FABP3 gene SNPs marker for detecting sheep milk production character and application of FABP3 gene SNPs marker

Abstract

The invention discloses an FABP3 gene SNPs marker for detecting sheep milk production traits and application of the FABP3 gene SNPs marker, and belongs to the technical field of biology. According to the invention, lactating sheep is taken as a research object, Sanger and other technologies are applied to detect a nucleotide sequence variation site of an FABP3 gene, a general linear mixing effect model is constructed, the correlation between nucleotide sequence variation and sheep lactation traits is researched, and a molecular genetic marker for regulating and controlling the sheep lactation traits is excavated; on the SNP1 site, the cream-fat percentages of AG and GG genotype individuals are respectively 0.99% and 1.01% higher than those of AA type individuals. On the site SNP2, the milk fat rates of TC and TT genotype individuals are 1.18% and 1.23% higher than those of CC type individuals respectively, and the daily lactation volumes of the TC and TT genotype individuals are 1.97% and 1.27% higher than those of the CC type individuals respectively.

Description

Technical Field

[0001] The invention relates to a FABP3 gene SNPs marker for detecting sheep milk production traits and application thereof, belonging to the field of biotechnology. Background Art

[0002] Lactation performance is an important economic trait of sheep, mainly including milk production, milk fat content, milk protein content, lactose content and other traits. These traits jointly affect the sales price of sheep milk. Milk fat is an important component of dairy products, which can improve the taste and nutritional value of dairy products. Generally speaking, the higher the milk fat content, the higher the nutritional value of sheep milk. Studies have shown that genetic factors are a major factor in regulating lactation traits including milk fat. Therefore, if the functional gene that regulates this trait can be found, molecular marker-assisted selection technology can be used to genetically improve the lactation traits of dairy sheep.

[0003] Fatty acid binding protein 3 (FABP3) is a member of the fatty acid binding protein family and consists of 4 exons and 3 introns. Studies have found that FABP3 effectively promotes the uptake of fatty acids by cells by binding to fatty acids to form a concentration difference between the inside and outside of the membrane. At the same time, the protein can transport fatty acids to specific parts of the cell such as mitochondria and participate in energy metabolism. Therefore, FABP3 is highly expressed in tissues such as myocardium, skeletal muscle, and breast that have a high demand for fatty acids. Studies have shown that FABP3 is involved in the intracellular transport of fatty acids in breast tissue and plays an important role in breast cell differentiation and ductal structure formation. Milk fat is the main energy component of sheep milk, and its regulation mainly depends on the transcription factors sterol regulatory element-binding protein 1 (SREBP1) and peroxisome proliferator-activated receptor gamma (PPARγ). FABP3, as a target gene of SREBP1 and PPARγ, plays an important role in the milk fat synthesis signaling pathway and promotes the metabolism of fatty acids in cells. Summary of the invention

[0004] In this study, 460 lactating sheep were used as the research subjects. Sanger sequencing and penta-primer amplification refractory mutation system (PARMS) technology were used to detect the SNPs of this gene, and the effects of nucleotide sequence variation on nine lactation traits such as milk production and milk protein in sheep were analyzed, in order to provide data reference for molecular marker-assisted selection of sheep.

[0005] The present invention provides a single nucleotide polymorphism genetic molecular marker related to sheep milk production traits, wherein the single nucleotide polymorphism genetic marker is located in the sheep FABP3 gene, and the single nucleotide polymorphism genetic molecular marker is any one or more combinations of the following (a) to (b);

[0006] (a) The single nucleotide polymorphism genetic molecular marker is that guanine G is replaced by adenine A at position c.246+20 of the FABP3 gene in the positive strand of chromosome 2 corresponding to the sheep genome sequence;

[0007] (b) The single nucleotide polymorphism genetic molecular marker is that the cytosine C at position c.348+12 of the FABP3 gene on the positive strand of chromosome 2 corresponding to the sheep genome sequence is replaced by thymine T.

[0008] The present invention provides an application of a reagent for detecting the genotype of at least one of the following two SNP sites in identifying or assisting in identifying sheep milk production traits;

[0009] The SNP site is a substitution of guanine G with adenine A at position c.246+20 of the FABP3 gene on the positive strand of chromosome 2 corresponding to the sequence information of the sheep reference genome ARS-UI_Ramb_V 3.0 version;

[0010] The SNP site is corresponding to the sequence information of the sheep reference genome ARS-UI_Ramb_V 3.0 version, in which the cytosine C at position c.348+12 of the FABP3 gene on the positive strand of chromosome 2 is replaced by thymine T.

[0011] In one embodiment of the present invention, the milk production trait is daily milk yield and / or milk fat rate and / or milk protein rate and / or ash content and / or non-fat milk solids content and / or dry matter content.

[0012] The present invention also provides the use of at least one of the following two SNP sites as a detection target in identifying or assisting in identifying sheep milk production traits;

[0013] The SNP site is a substitution of guanine G with adenine A at position c.246+20 of the FABP3 gene on the positive strand of chromosome 2 corresponding to the sequence information of the sheep reference genome ARS-UI_Ramb_V version 3.0;

[0014] Or the SNP site is that the cytosine C at position c.348+12 of the FABP3 gene on the positive strand of chromosome 2 corresponding to the sequence information of the sheep reference genome ARS-UI_Ramb_V version 3.0 is replaced by thymine T.

[0015] In one embodiment of the present invention, the milk production trait is daily milk yield and / or milk fat rate and / or milk protein rate and / or ash content and / or non-fat milk solids content and / or dry matter content.

[0016] The present invention also provides a method for identifying or assisting in identifying sheep milk production traits, the method being any one of the following 1)-2):

[0017] 1) comprising the following steps: detecting the genotype of the SNP site c.246+20G / A in the FABP3 gene of the tested sheep; the genotype of the SNP site c.246+20G / A is AG, GG or AA;

[0018] The milk fat rate of the test sheep whose genotype of the SNP site c.246+20G / A in the FABP3 gene is AG or GG is better than or auxiliary better than that of the test sheep whose genotype of the SNP site c.246+20G / A is AA;

[0019] 2) comprising the following steps: detecting the genotype of the SNP site c.348+12C / T in the FABP3 gene of the tested sheep; the genotype of the SNP site c.348+12C / T is TC, TT or CC;

[0020] The milk fat rate and daily milk production of the test sheep whose SNP site c.348+12C / T genotype in the FABP3 gene is TC or TT are better than or auxiliary better than those of the test sheep whose SNP site c.348+12C / T genotype is CC.

[0021] In one embodiment of the present invention, the milk production trait is daily milk yield and / or milk fat rate and / or milk protein rate and / or ash content and / or non-fat milk solids content and / or dry matter content.

[0022] The invention also provides application of the method in sheep screening or sheep breeding.

[0023] In one embodiment of the present invention, in the application, any of the following test sheep are selected for milk production or breeding: the test sheep whose genotype of the SNP site c.246+20G / A in the FABP3 gene is AG or GG;

[0024] Or the test sheep whose genotype at the SNP site c.348+12C / T in the FABP3 gene is TC or TT.

[0025] The present invention also provides a primer pair for detecting mutations in the FABP3 gene, wherein the upstream and downstream nucleotide sequences of the primer pair are respectively shown as SEQ ID NOs. 1-2; or the upstream and downstream nucleotide sequences of the primer pair are respectively shown as SEQ ID NOs. 3-4.

[0026] The present invention also provides a method for detecting molecular markers related to sheep milk production traits, the method comprising the following steps:

[0027] a) extracting genomic DNA from sheep blood as a sample, and performing PCR amplification on the sheep FABP3 gene using primers shown in SEQ ID NO.1, SEQ ID NO.2, SEQ ID NO.3, and SEQ ID NO.4;

[0028] b) performing mixed pool sequencing and sequence analysis on the above PCR amplification products to obtain the mutation site and determine the mutation type;

[0029] c) Performing FABP3 genotyping on the identified sheep individuals, and identifying the genotype and haplotype of the SNP site in the sheep FABP3 gene detection region according to the typing results.

[0030] In one embodiment of the present invention, the milk production trait is daily milk yield and / or milk fat rate and / or milk protein rate and / or ash content and / or non-fat milk solids content and / or dry matter content.

[0031] The present invention also provides a kit for detecting molecular markers, the kit comprising a primer pair, the nucleotide sequences of the upstream and downstream of the primer pair are respectively shown in SEQ ID NO.1-2; or the nucleotide sequences of the upstream and downstream of the primer pair are respectively shown in SEQ ID NO.3-4.

[0032] The present invention also provides the use of the following primer pair or primer combination, wherein the use is any one of the following (a)-(f):

[0033] (a) Identification or assistance in the identification of milk production traits in sheep;

[0034] (b) sheep screening;

[0035] (c) sheep breeding;

[0036] (d) preparing a kit for identifying or assisting in identifying sheep milk production traits;

[0037] (e) preparing a kit for sheep screening;

[0038] (f) Preparation of a kit for sheep breeding.

[0039] The nucleotide sequences of the upstream and downstream of the primer pair are shown as SEQ ID NO.1-2 respectively; or the nucleotide sequences of the upstream and downstream of the primer pair are shown as SEQ ID NO.3-4 respectively.

[0040] In one embodiment of the present invention, the milk production trait is daily milk yield and / or milk fat rate and / or milk protein rate and / or ash content and / or non-fat milk solids content and / or dry matter content.

[0041] Beneficial Effects

[0042] The present invention uses lactating sheep as the research object, applies Sanger and other technologies to detect the nucleotide sequence variation sites of the FABP3 gene, and constructs a general linear mixed effects model to study the correlation between nucleotide sequence variation and sheep lactation traits, and to explore molecular genetic markers that regulate sheep lactation traits; the present invention has achieved some positive effects and indeed has great advantages compared with the prior art, as follows:

[0043] (1) A SNP c.246+20G / A was found in the second intron region of the sheep FABP3 gene, named SNP1. There were two alleles, A and G, at the SNP1 locus, constituting three genotypes: AA, AG and GG. At the SNP1 locus, the milk fat percentage of individuals with AG and GG genotypes was 0.99% and 1.01% higher than that of individuals with AA genotype, respectively (P<0.05), and there was no significant difference in milk fat percentage between individuals with AG and GG genotypes. The presence or absence of allele A had no significant effect on lactation traits, but the presence of allele G was associated with a higher milk fat percentage (presence: 5.449±0.092; absence: 4.455±0.326) (P=0.003).

[0044] (2) A SNP c.348+12C / T was also found in the third intron region of the sheep FABP3 gene, named SNP2. There were two alleles, C and T, at the SNP2 locus, constituting three genotypes, CC, CT and TT. The milk fat percentage of individuals with TC and TT genotypes was 1.18% and 1.23% higher than that of individuals with CC genotype, respectively (P<0.05), and there was no significant difference in milk fat percentage between TC and TT individuals. The daily milk production of individuals with TC and TT genotypes was 1.97% and 1.27% higher than that of individuals with CC genotype, respectively (P<0.01), and there was no significant difference in daily milk production between TC and TT individuals. In SNP2, the presence of allele T was associated with a higher milk fat percentage (presence: 5.453±0.093; absence: 4.267±0.409) (P=0.006), and the presence and absence of allele C had no significant effect on lactation traits.

[0045] (3) A total of four haplotypes were established between the SNP1 and SNP2 sites of the FABP3 gene, namely CA (6.63%), TA (1.26%), TG (91.93%) and CG (0.18%). After eliminating the haplotype combinations CG and TA with a frequency lower than 5%, association analysis showed that the daily milk production of individuals with the CA haplotype was significantly higher than that of individuals with the TG haplotype (P<0.05). BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 :SNPs sites of sheep FABP3 gene.

[0047] Figure 2 : PARMS genotype of sheep FABP3 gene. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0049] The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial channels.

[0050] Unless otherwise specified, the quantitative tests in the following examples were performed three times and the results were averaged.

[0051] The detection methods involved in the following embodiments are as follows:

[0052] The following indicators were measured using the UL40BC milk composition analyzer:

[0053] Milk fat content: the percentage of fat in milk.

[0054] Milk protein rate: the percentage of protein contained in milk.

[0055] Ash content: The amount of minerals in milk.

[0056] Non-milk fat solids content: the content of nutrients in milk other than fat and water.

[0057] Dry matter content: the content of other nutrients in milk after removing water.

[0058] Acidity: The pH value of milk is an important physical and chemical indicator to measure the freshness of sheep milk.

[0059] The daily milk production of each test sheep was measured using a DeLaval 9JP-2X24 parallel milking machine.

[0060] Example 1: Gene sequencing and analysis of SNPs associated with milk fat rate and daily milk yield in sheep milk

[0061] 1. Collection of experimental animals and samples

[0062] (1) Blood collection

[0063] A total of 460 lactating ewes were selected from Gansu Yuansheng Agriculture and Animal Husbandry Technology Co., Ltd., including 32 East Friensian Milk sheep (EF), 56 Hu Sheep (H), 197 East Friensian Milk sheep ♂×Hu Sheep ♀ hybrid 1st generation sheep (F1), and 175 East Friensian Milk sheep ♂×Hu Sheep ♀ progressive hybrid 2nd generation sheep (F2). 5 mL blood samples were collected from each sheep at the jugular vein in a vacuum blood collection tube (containing EDTA anticoagulant) and stored in a -20℃ refrigerator for later use.

[0064] (2) Collection of breast milk

[0065] At the same time as blood samples were collected, information such as daily milk production, age, parity, and number of lambs of the above-mentioned experimental sheep was collected from the pedigree and production performance record sheets. In the middle of lactation, 50 mL of milk sample was collected from each sheep, and milk fat rate, milk protein rate, ash content, non-fat milk solids content, dry matter content, lactose content, and acidity were measured using a UL40BC milk component analyzer (U-Chuang, Hangzhou, China).

[0066] 2. Extraction of genomic DNA from sheep blood

[0067] The specific steps are as follows:

[0068] 800 μL of blood was dropped onto an FTA card and dried at room temperature. Blood DNA was then extracted using the two-step method described by Zhou et al. (2006).

[0069] The specific method is to use a sampler to take a 1.2mm diameter disk on the FTA card, place it in a 1.5mL centrifuge tube, add 200μL of 20mmol / L NaOH to the centrifuge tube, and incubate at room temperature for 30 minutes;

[0070] If the blood sample is stored for a long time, heat it in a 50°C water bath for 25 min. During the incubation period, the centrifuge tube should be turned over from time to time.

[0071] Discard the NaOH solution in the tube. Add 200 μL TE solution and let stand for 2 minutes;

[0072] Discard the TE buffer solution and air-dry the disk at room temperature for later use.

[0073] 3. FABP3 gene PCR primer design, amplification and sequencing

[0074] The specific steps are as follows:

[0075] (1) Primer design for FABP3 gene

[0076] The sheep FABP3 gene sequence (ENSOARG00020010991) was queried from the Ensembl database, and primers were designed using PrimerPremier 5.0 software and synthesized by Beijing Aoke Dingsheng Biological Company. The specific information is shown in Table 1.

[0077] Table 1: Primer information of sheep FABP3 gene

[0078] (2) PCR amplification

[0079] A 20 μL PCR reaction system was used, including a 1.2 mm DNA card, 1.6 μL of 10 μmol / L upstream and downstream primers, 10.4 μL of Taq DNA polymerase, and 8.0 μL of ddH2O. The PCR amplification conditions were: 94°C pre-denaturation for 5 min, 94°C denaturation for 30 s, annealing for 30 s (annealing temperature see Table 1), 72°C extension for 30 s, 30 cycles in total, and 72°C final extension for 7 min. The PCR product was detected by 1.5% agarose gel electrophoresis.

[0080] From the above amplified products, 5 samples of East Fleming sheep, Hu sheep, F1 and F2 populations were taken for PCR amplification. 2 μL of PCR products were taken from each sample and mixed into one sample. The mixed PCR products were sent to Yangling Tianrun Aoke Biotechnology Co., Ltd. for sequence determination, and Chromas software was used to screen SNPs sites.

[0081] (3) Experimental results

[0082] Sanger sequencing revealed a SNP in the second intron of the sheep FABP3 gene: c.246+20G / A, named SNP1; and a SNP in the third intron of the FABP3 gene: c.348+12C / T, named SNP2. Figure 1 ), no variant sites were found in the rest of the regions. There was no polymorphism in the regions amplified by primers P3 and P4.

[0083] SNP1: single nucleotide polymorphism site 1, which is: c.246+20 G / A, indicating that the FABP3 gene sequence located on sheep chromosome 2 has a base G / A mutation at c.246+20bp;

[0084] SNP2: represents single nucleotide polymorphism site 2, which is: c.348+12 C / T, indicating that there is a base C / T mutation at c.348+12bp in the FABP3 gene sequence located on sheep chromosome 2.

[0085] Based on the two SNPs found, primers for amplifying the above SNPs can be designed, including a forward primer and a reverse primer, wherein the forward primer and the reverse primer are respectively located upstream and downstream of the above two single nucleotide polymorphism sites. Based on the primers of the above SNPs, a kit for detecting the above SNPs can also be designed using existing technology.

[0086] Example 2: Correlation between genotyping and milk fat percentage and daily milk yield in sheep milk

[0087] 1. Experimental Methods

[0088] (1) Genotyping and haplotype construction

[0089] According to the sequencing results in Example 1, the SNPs sites that mutated in the second intron region and the third intron region of the FABP3 gene were counted, and the blood DNA samples extracted from the blood of 460 ewes in the lactation period selected in Example 1 were matched with the SNPs site information of the FABP3 gene, and genotyping was performed using the PARMS technology. The selected SNPs sites were sent to Wuhan Jingpeptide Biological Co., Ltd. for allele and genotyping.

[0090] (2) Gene frequency and genotype frequency analysis

[0091] Popgene32.0 software was used to calculate the genotype frequency and allele frequency of polymorphic sites. According to the allele type of the SNPs site, all possible haplotype combinations were constructed, and the frequency of each haplotype in the sample population was counted. Haplotype combinations with a frequency of less than 5% were eliminated for subsequent association analysis.

[0092] (3) Correlation analysis of lactation traits

[0093] Application of the molecular marker of the present invention in the association analysis between milk fat rate and daily milk production in sheep milk

[0094] A total of 460 dairy sheep in lactation were tested for polymorphism, their genotypes were determined, and the general linear mixed effects model of SPSS16.0 was used to analyze the correlation between the genotype, allele and haplotype of the FABP3 gene SNPs locus and the lactation traits of sheep. The analysis results were expressed as mean ± standard error.

[0095] In order to determine the fixed effects and random effects included in the model, we analyzed the effects of age, lambing number and parity on lactation traits in sheep. The results showed that lambing number and parity had no significant effect on lactation traits, but age had a very significant effect on lactation traits. SPSS16.0 general linear mixed effects model was used to analyze the correlation between FABP3 genotype (allele or haplotype) and lactation traits in sheep.

[0096] The model is Y = μ + Genotype (Allele or Haplotype) + Population + Age + e, where Y represents lactation traits, μ is the population mean, Genotype is the genotype, Allele is the allele, Haplotype is the haplotype, Population is the experimental population, Age is the age, and e is the random effect.

[0097] 2. Experimental results

[0098] The embodiments of the present invention have achieved some positive effects during the development or use process, and indeed have great advantages over the prior art. The following content is described in conjunction with data, charts, etc. of the test process.

[0099] (1) The results of sheep FABP3 genotype detection are shown in Table 2:

[0100] Table 2: Analysis of milk production traits corresponding to the genotypes of the sheep FABP3 gene SNP loci

[0101] The results showed that at SNP1, the milk fat percentage of individuals with AG and GG genotypes was 0.99% and 1.01% higher than that of individuals with AA genotype (P<0.05), and there was no significant difference in milk fat percentage between individuals with AG and GG genotypes. At SNP2, the milk fat percentage of individuals with TC and TT genotypes was 1.18% and 1.23% higher than that of individuals with CC genotype (P<0.05), and there was no significant difference in milk fat percentage between individuals with TC and TT genotypes. The daily milk production of individuals with TC and TT genotypes was 1.97% and 1.27% higher than that of individuals with CC genotype (P<0.01), and there was no significant difference in daily milk production between individuals with TC and TT genotypes.

[0102] The PARMS typing results of the two SNPs sites of the FABP3 gene are as follows Figure 2 There are two alleles, A and G, at the SNP1 (c.246+20 G / A) site, which constitute three genotypes, AA, AG, and GG; there are two alleles, C and T, at the SNP2 (c.348+12 C / T) site, which constitute three genotypes, CC, CT, and TT.

[0103] (2) Association analysis between FABP3 genotype and lactation traits

[0104] As shown in Table 3, the milk fat percentage of AG and GG genotype individuals was 0.99% and 1.01% higher than that of AA genotype individuals (P<0.05), and there was no significant difference in milk fat percentage between AG and GG genotype individuals. These three genotypes had no significant effect on the other lactation traits.

[0105] Table 3: Association analysis between sheep FABP3 SNP1 genotype and lactation traits

[0106] As shown in Table 4, the milk fat percentage of TC and TT genotype individuals was 1.18% and 1.23% higher than that of CC genotype individuals (P<0.05), and there was no significant difference in milk fat percentage between TC and TT genotype individuals; the daily milk production of TC and TT genotype individuals was 1.97% and 1.27% higher than that of CC genotype individuals (P<0.01), and there was no significant difference in daily milk production between TC and TT genotype individuals. These three genotypes had no significant effect on the other lactation traits.

[0107] Table 4: Association analysis between sheep FABP3 SNP2 genotype and lactation traits

[0108] (3) Effects of FABP3 alleles on lactation traits

[0109] In SNP1, the presence or absence of allele A had no significant effect on lactation traits, but the presence of allele G was associated with higher milk fat percentage (presence: 5.449 ± 0.092; absence: 4.455 ± 0.326) (P = 0.003) (Table 5).

[0110] Table 5: Correlation between sheep FABP3 SNP1 alleles and lactation traits

[0111] In SNP2, the presence of allele T was associated with higher milk fat percentage (presence: 5.453±0.093; absence: 4.267±0.409) (P=0.006), and the presence and absence of allele C had no significant effect on lactation traits (Table 6).

[0112] Table 6: Correlation between sheep FABP3 SNP2 allele and lactation traits

[0113] (4) Association analysis between FABP3 haplotypes and lactation traits

[0114] A total of four haplotypes were established between the SNP1 and SNP2 sites of the FABP3 gene, namely CA (6.63%), TA (1.26%), TG (91.93%) and CG (0.18%). After eliminating the haplotype combinations CG and TA with a frequency lower than 5%, association analysis showed that the daily milk production of individuals with CA haplotype was significantly higher than that of individuals with TG haplotype (P<0.05) (Table 7).

[0115] Table 7: Correlation between sheep FABP3 gene haplotypes and lactation traits

[0116] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. Use of a reagent for detecting the genotype of at least one of the following two SNP sites in identifying or assisting in identifying sheep milk production traits; the SNP site is the positive strand of chromosome 2 corresponding to the sheep genome sequence FABP3 The guanine G at position c.246+20 of the gene was replaced by adenine A; Or the SNP site is the positive strand of chromosome 2 corresponding to the sheep genome sequence FABP3 The cytosine C at position c.348+12 of the gene was replaced by thymine T.

2. Use of at least one of the following two SNP sites as a detection target in identifying or assisting in identifying sheep milk production traits; the SNP site is the positive strand of chromosome 2 corresponding to the sheep genome sequence information FABP3 The guanine G at position c.246+20 of the gene was replaced by adenine A; Or the SNP site is the positive strand of chromosome 2 corresponding to the sheep genome sequence FABP3 The cytosine C at position c.348+12 of the gene was replaced by thymine T; Preferably, the milk production trait is daily milk yield and / or milk fat rate and / or milk protein rate and / or ash content and / or non-fat milk solids content and / or dry matter content.

3. A single nucleotide polymorphism genetic molecular marker associated with sheep milk production traits, characterized in that: The single nucleotide polymorphism genetic marker is located in sheep FABP3 In the gene, the single nucleotide polymorphism genetic molecular marker is any one or more combinations of the following (a) to (b); (a) The single nucleotide polymorphism genetic molecular marker is the positive strand of chromosome 2 corresponding to the sheep genome sequence. FABP3 The guanine G at position c.246+20 of the gene was replaced by adenine A; (b) The single nucleotide polymorphism genetic molecular marker is the positive strand of chromosome 2 corresponding to the sheep genome sequence. FABP3 The cytosine C at position c.348+12 of the gene was replaced by thymine T.

4. A method for identifying or assisting in identifying the milk production traits of sheep, characterized in that: The method is any one of the following 1)-2): 1) The following steps are included: testing the sheep FABP3 The genotype of the SNP site c.246+20G / A in the gene; the genotype of the SNP site c.246+20G / A is AG , GG or AA ; Said FABP3 The genotype of the SNP site c.246+20G / A in the gene is AG or GG The milk fat rate of the tested sheep is better than or assisted by the SNP site c.246+20G / A genotype is AA of the tested sheep; 2) The following steps are included: testing the test sheep FABP3 The genotype of the SNP site c.348+12C / T in the gene; the genotype of the SNP site c.348+12C / T is TC , TT or CC ; Said FABP3 The genotype of the SNP site c.348+12C / T in the gene is TC or TT The milk fat rate and daily milk yield of the tested sheep are better than or assisted by the SNP site c.348+12C / T genotype. CC of the tested sheep.

5. Use of the method according to claim 4 in sheep screening or sheep breeding.

6. The use according to claim 5, characterized in that: In the application, any of the following sheep in claim 4 is selected for milk production or breeding; FABP3 The genotype of the SNP site c.246+20G / A in the gene is AG or GG of the tested sheep; or FABP3 The genotype of the SNP site c.348+12C / T in the gene is TC or TT of the tested sheep.

7. A detection FABP3 A primer pair for detecting a mutation in a gene, characterized in that The nucleotide sequences of the upstream and downstream of the primer pair are shown as SEQ ID NO.1-2 respectively; or the nucleotide sequences of the upstream and downstream of the primer pair are shown as SEQ ID NO.3-4 respectively.

8. A method for detecting molecular markers associated with sheep milk production traits, characterized in that: The steps include: a) Using sheep blood as a sample to extract genomic DNA, using the primers shown in SEQ ID NO.1, SEQ ID NO.2, SEQ ID NO.3, and SEQ ID NO.4 to genotype sheep FABP3 PCR amplification of genes; b) performing mixed pool sequencing and sequence analysis on the above PCR amplification products to obtain the mutation site and determine the mutation type; c) by identifying individual sheep FABP3 Genotyping, identification of sheep based on genotyping results FABP3 The genotype and haplotype of the SNP loci in the gene detection region.

9. A kit for detecting molecular markers related to sheep milk production traits, characterized in that: The kit comprises the primer pair according to claim 7.

10. Use of the primer pair or primer combination according to claim 7, wherein the use is any one of the following (a)-(f): (a) Identification or assistance in the identification of milk production traits in sheep; (b) sheep screening; (c) sheep breeding; (d) preparing a kit for identifying or assisting in identifying sheep milk production traits; (e) preparing a kit for sheep screening; (f) Preparation of a kit for sheep breeding.

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