Application of product for detecting SNP molecular marker related to birth litter weight character of large white pig

Abstract

According to the application of the product of the SNP molecular marker related to the birth litter weight character of the large white pig, the SNP molecular marker is as follows: A > G base mutation located at the 116767089 nucleic acid site of the second chromosome of the international pig genome Sscrofa 11.1 version, and the nucleotide sequence of the SNP molecular marker is as shown in SEQ ID No.1; the product at least comprises an upstream primer and a downstream primer, the nucleotide sequence of the upstream primer is as shown in SEQ ID No.2, and the nucleotide sequence of the downstream primer is as shown in SEQ ID No.3. The SNP molecular marker provided by the invention can be used for breeding, breeding and evaluating multi-variety sows with high reproductive performance.

Description

TECHNICAL FIELD

[0001] The present application relates to a SNP molecular marker technology, in particular to the application of a product for detecting a SNP molecular marker related to the litter birth weight trait of Large White pigs. BACKGROUND

[0002] The reproductive performance of sows is a core factor affecting the economic efficiency of pig production, and is directly related to the competitiveness and sustainable development ability of breeding enterprises.

[0003] Pig reproductive traits include multiple indicators, including age at first farrowing, gestation period, annual farrowing number, teat number, total litter size, live-born litter size, birth individual weight, birth litter weight, weaned piglet number, and weaned litter weight. Among them, birth litter weight, as the total weight of piglets at birth, is an important trait that comprehensively reflects the reproductive potential of sows, the development status of fetuses, and the level of nutrition management during pregnancy. This trait not only reflects the information of both litter size and individual birth weight, but also indirectly reveals the coordination degree of multiple physiological processes such as uterine capacity, embryo survival rate, placental function, and maternal health status.

[0004] In actual production, too low birth litter weight often means that part of the piglets have small initial birth weight, poor vitality, and weak disease resistance, which easily leads to initial birth death or elimination during the lactation stage, thereby reducing the weaning survival rate and increasing breeding costs and risks. In contrast, sows with higher birth litter weight usually provide more healthy and uniform piglets, which is beneficial to improve weaned litter weight and subsequent growth performance. Studies have shown that there is a significant positive correlation between birth litter weight and economic traits such as weaned litter weight, growth rate, and grower rate. Therefore, this trait has been widely regarded as one of the key indicators for evaluating and selecting high-reproductive sows. By including birth litter weight in breeding goals, not only can the overall reproductive efficiency of sow populations be improved, but also excellent boars or sow lines can be identified, and the genetic progress of the core herd can be accelerated.

[0005] However, most reproductive traits are low-heritability traits and are greatly affected by the environment. Traditional breeding methods progress slowly, have long cycles and high costs, and are difficult to meet the needs of modern high-efficiency breeding. With the development of molecular biology technology, molecular marker-assisted selection (MAS) provides a new technical path for pig breeding. This method detects genetic markers associated with target traits to achieve early selection of individual genotypes, thereby shortening the generation interval, improving breeding accuracy and efficiency.

[0006] Among various molecular markers, single nucleotide polymorphism (SNP) has become the mainstream of genetic marker development and application due to its wide distribution, high stability, easy standardization detection and high-throughput analysis. Compared with SSR, ISSR and other polymorphic markers, SNP has higher genetic stability and repeatability, and can be rapidly and massively screened by various technical platforms such as TaqMan probe method, mass spectrometry, gene chip and high-throughput sequencing. With the continuous reduction of sequencing cost, SNP markers of multiple species have been extensively explored and applied to genetic improvement of important economic traits.

[0007] However, the current case reports of key SNP markers related to pig litter size are still relatively limited. The literature “Genetic Diversity and Reproductive Traits Genome-wide Association Analysis of Zaizhuang Black Cover Pig”, Zhang Ran, Master's Thesis of Shandong Agricultural University, page 31, August 31, 2022, reported that the SNP related to pig litter size trait was located on chromosome 6 and 10, and the SNP related to pig individual birth weight trait was located on chromosome 1 and 2, and DCP2 gene was related to individual birth weight shape. Studies have shown that DCP2 is an mRNA capping enzyme that degrades maternal transcripts in oocytes, promoting oocyte maturation and embryo development. CN119842914A reported that the C>T mutation at position 105043272 on chromosome 14 of the international pig reference genome version 11.1 affects the reproductive traits (litter size, number of healthy piglets and litter size) of pigs; CN114250305B reported that the SNP marker is located within the GLRX3 gene at nucleotide position 151219997 on chromosome 14 of the international pig genome 10.2 version reference sequence, with T / C polymorphism, for evaluating pig live litter size and piglet litter size. However, a marker system suitable for efficient and large-scale molecular breeding practice has not been established.

[0008] Therefore, the development of SNP markers significantly related to litter size and suitable for high-throughput genotyping technology has important practical significance for realizing early selection of sow reproductive traits, improving breeding efficiency, reducing production costs and promoting genetic progress in the pig industry. SUMMARY

[0009] The first technical problem to be solved by the present application is to provide an application of a product for detecting SNP molecular markers related to litter size traits of Large White pigs in the selection of sow litter size traits.

[0010] The second technical problem to be solved by the present application is to provide an application of a product for detecting SNP molecular markers related to litter size traits of Large White pigs in the breeding of high-yield litter size breed sow lines.

[0011] The third technical problem to be solved by the present application is to provide an application of a product for detecting a SNP molecular marker related to a litter birth weight trait of a Large White pig in improving a litter birth weight trait of a sow population.

[0012] The fourth technical problem to be solved by the present application is to provide an application of a product for detecting a SNP molecular marker related to a litter birth weight trait of a Large White pig in early screening of a piglet growth and development condition.

[0013] The technical solution for solving the first technical problem of the present application is an application of a product for detecting a SNP molecular marker related to a litter birth weight trait of a Large White pig in breeding a sow for a litter birth weight trait, wherein the SNP molecular marker is located at an A>G base mutation at a nucleic acid site of 116767089 on a chromosome 2 of an international pig genome Sscrofa 11.1 version in a DCP2 gene.

[0014] The A>G base mutation refers to a single nucleotide polymorphism variation at the site, which can be specifically typed by an allele-specific PCR or a probe hybridization method, and the mutation causes a change in gene function and thus affects a reproductive trait and has a genetic correlation with a litter birth weight trait of a sow.

[0015] Specifically, by detecting a genotype at the site 116767089 in the DCP2 gene, the genetic potential of an individual can be directly determined. When the site is a G allele, it indicates that a superior genotype related to a high litter birth weight is carried. The detection product can specifically recognize the mutation site, and early screening can be realized at a DNA level. Based on the molecular detection of the marker, GG, GA and AA genotypes can be accurately distinguished, a genetic basis is provided for breeding decision-making, and a dependence on late phenotype observation is avoided.

[0016] Further, the nucleotide sequence of the SNP molecular marker is shown in SEQ ID No. 1. The product at least includes an upstream primer and a downstream primer, the nucleotide sequence of the upstream primer is shown in SEQ ID No. 2, and the nucleotide sequence of the downstream primer is shown in SEQ ID No. 3.

[0017] Further, the method of the application includes the following steps: 1) detecting the SNP molecular marker on a reserve breeding sow; 2) selecting and keeping the individual with GG or GA genotype at the nucleic acid site 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 version detected in step 1) as a breeding sow; and the individual with GG genotype at the nucleic acid site 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 version can effectively improve the litter birth weight of the sow.

[0018] In some embodiments, in the breeding process of the sow reproductive trait, the genomic DNA of the individual to be tested is first extracted, the target SNP site is amplified by using a detection product containing a specific primer pair, and the allele genotype of the 116767089 site is determined by genotyping. When the detection result is GG or GA genotype, it indicates that the individual carries the dominant allele G associated with the high birth weight trait, and the individual is preferentially selected and kept in the breeding population. By continuous multi-generation screening, the distribution frequency of the dominant allele in the population is gradually improved, thereby stably improving the litter birth weight of the sow at the genetic level.

[0019] The technical solution adopted by the present application to solve its second technical problem is the application of the product of the SNP molecular marker associated with the birth weight trait of Large White pigs in breeding a high-litter birth weight sow line; wherein the SNP molecular marker is located in the DCP2 gene, and is an A>G base mutation at the nucleic acid site 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 version.

[0020] Further, the method of the application comprises the following steps: 1) detecting the SNP molecular marker on the backup sow; 2) selecting and keeping the individual with GG or GA genotype at the nucleic acid site 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 version detected in step 1) as a breeding sow, and mating the breeding sow; 3) detecting the SNP molecular marker on the sow born in step 2), keeping the individual with GG or GA genotype at the nucleic acid site 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 version, eliminating the individual with AA genotype at the nucleic acid site 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 version, and breeding to breed a high-reproductive-performance sow line with high litter birth weight.

[0021] By detecting a specific SNP site located in the DCP2 gene, it can be directly determined whether the sow carries the G allele associated with high litter birth weight. The decapping enzyme encoded by the DCP2 gene is involved in the regulation of oocyte maturation and embryonic development, and the G allele at this site may affect embryonic survival rate by enhancing mRNA degradation efficiency. In the detection process, specific primers are used to amplify the target region, and probe hybridization or sequencing technology is used to complete genotyping to ensure the accuracy of genotyping. The screening step is based on the dominant genetic effect, and individuals carrying at least one G allele are retained, thereby increasing the frequency of the dominant allele at the population level. This method locks the key gene site that controls embryonic development, avoiding the interference of environmental factors on low heritability traits in traditional breeding, and realizing early precision selection based on genotype.

[0022] The technical scheme adopted by the present application to solve its third technical problem is the application of a product of a SNP molecular marker related to the litter birth weight trait of Large White pigs in improving the litter birth weight trait of a sow population; wherein the SNP molecular marker is located in the DCP2 gene at the A>G base mutation at the nucleic acid site of chromosome 2 of the international pig genome Sscrofa 11.1 version 116767089.

[0023] Further, the method of application comprises the following steps: 1) detecting the SNP molecular marker on the reserve sow; 2) selecting and retaining individuals with GG or GA genotypes at the nucleic acid site of chromosome 2 of the international pig genome Sscrofa 11.1 version 116767089 as breeding sows, and mating the breeding sows; 3) detecting the SNP molecular marker on the sows born in step 2), retaining individuals with GG or GA genotypes at the nucleic acid site of chromosome 2 of the international pig genome Sscrofa 11.1 version 116767089, eliminating individuals with AA genotypes at the nucleic acid site of chromosome 2 of the international pig genome Sscrofa 11.1 version 116767089, and breeding to increase the frequency of the dominant allele G at the nucleic acid site of chromosome 2 of the international pig genome Sscrofa 11.1 version 116767089 from generation to generation, thereby improving the litter birth weight trait of the sow population and increasing the litter birth weight of the sow population.

[0024] Among them, the dominant allele G refers to the genotype carrying G base at the SNP site, and individuals with GG or GA genotypes can be screened out by genotyping detection, and the enrichment of this allele can promote the genetic improvement of the litter birth weight trait of the sow population.

[0025] Among them, the population genetic improvement strategy refers to screening superior genotype individuals through multiple generations in succession, and specifically can adopt the method combining seed selection and offspring genotype detection to gradually increase the frequency of superior alleles in the population.

[0026] Specifically, by detecting the genotype of the SNP molecular marker, the reserve sow carrying the GG or GA genotype is preferentially selected and retained for mating and breeding. The genotype detection is continuously carried out in the offspring of mating, the individual carrying the AA genotype is eliminated, and the individual with the superior genotype is retained to enter the next round of breeding. Through the cyclic implementation of the strategy, the distribution frequency of the superior allele G in the population presents a trend of increasing generation by generation, so that the directional improvement of the litter birth weight trait of the sow population is realized at the genetic level.

[0027] The application solves the fourth technical problem by adopting the technical scheme that the product of the SNP molecular marker related to the litter birth weight trait of Large White is applied in early screening of piglet growth and development, wherein the SNP molecular marker is located in the DCP2 gene, and is an A>G base mutation at the nucleic acid site 116767089 of chromosome 2 in the international pig genome Sscrofa 11.1 version; the application is to identify the genotype of the SNP molecular marker of the candidate piglet, and when the allele genotype at the nucleic acid site 116767089 of chromosome 2 in the international pig genome Sscrofa 11.1 version is GG or GA genotype, the candidate piglet is retained for breeding.

[0028] Among them, genotype identification refers to determining the base composition of the target site through nucleic acid extraction, primer design and amplification, and typing detection technology, and specifically can adopt Sanger sequencing or high-throughput sequencing platform to realize, and its role is to quickly distinguish GG, GA and AA genotype individuals, and provide molecular basis for early breeding.

[0029] Among them, early screening refers to genotype detection before weaning or in the early growth stage of piglets, and specifically can collect ear tissue samples within 1-3 weeks after birth to realize, and its role is to shorten the breeding cycle and avoid relying on long-term phenotype data accumulation required by traditional breeding performance observation.

[0030] Specifically, the technical scheme is to collect DNA samples of candidate piglets, and perform genotype analysis on the 116767089 locus of chromosome 2 in the DCP2 gene. When the detection result is GG or GA genotype, it indicates that the individual carries at least one dominant allele G, which is significantly related to high birth litter weight, and therefore is retained for subsequent breeding. If the detection result is AA genotype, it indicates that the individual does not carry the dominant allele, and can be eliminated in advance. Through this screening mechanism, genetic advantage evaluation can be completed when the piglets are still in the breeding stage, compared with the traditional method of waiting for the sow to give birth to measure the phenotype data, the screening time can be shortened by at least one generation interval. In addition, by continuously selecting and retaining individuals with GG or GA genotypes, the frequency of the dominant allele G in the population will gradually increase, thereby systematically improving the birth litter weight.

[0031] In the present application, the product refers to a reagent or a kit. The sequence containing the molecular genetic marker nucleotide site is obtained by primer amplification in the reagent or kit, and its genotype is usually obtained by sequencing.

[0032] Compared with the prior art, the beneficial effects of the present application are as follows: The present application determines the molecular genetic marker related to the birth litter weight of sows, which helps to improve the birth litter weight performance of sows. Using the molecular genetic marker of the present application, the birth litter weight performance of breeding sows can be efficiently evaluated, and the accuracy and convenience of detection are improved. Using the molecular genetic marker, through genotype selection, breeding strategy optimization, improvement of the birth quality and quantity of piglets, and providing technical support for core breeding farms, it helps to realize more efficient and accurate genetic improvement. The present application provides a new method for improving the birth litter weight performance of sows of multiple breeds through the discovery and application of molecular genetic markers, which helps to improve the overall economic benefits of the pig industry and the scientificity of genetic improvement. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Manhattan plot of whole genome association analysis for different models of birth litter weight of sows.

[0034] Figure 2 QQ plot of whole genome association analysis for different models of birth litter weight of sows. Wherein, a is the GLM model; b is the FarmCPU model; c is the BLINK model.

[0035] Figure 3 SNP locus linkage disequilibrium analysis plot.

[0036] Figure 4 SNP locus different allele genotype and birth litter weight association analysis plot. DETAILED DESCRIPTION

[0037] Many specific details of the invention are set forth in the following description to enable those skilled in the art to implement and fully understand the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make various modifications without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Unless otherwise specified, the reagents and other materials used in this embodiment are all commercially available products.

[0040] Example 1: Screening of SNP molecular markers related to litter weight in sows 1. Material screening and phenotypic recording We collected 1938 purebred Large White pigs from Jiangxi Jiada Group, totaling 7510 breeding records from 2019 to 2024. We also collected litter weight phenotypic data, with a minimum of 3, a maximum of 34, a mean of 16.76, a standard deviation of 4.52, and a coefficient of variation of 26.94%.

[0041] 2. SNP chip detection and genotyping 2.1 DNA Sample Extraction and Quality Control DNA was extracted from tissue samples using a magnetic bead method. The concentration of DNA samples was detected using a Qubit real-time fluorescence instrument; the integrity of DNA samples was detected by 1% agarose gel electrophoresis, and samples that passed quality control were used for library preparation.

[0042] 2.2 SNP chip testing SNP genotyping was performed using the Compson "Zhongxin-1" chip. This chip contains 52,720 SNP loci, integrating genetic differences from multiple pig breeds and covering the entire pig genome. The chip detection process includes DNA sample preparation, denaturation, whole-genome amplification, DNA fragmentation, precipitation and resuspending, hybridization with the chip, extension, chip scanning, and finally, software genotyping output. Genome Studio software was used to visualize the chip data and obtain genotypic data.

[0043] 3. Genome-wide association analysis to locate target SNP loci. 3.1 Genome-wide association analysis The material data of the chip detection were subjected to whole genome association analysis by GAPIT3 (Wang J, Zhang Z. GAPIT version 3: boosting power and accuracy for genomic association and prediction [J]. Genomics, proteomics & bioinformatics, 2021, 19(4): 629-640.), and three statistical models, including general linear model (GLM), fixed random model circular probability unified model (FarmCPU), and Bayesian information and linkage disequilibrium iterative nested key model (BLINK), were used for whole genome association analysis, and the principal components were added to the model as covariates for correction. The collected birth litter weight phenotypic traits were subjected to whole genome association analysis, and the Manhattan plot and QQ plot are shown in Figure 1 and Figure 2 The significant SNP site was calculated by taking the logarithm of the Bonferroni corrected P value (p=0.05 / N, N is the number of SNPs) as the logarithm-log10.

[0044] 3.2 Mining significant marker sites In the whole genome range, 1 significant marker site in the birth litter weight phenotypic trait was co-localized by combining three GWAS methods. The significant SNP site located in the DCP2 gene, as shown in Figure 3 , was located at the nucleic acid site of 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 version. The P values calculated by GLM, FarmCPU and BLINK three statistical models were 3.49×10 -7 , Figure 2 7.84×10 -7 , Figure 2 and 8.17×10 -7 , Figure 2 respectively, the beta effect values were 0.527, 0.434 and 0.444 respectively, the direction was positive, and the allele type GG was the beneficial allele type.

[0045] Example 2: Detection of SNP molecular markers related to sow farrowing birth litter weight In this embodiment, the SNP site (international pig genome Sscrofa 11.1 version) at the nucleic acid site A / G of 116767089 bp on chromosome 2 was detected by designing upstream and downstream primers.

[0046] 1. Primer design of target gene sequence The objective gene is the sequence of 1000 bp before and after the SNP site at position 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 version, and the nucleotide sequence is as follows: According to the sequence of the target gene, the sequencing primer pair was designed by using BatchPrimer3, and the primer was synthesized by Invitrogen Company. The sequencing primer pair is as follows: Upstream primer: 5'-TCCTCCACCTTGCTTATTCATTCT-3' (SEQ ID No. 2) Downstream primer: 5'-CTTCTGGTTTCTGTCTTCCCTTTT-3' (SEQ ID No. 3) 2. Genome extraction of Large White pig The tissue sample of the Large White pig to be tested was collected, and the genomic DNA was extracted. After quality and concentration detection, the genomic DNA was stored at -20℃ for standby use.

[0047] 3. PCR amplification of SNP site related to litter birth weight trait of Large White pig The extracted DNA was used as a template, and the above-mentioned primer was used for PCR amplification.

[0048] Amplification system: 10 μL of 2x SuperReal PreMix Plus, 8 μL of ddH2O, 0.5 μL of upstream and downstream primers (10 μM concentration) respectively, 1 μL of cDNA template.

[0049] Amplification program: 95℃ pre-denaturation for 15 minutes; 95℃ denaturation for 20 seconds; 58℃ annealing for 20 seconds; 72℃ extension for 20 seconds; 40 cycles; 72℃ extension for 5 minutes.

[0050] After the amplification was completed, the temperature was maintained at 4℃ to keep the product and end the reaction.

[0051] 4. Sequencing and analysis of amplification product The PCR product was detected by agarose gel electrophoresis, and the amplification product was sent for sequencing. The sequence of the amplification product was obtained by sequencing. The sequencing results of the amplification product were compared and analyzed with the related gene fragments of Large White pig in GenBank, and it was judged whether the genotype of the sequence of the target SNP site related to the litter birth weight was GG, GA or AA.

[0052] Example 3 Verification of the molecular genetic marker of the application To further validate the identified SNP locus significantly associated with litter weight—locus 116767089 on chromosome 2 of the international porcine genome Sscrofa version 11.1—a large population with no genetic exchange with the GWAS population was used for validation. Data from a resequencing population of 560 Large White pigs from the Shaanxi Shunxin Large White breeding farm (average sequencing depth 15.6x) were used to detect the target SNP marker. The association between marker genotype and phenotype was analyzed, and the T-test was used to compare different genotypes.

[0053] The results showed that: Figure 4 As shown, the Sscrofa 11.1 version of the international pig genome, chromosome 2, nucleotide locus 116767089, reveals three genotypes (AA, AG, and GG) in a population of 560 Large White pigs. The average litter weight of AA-type Large White pigs was 18.18 kg; the average litter weight of AG-type Large White pigs was 18.66 kg; and the average litter weight of GG-type Large White pigs was 19.31 kg. The litter weight of GG-type Large White pigs differed significantly from that of AA-type pigs. p =0.0095), which is also significantly different from the GA type ( p =0.0153).

[0054] Example 4: A method for genetic improvement of sows with high litter weight. The specific steps in this embodiment are as follows: 1) SNP molecular markers related to litter weight were detected in replacement breeding pigs, genomic DNA was extracted, and the primers and methods described in Example 2 above were used for detection; 2) Select individuals with the genotype GG or GA as breeding pigs, and mate the selected boars and sows; 3) Perform SNP molecular marker testing on piglets born after mating, retain individuals with the genotype GG or GA, and cull individuals with the genotype AA, thereby cultivating a high-fertility, high-livestock pig breed.

[0055] Furthermore, steps (2) and (3) can be repeated based on step (3) to select breeding pigs with genotypes GG or GA generation by generation, eliminate individuals with genotype AA, and gradually increase the frequency of the allele G at this SNP locus in the pig population, thereby increasing the litter weight of offspring pigs.

[0056] Example 5: A method for early screening and selection of piglet growth and development. The specific steps in this embodiment are as follows: 1) SNP molecular markers related to litter weight were detected in piglets, genomic DNA was extracted, and the primers and methods described in Example 2 above were used for detection; 2) Individuals with genotype GG or GA are selected for continued breeding and mating, and iterative successive breeding is performed to increase the frequency of allele G, thereby increasing the birth litter weight of offspring piglets.

[0057] The above merely describes the preferred embodiments of the present application, and the protection scope of the present application is not limited to the above-described embodiments. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary researchers in the technical field, some improvements and refinements without departing from the principles of the present application shall also be considered as falling within the protection scope of the present application.

Claims

1. The application of a product containing SNP molecular markers associated with litter weight in Large White pigs for breeding of sows with litter weight; wherein the SNP molecular marker is an A>G base mutation located at nucleotide site 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 within the DCP2 gene; the nucleotide sequence of the SNP molecular marker is shown in SEQ ID No. 1; the product includes at least an upstream primer and a downstream primer, the nucleotide sequence of the upstream primer is shown in SEQ ID No. 2, and the nucleotide sequence of the downstream primer is shown in SEQ ID No.

3.

2. The application according to claim 1, characterized in that, The method of application includes the following steps: 1) Detect the SNP molecular markers in replacement breeding sows; 2) Select individuals with the GG or GA genotype at the nucleotide site at chromosome 116767089 of the international pig genome Sscrofa 11.1 version obtained in step 1) to effectively increase the birth litter weight of sows.

3. Application of products containing SNP molecular markers associated with birth litter weight in Large White pigs for breeding high birth litter weight sow breeds; the SNP molecular marker is an A>G base mutation located at nucleotide site 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 within the DCP2 gene; the nucleotide sequence of the SNP molecular marker is shown in SEQ ID No. 1; the product includes at least an upstream primer and a downstream primer, the nucleotide sequence of the upstream primer is shown in SEQ ID No. 2, and the nucleotide sequence of the downstream primer is shown in SEQ ID No.

3.

4. The application according to claim 3, characterized in that, The method of application includes the following steps: 1) Detect the SNP molecular markers in replacement breeding sows; 2) Select individuals with the GG or GA genotype at the nucleotide site at chromosome 2, 116767089 of the international pig genome Sscrofa 11.1 version obtained in step 1) as breeding sows, and mate these breeding sows; 3) Test the SNP molecular markers of the sows born from mating in step 2), retain individuals with the GG or GA genotype at the 116767089 nucleotide site, and cull individuals with the AA genotype at the 116767089 nucleotide site. Then breed them to cultivate a high-birth-weight, high-reproductive-performance sow breed.

5. Application of products containing SNP molecular markers associated with litter weight in Large White pigs in improving litter weight traits in sow populations; the SNP molecular marker is an A>G base mutation located at nucleotide site 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 within the DCP2 gene; the nucleotide sequence of the SNP molecular marker is shown in SEQ ID No. 1; the product includes at least an upstream primer and a downstream primer, the nucleotide sequence of the upstream primer is shown in SEQ ID No. 2, and the nucleotide sequence of the downstream primer is shown in SEQ ID No.

3.

6. The application according to claim 5, characterized in that, The method of application includes the following steps: 1) Detect the SNP molecular markers in replacement breeding sows; 2) Select individuals with the GG or GA genotype at the nucleotide site at chromosome 2, 116767089 of the international pig genome Sscrofa 11.1 version obtained in step 1) as breeding sows, and mate these breeding sows; 3) Test the SNP molecular markers of the sows born from mating in step 2), retain individuals with the GG or GA genotype at the 116767089 nucleotide locus, and cull individuals with the AA genotype at the 116767089 nucleotide locus. Breed these individuals to increase the frequency of the dominant allele G at the 116767089 nucleotide locus generation by generation, thereby improving the litter weight trait of the sow population and increasing the litter weight of the sow population.

7. The application of products containing SNP molecular markers related to litter weight in Large White pigs in early screening of piglet growth and development, characterized by: The SNP molecular marker is an A>G base mutation located at the nucleotide site 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 within the DCP2 gene; the nucleotide sequence of the SNP molecular marker is shown in SEQ ID No. 1; the product includes at least an upstream primer and a downstream primer, the nucleotide sequence of the upstream primer is shown in SEQ ID No. 2, and the nucleotide sequence of the downstream primer is shown in SEQ ID No. 3; the application involves identifying the genotype of the SNP molecular marker in candidate piglets, and retaining and breeding candidate piglets when the allele at the nucleotide site 116767089 on chromosome 2 of the international pig genome Sscrofa 11.1 is GG or GA.

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