take the supernatant and evaporate to remove ethanol, add deionized water, centrifuge, freeze-dry the precipitate, and obtain extract I; A3: Dunaliella salina, Isochrysis galbana, Thalassiosira wissenii and Steinernema coniformis in the logarithmic growth phase are centrifuged separately, the precipitates are freeze-dried to obtain algae powder, the algae powders of different algae are mixed, 10 times the weight of a mixed solvent of isopropanol / ethyl acetate is added, heated for extraction, centrifuged, the supernatant is rotary evaporated to remove the solvent, and freeze-dried to obtain extract II; A4: Dry and grind Polygonatum odoratum, Radix Ophiopogonis, Pericarpium Citri Reticulatae, Radix Aucklandiae and Rhizoma Piperis, add 10 times the weight of water, heat to 100°C, cool to 80-90°C, filter, concentrate the filtrate under reduced pressure, and freeze-dry to obtain Extract III; mix Extracts I, II and III uniformly to obtain a composite extract; The raw materials for preparing the sustained-release microspheres include the following components in parts by weight: 10-15 parts of ethyl cellulose, 1.5-2.5 parts of glycyrrhizic acid, 2-3 parts of ammonium bicarbonate, 2-3 parts of magnesium chloride, and 4-6 parts of sodium alginate; The method for preparing the sustained-release microspheres comprises the following steps: B1: Add ethyl cellulose and glycyrrhizic acid to dichloromethane, mix well, stir, add 0.1 g / mL ammonium bicarbonate aqueous solution, homogenize, add dropwise to 2 wt % polyvinyl alcohol aqueous solution, stir; B2: After stirring in step B1, 10 -3 MPa, stirred at 60°C to volatilize the dichloromethane, centrifuged, washed the precipitate with 2wt% acetic acid solution, anhydrous ethanol and distilled water, and vacuum dried to obtain modified microspheres; B3: The modified microspheres obtained in step B2 were mixed with 0.1 g / mL magnesium chloride solution, stirred, centrifuged, the precipitate was washed with deionized water, vacuum dried, added to sodium alginate aqueous solution, calcium chloride solution was added dropwise, stirred, filtered, the filter cake was washed with deionized water, and vacuum dried to obtain sustained-release microspheres.

2. The breeding method for increasing pig intramuscular fat content according to claim 1, characterized in that: In step A2, the ratio of the precipitate to the ethanol solution is 1 g:5 mL; the volume ratio of deionized water to the ethanol solution is 5:

1.

3. The breeding method for increasing pig intramuscular fat content according to claim 2, characterized in that: In step A3, the mass ratio of the freeze-dried algae powders of Dunaliella salina, Isochrysis galbana, Thalassiosira wissenschiff and Steinernema coniformis is 2:1:1.5:1.2; and the volume ratio of isopropanol to ethyl acetate in the isopropanol / ethyl acetate mixed solvent is 2:

1.

4. The breeding method for increasing pig intramuscular fat content according to claim 3, characterized in that: In step A4, the mass ratio of polygonatum odoratum, ophiopogon japonicus, tangerine peel, costusroot and piper longiped is 2:3:1:1:0.8; the mass ratio of extract I, extract II and extract III is 1:2-2.5:1.

5.

5. The breeding method for increasing pig intramuscular fat content according to claim 4, characterized in that: In step B1, the mass concentration of the ethyl cellulose in dichloromethane is 20 mg / mL.

6. The breeding method for increasing pig intramuscular fat content according to claim 5, characterized in that: In step B3, the volume ratio of the calcium chloride solution to the sodium alginate aqueous solution is 1:5.

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