SNP molecular marker of gene AKT3 related to milk production traits in dairy cows and its application

Abstract

The present invention discloses a single-nucleotide polymorphism (SNP) molecular marker for the gene AKT3, which is associated with milk production in dairy cows, and its application. One technical solution protected by the present invention is the use of a substance that detects the polymorphism or genotype of SNP1 in identifying or assisting in the identification of milk production traits in dairy cows. Experiments have demonstrated that SNP1-related molecular markers and corresponding genotypes can be used for early prediction and screening of milk production traits in dairy cows, facilitating the selection and breeding of high-milk-producing dairy cows.

Description

Technical Field

[0001] The present invention relates to a SNP molecular marker of a gene AKT3 related to milk production traits of dairy cows and application thereof in the field of molecular biotechnology. Background Art

[0002] Serine / threonine protein kinase (AKT), also known as protein kinase B (PKB), is a founding member of the protein kinase family consisting of AKT1, AKT2, and AKT3. It is involved in mediating a variety of biological responses, including inhibiting apoptosis and stimulating cell growth, and is involved in regulating cellular signaling by insulin and growth factors. AKT is a key downstream target of phosphatidylinositol 3-kinase (PI3K), mediating key functions of the PI3K pathway by phosphorylating and regulating apoptotic proteins and transcription factors. Numerous studies have demonstrated that AKT plays an important role in regulating various cellular functions. The AKT3 gene is expressed differently in the mammary gland of dairy cows at different stages of lactation. It regulates lactation by participating in the mTOR, AMPK, and insulin receptor signaling networks, with increased expression in early lactation (day 15).

[0003] Invented in 1983 by Mullis et al. in the United States, the polymerase chain reaction (PCR) is a rapid nucleic acid amplification technique that simulates the natural DNA replication process in vitro. Its greatest feature is its ability to significantly increase trace amounts of DNA. PCR utilizes the fact that DNA denatures into single strands at high temperatures in vitro. At low temperatures, primers pair with the single strands based on complementary bases. The temperature is then adjusted to the optimal reaction temperature for DNA polymerase, which synthesizes complementary strands along the phosphate-to-pentose (5'-3') direction. Currently, this technique has become one of the most commonly used and important molecular biology techniques. PCR products can be sequenced after agarose gel electrophoresis to identify genetic polymorphisms, making the detection method simple and easy. 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 or how to breed dairy cows.

[0005] In order to solve the above technical problems, the present invention first provides the use of a substance for detecting the polymorphism or genotype of SNP1 in identifying or assisting in identifying the milk production traits of dairy cows; the SNP1 is a SNP in the dairy cow genome, which is the 264th nucleotide of SEQ ID No.1 in the sequence list, which is T or C.

[0006] In order to solve the above technical problems, the present invention also provides the use of a substance for detecting the polymorphism or genotype of SNP1 in the preparation of a product for identifying or assisting in identifying the milk production traits of dairy cows; the SNP1 is a SNP in the dairy cow genome, which is the 264th nucleotide of SEQ ID No.1 in the sequence list, which is T or C.

[0007] In order to solve the above technical problems, the present invention also provides the use of a substance for detecting the polymorphism or genotype of SNP1 in dairy cow breeding or preparing dairy cow breeding products; the SNP1 is a SNP in the dairy cow genome, which is the 264th nucleotide of SEQID No.1 in the sequence list, which is T or C.

[0008] The milk production traits of dairy cows may be any one of milk yield, milk fat content, milk fat rate, milk protein content and milk protein rate and / or a combination of multiple ones.

[0009] The genotype (ie, allele) of the SNP1 may be genotype TT, genotype CC, or genotype CT. Genotype TT is a homozygous type of SNP1 T, genotype CC is a homozygous type of SNP1 C, and genotype CT is a heterozygous type of SNP1 T and C.

[0010] To solve the above technical problems, the present invention also provides a product, which contains the above-mentioned product for detecting the SNP1 polymorphism or genotype of the cow genome, and can be any one of the following G1)-G3):

[0011] G1) Products for detecting single nucleotide polymorphisms or genotypes related to milk production traits in dairy cows;

[0012] G2) Products that identify or assist in identifying the milk production traits of dairy cows;

[0013] G3) Products for dairy cattle breeding.

[0014] The milk production traits may be milk fat content and / or milk protein content, milk yield and / or milk fat percentage.

[0015] In order to solve the above technical problems, the present invention also provides a method for identifying or assisting in identifying the milk production traits of dairy cows, detecting the genotype of the SNP1 in the tested dairy cows, and identifying or assisting in identifying the milk production traits of the dairy cows based on the genotype of the SNP in the tested dairy cows:

[0016] The milk fat content of cows with the CC genotype of SNP1 is higher or potentially higher than that of cows with the TT or CT genotypes, and there is no significant difference in milk fat content between cows with the TT genotype and cows with the CT genotype; the CC is a homozygous type of SNP1 with C; the TT is a homozygous type of SNP1 with T; and the CT is a heterozygous type of SNP1 with C and T.

[0017] The present invention also provides a method for breeding dairy cows, comprising selecting a dairy cow whose SNP1 genotype is CC as a parent for breeding; the SNP1 is a SNP in the dairy cow genome, which is the 264th nucleotide of SEQ ID No.1 in the sequence table, which is C or T, and the CC is the homozygous type of the SNP1 being C.

[0018] The dairy cow breeding mentioned above is to cultivate dairy cow breeds with high milk composition.

[0019] The milk components mentioned above may specifically be milk yield, milk fat content, milk fat rate, milk protein content and / or milk protein rate.

[0020] In the above applications and methods, the substance for detecting the polymorphism or genotype of the SNP1 can be used to determine the nucleotide type of the SNP1 in the above cow genome by at least one of the following methods: DNA sequencing, restriction fragment length polymorphism, single-strand 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.

[0021] In the above application or method, the substance for detecting the SNP1 polymorphism or genotype may be the following: D1), D2) or D3):

[0022] D1) containing PCR primers for amplifying a dairy cow genomic DNA fragment including the SNP1;

[0023] D2) a PCR reagent containing the PCR primers described in D1);

[0024] D3) A kit containing the PCR primers described in D1) or the PCR reagents described in D2).

[0025] The PCR primers are a primer set consisting of the single-stranded DNA represented by positions 1 to 21 of SEQ ID No. 1 in the sequence listing and the single-stranded DNA reversely complementary to positions 759 to 780 of SEQ ID No. 1.

[0026] In the above applications and methods, the PCR primers may or may not be labeled with a label. The label refers to any atom or molecule that can be used to provide a detectable effect and can be attached to a nucleic acid. Labels include but are not limited to dyes; radioactive labels such as 32P; a binding moiety such as biotin; a hapten such as digoxigenin (DIG); a luminescent, phosphorescent or fluorescent moiety; and a fluorescent dye alone or in combination with a moiety that can inhibit or shift the emission spectrum by fluorescence resonance energy transfer (FRET). The label can provide a signal that can be detected by fluorescence, radioactivity, colorimetry, gravimetry, X-ray diffraction or absorption, magnetism, enzymatic activity, etc. The label can be a charged moiety (positive or negative) or, alternatively, can be charge neutral. The label can include a nucleic acid or protein sequence or a combination thereof, as long as the sequence comprising the label is detectable. In some embodiments, the nucleic acid is directly detected (e.g., directly reading the sequence) without a label.

[0027] In the above applications and methods, the product may be a reagent, a kit, or a system. The system may include a combination of a reagent or kit, an instrument, and analytical software, such as a product consisting of PCR primers, a PARMS master mix reagent, a microplate reader, and the online software SNP decoder (http: / / www.snpway.com / snpdecoder01 / ), or a combination product consisting of PCR primers, a PARMS master mix reagent, the online software SNP decoder, and a fluorescence quantitative PCR instrument. The product may include the above-mentioned substance for detecting the polymorphism or genotype of the SNP1 and / or SNP2 and / or SNP3 sites in the cow genome.

[0028] In the examples of the present invention, genetic variation analysis of the AKT3 gene in a related population of dairy cows revealed that SNP1 is located in the AKT3 gene, a gene associated with milk production in the dairy cow genome, and its 2000 bp upstream flanking sequence, i.e., position 264 of SEQ ID No. 1 in the sequence listing. In the examples of the present invention, the dominant allele at the SNP1 site is C, indicating that the SNP1 site can be used for molecular marker-assisted selection breeding of dairy cows and the selection of high-milk-producing dairy cow breeds. DETAILED DESCRIPTION

[0029] 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.

[0030] 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.

[0031] The Chinese Holstein cattle in the following examples were obtained from the Beijing Dairy Center.

[0032] The data in the examples are all data of lactation period 1. Lactation period 1 refers to the lactation period after the first parturition.

[0033] The milk yield in the examples refers to the individual 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 by monthly DHI (Dairy Herd Improvement) measurements. 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.

[0034] The milk fat content in the examples refers to the 305-day milk fat content, which is calculated as milk fat percentage x 305-day milk production. Milk fat percentage is determined by measuring the monthly Dairy Herd Improvement (DHI). The average milk fat percentage for a lactation period can be calculated by plotting a milk fat percentage lactation curve using three or more DHI data points within the same lactation period.

[0035] The milk protein content in the examples refers to the 305-day milk protein content, which is calculated as milk protein rate x 305-day milk production. The milk protein rate is determined by measuring the monthly Dairy Herd Improvement (DHI). The average milk protein rate for a lactation period can be calculated by plotting a milk protein rate lactation curve using three or more DHI data from the same lactation period.

[0036] Example 1. Discovery of molecular markers

[0037] 1. Related Basic Research

[0038] The inventor's research group used liver tissues from three Chinese Holstein cows at different lactation stages (dry period, early lactation, and peak lactation) as experimental materials and conducted proteomic analysis, finding significant differences in AKT3 expression across different lactation stages (P < 0.05).

[0039] 2. Gene polymorphism detection

[0040] 1. A total of 45 Chinese Holstein bulls in the Beijing area were selected as the test population for genetic polymorphism detection. Genomic DNA was extracted from semen samples of these 45 Chinese Holstein bulls. The DNA concentration was accurately measured using a nucleic acid quality detector. The DNA was diluted to a concentration of 50 ng / μL, and equal amounts of DNA were mixed and used as templates for PCR amplification.

[0041] 2. Based on the bovine AKT3 gene sequence and the sequences of its upstream and downstream regulatory regions, 25 pairs of primers were designed as shown in Table 1.

[0042] Table 1 AKT3 gene PCR amplification primer sequence information

[0043]

[0044]

[0045] 3. Using the pooled DNA obtained in step 1 as a template, perform PCR amplification using each primer pair to obtain a PCR amplification product. The PCR reaction system is shown in Table 2, and the PCR reaction conditions are shown in Table 3.

[0046] Table 2 PCR reaction system

[0047]

[0048] Table 3 PCR reaction conditions

[0049]

[0050] 4. Sequencing of the PCR amplified products revealed one SNP marker (designated SNP1) in the upstream 2000 bp flanking sequence of the AKT3 gene in the bull population; one SNP marker (designated SNP2) in intron 1 between exons 1 and 2; and one SNP marker (designated SNP3) in intron 6 between exons 6 and 7. The three SNP markers are listed in Table 4.

[0051] Table 4 Three SNPs found in the AKT3 gene

[0052] Gene location name SNPs physical location Polymorphic Form 5' regulatory region SNP1 g.33367767T>C Chr16:33367767bp T / C Intron 1 SNP2 g.33417238C>T Chr16:33417238bp C / T Intron 6 SNP3 g.33551706T>C Chr16:33551706bp T / C

[0053] Among them, SNP1 corresponds to g.33367767T>C, and was obtained by sequencing analysis of the product obtained by PCR amplification using a primer pair consisting of 3F and 3R (the PCR amplification product is shown in SEQ ID No. 1). Its nucleotide is T or C, corresponding to position 264 of SEQ ID No. 1 in the sequence listing, and is represented by Y. SNP2 corresponds to g.33417238C>T, and was obtained by sequencing analysis of the product obtained by PCR amplification using a primer pair consisting of 4F and 4R (the PCR amplification product is shown in SEQ ID No. 2). Its nucleotide is C or T, corresponding to position 110 of SEQ ID No. 2 in the sequence listing, and is represented by Y. SNP3 corresponds to g.33551706T>C, and was obtained by sequencing analysis of the product obtained by PCR amplification using a primer pair consisting of 9F and 9R (the PCR amplification product is shown in SEQ ID No. 3). Its nucleotide is T or C, corresponding to position 111 of SEQ ID No. 3 in the sequence listing, and is represented by Y.

[0054] g.33367767T>C, g.33417238C>T, and g.33551706T>C are the names of SNP1, SNP2, and SNP3, respectively. SNP naming is generally based on the rules used when the SNP was first discovered. Therefore, in the present invention, the polymorphic form of g.33367767T>C is T or C, the polymorphic form of g.33417238C>T is C or T, and the polymorphic form of g.33551706T>C is T or C.

[0055] 3. Correlation Analysis

[0056] (1) Obtaining the test population

[0057] The experimental group consisted of 944 Chinese Holstein cows.

[0058] (2) Genotyping

[0059] Each individual in the test group was genotyped separately.

[0060] I. Genotyping based on g.33367767T>C.

[0061] 1. Take blood from the test individual and extract genomic DNA.

[0062] 2. Using genomic DNA as a template, PCR amplification was performed using a primer pair consisting of 3F (as shown in positions 1-21 of SEQ ID No. 1) and 3R (reverse complementary to the sequence of positions 759-780 of SEQ ID No. 1), and then the PCR amplification product was recovered and sequenced.

[0063] The reaction system for PCR amplification is shown in Table 5. The reaction conditions for PCR amplification are shown in Table 6.

[0064] The PCR amplification products of each test individual were all 780 bp, wherein the 264th position was g.33367767T>C, namely SNP1 (corresponding to the 264th position from the 5' end of SEQ ID No. 1 in the sequence listing).

[0065] Table 5 PCR reaction system

[0066]

[0067] Table 6 PCR reaction conditions

[0068]

[0069] II. Genotyping based on g.33417238C>T.

[0070] 1. Take blood from the test individual and extract genomic DNA.

[0071] 2. Using genomic DNA as a template, PCR amplification was performed using a primer pair consisting of 4F (as shown in positions 1-25 of SEQ ID No. 2) and 4R (reverse complementary to the sequence of positions 219-240 of SEQ ID No. 2), and then the PCR amplification product was recovered and sequenced.

[0072] The reaction system for PCR amplification is shown in Table 7. The reaction conditions for PCR amplification are shown in Table 8.

[0073] The PCR amplification products of each test individual were all 240 bp, wherein the 110th position was g.33417238C>T, namely SNP2 (corresponding to the 110th position from the 5' end of SEQ ID No. 2 in the sequence listing).

[0074] Table 7 PCR reaction system

[0075]

[0076] Table 8 PCR reaction conditions

[0077]

[0078] III Genotyping based on g.33551706T>C.

[0079] 1. Take blood from the test individual and extract genomic DNA.

[0080] 2. Using genomic DNA as a template, PCR amplification was performed using a primer pair consisting of 9F (as shown in positions 1-23 of SEQ ID No. 3) and 9R (reverse complementary to the sequence of positions 318-339 of SEQ ID No. 3), and then the PCR amplification product was recovered and sequenced.

[0081] The reaction system for PCR amplification is shown in Table 9. The reaction conditions for PCR amplification are shown in Table 10.

[0082] The PCR amplification products of each test individual were all 339 bp, wherein the 111th position was g.33551706T>C, namely SNP3 (corresponding to the 111th position from the 5' end of SEQ ID No. 3 in the sequence listing).

[0083] Table 9 PCR reaction system

[0084]

[0085] Table 10 PCR reaction conditions

[0086]

[0087]

[0088] (3) Detection of milk production traits

[0089] Each cow in the test group was tested for milk production traits.

[0090] Milk production traits include the following five indicators: milk yield, milk fat content, milk fat rate, milk protein content and milk protein rate.

[0091] The records of each individual 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.

[0092] (IV) Association analysis model between single SNP loci and traits

[0093] The genotypes and milk production phenotypes of the SNP1 site (i.e., AKT3 gene g.33367767T>C), SNP2 site (i.e., AKT3 gene g.33417238C>T), and SNP3 site (i.e., AKT3 gene g.33551706T>C) are shown in Tables 11, 12, and 13.

[0094] Table 11 Phenotypes of some milk production traits and genotypes of three SNP loci in 944 Chinese Holstein cows

[0095]

[0096]

[0097]

[0098] Table 12 Descriptive statistics of phenotypic values of five milk production traits in a population of 944 Chinese Holstein cows

[0099] Traits average value Standard deviation Minimum Maximum Coefficient of variation Milk production (kg) 10941.36 1858.38 4925.97 16512.08 0.17 Milk fat content (kg) 395.10 83.57 145.05 658.25 0.21 Milk protein amount (kg) 325.04 57.36 137.86 467.03 0.18 Milk fat content (%) 3.62 0.51 2.21 5.43 0.14 Milk protein rate (%) 2.97 0.19 2.20 3.54 0.07

[0100] Table 13 Allele frequencies and genotype frequencies of the three SNP sites in the AKT3 gene

[0101]

[0102] The results showed that there were three genotypes at the SNP1 site (referred to as SNP1 genotypes), namely TT, TC or CC. Genotype TT was the homozygous type of SNP1 with T, genotype CC was the homozygous type of SNP1 with C, and genotype CT was the heterozygous type of SNP1 with T and C. There were three genotypes at the SNP2 site (referred to as SNP2 genotypes), namely CC, TT or CT. Genotype CC was the homozygous type of SNP2 with C, genotype TT was the homozygous type of SNP2 with T, and genotype CT was the heterozygous type of SNP2 with C and T. There were three genotypes at the SNP3 site (referred to as SNP3 genotypes), namely TT, TC or CC. Genotype TT was the homozygous type of SNP3 with T, genotype CC was the homozygous type of SNP3 with C, and genotype CT was the heterozygous type of SNP3 with T and C.

[0103] The MIXED procedure in SAS 9.2 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:

[0104] Y=μ+hys+b×M+G+a+e

[0105] Where 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; hys is the field year and 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.

[0106] The results of the association analysis between SNP1 site (i.e., AKT3 gene g.33367767T>C) and milk production traits are shown in Table 14.

[0107] Table 14 Association analysis between AKT3 gene g.33367767T>C and milk production traits (least squares mean ± standard error)

[0108] genotype Milk production (kg) Milk fat content (kg) Milk fat content (%) Milk protein amount (kg) Milk protein rate (%) CC(154) 10340±81.2617 <![CDATA[347.07±3.473 A ]]> 3.3763±0.03307 304.7±2.5302 2.9638±0.02329 CT(469) 10215±61.9918 <![CDATA[337.58±2.743 B ]]> 3.3292±0.02552 301.24±1.9969 2.9641±0.01906 TT(321) 10283±66.2605 <![CDATA[338.73±2.9128 B ]]> 3.3186±0.02722 303.37±2.1209 2.9659±0.02011 P-value 0.1435 0.0035** 0.1572 0.1564 0.9908

[0109] Note: ** P<0.01 indicates that the difference is extremely significant. A,B Data in the same column with different superscripts indicate extremely significant differences.

[0110] As shown in Table 14, SNP1 (g.33367767T>C) was extremely significantly associated with milk fat yield (P=0.0035). For the milk fat yield trait, the dominant allele was C. The milk fat yield of CC genotype cows was higher than that of TT or CT genotype cows, and there was no significant difference in milk fat yield between TT genotype cows and CT genotype cows.

[0111] The results of the association analysis between SNP2 site (i.e., AKT3 gene g.33417238C>T) and milk production traits are shown in Table 15.

[0112] Table 15 Association analysis between AKT3 gene g.33417238C>T and milk production traits (least squares mean ± standard error)

[0113] genotype Milk production (kg) Milk fat content (kg) Milk fat content (%) Milk protein amount (kg) Milk protein rate (%) CC(341) 10217±67.3455 339.12±2.9486 3.3442±0.02763 <![CDATA[301.87±2.1471 b ]]> 2.973±0.02026 CT(449) 10251±62.2478 339.34±2.7504 3.3308±0.02561 <![CDATA[301.65±2.0024 b ]]> 2.9568±0.01908 TT(154) 10358±79.7972 340.14±3.4288 3.3139±0.03253 <![CDATA[306.41±2.4977 a ]]> 2.9729±0.02312 P-value 0.1765 0.9452 0.6096 0.061 0.4211

[0114] As shown in Table 15, there was no significant correlation between SNP2 (g.33417238C>T) and milk yield, milk fat content, milk fat percentage, milk protein content or milk protein percentage.

[0115] The results of the association analysis between SNP3 site (i.e., AKT3 gene g.33551706T>C) and milk production traits are shown in Table 16.

[0116] Table 16 Association analysis between AKT3 gene g.33551706T>C and milk production traits (least squares mean ± standard error)

[0117] genotype Milk production (kg) Milk fat content (kg) Milk fat content (%) Milk protein amount (kg) Milk protein rate (%) CC(18) 10530±182.04 335.68±7.4222 3.2019±0.07296 <![CDATA[304.67±5.413 ab ]]> 2.908±0.0471 CT(259) 10217±69.602 337.96±3.0373 3.3293±0.02852 <![CDATA[300.02±2.2118 b ]]> 2.951±0.02084 TT(667) 10268±60.0028 340.15±2.6728 3.338±0.02476 <![CDATA[303.52±1.9456 a ]]> 2.9726±0.0187 P-value 0.1763 0.5819 0.164 0.1036 0.1684

[0118] As shown in Table 16, there was no significant correlation between SNP3 (g.33551706T>C) and milk yield, milk fat content, milk fat percentage, milk protein content or milk protein percentage.

[0119] (V) Analysis of genetic effects

[0120] SAS 9.2 software was used to perform significance tests of SNP additive effect, dominant effect and substitution effect.

[0121] The basic calculation formula is as follows:

[0122] 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.

[0123] The results of the tests for additive effect, dominance effect and allele substitution effect are shown in Table 17.

[0124] Table 17 Test results of additive effect, dominance effect and substitution effect of AKT3 gene alleles

[0125]

[0126] Note: * P<0.05 indicates significant difference; ** P<0.01 indicates that the difference is extremely significant.

[0127] The results showed that SNP1 (g.33367767T>C) had extremely significant additive effect, dominant effect and allele substitution effect on milk fat content.

[0128] The molecular markers disclosed 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: simplicity, speed, sensitivity, reliable, stable and accurate results, and are suitable for the needs of large-scale laboratory group testing.

[0129] 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.

[0130]

[0131]

Claims

1. Application, characterized by: The application is the use of a substance for detecting the polymorphism or genotype of SNP1 in identifying or assisting in identifying the milk production trait of dairy cows; the SNP1 is a SNP in the dairy cow genome, which is the 264th nucleotide of SEQ ID No.1 in the sequence list, which is T or C; the dairy cow is a Holstein cow; and the milk production trait is milk fat content.

2. Application, characterized by: The application is the use of a substance for detecting the polymorphism or genotype of SNP1 in the preparation of a product for identifying or assisting in identifying the milk production trait of a dairy cow; the SNP1 is a SNP in the dairy cow genome, which is the 264th nucleotide of SEQ ID No. 1 in the sequence list, which is T or C; the dairy cow is a Holstein cow; and the milk production trait is milk fat content.

3. Application, characterized by: The application is the use of a substance for detecting the polymorphism or genotype of SNP1 in dairy cow breeding or the preparation of dairy cow breeding products; the SNP1 is a SNP in the dairy cow genome, which is the 264th nucleotide of SEQ ID No.1 in the sequence list, which is T or C; the dairy cow is a Holstein cow; the dairy cow breeding is to cultivate a dairy cow breed with high milk components; the milk component is milk fat content.

4. A method for identifying or assisting in identifying the milk production traits of dairy cows, characterized in that: The method comprises detecting the genotype of the SNP1 of claim 1 in a dairy cow to be tested, and identifying or assisting in identifying the milk production trait of the dairy cow based on the genotype of the SNP in the dairy cow to be tested; the dairy cow is a Holstein cow; and the milk production trait is milk fat content: The milk fat content of cows with the CC genotype of SNP1 is higher or potentially higher than that of cows with the TT or CT genotypes, and there is no significant difference in milk fat content between cows with the TT genotype and cows with the CT genotype; the CC is a homozygous type of SNP1 with C; the TT is a homozygous type of SNP1 with T; and the CT is a heterozygous type of SNP1 with C and T.

5. Application of the method according to claim 4 in dairy cow breeding; the dairy cow breeding is to cultivate dairy cow breeds with high milk components; the milk component is milk fat content.

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