A SNP molecular marker associated with rapid growth trait in pigs and its application

Abstract

This invention discloses a SNP molecular marker associated with the rapid growth trait in pigs and its application, relating to the field of molecular marker technology. The SNP molecular marker is located at position 55754471 bp on chromosome 17 of the international pig reference genome Sscrofa version 10.2. The nucleotide sequence of this position is C or T, denoted as C>T, and is located at... SULF2 Within the gene, T represents a superior allele associated with rapid growth. The SNP locus provided in this invention is used for breeding fast-growing pig breeds. By combining primers and kits designed for the SNP molecular marker with methods for selecting or assisting in the selection of fast-growing pigs based on this marker, it is possible to effectively and accurately screen pigs with excellent growth performance. This invention enables precise prediction and efficient screening of fast-growing individuals in Large White pigs, significantly improving the efficiency of breeding superior pigs and accelerating the process of herd improvement.

Description

Technical Field

[0001] This invention relates to the fields of molecular biotechnology and molecular marker technology, and in particular to a SNP molecular marker associated with the rapid growth trait in pigs and its application. Background Technology

[0002] The Large White pig is a highly valuable meat pig breed in the global large-scale pig farming industry. Its rapid growth trait, especially its outstanding performance in reaching 100kg weight at the age of 100kg, is a key characteristic driving improved farming efficiency. This breed has a short age of 100kg weight and a stable growth rate. Under standard fattening conditions, excellent individuals can reach 100kg weight in less than 140 days, with an average of 150-160 days. It also boasts a high feed conversion ratio, achieving rapid weight gain with lower feed inputs, effectively reducing time and resource consumption throughout the farming cycle. Furthermore, the Large White pig is adaptable to different farming models. Whether in intensive stall farming or standardized free-range farming, its growth performance in reaching 100kg weight at the age of 100kg remains stable. When used as superior parent stock in crossbreeding, it can significantly enhance the rapid growth trait of offspring, further shortening the age of 100kg weight in hybrid offspring while maintaining good carcass quality. It is a core breed for ensuring efficient pork supply and optimizing the pig farming industry chain.

[0003] The age at which pigs reach 100 kg body weight is a core indicator for evaluating the growth traits of Large White pigs, directly determining the length of the fattening cycle and the turnover rate, thus having a decisive impact on the economic benefits of pig farming. A shorter age at 100 kg body weight can accelerate the frequency of pig slaughter, improve the utilization efficiency of farm facilities and equipment, reduce the risks during the disease control period, and reduce the cost of feed, labor, and other feed per unit body weight. Molecular marker-assisted breeding technology can precisely locate genes or genetic loci related to the age at 100 kg body weight, quickly screen out superior genotype individuals with a shorter age at 100 kg body weight, avoid the lag of phenotypic selection in traditional breeding, significantly shorten the breeding cycle, reduce breeding costs, and thus improve the overall growth performance of the herd. Therefore, it is of great significance to carry out molecular marker-assisted breeding with the age of 100kg body weight as the core. By identifying individuals with rapid growth genetic characteristics in advance, we can not only stabilize the genetic transmission of the rapid growth trait in Large White pigs, but also continuously optimize the growth efficiency of the population, promote the development of the breeding industry towards high efficiency and intensification, and better meet the market's demand for rapid supply of pork products. Summary of the Invention

[0004] To address the problem of insufficient efficiency in genetic improvement of the fast growth trait in pigs, this invention proposes a SNP molecular marker associated with the fast growth trait and its application. This marker can be used for the selection or assisted selection of fast-growing pigs (short time to reach 100kg weight). Through the application of this molecular marker, early screening in breeding for the fast growth trait in pigs can be achieved, effectively shortening the breeding cycle, improving selection efficiency, and promoting genetic improvement and optimization of rapid growth performance in the population.

[0005] The objective of this invention is achieved through the following technical solutions:

[0006] A single nucleotide polymorphism (SNP) molecular marker associated with the rapid growth trait in pigs has been identified. This SNP is located at 55754471 bp on chromosome 17 of the international pig reference genome Sscrofa version 10.2. The nucleotide sequence at this site is either C or T, denoted as C>T. SULF2 Within the gene, T is a superior allele associated with rapid growth. The discovery of this molecular marker provides potential candidate gene support for improving the rapid growth performance of pigs and optimizing the age-to-weight-100kg target.

[0007] SULF2 The gene (Sulfatase 2) encodes a sulfatase family protein that can regulate growth and development-related signaling pathways, such as insulin-like growth factor and fibroblast growth factor, by modifying glycosaminoglycans in the extracellular matrix. Studies have shown that... SULF2 Gene expression levels are closely related to metabolic rate, muscle growth efficiency, and organ development in animals; abnormal gene function can lead to growth retardation, metabolic disorders, and other problems. Based on its central role in the growth regulatory network, this study will... SULF2 The gene was identified as a candidate gene affecting the growth traits of Large White pigs.

[0008] This invention also provides a method for breeding / assisted breeding of pigs that shorten / increase the number of days to reach 100kg body weight using the above-mentioned SNP molecular markers, comprising the following steps:

[0009] 1) Detect the SNP molecular marker at the 55754471bp site on chromosome 17 of the pig genome to determine whether the base at this site is C or T, thereby determining whether the genotype of the pig to be tested is CC, CT or TT;

[0010] 2) Based on the breeding objectives, select pigs with the corresponding genotypes for subsequent selection and / or breeding operations;

[0011] 3) Select pigs with a fast growth phenotype. In step 1), select individuals with genotype TT or genotype TT and / or CT as breeding pigs, and cull individuals with genotype CC. If selecting pigs with slow growth rate, select individuals with genotype CC obtained in step 1).

[0012] This invention also provides an application of the aforementioned SNP molecular marker in pig genetic breeding. Utilizing this molecular marker facilitates the accurate assessment of rapid growth performance in breeding pigs, avoiding the lag inherent in traditional breeding methods that rely on phenotypic observation. This provides crucial technical support and theoretical basis for the efficient breeding of the rapid growth trait in Large White pigs. Rapid assessment of individual genotypes helps optimize the growth potential of breeding pigs, significantly shortens the breeding cycle, and improves the efficiency of genetic improvement. This, in turn, reduces fattening costs and increases slaughter efficiency for the livestock industry, creating greater economic benefits and providing the market with high-quality, efficiently produced pork products.

[0013] This invention also provides a method for applying the above-mentioned SNP molecular markers in breeding fast-growing pig breeds, comprising the following steps:

[0014] 1) Test replacement breeding pigs for SNP molecular markers as described above to determine their genotype as CC, CT, or TT;

[0015] 2) To improve the growth performance of pigs, individuals with the TT or CT genotype detected in step 1) are selected as breeding pigs and bred with the selected boars and sows.

[0016] 3) Test the piglets born from mating in step 2) for SNP molecular markers as described above. Based on the test results, selectively retain individuals with genotype TT or CT and eliminate individuals with genotype CC to cultivate a fast-growing performance pig breed with a short age of 100kg weight.

[0017] Preferably, the operations of steps 2)-3) are repeated with the individuals bred in step 3), thereby selecting breeding pigs with molecular marker genotypes of TT or CT in the offspring and eliminating individuals with the CC genotype, so as to increase the frequency of allele T in the offspring pig population generation by generation and shorten the growth time of the offspring.

[0018] This method enables efficient screening and breeding of fast-growing pigs based on molecular markers, avoiding the blind spots of traditional breeding. It provides technical support and practical approaches for improving the rapid growth performance of pigs, reducing breeding and fattening costs, and increasing the efficiency of the industry's slaughter.

[0019] The present invention also provides a primer pair for the above-mentioned SNP molecular marker, the primer pair comprising: an upstream primer with a sequence as shown in SEQ ID NO: 2 and a downstream primer with a sequence as shown in SEQ ID NO: 3.

[0020] The present invention also provides a kit for the above-mentioned SNP molecular markers, the kit containing the above-mentioned primer pairs.

[0021] The preferred primer pairs or kits described above are used in the selective / assisted selective breeding of pigs that shorten / increase the number of days to reach 100 kg body weight.

[0022] The present invention also provides a method for obtaining the above-mentioned SNP molecular markers, comprising the following steps:

[0023] 1) To eliminate the problem of growth rate being affected by various factors during the growth of different batches of sows, the weight data and related data of the pigs in the test group were collected, including various influencing factors such as batch number, final weight, final age, and birth weight, which were used as covariates; the age data were corrected by a correction formula and abnormal individuals with missing age values ​​reaching 100kg weight were removed, and the phenotypic data were subjected to quality control analysis.

[0024] 2) Collect pig tissue samples, extract genomic DNA and test its quality. After genotyping, perform quality control on the genotyping data. The quality control method is as follows: First, extract data from chromosomes 1 to 18, then filter out SNP sites with a deletion rate higher than 2%; then filter out individuals with a deletion rate higher than 2%; remove sites with a minimum allelefrequency (MAF) of less than 0.05; finally, perform a Hardy-Weinberg equilibrium (HWE) test on each SNP and remove sites with a p-value less than 10. -4 The SNP sites were identified, and the genotyping data were self-filled using Beagle software for subsequent analysis.

[0025] 3) A mixed linear model was used for analysis. The population kinship matrix, the significant influencing factors of the age at which the pigs reached 100 kg weight (including the number of farms, the age at which the pigs were tested, and the birth weight) and the first three PCs were used as covariates to screen for SNP loci that were significantly associated with the age at which the pigs reached 100 kg weight.

[0026] Preferably, the correction formula in step 1) is:

[0027] ,

[0028] Where: AGE—age at 100kg weight, in days (d); S1—number of days from birth to the day of weighing, in days (d); W T —Target weight; W1—Actual weight measured on the day of measurement, in kilograms (kg); A—Correction parameter, the correction parameter is 46.415 for a target weight of 100kg.

[0029] The above method was used to screen for the SNP molecular markers associated with the aforementioned fast growth trait in pigs. The site is located at the 55754471bp site on chromosome 17 and is a C>T base mutation.

[0030] This method enables efficient screening and breeding of fast-growing pig breeds based on molecular markers, avoiding the blind spots of traditional breeding. It provides technical support and practical approaches for improving pig growth performance, reducing breeding and fattening costs, and increasing the industry's output efficiency.

[0031] This invention has the following advantages and innovations:

[0032] 1. For the first time, through genome-wide association analysis (GWAS), SULF2 A SNP locus (g.55754471 C>T) significantly associated with the age at which Large White pigs reach 100 kg body weight was identified in the genome. Studies showed that the genotype at this locus was highly correlated with the trait of reaching 100 kg body weight at the age of 100 kg. Individuals with the TT genotype had the fastest growth rate and the shortest age at 100 kg body weight, followed by the CT genotype, while the CC genotype had the slowest growth rate and the longest age at 100 kg body weight. This locus can serve as a genetic marker to aid in marker-assisted breeding and genetic improvement of the rapid growth trait in Large White pigs.

[0033] 2. For the aforementioned SNP sites, this invention designs a molecular marker identification primer and kit, and develops an efficient molecular marker-assisted breeding method. This method allows for the rapid screening of breeding pigs with superior growth traits, accelerating the breeding process, improving offspring growth capacity, and saving fattening costs. This technology has significant economic value and application potential.

[0034] 3. Gene chip-based genotyping technology performs excellently in non-diagnostic evaluations. Compared with traditional PCR-RFLP technology, gene chip detection is simpler, more efficient, and has higher sensitivity and specificity, providing a convenient and reliable tool for improving the breeding efficiency of Large White pigs.

[0035] 4. This invention also establishes a GWAS-based SNP molecular marker screening method and further clarifies its relationship with the growth performance of Large White pigs through functional validation. The screened SNP sites are accurate and comprehensive, significantly improving the efficiency of genetic improvement and accelerating the improvement of the growth performance of Large White pigs.

[0036] 5. This study provides 200 bp sequence information upstream and downstream of this SNP marker (total length 401 bp), and its detailed nucleotide sequence is recorded in SEQ ID NO:1 of the sequence listing. The SNP site is located at base R at position 201 of the sequence, exhibiting a single-base mutation of C>T. The sequence polymorphism caused by this mutation provides a molecular basis for assessing pig growth performance and further promotes the improvement of pig breeding efficiency. Attached Figure Description

[0037] Figure 1 This is a Manhattan plot of genome-wide association analysis of the present invention. The red circles mark the SNP molecular markers screened by the present invention, which are located on chromosome 17 of Large White pigs.

[0038] Figure 2 QQ plot of genome-wide association analysis for Large White pigs at 100kg body weight;

[0039] Figure 3 SNP density distribution map used in genome-wide association analysis of Large White pigs at 100kg body weight;

[0040] Figure 4 PCA map of the genomes of 744 Large White pigs;

[0041] Figure 5 A distribution of traits at age 100 kg in individuals with different genotypes at loci related to growth traits in Large White pigs;

[0042] Figure 6 This is a population distribution map of different genotypes and alleles at loci related to growth traits in Large White pigs. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In the present invention, unless otherwise specified, the equipment and raw materials used can be purchased from the market or are commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0044] All embodiments of the present invention were conducted using Large White pigs. In practical applications, other breeds of pigs or livestock can also be selected.

[0045] Example 1

[0046] A single nucleotide polymorphism (SNP) molecular marker associated with the rapid growth trait in pigs has been identified. This SNP is located at 55754471 bp on chromosome 17 of the international pig reference genome Sscrofa version 10.2. The nucleotide sequence at this site is either C or T, denoted as C>T. SULF2 Within the gene, T is a superior allele associated with rapid growth.

[0047] Example 2

[0048] A method for obtaining the SNP molecular marker described in Example 1 includes the following steps:

[0049] 1) Statistical analysis of the test population and phenotypic data

[0050] To eliminate the impact of various factors on growth rate during the growth of different batches of sows, growth data and related data of the pigs in the test group were statistically analyzed, including various influencing factors such as farm number, final body weight, final age, and birth weight, which were used as covariates. In this embodiment, a Large White pig breed was selected from a large domestic breeding farm, with a sample size of 748 pigs. Individual information after birth was recorded, along with environmental factors (influencing factors) affecting growth rate, including farm number, year, season, and birth weight.

[0051] The age data was corrected using relevant formulas:

[0052] ,

[0053] In the formula:

[0054] AGE—age in days (d) at which 100kg weight is reached; S1—number of days (d) from birth to the day of weighing; W T —Target weight; W1—Actual weight measured on the day of measurement, in kilograms (kg); A—Correction parameter, the correction parameter for a target weight of 100kg, which is 46.415.

[0055] Phenotypic data were quality controlled by removing outliers with missing values ​​for age at 100kg weight. Combined with genotypic data filtering, 744 corrected values ​​for age at 100kg weight were ultimately retained. The average age at 100kg weight in the Large White pig population used in this example was 152.80 days, with a minimum of 118.61 days and a maximum of 216.13 days.

[0056] 2) Data acquisition and quality control

[0057] Ear tissue samples were collected from Large White pigs for DNA extraction. In this embodiment, the extracted DNA was genotyped using the "Zhongxin-1" pig 50K SNP chip, and based on location information combined with low-depth sequencing data, approximately 50,000 SNP loci were obtained for subsequent genome-wide association studies (GWAS).

[0058] First, this embodiment uses vcftools-0.1.16 to extract chromosome data from 1 to 18. Then, PLINK v1.9 is used for quality control of the genotype data. First, SNPs with a deletion rate higher than 2% are filtered out; then, individuals with a deletion rate higher than 2% are filtered out; sites with a minimum allele frequency (MAF) less than 0.05 are removed; finally, a Hardy-Weinberg equilibrium (HWE) test is performed on each SNP, eliminating sites with a p-value less than 10. -4 SNP loci were identified. The genotyping data were self-filled using Beagle software for subsequent analysis.

[0059] 3) Genome-wide association analysis

[0060] This embodiment employs a mixed linear model for analysis, using the R package rMVP. The population kinship matrix, selected significant influencing factors at 100kg body weight (including farm number, age at birth, and birth weight), and the first three PC groups are used as covariates in the analysis. SNP loci significantly associated with 100kg body weight age in Large White pigs are screened. Simultaneously, a genome-wide association analysis (QQ) plot, SNP density distribution map, and PCA plot at 100kg body weight age are generated (results are shown in [link to results]). Figure 1-4 Analysis revealed four SNP loci significantly associated with the age of Large White pigs reaching 100 kg (see Table 1 for details). Based on information from the pig reference genome (Sscrofa 10.2 Assembly), these loci were further located... SULF2 Genes were selected as candidate genes. Among them, CNCB10011911 is a candidate marker associated with the age of reaching 100kg body weight. This marker is located at 55754471bp on chromosome 17, where cytosine C is changed to thymine T, represented as g.55754471 C>T.

[0061] Table 1. SNP markers and candidate genes related to age at 100kg in Large White pigs.

[0062]

[0063] Example 3

[0064] Molecular marker application and validation

[0065] To further analyze the relationship between different genotypes (CC, CT, TT) of the candidate marker locus g.55754471 C>T and the age at which Large White pigs reached 100 kg body weight, analysis of variance (ANOVA) was used to assess the age at which 744 Large White pigs reached 100 kg body weight, and the significance of differences between different genotypes was compared using the Tukey HSD test (see Table 2 for details). In addition, violin plots were created using the R packages ggplot2 and ggpubr to visually display the distribution of different genotypes at the age at 100 kg body weight, and significance markers were added to highlight differences (e.g., Figure 5 As shown), the sub-site was optimal by comparing it with other sites; the genotype population distribution map was plotted using the R packages ggplot2, dplyr, and tidyr, showing the proportion of different genotypes and alleles in the population (e.g., Figure 6 (As shown).

[0066] Table 2. Differences in age at 100kg weight among different Large White pig genotypes using molecular marker g. 55754471 C>T

[0067]

[0068] Note: *** indicates that the difference in age at which different genotypes reach 100kg weight is extremely significant (P≤0.01); * indicates that the difference in age at which different genotypes reach 100kg weight is significant (P≤0.05).

[0069] The analysis results showed that the marker site g.55754471 C>T was significantly associated with the growth trait (age to reach 100 kg body weight) in Large White pigs. The mean age to reach 100 kg body weight for individuals with the TT genotype was 149.95 days, significantly lower than that of the CT genotype (156.18 days) and extremely significantly lower than that of the CC genotype (159.42 days). This site is located at 55754471 bp on chromosome 17 of the pig reference genome Sscrofa 10.2, and is a mutation from cytosine (C) to thymine (T). As a SNP molecular marker CNCB10011911 closely associated with the growth trait (age to reach 100 kg body weight) in Large White pigs, this site can be used for marker-assisted selection. Individuals with the TT genotype are suitable as preferred candidates for further selection or breeding to improve the growth performance of Large White pigs and shorten the overall age to reach 100 kg body weight.

[0070] Example 4

[0071] Design of primers for identifying SNP molecular markers associated with traits at age 100 kg in pigs and their applications.

[0072] This example demonstrates the design of upstream and downstream primers for detecting the C / T nucleotide site at 55754471 bp on chromosome 17, the SNP site obtained in Example 2.

[0073] 1. Primer design for the target gene sequence

[0074] Based on the target gene sequence, optimized amplification primers were designed using primer design software, and primer pairs were obtained.

[0075] The sequence is as follows:

[0076] Upstream primer: 5'-CTGTGGACGTGATTAAACAGC-3' (e.g., SEQ ID NO: 2)

[0077] Downstream primer: 5'-AAGCCATTAGACTTCAAACCC-3' (e.g., SEQ ID NO: 3)

[0078] 2. Large White pig genome extraction

[0079] Tissue samples were collected from the Large White pigs to be tested, genomic DNA was extracted, and after quality and concentration testing, the samples were stored at -20℃ for later use.

[0080] 3. Touchdown PCR amplification of trait-related SNP loci in Large White pigs at age 100kg body weight.

[0081] Using the extracted DNA as a template, PCR amplification was performed using the primers described above.

[0082] Amplification system: 10 μL of 2×SuperReal PreMix Plus, 8 μL of ddH2O, 0.5 μL each of upstream and downstream primers, and 1 μL of DNA template.

[0083] Amplification procedure:

[0084] Pre-denaturation at 95°C for 5 minutes;

[0085] Denature at 95°C for 20 seconds;

[0086] Anneal at 68°C-57°C for 20 seconds, then decrease the temperature by 1°C for each subsequent cycle;

[0087] Extend the heat to 72°C for 20 seconds;

[0088] The above process involves 11 cycles;

[0089] Denature at 95°C for 20 seconds;

[0090] Anneal at 51°C for 20 seconds;

[0091] Extend the heat to 72°C for 20 seconds;

[0092] The above procedure repeats 29 times;

[0093] Finally, extend the heat to 72°C for 5 minutes.

[0094] After amplification, the temperature was maintained at 4°C to preserve the product and terminate the reaction.

[0095] 4. Sequencing and analysis of amplified products

[0096] The PCR products were detected by agarose gel electrophoresis, and the amplified products were sent for sequencing to obtain the sequence of the amplified product (as shown in SEQ ID NO: 4). The sequencing results of the amplified product were compared and analyzed with the relevant gene fragments of large white pigs in GenBank (as shown in SEQ ID NO: 1) to determine whether the genotype of the target SNP locus related to the age of 100kg body weight was CC, CT, or TT.

[0097] Based on the above results, select Large White pigs that reach 100kg weight at a short time, i.e., those with excellent growth traits. If the Large White pigs reach 100kg weight at a short time, select those with the TT and CT genotypes; otherwise, select those with the CC genotype.

[0098] Those skilled in the art can design other primers for amplifying the molecular genetic marker or probes for identifying the molecular genetic marker based on the molecular genetic marker described above, thereby enabling the detection of the genetic marker. For example, the molecular genetic marker can be obtained by PCR amplification, and the corresponding sequence can be obtained by cloning and sequencing. Therefore, the present invention also includes primers for amplifying the molecular genetic marker or probes for identifying the molecular genetic marker, as well as kits containing the primers or probes.

[0099] Example 5

[0100] This embodiment provides a method for shortening / increasing the number of days to age for pigs reaching 100kg body weight through SNP molecular marker selection / assisted selection obtained in Example 2, including the following steps:

[0101] 1) Extract genomic DNA from Large White pigs and detect the SNP molecular marker at the 55754471bp site on chromosome 17 of the pig genome to determine whether the base at this site is C or T, thereby determining whether the genotype of the pig to be tested is CC, CT or TT.

[0102] 2) Based on the breeding objectives, select Large White pigs with the corresponding genotypes for subsequent selection and / or breeding operations;

[0103] 3) Select pigs with a fast growth phenotype. In step 1), select individuals with genotype TT or genotype TT and / or CT as breeding pigs, and cull individuals with genotype CC. If selecting pigs with slow growth rate, select individuals with genotype CC obtained in step 1).

[0104] Studies have shown that TT-type Large White pigs reach 100kg weight in a shorter time than CC-type pigs, with each TT-type pig taking 7.064 days less than the CC-type. Using the dominant TT genotype (151.01 days) as a benchmark, comparing the cost differences between CT and CC genotypes, with feed costs calculated at an average daily feed intake of 2.8kg and a compound feed cost of 3.0 yuan / kg, the CC genotype requires 7.06 days longer to raise and consumes an additional 19.768kg of feed, resulting in an extra feed cost of 59.3 yuan / head. Regarding fixed cost allocation, calculated at an average daily labor, depreciation, and energy cost of 1.04 yuan, the CC genotype bears an additional cost of 7.3 yuan / head compared to the TT genotype. Overall, the TT genotype saves 66.6 yuan per head compared to the CC genotype in terms of cost optimization.

[0105] If the proportion of the TT genotype in the population increases to 60% (20% higher than the current average), the average fattening cost per farm can be reduced by about 4.2%-4.5%, significantly increasing the profitability of farming.

[0106] Example 6

[0107] This embodiment provides a method for applying the SNP molecular marker obtained in Example 2 to the breeding of fast-growing pig breeds, including the following steps:

[0108] 1) Detect SNP molecular markers related to the fast growth trait in replacement breeding pigs at the 55754471bp locus on chromosome 17 to determine their genotype as CC, CT, or TT;

[0109] 2) Select boars and sows with genotypes TT or CT as breeding stock and mate them. Prioritize TT×TT or TT×CT combinations to increase the probability of offspring carrying the T allele.

[0110] 3) Detect the SNP genotype of piglets born after mating, retain individuals with TT or CT genotypes, and eliminate individuals with CC genotypes, thereby cultivating pig breeds with excellent growth performance.

[0111] Optional operations:

[0112] The above method can be used to continuously select breeding pigs with genotypes TT or CT by repeating steps 2) and 3) over multiple generations, while culling individuals with genotype CC. As the number of breeding generations increases, the frequency of the dominant allele T in the pig herd gradually increases, and the growth performance of the offspring pigs (age to reach 100kg body weight) will be further optimized, and the overall fattening cycle of the herd can be significantly shortened.

[0113] Example 7

[0114] This embodiment provides a kit for detecting SNP molecular markers as described in Example 1, the kit containing primer pairs as described in Example 4.

[0115] Example 8

[0116] This embodiment provides the application of the primer pair as described in Example 4 or the kit as described in Example 7 in the selection / assisted selection of pigs to shorten / increase the number of days to reach 100 kg body weight.

[0117] This invention can be replaced or modified according to the technical solution, and all such modifications or replacements should fall within the protection scope of this invention.

Claims

1. The use of a SNP molecular marker in the genetic breeding of the fast growth trait of Large White pigs, characterized in that, The SNP molecular marker is located at the site of 55754471 bp of chromosome 17 of the international pig reference genome Sscrofa 10.2 version, the nucleotide sequence of the site is C or T, recorded as C>T, located in SULF2 Intronic, wherein T is a good allele related to the fast growth trait.

2. A method for breeding / assisted breeding of Large White pigs with a reduction of 100 kg body weight in days of age using SNP molecular markers, characterized in that, The SNP molecular marker of claim 1 comprises the following steps: 1) detecting the SNP molecular marker at the site of 55754471 bp on the 17th chromosome of the pig genome, determining the base at the site as C or T, and judging the genotype of the pig to be CC, CT or TT; 2) selecting individuals with genotypes of TT and / or CT as breeding pigs, and eliminating individuals with genotype CC.

3. The use of a SNP molecular marker in breeding a fast-growing Large White pig line, characterized in that, The SNP molecular marker of claim 1 comprises the following steps: 1) detecting the SNP molecular marker of claim 1 on the back-up breeding pigs, and determining the genotypes of the back-up breeding pigs as CC, CT or TT; 2) selecting individuals with genotypes of TT or CT as breeding pigs in terms of improving the growth performance of the pigs, and mating the breeding pigs; 3) detecting the SNP molecular marker of claim 1 on the piglets born from the mating in step 2), and selectively retaining individuals with genotypes of TT or CT and eliminating individuals with genotype CC, so as to breed a pig line with fast growth performance and short time to reach 100 kg body weight.

4. Use according to claim 3, characterized in that, The operation of steps 2) to 3) is repeated with the individuals bred in step 3), so as to retain individuals with genotypes of TT or CT as breeding pigs in the offspring, eliminate individuals with genotype CC, and increase the frequency of allele T in the offspring pig population and shorten the growth time of the offspring.

5. The primer pair for detecting the SNP molecular marker of claim 1 is applied in the breeding / assisted breeding of large white pigs with shortened days to 100 kg body weight, characterized in that, The primer pair comprises an upstream primer with the sequence as shown in SEQ ID NO: 2 and a downstream primer with the sequence as shown in SEQ ID NO:

3.

6. The use of a kit for detecting the SNP molecular marker of claim 1 in the selection / assisted selection of large white pigs with a reduction of up to 100 kg of body weight in days of age, characterized by, The kit comprises a primer pair, wherein the primer pair comprises an upstream primer with the sequence as shown in SEQ ID NO: 2 and a downstream primer with the sequence as shown in SEQ ID NO: 3.

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