A SNP molecular marker for the gene M-SAA3.2 related to milk production traits in dairy cows and its application

Abstract

The present invention discloses a SNP molecular marker for the gene M‑SAA3.2 related to the milk production trait of dairy cows and its application. By performing whole-genome resequencing on 409 dairy cows, the present invention discovered a total of 16 SNP sites correlated with dairy cow traits in the 2000bp upstream and downstream regulatory regions and all exon regions of the M‑SAA3.2 gene, and discovered the dominant genotype of each SNP site through association analysis. The SNP sites and dominant genotypes discovered by the present invention are of great significance for the auxiliary identification and early screening of cattle populations with excellent milk production traits, which is not only conducive to reducing breeding costs, but also conducive to improving the milk production and quality of dairy cows in actual production.

Description

Technical Field

[0001] The present invention relates to the field of molecular biotechnology, and in particular to a SNP molecular marker of a gene M-SAA3.2 related to milk production traits of dairy cows and an application thereof. Background Art

[0002] Serum amyloid A (SAA) is a highly heterogeneous protein in the apolipoprotein family. Five different genes have been identified: SAA1, SAA2, SAA3, SAA4, and M-SAA3.2. Studies have shown that SAA family genes regulate the body by participating in cholesterol metabolism and regulating plasma triglyceride and glucose levels. The M-SAA3.2 gene (ARS-UCD1.2) is located on chromosome 29 in dairy cows. It consists of four exons and three introns, with a sequence length of 3988 base pairs, encoding a protein of 142 amino acids.

[0003] Whole-genome resequencing involves sequencing the genomes of different individuals from a species with a known genome sequence, and then analyzing the differences between individuals or populations. Whole-genome resequencing allows for the identification of numerous single nucleotide polymorphisms, insertions and deletions, and structural variation sites through sequence alignment. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to identify or assist in identifying the milk production traits of dairy cows.

[0005] In order to solve the above technical problems, the present invention first provides a new use of a substance for detecting the polymorphism or genotype of at least one SNP site among 16 SNP sites.

[0006] The present invention provides the use of a substance for detecting the polymorphism or genotype of at least one SNP site among 16 SNP sites in identifying or assisting in identifying the milk production traits of dairy cows.

[0007] The present invention also provides the use of a substance for detecting the polymorphism or genotype of at least one of the 16 SNP sites in the preparation of a product for identifying or assisting in identifying the milk production traits of dairy cows.

[0008] The present invention also provides the use of a substance for detecting the polymorphism or genotype of at least one of the 16 SNP sites in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk fat rate and / or high milk protein content.

[0009] The present invention also provides the use of a substance for detecting the polymorphism or genotype of at least one of the 16 SNP sites in the preparation of a product for screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk fat rate and / or high milk protein content.

[0010] The present invention also provides the use of a substance for detecting the polymorphism or genotype of at least one of the 16 SNP sites in dairy cow breeding.

[0011] The present invention also provides the use of a substance for detecting the polymorphism or genotype of at least one of the 16 SNP sites in the preparation of a product for dairy cow breeding.

[0012] In order to solve the above technical problems, the present invention further provides a method for identifying or assisting in identifying the milk production traits of dairy cows.

[0013] The method for identifying or assisting in identifying the milk production traits of dairy cows provided by the present invention is any one of the following X1) to X16):

[0014] X1) comprising the following steps: detecting whether the genotype of the SNP1 site of the test cow is AA, GG or AG, and judging the milk production traits of the test cow according to the genotype of the SNP1 site: the milk yield, milk fat content and milk protein content of the AA genotype cow are higher than those of the GG genotype cow, and the milk yield, milk fat content and milk protein content of the GG genotype cow are higher than those of the AG genotype cow; the AA genotype is a homozygous type with the SNP1 site being A; the GG genotype is a homozygous type with the SNP1 site being G; and the AG genotype is a heterozygous type with the SNP1 site being A and G;

[0015] X2) comprising the following steps: detecting whether the genotype of the SNP2 site of the test cow is TT, CC or CT, and judging the milk production traits of the test cow according to the genotype of the SNP2 site: the milk production, milk fat content and milk protein content of the TT genotype cow are higher than those of the CC genotype cow, and the milk production, milk fat content and milk protein content of the CC genotype cow are higher than those of the CT genotype cow; the TT genotype is a homozygous type with the SNP2 site being T; the CC genotype is a homozygous type with the SNP1 site being C; and the CT genotype is a heterozygous type with the SNP2 site being C and T;

[0016] X3) comprising the steps of: detecting whether the genotype of the SNP3 site of the test cow is TT, CC or CT, and judging the milk production traits of the test cow according to the genotype of the SNP3 site: the milk fat content and milk protein content of the TT genotype cow are higher than those of the CC genotype cow, and the milk fat content and milk protein content of the CC genotype cow are higher than those of the CT genotype cow; the TT genotype is a homozygous type with the SNP3 site being T; the CC genotype is a homozygous type with the SNP3 site being C; and the CT genotype is a heterozygous type with the SNP3 site being C and T;

[0017] X4) comprising the steps of: detecting whether the genotype of the SNP4 site of the test cow is GG, AA or AG, and judging the milk production traits of the test cow according to the genotype of the SNP4 site: the milk production, milk fat content and milk protein content of the GG genotype cow are higher than those of the AA genotype cow, and the milk production, milk fat content and milk protein content of the AA genotype cow are higher than those of the AG genotype cow; the GG genotype is a homozygous type with the SNP4 site being G; the AA genotype is a homozygous type with the SNP4 site being A; and the AG genotype is a heterozygous type with the SNP4 site being A and G;

[0018] X5) comprising the following steps: detecting whether the genotype of the SNP5 site of the test cow is CC, AA or AC, and judging the milk production traits of the test cow according to the genotype of the SNP5 site: the milk production, milk fat content and milk protein content of the CC genotype cow are higher than those of the AA genotype cow, and the milk production, milk fat content and milk protein content of the AA genotype cow are higher than those of the AC genotype cow; the CC genotype is a homozygous type with the SNP5 site being C; the AA genotype is a homozygous type with the SNP5 site being A; and the AC genotype is a heterozygous type with the SNP5 site being A and C;

[0019] X6) comprising the steps of detecting whether the genotype of the SNP6 site of the test cow is GG, AA or AG, and judging the milk production traits of the test cow according to the genotype of the SNP6 site: the milk production, milk fat content and milk protein content of the GG genotype cow are higher than those of the AA genotype cow, and the milk production, milk fat content and milk protein content of the AA genotype cow are higher than those of the AG genotype cow; the GG genotype is a homozygous type of the SNP6 site being G; the AA genotype is a homozygous type of the SNP6 site being A; and the AG genotype is a heterozygous type of the SNP6 site being A and G;

[0020] X7) comprising the following steps: detecting whether the genotype of the SNP7 site of the test cow is TT, CC or CT, and judging the milk production traits of the test cow according to the genotype of the SNP7 site: the milk production, milk fat content and milk protein content of the TT genotype cow are higher than those of the CC genotype cow, and the milk production, milk fat content and milk protein content of the CC genotype cow are higher than those of the CT genotype cow; the TT genotype is a homozygous type with the SNP7 site being T; the CC genotype is a homozygous type with the SNP7 site being C; and the CT genotype is a heterozygous type with the SNP7 site being C and T;

[0021] X8) comprising the following steps: detecting whether the genotype of the SNP8 site of the test cow is TT, CT or CC, and judging the milk production traits of the test cow according to the genotype of the SNP8 site: the milk production, milk fat content, milk fat rate and milk protein content of the TT genotype cow are higher than those of the CT genotype cow, and the milk production, milk fat content, milk fat rate and milk protein content of the CT genotype cow are higher than those of the CC genotype cow; the TT genotype is a homozygous type with the SNP8 site being T; the CC genotype is a homozygous type with the SNP8 site being C; and the CT genotype is a heterozygous type with the SNP8 site being C and T;

[0022] X9) comprises the following steps: detecting whether the genotype of the SNP9 site of the test cow is GG, AG or AA, and judging the milk production traits of the test cow according to the genotype of the SNP9 site: the milk production, milk fat amount, milk fat rate and milk protein amount of the GG genotype cow are higher than those of the AG genotype cow, and the milk production, milk fat amount, milk fat rate and milk protein amount of the AG genotype cow are higher than those of the AA genotype cow; the GG genotype is a homozygous type of the SNP9 site being G; the AA genotype is a homozygous type of the SNP9 site being A; the AG genotype is a heterozygous type of the SNP9 site being A and G;

[0023] X10) comprises the following steps: detecting whether the genotype of the SNP10 site of the test cow is AA, GG or AG, and judging the milk production traits of the test cow according to the genotype of the SNP10 site: the milk production, milk fat content and milk protein content of the AA genotype cow are higher than those of the GG genotype cow, and the milk production, milk fat content and milk protein content of the GG genotype cow are higher than those of the AG genotype cow; the AA genotype is a homozygous type with the SNP10 site being A; the GG genotype is a homozygous type with the SNP10 site being G; and the AG genotype is a heterozygous type with the SNP10 site being A and G;

[0024] X11) comprising the following steps: detecting whether the genotype of the SNP11 site of the test cow is GG, CC or GC, and judging the milk production traits of the test cow according to the genotype of the SNP11 site: the milk production, milk fat content and milk protein content of the GG genotype cow are higher than those of the CC genotype cow, and the milk production, milk fat content and milk protein content of the CC genotype cow are higher than those of the GC genotype cow; the GG genotype is a homozygous type of the SNP11 site being G; the CC genotype is a homozygous type of the SNP11 site being C; and the GC genotype is a heterozygous type of the SNP11 site being G and C;

[0025] X12) comprising the following steps: detecting whether the genotype of the SNP12 site of the test cow is TT, GG or GT, and judging the milk production traits of the test cow according to the genotype of the SNP12 site: the milk production, milk fat content and milk protein content of the TT genotype cow are higher than those of the GG genotype cow, and the milk production, milk fat content and milk protein content of the GG genotype cow are higher than those of the GT genotype cow; the TT genotype is a homozygous type with the SNP12 site being T; the GG genotype is a homozygous type with the SNP12 site being G; and the GT genotype is a heterozygous type with the SNP12 site being G and T;

[0026] X13) comprises the following steps: detecting whether the genotype of the SNP13 site of the test cow is AA, GG or AG, and judging the milk production traits of the test cow according to the genotype of the SNP13 site: the milk production, milk fat content and milk protein content of the AA genotype cow are higher than those of the GG genotype cow, and the milk production, milk fat content and milk protein content of the GG genotype cow are higher than those of the AG genotype cow; the AA genotype is a homozygous type with the SNP13 site being A; the GG genotype is a homozygous type with the SNP13 site being G; and the AG genotype is a heterozygous type with the SNP13 site being A and G;

[0027] X14) comprises the following steps: detecting whether the genotype of the SNP14 site of the test cow is AA, GG or AG, and judging the milk production traits of the test cow according to the genotype of the SNP14 site: the milk production, milk fat content and milk protein content of the AA genotype cow are higher than those of the GG genotype cow, and the milk production, milk fat content and milk protein content of the GG genotype cow are higher than those of the AG genotype cow; the AA genotype is a homozygous type of the SNP14 site A; the GG genotype is a homozygous type of the SNP14 site G; the AG genotype is a heterozygous type of the SNP14 site A and G;

[0028] X15) comprises the following steps: detecting whether the genotype of the SNP15 site of the test cow is TT, CC or CT, and judging the milk production traits of the test cow according to the genotype of the SNP15 site: the milk production, milk fat content and milk protein content of the TT genotype cow are higher than those of the CC genotype cow, and the milk production, milk fat content and milk protein content of the CC genotype cow are higher than those of the CT genotype cow; the TT genotype is a homozygous type of the SNP15 site being T; the CC genotype is a homozygous type of the SNP15 site being C; and the CT genotype is a heterozygous type of the SNP15 site being C and T;

[0029] X16) includes the following steps: detecting whether the genotype of the SNP16 site of the test cow is CC, GG or GC, and judging the milk production traits of the test cow according to the genotype of the SNP16 site: the milk production, milk fat content and milk protein content of the CC genotype cow are higher than those of the GG genotype cow, and the milk production, milk fat content and milk protein content of the GG genotype cow are higher than those of the GC genotype cow; the CC genotype is a homozygous type with the SNP16 site being C; the GG genotype is a homozygous type with the SNP16 site being G; the GC genotype is a heterozygous type with the SNP16 site being G and C.

[0030] The application of the above method in screening or assisting screening of dairy cows with high milk production and / or high milk fat content and / or high milk fat rate and / or high milk protein content or in dairy cow breeding also falls within the scope of protection of the present invention.

[0031] In order to solve the above technical problems, the present invention also provides a method for screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk fat rate and / or high milk protein content.

[0032] The method for screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk fat rate and / or high milk protein content provided by the present invention is any one of the following Y1) to Y16):

[0033] Y1) comprising the step of selecting a dairy cow whose genotype at the SNP1 site is AA;

[0034] Y2) comprising the step of selecting a dairy cow whose genotype at the SNP2 site is TT;

[0035] Y3) comprising the step of selecting a dairy cow whose genotype at the SNP3 site is TT;

[0036] Y4) comprising the step of selecting a dairy cow whose genotype at the SNP4 site is GG;

[0037] Y5) comprising the step of selecting a dairy cow whose genotype at the SNP5 site is CC;

[0038] Y6) comprising the step of selecting a dairy cow whose genotype at the SNP6 site is GG;

[0039] Y7) comprising the step of selecting a dairy cow whose genotype at the SNP7 site is TT;

[0040] Y8) comprising the step of selecting a dairy cow whose genotype at the SNP8 site is TT;

[0041] Y9) comprising the step of selecting a dairy cow whose genotype at the SNP9 site is GG;

[0042] Y10) comprising the step of selecting a dairy cow whose genotype at the SNP10 site is AA;

[0043] Y11) comprising the step of selecting a dairy cow whose genotype at the SNP11 site is GG;

[0044] Y12) comprising the step of selecting a dairy cow whose genotype at the SNP12 site is TT;

[0045] Y13) comprising the step of selecting a dairy cow whose genotype at the SNP13 site is AA;

[0046] Y14) comprising the step of selecting a dairy cow whose genotype at the SNP14 site is AA;

[0047] Y15) comprising the step of selecting a dairy cow whose genotype at the SNP11 site is TT;

[0048] Y16) includes the step of selecting a dairy cow whose genotype at the SNP12 site is CC.

[0049] In order to solve the above technical problems, the present invention also provides a method for breeding dairy cows.

[0050] The dairy cow breeding method provided by the present invention comprises the step of using dairy cows with high milk production and / or high milk fat content and / or high milk fat rate and / or high milk protein content screened according to the above method as breeding materials for breeding.

[0051] In order to solve the above technical problems, the present invention finally provides a product; the function of the product is any one of the following Z1)-Z3):

[0052] Z1) Identify or assist in identifying the milk production traits of dairy cows;

[0053] Z2) screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk fat percentage and / or high milk protein content;

[0054] Z3) Dairy cattle breeding.

[0055] The product provided by the present invention includes a substance for detecting the polymorphism or genotype of at least one SNP site among 16 SNP sites.

[0056] Any of the above 16 SNP sites is SNP1 site, SNP2 site, SNP3 site, SNP4 site, SNP5 site, SNP6 site, SNP7 site, SNP8 site, SNP9 site, SNP10 site, SNP11 site, SNP12 site, SNP13 site, SNP14 site, SNP15 site and SNP16 site.

[0057] The polymorphism of any of the above-mentioned SNP1 sites is A or G, corresponding to the 114th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0058] The polymorphism of any of the above-mentioned SNP2 sites is C or T, corresponding to the 210th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0059] The polymorphism of any of the above-mentioned SNP3 sites is C or T, corresponding to the 333rd nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0060] The polymorphism of any of the above-mentioned SNP4 sites is A or G, corresponding to the 506th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0061] The polymorphism of any of the above-mentioned SNP5 sites is A or C, corresponding to the 576th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0062] The polymorphism of any of the above-mentioned SNP6 sites is G or A, corresponding to the 797th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0063] The polymorphism of any of the above-mentioned SNP7 sites is C or T, corresponding to the 1814th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0064] The polymorphism of any of the above-mentioned SNP8 sites is C or T, corresponding to the 2626th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0065] The polymorphism of any of the above-mentioned SNP9 sites is A or G, corresponding to the 2627th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0066] The nucleotide at any of the above-mentioned SNP10 sites is G or A, corresponding to the 2672nd nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0067] The polymorphism of any of the above-mentioned SNP11 sites is C or G, corresponding to the 6537th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0068] The polymorphism of any of the above-mentioned SNP12 sites is G or T, corresponding to the 7402nd nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0069] The polymorphism of any of the above-mentioned SNP13 sites is G or A, corresponding to the 7495th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0070] The polymorphism of any of the above-mentioned SNP14 sites is G or A, corresponding to the 7714th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0071] The polymorphism of any of the above-mentioned SNP15 sites is C or T, corresponding to the 7887th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0072] The polymorphism of any of the above-mentioned SNP16 sites is G or C, corresponding to the 7929th nucleotide from the 5' end of SEQ ID No. 1 in the sequence listing.

[0073] Any of the above-mentioned substances for detecting the polymorphism or genotype of at least one of the 16 SNP sites includes substances for detecting the polymorphism or genotype of the above-mentioned SNP1 site and / or the above-mentioned SNP2 site and / or the above-mentioned SNP3 site and / or the above-mentioned SNP4 site and / or the above-mentioned SNP5 site and / or the above-mentioned SNP6 site and / or the above-mentioned SNP7 site and / or the above-mentioned SNP8 site and / or the above-mentioned SNP9 site and / or the above-mentioned SNP10 site and / or the above-mentioned SNP11 site and / or the above-mentioned SNP12 site and / or the above-mentioned SNP13 site and / or the above-mentioned SNP14 site and / or the above-mentioned SNP15 site and / or the above-mentioned SNP16 site.

[0074] Further, the material for detecting the polymorphism or genotype of the above-mentioned SNP1 site and / or the above-mentioned SNP2 site and / or the above-mentioned SNP3 site and / or the above-mentioned SNP4 site and / or the above-mentioned SNP5 site and / or the above-mentioned SNP6 site and / or the above-mentioned SNP7 site and / or the above-mentioned SNP8 site and / or the above-mentioned SNP9 site and / or the above-mentioned SNP10 site and / or the above-mentioned SNP11 site and / or the above-mentioned SNP12 site and / or the above-mentioned SNP13 site and / or the above-mentioned SNP14 site and / or the above-mentioned SNP15 site and / or the above-mentioned SNP16 site can be determined by at least one of the following methods in the genome of the dairy cow: Or the reagents and / or instruments required for the polymorphism or genotype of the above-mentioned SNP2 site and / or the above-mentioned SNP3 site and / or the above-mentioned SNP4 site and / or the above-mentioned SNP5 site and / or the above-mentioned SNP6 site and / or the above-mentioned SNP7 site and / or the above-mentioned SNP8 site and / or the above-mentioned SNP9 site and / or the above-mentioned SNP10 site and / or the above-mentioned SNP11 site and / or the above-mentioned SNP12 site and / or the above-mentioned SNP13 site and / or the above-mentioned SNP14 site and / or the above-mentioned SNP15 site and / or the above-mentioned SNP16 site: DNA sequencing, restriction fragment length polymorphism, single-stranded conformation polymorphism, denaturing high performance liquid chromatography and SNP chip. Among them, the SNP chip includes a chip based on nucleic acid hybridization reaction, a chip based on single base extension reaction, a chip based on allele-specific primer extension reaction, a chip based on "one-step" reaction, a chip based on primer ligation reaction, a chip based on restriction endonuclease reaction, a chip based on protein DNA binding reaction, and a chip based on fluorescent molecule DNA binding reaction. The DNA sequencing includes Sanger sequencing, Roche454 pyrosequencing, Illumina Solexa synthesis sequencing, single molecule fluorescence sequencing, and nanopore sequencing.

[0075] Furthermore, the DNA sequencing is whole genome resequencing.

[0076] In a specific embodiment of the present invention, Shenzhen BGI Genomics Technology Service Co., Ltd. is commissioned to complete whole-genome resequencing of genomic DNA from blood samples of individual test cows. After resequencing, the sequence is aligned to the reference genome to directly obtain the genotype of each of the above-mentioned SNP sites.

[0077] Any of the above-mentioned products may be a reagent or a kit or a system. The system may include a combination product of a reagent or a kit, an instrument and an analysis software, such as a product consisting of PCR primers, an enzyme-linked microplate reader and an online software SNP decoder, or a combination product consisting of PCR primers, an online software SNP decoder and a fluorescence quantitative PCR instrument.

[0078] Any of the above-mentioned milk production traits is milk yield (such as 305-day milk yield), milk fat content (such as 305-day milk fat content), milk fat rate and / or milk protein content (such as 305-day milk protein content).

[0079] The purpose of any of the above-mentioned dairy cow breeding is to cultivate dairy cow breeds with high milk production and / or high milk fat content and / or high milk fat rate and / or high milk protein content.

[0080] Any of the above-mentioned dairy cows can specifically be Chinese Holstein cows.

[0081] By performing whole-genome resequencing on 409 dairy cows, this study discovered 16 SNPs associated with dairy cow traits within the 2000-bp upstream and downstream regulatory regions and all exons of the M-SAA3.2 gene. Association analysis also revealed the dominant genotype for each SNP. The SNPs and dominant genotypes discovered in this study are crucial for assisting in the identification and early screening of herds of cattle with excellent milk production traits, helping to reduce breeding costs and improve milk production and quality in actual dairy production. DETAILED DESCRIPTION

[0082] The present invention will be further described in detail below in conjunction with specific embodiments. The examples provided are only for illustrating the present invention and are not intended to limit the scope of the present invention. The examples provided below can serve as a guide for further improvements by those skilled in the art and are not intended to limit the present invention in any way.

[0083] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.

[0084] The Chinese Holstein cows (cows) in the following examples were from Hebei Shounong Animal Husbandry Development Co., Ltd.

[0085] The data in the following examples are all data of lactation period 1. Lactation period 1 refers to the lactation period after the first parturition.

[0086] The milk yield in the following examples refers to an individual's 305-day milk yield, which refers to the total milk production from the first day of calving to the 305th day. If the actual number of milking days is less than 305, the actual milk production is used as the 305-day milk yield. If the actual number of milking days exceeds 305, milk production after 306 days is not included. Milk yield is determined monthly by the Dairy Herd Improvement (DHI). The 305-day milk yield for that lactation period can be calculated by plotting a milk yield lactation curve using three or more DHI data from the same lactation period.

[0087] The milk fat content in the following examples refers to the individual 305-day milk fat content, where 305-day milk fat content = milk fat rate × 305-day milk production. The milk fat rate is determined by monthly DHI (DHI, Dairy Herd Improvement) measurements. The average milk fat rate for the lactation period can be obtained by plotting a milk fat rate lactation curve using three or more DHI data within the same lactation period.

[0088] The milk protein amount in the following examples refers to the individual 305-day milk protein amount, where 305-day milk protein amount = milk protein rate × 305-day milk production. The milk protein rate is determined by monthly DHI (DHI, Dairy Herd Improvement) measurements. The average milk protein rate for the lactation period can be calculated by plotting a milk protein rate lactation curve using three or more DHI data within the same lactation period.

[0089] Example 1: Discovery of SNPs associated with milk production traits in dairy cows

[0090] 1. Related Basic Research

[0091] The inventor's research group conducted transcriptome sequencing on the mammary tissues of two lactating Chinese Holstein cows with high milk protein and milk fat rates and two with low milk protein and milk fat rates. By integrating and analyzing RNA-Seq, QTL, GWAS and biological function results, they found that SAA family genes are important candidate functional genes affecting milk production traits.

[0092] 2. Genotyping

[0093] A total of 409 Chinese Holstein dairy cows from Hebei Shounong Animal Husbandry Development Co., Ltd. were selected as the experimental population. Genomic DNA was extracted from blood samples of the 409 Chinese Holstein dairy cows. Resequencing was completed by Shenzhen BGI Genomics Technology Service Co., Ltd. to detect SNPs across the entire genome. SNP sites within the 2000 bp upstream and downstream regulatory regions and all exon regions of the M-SAA3.2 gene were extracted, including the following 16 SNPs: SNP1 site (g.26500216A>G), SNP2 site (g.26500312C>T), SNP3 site (g.26500435C>T), SNP4 site (g.26500608A>G), SNP5 site (g.26500678A> C), SNP6 (g.26500899G>A), SNP7 (g.26501916C>T), SNP8 (g.26502728C>T), SNP9 (g.26502729A>G), SNP10 (g.26502774G>A), SNP11 (g.26506639C>G), SNP12 (g.26507504G>T), SNP13 (g.26507597G>A), SNP14 (g.26507816G>A), SNP15 (g.26507958C>T) and SNP16 (g.26508031G>C).

[0094] Among them, the nucleotide at the SNP1 site is A or G, corresponding to the 114th position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at the SNP2 site is C or T, corresponding to the 210th position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at the SNP3 site is C or T, corresponding to the 333rd position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at the SNP4 site is A or G, corresponding to the 506th position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at the SNP5 site is A or C, corresponding to the 576th position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at the SNP6 site is G or A, corresponding to the 797th position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at the SNP7 site is C or T, corresponding to the 1814th position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at the SNP8 site is C or T, corresponding to the 5 The nucleotide at SNP9 is A or G, corresponding to the 2627th position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at SNP10 is G or A, corresponding to the 2672nd position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at SNP11 is C or G, corresponding to the 6537th position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at SNP12 is G or T, corresponding to the 7402nd position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at SNP13 is G or A, corresponding to the 7495th position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at SNP14 is G or A, corresponding to the 7714th position from the 5' end of SEQ ID No.1 in the sequence listing; the nucleotide at SNP15 is C or T, corresponding to the 7714th position from the 5' end of SEQ ID No.1 in the sequence listing No.1 is the 7887th position from the 5' end; the nucleotide at the SNP16 site is G or C, corresponding to the 7929th position from the 5' end of SEQ ID No.1 in the sequence list.

[0095] 3. Correlation Analysis

[0096] 1. Test population

[0097] The experimental group consisted of 409 Chinese Holstein cows.

[0098] 2. Milk production trait testing

[0099] The milk production traits of each cow in the test group were tested. Milk production traits include the following five indicators: milk yield, milk fat content, milk fat percentage, milk protein content, and milk protein percentage. The milk production phenotypes are shown in Tables 1 and 2.

[0100] The records of each individual cow include the cow's individual number, father number, mother number, grandfather number, grandmother number, maternal grandfather number, maternal grandmother number, date of birth, lactation period, calving date, milk production, milk fat content and milk protein content.

[0101] Table 1. Descriptive statistics of phenotypic values ​​of five milk production traits in 409 Chinese Holstein cows

[0102] Traits average value Standard deviation Minimum Maximum Coefficient of variation Milk production (kg) 9978.31 2013.95 1923 14692 0.20 Milk fat content (kg) 405.05 81.12 64.81 595.01 0.20 Milk fat content (%) 4.08 0.43 2.91 5.38 0.11 Milk protein amount (kg) 350.36 68.89 79.80 519.37 0.20 Milk protein rate (%) 3.52 0.21 0.21 4.15 0.06

[0103] Table 2. Phenotypes of some milk production traits of 409 Chinese Holstein cows

[0104]

[0105]

[0106] 3. Association analysis model between single SNP loci and milk production traits

[0107] SNP1 site (g.26500216A>G), SNP2 site (g.26500312C>T), SNP3 site (g.26500435C>T), SNP4 site (g.26500608A>G), SNP5 site (g.26500678A>C), SNP6 site (g.26500899G>A), SNP7 site (g.26501916C>T), SNP8 site (g.26502728C>T), SNP9 site (g.265 The allele frequencies and genotype frequencies of SNP10 (g.26502774G>A), SNP11 (g.26506639C>G), SNP12 (g.26507504G>T), SNP13 (g.26507597G>A), SNP14 (g.26507816G>A), SNP15 (g.26507958C>T) and SNP16 (g.26508031G>C) are shown in Table 3.

[0108] Table 3. Allele frequencies and genotype frequencies of 16 SNP loci

[0109]

[0110]

[0111] The results showed that there were three genotypes at SNP1 (referred to as SNP1 genotypes), namely AA, AG or GG. Genotype AA was the homozygous type of SNP1 A, genotype GG was the homozygous type of SNP1 G, and genotype AG was the heterozygous type of SNP1 A and G. There were three genotypes at SNP2 (referred to as SNP2 genotypes), namely CC, CT or TT. Genotype CC was the homozygous type of SNP2 C, genotype TT was the homozygous type of SNP2 T, and genotype CT was the heterozygous type of SNP2 C and T. There were three genotypes at SNP3 (referred to as SNP3 genotypes), namely CC, CT or TT. Genotype TT was the homozygous type of SNP3 T, and genotype CC was the heterozygous type of SNP3 C. Homozygous type, genotype CT is the heterozygous type of SNP3 T and C; SNP4 site has 3 genotypes (referred to as SNP4 genotype), namely AA, AG or GG, genotype AA is the homozygous type of SNP4 is A, genotype GG is the homozygous type of SNP4 is G, genotype AG is the heterozygous type of SNP4 is A and G; SNP5 site has 3 genotypes (referred to as SNP5 genotype), namely AA, AC or CC, genotype AA is the homozygous type of SNP5 is A, genotype CC is the homozygous type of SNP5 is C, genotype AC is the heterozygous type of SNP5 is A and C; SNP6 site has 3 genotypes (referred to as SNP6 genotype), namely AA, AG or GG, genotype AA is the homozygous type of SNP6 is A The genotype GG is the homozygous type of SNP6 G, and the genotype AG is the heterozygous type of SNP6 A and G; the SNP7 site has three genotypes (referred to as SNP7 genotypes), namely CC, CT or TT, the genotype CC is the homozygous type of SNP7 A, the genotype TT is the homozygous type of SNP7 G, and the genotype CT is the heterozygous type of SNP7 C and T; the SNP8 site has three genotypes (referred to as SNP8 genotypes), namely CC, CT or TT, the genotype CC is the homozygous type of SNP8 C, the genotype TT is the homozygous type of SNP7 G, and the genotype CT is the heterozygous type of SNP7 C and T; the SNP9 site has three genotypes (referred to as SNP9 genotypes), namely AA, AG or GG, genotype AA is the homozygous type of SNP9 for A, genotype GG is the homozygous type of SNP9 for G, and genotype AG is the heterozygous type of SNP9 for A and G; SNP10 site has three genotypes (referred to as SNP10 genotypes), namely AA, AG or GG, genotype AA is the homozygous type of SNP10 for A, genotype GG is the homozygous type of SNP10 for G, and genotype AG is the heterozygous type of SNP10 for A and G; SNP11 site has three genotypes (referred to as SNP11 genotypes), namely CC, CG or GG, genotype CC is the homozygous type of SNP11 for C, genotype GG is the homozygous type of SNP11 for G, and genotype CG is the heterozygous type of SNP11 for C and G;There are three genotypes at the SNP12 site (referred to as SNP12 genotypes), namely TT, TG or GG. Genotype TT is the homozygous type of SNP12 T, genotype GG is the homozygous type of SNP12 G, and genotype TG is the heterozygous type of SNP12 T and G; there are three genotypes at the SNP13 site (referred to as SNP13 genotypes), namely AA, AG or GG. Genotype AA is the homozygous type of SNP13 A, genotype GG is the homozygous type of SNP13 G, and genotype AG is the heterozygous type of SNP13 A and G; there are three genotypes at the SNP14 site (referred to as SNP14 genotypes), namely AA, AG or GG. Genotype AA is the homozygous type of SNP1 4 is the homozygous type for A, genotype GG is the homozygous type for SNP14 is G, and genotype AG is the heterozygous type for SNP14 is A and G; SNP15 has three genotypes (referred to as SNP15 genotypes), namely CC, CT, or TT. Genotype CC is the homozygous type for SNP15 is C, genotype TT is the homozygous type for SNP15 is T, and genotype CT is the heterozygous type for SNP15 is C and T; SNP16 has three genotypes (referred to as SNP16 genotypes), namely CC, CG, or GG. Genotype CC is the homozygous type for SNP16 is C, genotype GG is the homozygous type for SNP16 is G, and genotype CG is the heterozygous type for SNP16 is C and G.

[0112] The MIXED procedure in SAS9.2 software was used to conduct association analysis between the five indicators of milk production and genotypes. The association analysis used an animal model, and the specific model is as follows:

[0113] y=μ+YS+b×M+G+a+e.

[0114] Wherein, Y is the observed value of milk production traits (milk yield, milk fat content, milk fat percentage, milk protein content or milk protein percentage); μ is the overall mean; YS is the year-season effect; b is the regression coefficient of the covariate M; M is the effect of calving age; G is the genotype effect; a is the individual random additive genetic effect; and e is the random residual effect.

[0115] The results of association analysis between 16 SNP sites of the M-SAA3.2 gene and milk production traits are shown in Table 4.

[0116] Table 4. Association analysis between 16 SNPs in the M-SAA3.2 gene and milk production traits (least squares mean ± standard error)

[0117]

[0118]

[0119]

[0120] Note: Data in the same column with different lowercase letters indicate significant differences (P<0.05), and data with different capital letters indicate extremely significant differences (P<0.01); *

[0121] Indicates significant difference (P<0.05), ** indicates extremely significant difference (P<0.01).

[0122] As shown in Table 4, SNP1 locus (g.26500216A>G) was significantly associated with milk yield, milk fat content and milk protein content (P < 0.0001). The milk yield, milk fat content and milk protein content of AA genotype cows were higher than those of GG genotype cows, and the milk yield, milk fat content and milk protein content of GG genotype cows were higher than those of AG genotype cows; SNP2 locus (g.26500312C>T) was significantly associated with milk yield, milk fat content and milk protein content (P < 0.0001). The milk yield, milk fat content and milk protein content of TT genotype cows were higher than those of CC genotype cows, and the milk yield, milk fat content and milk protein content of CC genotype cows were higher than those of CT genotype cows; SNP3 locus ( The SNP4 locus (g.26500608A>G) was extremely significantly associated with milk yield, milk fat content and milk protein content (P≤0.0002), and the milk fat content and milk protein content of TT genotype cows were higher than those of CC genotype cows, and the milk yield, milk fat content and milk protein content of CC genotype cows were higher than those of CT genotype cows; the SNP5 locus (g.26500678A>C) was extremely significantly associated with milk yield, milk fat content and milk protein content (P<0.0001), and the milk yield, milk fat content and milk protein content of GG genotype cows were higher than those of AA genotype cows, and the milk yield, milk fat content and milk protein content of AA genotype cows were higher than those of AG genotype cows; the SNP6 locus (g.26500678A>C) was extremely significantly associated with milk yield, milk fat content and milk protein content The milk production, milk fat and milk protein content of CC genotype dairy cows were significantly higher than those of AA genotype dairy cows, and the milk production, milk fat and milk protein content of AA genotype dairy cows were significantly higher than those of AC genotype dairy cows. SNP6 locus (g.26500899G>A) was significantly associated with milk production, milk fat and milk protein content (P<0.0001). The milk production, milk fat and milk protein content of GG genotype dairy cows were significantly higher than those of AA genotype dairy cows, and the milk production, milk fat and milk protein content of AA genotype dairy cows were significantly higher than those of AG genotype dairy cows. SNP7 locus (g.26501916C>T) was significantly associated with milk production, milk fat and milk protein content (P<0.0 001), the milk yield, milk fat content and milk protein content of TT genotype cows were higher than those of CC genotype cows, and the milk yield, milk fat content and milk protein content of CC genotype cows were higher than those of CT genotype cows; SNP8 locus (g.26502728C>T) was extremely significantly associated with milk yield, milk fat content, milk fat percentage and milk protein content (P≤0.0034), the milk yield, milk fat content, milk fat percentage and milk protein content of TT genotype cows were higher than those of CT genotype cows, and the milk yield, milk fat content, milk fat percentage and milk protein content of CT genotype cows were higher than those of CC genotype cows; SNP9 locus (g.26502729A>G) was extremely significantly associated with milk yield, milk fat content, milk fat percentage and milk protein content (P≤0.0034), the milk production, milk fat content, milk fat percentage and milk protein content of GG genotype cows were higher than those of AG genotype cows, and the milk production, milk fat content, milk fat percentage and milk protein content of AG genotype cows were higher than those of AA genotype cows; SNP10 (g.26502774G>A) was extremely significantly associated with milk production, milk fat content and milk protein content (P≤0.0003), the milk production, milk fat content and milk protein content of AA genotype cows were higher than those of GG genotype cows, and the milk production, milk fat content and milk protein content of GG genotype cows were higher than those of AG genotype cows; SNP11 site (g.26506639C>G) was significantly associated with milk production, milk fat content and milk protein content of AA genotype cows. Milk fat content and milk protein content were extremely significantly correlated (P≤0.0004). The milk yield, milk fat content and milk protein content of GG genotype cows were higher than those of CC genotype cows, and the milk yield, milk fat content and milk protein content of CC genotype cows were higher than those of GC genotype cows. SNP12 (g.26507504G>T) was extremely significantly correlated with milk yield, milk fat content and milk protein content (P<0.0001). The milk yield, milk fat content and milk protein content of TT genotype cows were higher than those of GG genotype cows, and the milk yield, milk fat content and milk protein content of GG genotype cows were higher than those of GT genotype cows. SNP13 (g.26507597G >A) was significantly associated with milk yield, milk fat content and milk protein content (P < 0.0001). The milk yield, milk fat content and milk protein content of AA genotype dairy cows were higher than those of GG genotype dairy cows, and the milk yield, milk fat content and milk protein content of GG genotype dairy cows were higher than those of AG genotype dairy cows. SNP14 (g.26507816G>A) was significantly associated with milk yield, milk fat content and milk protein content (P ≤ 0.0013). The milk yield, milk fat content and milk protein content of AA genotype dairy cows were higher than those of GG genotype dairy cows, and the milk yield, milk fat content and milk protein content of GG genotype dairy cows were higher than those of AG genotype dairy cows. SNP15 (g. SNP16 (g.26507958C>T) was significantly associated with milk yield, milk fat content, and milk protein content (P<0.0001). The milk yield, milk fat content, and milk protein content of cows with the TT genotype were higher than those of cows with the CC genotype, which in turn were higher than those of cows with the CT genotype. SNP16 (g.26508031G>C) was significantly associated with milk yield, milk fat content, and milk protein content (P<0.0001). The milk yield, milk fat content, and milk protein content of cows with the CC genotype were higher than those of cows with the GG genotype, which in turn were higher than those of cows with the GC genotype.

[0123] 4. Analysis of genetic effects

[0124] SAS9.2 software was used to perform significance tests of SNP additive effect, dominant effect and substitution effect.

[0125] The basic calculation formula is as follows: a = (AA-BB) / 2, d = AB-(AA+BB) / 2, α = a+d(qp); a is the additive effect, d is the dominant effect, α is the allele substitution effect; AA, AB, BB are the least square means of the milk production traits of the corresponding genotypes; p is the frequency of allele A, and q is the frequency of allele B.

[0126] The results of the tests for additive effect, dominance effect and allele substitution effect are shown in Table 5 .

[0127] Table 5. Test results of additive effect, dominance effect and substitution effect of 16 SNPs in the M-SAA3.2 gene

[0128]

[0129]

[0130] Note: * indicates significant difference (P<0.05), ** indicates extremely significant difference (P<0.01).

[0131] As shown in Table 5, the additive effect of SNP1 (g.26500216A>G) on milk yield, milk fat content and milk protein content was extremely significant; the additive effect of SNP2 (g.26500312C>T) on milk yield, milk fat content and milk protein content was extremely significant; the additive effect of SNP4 (g.26500608A>G) on milk yield, milk fat content and milk protein content was extremely significant; the additive effect of SNP5 (g.26500678A>C) on milk yield, milk fat content and milk protein content was extremely significant; the additive effect of SNP6 (g.26500899G>A) on milk yield and milk fat content was significant; the additive effect of SNP7 (g.26501916C>T) on milk yield, milk fat content and milk protein content was significant; the additive effect of SNP8 (g.26500608A>G) on milk yield, milk fat content and milk protein content was extremely significant. The SNP site (g.26502728C>T) had a significant additive effect on milk yield, milk fat content, milk fat percentage and milk protein content; the SNP9 site (g.26502729A>G) had a significant additive effect on milk yield, milk fat content, milk fat percentage and milk protein content; the SNP12 site (g.26507504G>T) had an extremely significant additive effect on milk yield, milk fat content and milk protein content; the SNP13 site (g.26507597G>A) had a significant additive effect on milk yield, milk fat content and milk protein content; the SNP15 site (g.26507958C>T) had an extremely significant additive effect on milk yield, milk fat content and milk protein content; the SNP16 site (g.26508031G>C) had an extremely significant additive effect on milk yield, milk fat content and milk protein content. The 12 SNP sites of this gene have significant additive effects on milk yield, milk fat content, milk fat rate and / or milk protein content, indicating that the effects of these mutation sites on the above-mentioned milk production traits can be inherited.

[0132] In summary, the molecular markers discovered in the present invention can be used to assist in identifying dairy cow groups with excellent milk production traits (305-day milk production, milk fat content, milk fat percentage, milk protein content and milk protein percentage). They have the following advantages: simple, rapid, sensitive, reliable, stable and accurate results, and are suitable for the needs of large-scale laboratory group testing.

[0133] The present invention has been described in detail above. It will be apparent to those skilled in the art that the present invention may be practiced over a wide range of parameters, concentrations, and conditions without departing from the spirit and scope of the present invention and without unnecessary experimentation. Although specific embodiments have been given herein, it should be understood that further modifications may be made to the present invention. In summary, this application is intended to encompass any variations, uses, or improvements to the present invention, including those made by conventional techniques known in the art that depart from the scope of the present invention. Applications of the essential features may be made within the scope of the following claims.

Claims

1. For any of the following applications: A1) Use of substances for detecting polymorphism or genotype of SNP1 locus in identifying or assisting in identifying milk yield, milk fat content and milk protein content of dairy cows; A2) Use of substances for detecting polymorphism or genotype of SNP2 locus in identifying or assisting in identifying milk yield, milk fat content and milk protein content of dairy cows; A3) Use of a substance for detecting the polymorphism or genotype of the SNP3 locus in identifying or assisting in identifying the milk fat and milk protein content of dairy cows; A4) Use of a substance for detecting the polymorphism or genotype of the SNP4 locus in identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; A5) Use of a substance for detecting the polymorphism or genotype of the SNP5 locus in identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; A6) Use of a substance for detecting the polymorphism or genotype of the SNP6 locus in identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; A7) Use of a substance for detecting the polymorphism or genotype of the SNP7 locus in identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; A8) Use of a substance for detecting the polymorphism or genotype of the SNP8 locus in identifying or assisting in identifying the milk yield, milk fat content, milk fat percentage, and milk protein content of dairy cows; A9) Use of a substance for detecting the polymorphism or genotype of the SNP9 locus in identifying or assisting in identifying the milk yield, milk fat content, milk fat percentage, and milk protein content of dairy cows; A10) Use of a substance for detecting the polymorphism or genotype of SNP10 in identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; A11) Use of a substance for detecting the polymorphism or genotype of the SNP11 locus in identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; A12) Use of a substance for detecting the polymorphism or genotype of SNP12 in identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; A13) Use of a substance for detecting the polymorphism or genotype of the SNP13 locus in identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; A14) Use of a substance for detecting the polymorphism or genotype of SNP14 in identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; A15) Use of a substance for detecting the polymorphism or genotype of the SNP15 locus in identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; A16) Use of a substance for detecting the polymorphism or genotype of SNP16 in identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; The polymorphism of the SNP1 site is A or G, corresponding to the 114th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP2 site is C or T, corresponding to the 210th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP3 site is C or T, corresponding to the 333rd nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP4 site is A or G, corresponding to the 506th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP5 site is A or C, corresponding to the 576th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP6 site is G or A, corresponding to the 797th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP7 site is C or T, corresponding to the 1814th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP8 site is C or T, corresponding to the 2626th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP9 site is A or G, corresponding to the 2627th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The nucleotide at the SNP10 site is G or A, corresponding to the 2672nd nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP11 site is C or G, corresponding to the 6537th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP12 site is G or T, corresponding to the 7402nd nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP13 site is G or A, corresponding to the 7495th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP14 site is G or A, corresponding to the 7714th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP15 site is C or T, corresponding to the 7887th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP16 site is G or C, corresponding to the 7929th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The dairy cows are Chinese Holstein cows.

2. Any application of B1) to B16) below: B1) Use of a substance for detecting the polymorphism or genotype of the SNP1 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; B2) Use of a substance for detecting the polymorphism or genotype of the SNP2 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; B3) Use of a substance for detecting the polymorphism or genotype of the SNP3 locus in the preparation of a product for identifying or assisting in identifying the milk fat and milk protein content of dairy cows; B4) Use of a substance for detecting the polymorphism or genotype of the SNP4 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; B5) Use of a substance for detecting the polymorphism or genotype of the SNP5 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; B6) Use of a substance for detecting the polymorphism or genotype of the SNP6 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; B7) Use of a substance for detecting the polymorphism or genotype of the SNP7 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; B8) Use of a substance for detecting the polymorphism or genotype of the SNP8 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, milk fat percentage, and milk protein content of dairy cows; B9) Use of a substance for detecting the polymorphism or genotype of the SNP9 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, milk fat percentage, and milk protein content of dairy cows; B10) Use of a substance for detecting the polymorphism or genotype of the SNP10 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; B11) Use of a substance for detecting the polymorphism or genotype of the SNP11 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; B12) Use of a substance for detecting the polymorphism or genotype of the SNP12 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; B13) Use of a substance for detecting the polymorphism or genotype of the SNP13 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; B14) Use of a substance for detecting the polymorphism or genotype of the SNP14 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; B15) Use of a substance for detecting the polymorphism or genotype of the SNP15 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; B16) Use of a substance for detecting the polymorphism or genotype of the SNP16 locus in the preparation of a product for identifying or assisting in identifying the milk yield, milk fat content, and milk protein content of dairy cows; The polymorphism of the SNP1 site is A or G, corresponding to the 114th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP2 site is C or T, corresponding to the 210th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP3 site is C or T, corresponding to the 333rd nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP4 site is A or G, corresponding to the 506th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP5 site is A or C, corresponding to the 576th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP6 site is G or A, corresponding to the 797th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP7 site is C or T, corresponding to the 1814th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP8 site is C or T, corresponding to the 2626th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP9 site is A or G, corresponding to the 2627th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The nucleotide at the SNP10 site is G or A, corresponding to the 2672nd nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP11 site is C or G, corresponding to the 6537th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP12 site is G or T, corresponding to the 7402nd nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP13 site is G or A, corresponding to the 7495th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP14 site is G or A, corresponding to the 7714th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP15 site is C or T, corresponding to the 7887th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP16 site is G or C, corresponding to the 7929th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The dairy cows are Chinese Holstein cows.

3. Use of a substance for detecting the polymorphism or genotype of the 16 SNP sites in claim 1 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk fat percentage and / or high milk protein content; The dairy cows are Chinese Holstein cows.

4. Use of a substance for detecting the polymorphism or genotype of the 16 SNP sites in claim 1 in the preparation of a product for screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk fat percentage and / or high milk protein content; The dairy cows are Chinese Holstein cows.

5. A method for identifying or assisting in identifying milk production traits of dairy cows, comprising any one of the following: X1) to X16): X1) comprising the steps of: detecting whether the genotype of the SNP1 locus of the test cow is AA, GG, or AG, and determining the milk production traits of the test cow according to the genotype of the SNP1 locus: the milk yield, milk fat content, and milk protein content of the AA genotype cow are higher than those of the GG genotype cow, and the milk yield, milk fat content, and milk protein content of the GG genotype cow are higher than those of the AG genotype cow; X2) comprising the steps of: detecting whether the genotype of the SNP2 locus of the test cow is TT, CC, or CT, and determining the milk production traits of the test cow according to the genotype of the SNP2 locus: the milk yield, milk fat content, and milk protein content of the TT genotype cow are higher than those of the CC genotype cow, and the milk yield, milk fat content, and milk protein content of the CC genotype cow are higher than those of the CT genotype cow; X3) comprising the steps of: detecting whether the genotype of the SNP3 locus of the test cow is TT, CC, or CT, and determining the milk production traits of the test cow according to the genotype of the SNP3 locus: the milk fat content and milk protein content of the TT genotype cow are higher than those of the CC genotype cow, and the milk fat content and milk protein content of the CC genotype cow are higher than those of the CT genotype cow; X4) comprising the following steps: detecting whether the genotype of the SNP4 locus of the test cow is GG, AA, or AG, and determining the milk production traits of the test cow according to the genotype of the SNP4 locus: the milk yield, milk fat content, and milk protein content of the GG genotype cow are higher than those of the AA genotype cow, and the milk yield, milk fat content, and milk protein content of the AA genotype cow are higher than those of the AG genotype cow; X5) comprising the steps of: detecting whether the genotype of the SNP5 locus of the test cow is CC, AA, or AC, and determining the milk production traits of the test cow according to the genotype of the SNP5 locus: the milk yield, milk fat content, and milk protein content of the CC genotype cow are higher than those of the AA genotype cow, and the milk yield, milk fat content, and milk protein content of the AA genotype cow are higher than those of the AC genotype cow; X6) comprising the steps of: detecting whether the genotype of the SNP6 locus of the test cow is GG, AA, or AG, and determining the milk production traits of the test cow according to the genotype of the SNP6 locus: the milk yield, milk fat content, and milk protein content of the GG genotype cow are higher than those of the AA genotype cow, and the milk yield, milk fat content, and milk protein content of the AA genotype cow are higher than those of the AG genotype cow; X7) comprising the steps of: detecting whether the genotype of the SNP7 locus of the test cow is TT, CC, or CT, and determining the milk production traits of the test cow according to the genotype of the SNP7 locus: the milk yield, milk fat content, and milk protein content of the TT genotype cow are higher than those of the CC genotype cow, and the milk yield, milk fat content, and milk protein content of the CC genotype cow are higher than those of the CT genotype cow; X8) comprising the steps of: detecting whether the genotype of the SNP8 locus of the test cow is TT, CT, or CC, and judging the milk production traits of the test cow according to the genotype of the SNP8 locus: the milk yield, milk fat content, milk fat percentage, and milk protein content of the TT genotype cow are higher than those of the CT genotype cow, and the milk yield, milk fat content, milk fat percentage, and milk protein content of the CT genotype cow are higher than those of the CC genotype cow; X9) comprising the following steps: detecting whether the genotype of the SNP9 locus of the test cow is GG, AG or AA, and judging the milk production traits of the test cow according to the genotype of the SNP9 locus: the milk yield, milk fat amount, milk fat percentage and milk protein amount of the GG genotype cow are higher than those of the AG genotype cow, and the milk yield, milk fat amount, milk fat percentage and milk protein amount of the AG genotype cow are higher than those of the AA genotype cow; X10) comprising the following steps: detecting whether the genotype of the SNP10 site of the test cow is AA, GG, or AG, and judging the milk production traits of the test cow according to the genotype of the SNP10 site: the milk yield, milk fat content, and milk protein content of the AA genotype cow are higher than those of the GG genotype cow, and the milk yield, milk fat content, and milk protein content of the GG genotype cow are higher than those of the AG genotype cow; X11) comprising the steps of: detecting whether the genotype of the SNP11 site of the test cow is GG, CC, or GC, and determining the milk production traits of the test cow according to the genotype of the SNP11 site: the milk yield, milk fat content, and milk protein content of the GG genotype cow are higher than those of the CC genotype cow, and the milk yield, milk fat content, and milk protein content of the CC genotype cow are higher than those of the GC genotype cow; X12) comprising the steps of: detecting whether the genotype of the SNP12 locus of the test cow is TT, GG, or GT, and determining the milk production traits of the test cow according to the genotype of the SNP12 locus: the milk yield, milk fat content, and milk protein content of the TT genotype cow are higher than those of the GG genotype cow, and the milk yield, milk fat content, and milk protein content of the GG genotype cow are higher than those of the GT genotype cow; X13) comprising the steps of: detecting whether the genotype of the SNP13 site of the test cow is AA, GG, or AG, and determining the milk production traits of the test cow according to the genotype of the SNP13 site: the milk yield, milk fat content, and milk protein content of the AA genotype cow are higher than those of the GG genotype cow, and the milk yield, milk fat content, and milk protein content of the GG genotype cow are higher than those of the AG genotype cow; X14) comprising the following steps: detecting whether the genotype of the SNP14 site of the test cow is AA, GG or AG, and judging the milk production traits of the test cow according to the genotype of the SNP14 site: the milk yield, milk fat content and milk protein content of the AA genotype cow are higher than those of the GG genotype cow, and the milk yield, milk fat content and milk protein content of the GG genotype cow are higher than those of the AG genotype cow; X15) comprising the following steps: detecting whether the genotype of the SNP15 site of the test cow is TT, CC or CT, and judging the milk production traits of the test cow according to the genotype of the SNP15 site: the milk yield, milk fat content and milk protein content of the TT genotype cow are higher than those of the CC genotype cow, and the milk yield, milk fat content and milk protein content of the CC genotype cow are higher than those of the CT genotype cow; X16) comprising the following steps: detecting whether the genotype of the SNP16 site of the test dairy cow is CC, GG or GC, and judging the milk production traits of the test dairy cow according to the genotype of the SNP16 site: the milk yield, milk fat content and milk protein content of the CC genotype dairy cow are higher than those of the GG genotype dairy cow, and the milk yield, milk fat content and milk protein content of the GG genotype dairy cow are higher than those of the GC genotype dairy cow; The polymorphism of the SNP1 site is A or G, corresponding to the 114th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP2 site is C or T, corresponding to the 210th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP3 site is C or T, corresponding to the 333rd nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP4 site is A or G, corresponding to the 506th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP5 site is A or C, corresponding to the 576th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP6 site is G or A, corresponding to the 797th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP7 site is C or T, corresponding to the 1814th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP8 site is C or T, corresponding to the 2626th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP9 site is A or G, corresponding to the 2627th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The nucleotide at the SNP10 site is G or A, corresponding to the 2672nd nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP11 site is C or G, corresponding to the 6537th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP12 site is G or T, corresponding to the 7402nd nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP13 site is G or A, corresponding to the 7495th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP14 site is G or A, corresponding to the 7714th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP15 site is C or T, corresponding to the 7887th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP16 site is G or C, corresponding to the 7929th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The dairy cows are Chinese Holstein cows.

6. Any application of Y1) to Y16) below: Y1) Use of the method described in X1) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; Y2) Use of the method described in X2) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; Y3) Use of the method described in X3) of claim 5 in screening or assisting in screening dairy cows with high milk fat content and / or high milk protein content; Y4) Use of the method described in X4) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; Y5) Use of the method described in X5) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; Y6) Use of the method described in X6) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; Y7) Use of the method described in X1) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; Y8) Use of the method described in X8) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk fat percentage and / or high milk protein content; Y9) Use of the method described in X9) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk fat percentage and / or high milk protein content; Y10) Use of the method described in X10) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; Y11) Use of the method described in X11) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; Y12) Use of the method described in X12) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; Y13) Use of the method described in X13) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; Y14) Use of the method described in X14) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; Y15) Use of the method described in X15) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; Y16) Use of the method described in X16) of claim 5 in screening or assisting in screening dairy cows with high milk production and / or high milk fat content and / or high milk protein content; The dairy cows are Chinese Holstein cows.

7. Use any of the following methods: Z1)-Z16): Z1) A method for screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with an AA genotype at the SNP1 locus; Z2) A method for selecting or assisting in selecting dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with a genotype of TT at the SNP2 locus; Z3) A method for screening or assisting in screening dairy cows with high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with a genotype of TT at the SNP3 locus; Z4) A method for screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with a genotype of GG at the SNP4 locus; Z5) A method for screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with a genotype of CC at the SNP5 locus; Z6) A method for screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with a genotype of GG at the SNP6 locus; Z7) A method for screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with a genotype of TT at the SNP7 locus; Z8) A method for screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk fat percentage and / or high milk protein content, comprising the step of selecting dairy cows with a genotype of TT at SNP8; Z9) A method for screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk fat percentage and / or high milk protein content, comprising the step of selecting dairy cows with a genotype of GG at the SNP9 locus; Z10) A method for screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with an AA genotype at SNP10; Z11) A method for screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with a genotype of GG at the SNP11 locus; Z12) A method for selecting or assisting in selecting dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with a genotype of TT at SNP12; Z13) A method for screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with an AA genotype at SNP13; Z14) A method for selecting or assisting in selecting dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with an AA genotype at SNP14; Z15) A method for screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with a genotype of TT at the SNP15 locus; Z16) A method for screening or assisting in screening dairy cows with high milk yield and / or high milk fat content and / or high milk protein content, comprising the step of selecting dairy cows with a CC genotype at SNP16; The polymorphism of the SNP1 site is A or G, corresponding to the 114th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP2 site is C or T, corresponding to the 210th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP3 site is C or T, corresponding to the 333rd nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP4 site is A or G, corresponding to the 506th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP5 site is A or C, corresponding to the 576th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP6 site is G or A, corresponding to the 797th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP7 site is C or T, corresponding to the 1814th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP8 site is C or T, corresponding to the 2626th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP9 site is A or G, corresponding to the 2627th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The nucleotide at the SNP10 site is G or A, corresponding to the 2672nd nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP11 site is C or G, corresponding to the 6537th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP12 site is G or T, corresponding to the 7402nd nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP13 site is G or A, corresponding to the 7495th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP14 site is G or A, corresponding to the 7714th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP15 site is C or T, corresponding to the 7887th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The polymorphism of the SNP16 site is G or C, corresponding to the 7929th nucleotide from the 5' end of SEQ ID No. 1 in the sequence list; The dairy cows are Chinese Holstein cows.

8. A method for breeding dairy cows, comprising the step of breeding dairy cows screened according to the method of claim 7 as breeding materials; the dairy cows are Chinese Holstein cows.

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