Breeding method of commercial pigs

Abstract

The invention discloses a commercial pig breeding method, and belongs to the technical field of animal husbandry. The method comprises the following steps: hybridizing a landrace boar LL serving as a first-generation male parent and a large Yorkshire pig YY serving as a first-generation female parent to produce a binary hybrid sow LY; and producing by taking the binary hybrid sow LY as a second-generation female parent and a large Yorkshire boar YY as a terminal male parent to obtain a three-way hybrid commercial pig YLY. According to the obtained YLY three-way hybrid commercial pig, the advantages of the Changbai breed and the large Yorkshire breed are fully utilized, the reproductive performance advantages of two-way hybrid sows are reserved, the fattening effect and the growth speed of the commercial pig are effectively improved, higher economic benefits can be brought, and important application value and popularization prospects are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of animal husbandry, and in particular relates to a method for breeding commercial pigs. Background Art

[0002] In modern commercial pig production, hybridization technology is an important means to improve production efficiency and economic benefits. The traditional binary hybridization model usually uses two breeds of pigs for hybridization, such as Landrace boars and Yorkshire sows, to obtain offspring with higher growth rates and lean meat rates. However, this model has certain limitations. For example, the sows themselves do not have hybrid vigor, resulting in a low lean meat rate in commercial pigs. In order to overcome these shortcomings, three-way hybridization technology came into being. Three-way hybridization is further carried out on the basis of binary hybridization, that is, the sows obtained by binary hybridization are hybridized with a third breed of boars, so as to make full use of the hybrid vigor of the mother, and combine the excellent traits of the father to further improve the lean meat rate and growth performance of commercial pigs. This model can not only improve the production performance of commercial pigs, but also effectively solve the problem of insufficient number of original sows. At present, the most classic and widely used three-way hybrid model for producing commercial pigs in the world is the DLY three-way hybrid model. The DLY three-way hybrid model is a commercial meat pig obtained by mating three breeds of Duroc pigs (DD), Landrace pigs (LL) and Yorkshire pigs (YY) through a specific hybrid combination model. The specific hybrid model is to first hybridize the Landrace boar with the Yorkshire sow to obtain a two-way hybrid pig (LY), and then hybridize the two-way hybrid sow with the terminal sire Duroc boar to finally obtain the DLY three-way hybrid commercial pig. However, the offspring of DLY three-way hybrid commercial pigs are prone to produce spotted pigs, which affects the quality of commercial meat pigs, and the growth rate and offspring performance of Duroc breeding pigs are not as good as those of fast-growing Yorkshire pigs. The offspring of Duroc breeding pigs have low feed utilization, violent temperament, timidity, and are easy to hurt people. Summary of the invention

[0003] In view of the deficiencies in the prior art, the object of the present invention is to provide a method for breeding commercial pigs, so as to provide high-quality commercial pigs with faster growth rate and higher economic benefits.

[0004] The technical solution of the present invention to solve the above technical problems is as follows: a method for breeding commercial pigs is provided, comprising: The Landrace boar is used as the first generation sire and the Large Yorkshire pig is used as the first generation dam to produce a two-way hybrid sow; the two-way hybrid sow is used as the second generation dam and the Large Yorkshire boar is bred as the terminal sire to produce a three-way hybrid commercial pig and breed it to market; the breeding steps for the second generation dam are as follows: (1) Breeding: Breeding Landrace boars and Yorkshire sows; (2) Newborn selection: select sows with a total of ≥13 piglets and ≥7 pairs of teats; then select healthy piglets with a body weight >0.8 kg, normal reproductive organ development, good vitality, strong limbs, and normal walking; if there are deformities in the same litter, no breeding pigs will be selected from the litter; (3) Weaning selection: Select pigs with weaning weight ≥ 5 kg and no abnormalities at 21 days of age; (4) Nursery, rearing and selection: During the period of 22-150 days of age, pigs with abnormal health status, slow growth rate and spotted pigs are eliminated; (5) Breeder pig selection: During the period of 140-160 days of age, select pigs with a body weight ≥ 93 kg and in good health as breeding pigs.

[0005] Furthermore, in step (1), the ssGBLUP model is established to evaluate the breeding values ​​of the first-generation sire Landrace boars and the first-generation dam Yorkshire pigs, and then the comprehensive breeding value is calculated in combination with the phenotypic indicators, the phenotypic indicators being the corrected age per 100 kg, the corrected backfat thickness per 100 kg, the corrected eye muscle thickness per 100 kg, feed conversion efficiency, number of live piglets and number of teat pairs; the Landrace boars are selected from the top 20% of the comprehensive breeding values ​​in the test batch, and the Yorkshire sows are selected from the top 50% of the comprehensive breeding values ​​in the test batch; the ssGBLUP model is as follows:

[0006] Among them, y is the phenotypic value; Xβ is the fixed effect part; Zgug is the genome random effect part; Zfuf is the traditional family random effect part; e is the error term; The calculation formula of comprehensive breeding value is as follows:

[0007]

[0008]

[0009]

[0010] Among them, EBV is the estimated breeding value calculated by the ssGBLUP model; Age is the corrected age per 100 kg, BFT is the corrected back fat thickness per 100 kg, lean is the corrected eye muscle thickness per 100 kg, FCR is feed conversion efficiency, NV is the number of live pigs, NT is the number of teat pairs; W1 to W6 are -16%, -12%, 8%, -14%, 40% and 10% respectively; the comprehensive breeding value will be standardized to a mean of 100 and a standard deviation of 25; the A value is the original comprehensive index; the B value is the average of the A values ​​of historically measured pigs; the C value is the standard deviation of the A values ​​of historically measured pigs.

[0011] Furthermore, the Landrace boars ranked in the top 20% of the comprehensive breeding value and the Yorkshire sows ranked in the top 50% of the comprehensive breeding value were selected again, and the phenotypic control standards were: corrected age per 100 kg ≤ 144 d, corrected back fat thickness per 100 kg ≤ 10.8 mm, corrected eye muscle thickness per 100 kg ≥ 49 mm, feed conversion efficiency ≤ 2.3, live piglets ≥ 13, and number of nipple pairs ≥ 7 pairs.

[0012] Furthermore, step (1) is carried out by artificial insemination.

[0013] Further, the breeding steps of the terminal male parent are as follows: (1) Establish a basic herd: 600 sows with an annual renewal rate of not less than 80%; 60 boars with an annual renewal rate of not less than 100%; (2) Selection at birth: Select piglets with a total of ≥7 piglets and ≥6 pairs of teats; then select ≥3 piglets from each litter that weigh >0.8 kg, have normal reproductive organ development, good vitality, strong limbs, and can walk normally; if there are deformities in the same litter, no piglets will be selected for breeding; (3) Weaning selection: Select pigs with weaning weight ≥ 5 kg and no abnormalities at 21 days of age; (4) Nursery, rearing and selection: During the period of 22-150 days of age, pigs with abnormal health status, slow growth rate and spotted pigs are eliminated; (5) Selection of boars: Establish the ssGBLUP model to evaluate the breeding value of the selected batches, and then calculate the comprehensive breeding value based on the phenotypic indicators. The phenotypic indicators are corrected age per 100 kg, corrected back fat thickness per 100 kg, corrected eye muscle thickness per 100 kg, and feed conversion efficiency. Select the top 20% of the comprehensive breeding value as the terminal sire. The ssGBLUP model is as follows:

[0014] Among them, y is the phenotypic value; Xβ is the fixed effect part; Zgug is the genome random effect part; Zfuf is the traditional family random effect part; e is the error term; The calculation formula of comprehensive breeding value is as follows:

[0015]

[0016]

[0017]

[0018] Among them, EBV is the estimated breeding value calculated by the ssGBLUP model; Age is the corrected age per 100 kg, BFT is the corrected back fat thickness per 100 kg, lean is the corrected eye muscle thickness per 100 kg, and FCR is feed conversion efficiency; W1 to W4 are -14%, -16%, 10% and -60% respectively; the comprehensive breeding value will be standardized to a mean of 100 and a standard deviation of 25; the A value is the original comprehensive index; the B value is the average of the A values ​​of historically measured pigs; and the C value is the standard deviation of the A values ​​of historically measured pigs.

[0019] Furthermore, the terminal sire boars ranked in the top 20% of the comprehensive breeding value were selected again, and the phenotypic control standards were: corrected age per 100 kg ≤ 126 d, corrected back fat thickness per 100 kg ≤ 9 mm, corrected eye muscle thickness per 100 kg ≥ 54 mm, and feed conversion efficiency ≤ 2.

[0020] Furthermore, the feeding conditions for breeding three-way hybrid commercial pigs to market are as follows: (1) Feeding: Feed the piglets after weaning at 21 days of age; (2) Stocking density: 21-70 days old is the nursery stage, 70 days old to market is the fattening stage; the density in the nursery stage is 0.37 m 2 / head, the density in the fattening stage is ≥0.9 m 2 / head; (3) Temperature: The temperature is 28°C when the pigs are brought in during the nursery stage, and then it is lowered by 1°C every week. The temperature is 21°C when the pigs are transferred to the fattening stage at 70 days of age, and the temperature during the fattening stage is 18-22°C. (4) Drinking water: The water flow rate of the drinking spout for pigs in the nursery stage is 0.8 L / min, and the water flow rate of the drinking spout for pigs in the fattening stage is 1.2 L / min; (5) Lighting: During the nursery stage, the light intensity is 110 lux, and the light duration is 16 to 18 h. During the fattening stage, the light intensity is 110 lux, and the light duration is 10 to 12 h.

[0021] Furthermore, after weaning at 21 days of age, the feeding is divided into five stages. The first stage is from 21 to 35 days of age, and the piglets are fed with starter feed; the second stage is from 36 to 50 days of age, and the piglets are fed with compound feed; the third stage is from 51 to 76 days of age, and the piglets are fed with compound feed; the fourth stage is from 77 to 124 days of age, and the early growing pigs are fed with compound feed; the fifth stage is from 125 to market, and the pigs are fed with late growing pigs with compound feed.

[0022] The present invention has the following beneficial effects: 1. The YLY three-way hybrid commercial pig obtained by the present invention fully utilizes the advantages of the two breeds of Landrace and Great Yorkshire, retains the reproductive performance advantages of the two-way hybrid sow, and further improves the production performance of the offspring by reintroducing the terminal paternal fast-growing Great Yorkshire pig, while reducing the demand for boars of multiple breeds, reducing breeding costs and management difficulties.

[0023] 2. The YLY three-way hybrid commercial pigs bred by the present invention have achieved multi-level optimization of the production performance of commercial pigs, effectively improved the fattening effect and growth rate of commercial pigs, and increased the fattening rate of traditional three-way DLY commercial pigs by 16% during the growth period. At the same time, the feed utilization rate has also been improved. Therefore, the YLY three-way hybrid commercial pigs are more competitive in the market, can bring higher economic benefits, and have important application value and promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the breeding method of commercial pigs of the present invention. DETAILED DESCRIPTION

[0025] The suckling pig trough feed, suckling pig feed, piglet feed, growing pig early feed and growing pig late feed used in the embodiments of the present invention were purchased from Sichuan Dekang Agriculture and Animal Husbandry Food Group Co., Ltd. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially.

[0026] The principles and features of the present invention are described below in conjunction with embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0027] Embodiment 1: Figure 1 Schematic diagram of the commercial pig breeding method according to an embodiment of the present invention, as shown in Figure 1 As shown, this embodiment provides a method for breeding commercial pigs, and the specific steps are as follows: 1. Breeding of the second generation of LY sows (1) Breeding: Yorkshire pigs (YY) were used as the first-generation female parent, and Landrace boars (LL) were used as the first-generation male parent, both of which were from the core breeding farm. The ssGBLUP model breeding value was established, and the comprehensive breeding value was calculated in combination with phenotypic indicators. The sows ranked in the top 50% of the comprehensive breeding value in the test batch were selected, and the semen of the boars ranked in the top 20% of the comprehensive breeding value in the test batch was selected, and the selection was carried out again based on the phenotypic indicators. The lower limits of the relevant phenotypic data selection indicators are shown in Table 1. Artificial insemination was used to breed the sows in estrus. Composite breeding values ​​based on phenotypic data andThe genome sequencing data is calculated using ssGBLUP. The ssGBLUP model is as follows:

[0028] Among them, y is the phenotypic value; Xβ is the fixed effect part (such as environmental effect or treatment effect); Zgug is the genomic random effect part, indicating that the genetic effect of the individual is determined by the genotype (through the genomic data matrix Zg); Zfuf is the traditional family random effect part, indicating that the genetic effect of the individual comes from the family relationship (through the family data matrix Zf); e is the error term, which is usually a random error from the phenotypic measurement; The phenotypic indicators for calculating the comprehensive breeding value are shown in Table 1: Table 1 Key phenotypic indicators for selecting breeding pigs

[0029] The steps for calculating the comprehensive breeding value are as follows:

[0030]

[0031]

[0032]

[0033] Among them, EBVx is the estimated breeding value (ebv) calculated by the ssGBLUP model through the traits involved in the breeding pigs; Age is the corrected age per 100 kg; BFT is the corrected back fat thickness per 100 kg; lean is the corrected eye muscle thickness per 100 kg; FCR is feed conversion efficiency (feed-to-meat ratio); NV is the number of live pigs; NT is the number of teat pairs; W1 to W6 are the weights corresponding to the selection indicators -16%, -12%, 8%, -14%, 40% and 10% respectively, because the corrected age per 100 kg, the corrected back fat thickness per 100 kg and feed conversion efficiency are negative indicators, so the coefficient is negative; the comprehensive breeding value will be standardized to a mean of 100 and a standard deviation of 25; the A value is the original comprehensive index; the B value is the average of the A values ​​of historically measured pigs; the C value is the standard deviation of the A values ​​of historically measured pigs.

[0034] (2) Newborn selection (0-day-old): Select sows with a total of ≥13 piglets and ≥7 pairs of teats, and then select healthy piglets (weight >0.8 kg) with normal reproductive organ development, good vitality, strong limbs, and normal walking. If there are deformities in the same litter, no breeding pigs will be selected from the litter.

[0035] (3) Weaning selection (21 days of age): Select pigs with a weaning weight ≥ 5 kg; no abnormal health conditions such as obvious emaciation, poor mental state, etc.; no clinical symptoms of disease (diarrhea, hunched back, skin plaques, abnormal breathing, etc.); and no visual abnormalities (disability, intestinal leakage, hernia, limb injuries, and abscesses with a diameter greater than 3 cm).

[0036] (4) Nursery, rearing and selection (22-150 days of age): Eliminate seriously sick and weak breeding pigs with no breeding value, and those whose growth and development speed is seriously unable to keep up with the average level of the group (the weight is 60% lower than the average weight of the same batch of pigs); eliminate pigs with serious limb injuries, developmental abnormalities or limb and hoof damage, and those with serious tail biting or ear biting that make them worthless for breeding; eliminate spotted pigs and other pigs that are not suitable for breeding.

[0037] (5) Selection of reserve breeding pigs (around 150 days old): The selected reserve breeding pigs must be healthy and have an appropriate growth rate (weight not lower than the standard line of 93 kg at 150 days of age); their limbs and hooves must be normal and strong, without obvious limb and hoof diseases, arched back, and no clinical manifestations of disease; the size and shape of the sow's vulva should be normal and not upturned; there should be no breeding pigs with serious limb injuries or developmental abnormalities, severe tail biting, or ear biting that make them worth breeding; there should be no hermaphroditic pigs, spotted pigs, etc. that are not suitable for breeding.

[0038] 2. Terminal sire breeding (1) Establish a terminal sire Yorkshire (YY) basic group: 600 sows and 60 boars. The annual renewal rate of sows shall not be less than 80%, and the annual renewal rate of boars shall not be less than 100%.

[0039] (2) Selection of newborn piglets (0 days old): Select piglets with a total of ≥ 7 piglets and ≥ 6 pairs of teats; then select ≥ 3 healthy piglets (weight > 0.8 kg) from each litter with good vitality, strong limbs, and normal walking; select piglets with normal reproductive organ development, and those with deformities in the same litter will not be selected for breeding; genomic samples of all selected piglets are collected for genome sequencing.

[0040] (3) Weaning selection (21 days old): the same as the standard for “second generation LY sow breeding”; (4) Nursery, rearing and selection (22-135 days old): The same as the standard for "second-generation LY sow breeding"; at the same time, all selected pigs enter the breeding system at 70 days of age to measure feed-to-meat ratio and growth rate; weigh at 135 days of age, and use B-ultrasound to measure back fat thickness and eye muscle thickness.

[0041] (5) Selection of boars: Select Yorkshire boars in the top 20% of the comprehensive breeding value of this batch, and select them again based on phenotypic indicators. The lower limits of phenotypic indicators are shown in Table 2. At the same time, the boars are selected on site based on their appearance, such as back line, belly line, testicles, foreskin, secretions, limbs, etc., as the terminal sires. The calculation method of the comprehensive breeding value is the same as that of the comprehensive breeding value in step (1) of the second-generation maternal LY sow breeding. The difference lies in the different key phenotypic indicators. The reference phenotypic indicators of the terminal sires are shown in Table 2: Table 2 Phenotypic indicators for terminal male parent selection

[0042] The calculation steps of terminal sire comprehensive breeding value are as follows:

[0043]

[0044]

[0045]

[0046] Among them, EBVx is the estimated breeding value (ebv) calculated by the ssGBLUP model through the traits involved in the breeding pigs; Age is the corrected age per 100 kg; BFT is the corrected back fat thickness per 100 kg; lean is the corrected eye muscle thickness per 100 kg; FCR is feed conversion efficiency (feed-to-meat ratio); W1 to W4 are the weights corresponding to the selection indicators, -14%, -16%, 10% and -60% respectively, because the corrected age per 100 kg, the corrected back fat thickness per 100 kg and the feed conversion efficiency are negative indicators, so the coefficient is a negative value; the comprehensive breeding value will be standardized to a mean of 100 and a standard deviation of 25; the A value is the original comprehensive index; the B value is the average of the A values ​​of historically measured pigs; the C value is the standard deviation of the A values ​​of historically measured pigs.

[0047] 3. Target commercial pig breeding (1) Breeding: The above-mentioned LY sows are mated with Yorkshire terminal boars to obtain YLY three-way hybrid commercial pigs.

[0048] (2) Feeding ① Feeding: Weaning at 21 days old, after weaning, the pigs are divided into five feeding stages according to their age. The first stage is from 21 to 35 days old, feeding suckling pig trough compound feed; the second stage is from 36 to 50 days old, feeding suckling pig compound feed; the third stage is from 51 to 76 days old, feeding piglet compound feed; the fourth stage is from 77 to 124 days old, feeding early growing pig compound feed; the fifth stage is from 125 to market, feeding late growing pig compound feed, and feeding freely throughout the whole process; ② Stocking density: Use full slatted floor pens for stocking, and the density during the nursery stage (21-70 days old, maximum body weight about 30 kg) is 0.37 m 2 / head, and the density of the fattening stage is ≥0.9 m 2 / head; ③ Temperature: The temperature is 28℃ when the pigs are brought in during the nursery stage, and then it is lowered by 1℃ every week. The temperature is 21℃ when the pigs are transferred to the fattening stage at 70 days of age, and the temperature in the fattening stage is 18-22℃; ④ Drinking water: Drinking water should be clean, sufficient and convenient for pigs to eat. The water flow rate of the drinking spout should reach 0.8 L / min in the nursery stage and 1.2 L / min in the fattening stage; ⑤ Lighting: During the nursery stage, the light intensity is 110 lux, and the light duration is 16 to 18 h; during the fattening stage, the light intensity is 110 lux, and the light duration is 10 to 12 h.

[0049] The traditional DLY commercial pigs weighing 30-120 kg have a daily weight gain of 865 g and a feed-to-meat ratio of 2.6; the YLY three-way hybrid commercial pigs bred by this embodiment have white hair all over their bodies, a sturdy body, a daily weight gain of 1001 g at 30-120 kg, a feed-to-meat ratio of 2.4, and a significant growth rate; the growth rate and feed conversion rate of the long commercial pigs bred by the present invention are significantly better than those of DLY commercial pigs.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for breeding commercial pigs, characterized in that: The Landrace boar is used as the first generation sire and the Large Yorkshire pig is used as the first generation dam to produce a two-way hybrid sow; the two-way hybrid sow is used as the second generation dam and the Large Yorkshire boar is bred as the terminal sire to produce a three-way hybrid commercial pig and breed it to market; the breeding steps of the second generation dam are as follows: (1) Breeding: Breeding Landrace boars and Yorkshire sows; (2) Newborn selection: select sows with a total of ≥13 piglets and ≥7 pairs of teats; then select healthy piglets with a body weight >0.8 kg, normal reproductive organ development, good vitality, strong limbs, and normal walking; if there are deformities in the same litter, no breeding pigs will be selected from the litter; (3) Weaning selection: Select pigs with weaning weight ≥ 5 kg and no abnormalities at 21 days of age; (4) Nursery, rearing and selection: During the period of 22-150 days of age, pigs with abnormal health status, slow growth rate and spotted pigs are eliminated; (5) Breeder pig selection: During the period of 140-160 days of age, select pigs with a body weight ≥ 93 kg and in good health as breeding pigs.

2. The breeding method according to claim 1, characterized in that: In step (1), a ssGBLUP model is established to evaluate the breeding values ​​of the first-generation sire Landrace boars and the first-generation dam Yorkshire pigs, and then the comprehensive breeding value is calculated in combination with phenotypic indicators, wherein the phenotypic indicators are corrected age per 100 kg, corrected backfat thickness per 100 kg, corrected eye muscle thickness per 100 kg, feed conversion efficiency, number of live piglets and number of teat pairs; Landrace boars are selected from the top 20% of the comprehensive breeding values ​​in the test batch, and Yorkshire sows are selected from the top 50% of the comprehensive breeding values ​​in the test batch; the ssGBLUP model is as follows: Among them, y is the phenotypic value; Xβ is the fixed effect part; Zgug is the genome random effect part; Zfuf is the traditional family random effect part; e is the error term; The calculation formula of comprehensive breeding value is as follows: Among them, EBV is the estimated breeding value calculated by the ssGBLUP model; Age is the corrected age per 100 kg, BFT is the corrected back fat thickness per 100 kg, lean is the corrected eye muscle thickness per 100 kg, FCR is feed conversion efficiency, NV is the number of live pigs, NT is the number of teat pairs; W1 to W6 are -16%, -12%, 8%, -14%, 40% and 10% respectively; the comprehensive breeding value will be standardized to a mean of 100 and a standard deviation of 25; the A value is the original comprehensive index; the B value is the average of the A values ​​of historically measured pigs; the C value is the standard deviation of the A values ​​of historically measured pigs.

3. The breeding method according to claim 2, characterized in that: The Landrace boars ranked in the top 20% of the comprehensive breeding value and the Yorkshire sows ranked in the top 50% of the comprehensive breeding value were selected again, and the phenotypic control standards were: corrected age per 100 kg ≤ 144 d, corrected back fat thickness per 100 kg ≤ 10.8 mm, corrected eye muscle thickness per 100 kg ≥ 49 mm, feed conversion efficiency ≤ 2.3, live piglets ≥ 13, and number of nipple pairs ≥ 7 pairs.

4. The breeding method according to claim 1, characterized in that: Step (1) breeding is carried out by artificial insemination.

5. The breeding method according to claim 1, characterized in that: The breeding steps of the terminal male parent are as follows: (1) Establish a basic herd: 600 sows with an annual renewal rate of not less than 80%; 60 boars with an annual renewal rate of not less than 100%; (2) Selection at birth: Select piglets with a total of ≥7 piglets and ≥6 pairs of teats; then select ≥3 piglets from each litter that weigh >0.8kg, have normal reproductive organ development, good vitality, strong limbs, and can walk normally; if there are deformities in the same litter, no piglets will be selected for breeding; (3) Weaning selection: Select pigs with weaning weight ≥ 5 kg and no abnormalities at 21 days of age; (4) Nursery, rearing and selection: During the period of 22-150 days of age, pigs with abnormal health status, slow growth rate and spotted pigs are eliminated; (5) Selection of boars: Establish a ssGBLUP model to evaluate the breeding value of the selected batches, and then calculate the comprehensive breeding value based on phenotypic indicators. The phenotypic indicators are corrected age per 100 kg, corrected back fat thickness per 100 kg, corrected eye muscle thickness per 100 kg, and feed conversion efficiency. Select the top 20% of the comprehensive breeding value as the terminal sire. The ssGBLUP model is as follows: Among them, y is the phenotypic value; Xβ is the fixed effect part; Zgug is the genome random effect part; Zfuf is the traditional family random effect part; e is the error term; The calculation formula of comprehensive breeding value is as follows: Among them, EBV is the estimated breeding value calculated by the ssGBLUP model; Age is the corrected age per 100 kg, BFT is the corrected back fat thickness per 100 kg, lean is the corrected eye muscle thickness per 100 kg, and FCR is feed conversion efficiency; W1 to W4 are -14%, -16%, 10% and -60% respectively; the comprehensive breeding value will be standardized to a mean of 100 and a standard deviation of 25; the A value is the original comprehensive index; the B value is the average of the A values ​​of historically measured pigs; and the C value is the standard deviation of the A values ​​of historically measured pigs.

6. The breeding method according to claim 5, characterized in that: The terminal sire boars ranked in the top 20% of the comprehensive breeding value were selected again, and the phenotypic control standards were: corrected age per 100 kg ≤ 126 days, corrected back fat thickness per 100 kg ≤ 9 mm, corrected eye muscle thickness per 100 kg ≥ 54 mm, and feed conversion efficiency ≤ 2.

7. The breeding method according to claim 1, characterized in that: The feeding conditions for breeding the three-way hybrid commercial pigs until they are ready for slaughter are as follows: (1) Feeding: Feed the piglets after weaning at 21 days of age; (2) Stocking density: 21-70 days old is the nursery stage, 70 days old to market is the fattening stage; the density in the nursery stage is 0.37m 2 / head, the density in the fattening stage is ≥0.9 m 2 / head; (3) Temperature: The temperature is 28°C when the pigs are brought in during the nursery stage, and then it is lowered by 1°C every week. The temperature is 21°C when the pigs are transferred to the fattening stage at 70 days of age, and the temperature during the fattening stage is 18-22°C. (4) Drinking water: The water flow rate of the drinking spout for pigs in the nursery stage is 0.8 L / min, and the water flow rate of the drinking spout for pigs in the fattening stage is 1.2 L / min; (5) Lighting: During the nursery stage, the light intensity is 110 lux, and the light duration is 16 to 18 h. During the fattening stage, the light intensity is 110 lux, and the light duration is 10 to 12 h.

8. The breeding method according to claim 7, characterized in that: After weaning at 21 days of age, the feeding is divided into five stages. The first stage is from 21 to 35 days of age, and the piglets are fed with starter feed; the second stage is from 36 to 50 days of age, and the piglets are fed with compound feed; the third stage is from 51 to 76 days of age, and the piglets are fed with compound feed; the fourth stage is from 77 to 124 days of age, and the early growing pigs are fed with compound feed; the fifth stage is from 125 to market, and the pigs are fed with late growing pigs with compound feed.

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