FABP3 gene snps marker for detecting milk production traits of sheep and application thereof

Abstract

The application discloses a kind of for detecting sheep milk production character FABP3 Gene SNPs marker and its application belong to the field of biotechnology.The present application takes lactating milk sheep as research object, applies Sanger technique to detect FABP3 Nucleotide sequence variation site of gene, and constructs general linear mixed effect model, studies the correlation between nucleotide sequence variation and sheep lactation character, and excavates the molecular genetic marker of regulating sheep lactation character;At SNP1 site, AG And GG The milk fat rate of genotype individual is respectively 0.99% and 1.01% higher than that of AA Type individual.In SNP2 site, TC And TT The milk fat rate of genotype individual is respectively 1.18% and 1.23% higher than that of CC Type individual, TC And TT The daily lactation of genotype individual is respectively 1.97% and 1.27% higher than that of CC Type individual.

Description

TECHNICAL FIELD

[0001] The present application relates to a FABP3 gene SNP marker for detecting the lactation traits of sheep and its application, and belongs to the technical field of biotechnology. BACKGROUND

[0002] Lactation performance is an important economic trait of sheep, mainly including milk yield, milk fat content, milk protein content, milk lactose content and other traits. These traits jointly affect the selling 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 functional genes that regulate these traits can be found, molecular marker-assisted selection techniques can be used to genetically improve the lactation traits of milk sheep.

[0003] Fatty acid binding protein 3 (FABP3) is a member of the fatty acid binding protein family, which is composed of 4 exons and 3 introns. Studies have found that FABP3 can effectively promote the uptake of fatty acids by cells by binding to fatty acids to form a concentration difference inside and outside the membrane. At the same time, this protein can transport fatty acids to specific intracellular sites such as mitochondria and participate in energy metabolism. Therefore, FABP3 is highly expressed in tissues such as myocardium, skeletal muscle and mammary gland that have high demand for fatty acids. Studies have shown that FABP3 is involved in the intracellular transport of fatty acids in mammary gland tissue and plays an important role in mammary gland cell differentiation and duct 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), and 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 by cells. SUMMARY

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

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

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

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

[0008] This invention provides a reagent for detecting the genotype of at least one of two SNP loci in the following applications in identifying or assisting in the identification of milk production traits in sheep;

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

[0010] The SNP site refers to 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 sheep reference genome ARS-UI_Ramb_V 3.0, where thymine T is replaced by cytosine C.

[0011] In one embodiment of the present invention, the milk production characteristics are daily milk yield and / or milk fat percentage and / or milk protein percentage and / or ash content and / or nonfat milk solids content and / or dry matter content.

[0012] This invention also provides the application of at least one of the following two SNP sites as a detection target in the identification or auxiliary identification of sheep milk production traits;

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

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

[0015] In one embodiment of the present invention, the milk production characteristics are daily milk yield and / or milk fat percentage and / or milk protein percentage and / or ash content and / or nonfat milk solids content and / or dry matter content.

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

[0017] 1) Includes 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 percentage of the tested sheep with the genotype AG or GG at the SNP site c.246+20G / A in the FABP3 gene was better than or slightly better than that of the tested sheep with the genotype AA at the SNP site c.246+20G / A.

[0019] 2) Includes 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 percentage and daily milk production of the tested sheep with the genotype TC or TT at the SNP site c.348+12C / T in the FABP3 gene were superior to or slightly superior to those of the tested sheep with the genotype CC at the SNP site c.348+12C / T.

[0021] In one embodiment of the present invention, the milk production characteristics are daily milk yield and / or milk fat percentage and / or milk protein percentage and / or ash content and / or nonfat milk solids content and / or dry matter content.

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

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

[0024] Or, 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 shown in SEQ ID NO. 1-2, respectively; or the upstream and downstream nucleotide sequences of the primer pair are shown in SEQ ID NO. 3-4, respectively.

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

[0027] a) Genomic DNA was extracted from sheep blood samples, and the sheep FABP3 gene was amplified by PCR using primers shown in SEQ ID NO.1, SEQ ID NO.2, SEQ ID NO.3, and SEQ ID NO.4;

[0028] b) Perform pooled sequencing and sequence analysis on the above PCR amplification products to obtain the mutation sites and determine the mutation types;

[0029] c) By performing FABP3 genotyping on individual sheep, the genotype and haplotype of the SNP loci in the FABP3 gene detection region of the sheep are identified based on the genotyping results.

[0030] In one embodiment of the present invention, the milk production characteristics are daily milk yield and / or milk fat percentage and / or milk protein percentage and / or ash content and / or nonfat milk solids content and / or dry matter content.

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

[0032] This invention also provides applications of the following primer pairs or primer combinations, wherein the application is any one of (a)-(f):

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

[0034] (b) Sheep selection;

[0035] (c) Sheep breeding;

[0036] (d) Prepare a kit for identifying or assisting in the identification of milk production traits in sheep;

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

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

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

[0040] In one embodiment of the present invention, the milk production characteristics are daily milk yield and / or milk fat percentage and / or milk protein percentage and / or ash content and / or nonfat milk solids content and / or dry matter content.

[0041] Beneficial effects

[0042] This invention uses lactating sheep as the research subject, applies Sanger and other techniques to detect nucleotide sequence variation sites in the FABP3 gene, and constructs a general linear mixed-effects model to study the correlation between nucleotide sequence variation and sheep lactation traits, thereby identifying molecular genetic markers regulating sheep lactation traits. This invention has achieved some positive results and indeed possesses significant advantages compared to existing technologies, as detailed below:

[0043] (1) A SNP c.246+20G / A was found in the second intron region of the sheep FABP3 gene and named SNP1. There are two alleles, A and G, at the SNP1 site, which constitute three genotypes: AA, AG and GG. At the SNP1 site, the milk fat percentage of individuals with the AG and GG genotypes is 0.99% and 1.01% higher than that of individuals with the AA genotype, respectively (P<0.05). There is no significant difference in milk fat percentage between individuals with the AG and GG genotypes. The presence or absence of allele A has no significant effect on lactation traits, but the presence of allele G is correlated with a higher milk fat percentage (present: 5.449±0.092; absent: 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 are two alleles, C and T, at the SNP2 site, constituting three genotypes: CC, CT and TT; the milk fat percentage of individuals with TC and TT genotypes is 1.18% and 1.23% higher than that of individuals with CC genotypes, respectively (P<0.05), and there is no significant difference in milk fat percentage between individuals with TC and TT genotypes; the daily milk yield of individuals with TC and TT genotypes is 1.97% and 1.27% higher than that of individuals with CC genotypes, respectively (P<0.01), and there is no significant difference in daily milk yield between individuals with TC and TT genotypes; in SNP2, the presence of allele T is associated with a higher milk fat percentage (present: 5.453±0.093; deleted: 4.267±0.409) (P=0.006), while the presence and deletion of allele C have no significant effect on the lactation trait.

[0045] (3) Four haplotypes were established between SNP1 and SNP2 sites of the FABP3 gene: CA (6.63%), TA (1.26%), TG (91.93%), and CG (0.18%). After removing haplotype combinations CG and TA with frequencies below 5%, association analysis revealed that individuals with the CA haplotype had significantly higher daily milk production than those with the TG haplotype (P<0.05). Attached Figure Description

[0046] Figure 1 SNP sites of the sheep FABP3 gene.

[0047] Figure 2 PARMS typing diagram of sheep FABP3 gene. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0049] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0050] Unless otherwise specified, the quantitative experiments in the following examples are all repeated three times, and the results are averaged.

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

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

[0053] Milk fat percentage: The percentage of fat contained in milk.

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

[0055] Ash content: The mineral content in milk.

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

[0057] Dry matter content: The content of other nutrients in milk after water is removed.

[0058] Acidity: The pH value of milk is an important physicochemical indicator for measuring the freshness of sheep milk.

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

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

[0061] 1. Collection of experimental animals and samples

[0062] (1) Blood collection

[0063] At Gansu Yuansheng Agricultural and Animal Husbandry Technology Co., Ltd., 460 lactating ewes were selected, including 32 East Friensian Milk sheep (EF), 56 Hu sheep (H), 197 F1 generation crossbred ewes of ♂ East Friensian Milk sheep × ♀ Hu sheep, and 175 F2 generation progressive crossbred ewes of ♂ East Friensian Milk sheep × ♀ Hu sheep. A 5 mL blood sample was collected from each sheep via the jugular vein into a vacuum blood collection tube (containing EDTA anticoagulant) and stored at -20℃ for later use.

[0064] (2) Collection of breast milk

[0065] While collecting blood samples, information such as daily milk production, age, parity, and number of lambs for the experimental sheep was collected from pedigree and production performance records. During mid-lactation, 50 mL of milk was collected from each sheep, and milk composition indicators such as milk fat percentage, milk protein percentage, ash content, non-fat milk solids content, dry matter content, lactose content, and acidity were determined using a UL40BC milk composition analyzer (U-Creative, Hangzhou, China).

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

[0067] The specific steps are as follows:

[0068] Take 800 μL of blood and drop it onto an FTA card. After drying at room temperature, extract blood DNA using the two-step method described by Zhou et al. (2006).

[0069] The specific method is to use a sampler to take a 1.2 mm diameter disc from the FTA card, place it in a 1.5 mL centrifuge tube, add 200 μL of 20 mmol / 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 minutes. 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 of LTE solution and let stand for 2 minutes.

[0072] Discard the TE buffer solution and air dry the disc 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 the FABP3 gene

[0076] The sheep FABP3 gene sequence (ENSOARG00020010991) was retrieved from the Ensembl database. Primers were designed using PrimerPremier 5.0 software and synthesized by Beijing Aoke Dingsheng Biotechnology Co., Ltd. Specific information is shown in Table 1.

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

[0078]

[0079] (2) PCR amplification

[0080] A 20 μL PCR reaction system was used, including one 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. PCR amplification conditions were: 94℃ pre-denaturation for 5 min, 94℃ denaturation for 30 s, annealing for 30 s (annealing temperatures are shown in Table 1), 72℃ extension for 30 s, for a total of 30 cycles, followed by a final extension at 72℃ for 7 min. PCR products were detected by 1.5% agarose gel electrophoresis.

[0081] Five samples each from the above amplification products were taken from the Dongfuli sheep, Hu sheep, F1, and F2 populations and subjected to PCR amplification. 2 μL of PCR product from each sample was mixed into a single sample, and the mixed PCR products were sent to Yangling Tianrun Aoke Biotechnology Co., Ltd. for sequencing. SNP sites were screened using Chromas software.

[0082] (3) Experimental results

[0083] Sanger sequencing revealed one SNP in the second intron region of the sheep FABP3 gene: c.246+20G / A, named SNP1; and another SNP in the third intron region of the FABP3 gene: c.348+12C / T, named SNP2. Figure 1 No variant sites were found in the remaining regions. The regions amplified by primers P3 and P4 showed no polymorphism.

[0084] SNP1: Represents 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 G / A mutation at c.246+20bp;

[0085] SNP2: Represents single nucleotide polymorphism site 2, which is c.348+12 C / T, indicating that there is a C / T mutation at c.348+12bp in the FABP3 gene sequence located on sheep chromosome 2.

[0086] Based on the two discovered SNPs, primers for amplifying these SNPs can be designed, including forward and reverse primers, located upstream and downstream of the two single nucleotide polymorphism sites, respectively. Kits for detecting these SNPs can also be designed using existing techniques based on the primers.

[0087] Example 2: Correlation between genotyping and sheep milk fat percentage and daily milk yield

[0088] 1. Experimental Methods

[0089] (1) Genotyping and haplotype construction

[0090] Based on the sequencing results in Example 1, SNPs with mutations in the second and third intron regions of the FABP3 gene were identified. Blood DNA samples extracted from all 460 lactating ewes selected in Example 1 were correlated with the FABP3 gene SNP information, and genotyping was performed using PARMS technology. The samples were then sent to Wuhan Jingtai Biotechnology Co., Ltd. for allele and genotyping of the selected SNPs.

[0091] (2) Gene frequency and genotype frequency analysis

[0092] Popgene 32.0 software was used to calculate the genotype and allele frequencies of polymorphic loci. Based on the allele types of the SNPs, all possible haplotype combinations were constructed, and the frequency of each haplotype in the sample population was calculated. Haplotype combinations with frequencies below 5% were removed for subsequent association analysis.

[0093] (3) Correlation analysis of lactation traits

[0094] Application of the Molecular Markers of the Present Invention in the Correlation Analysis of Milk Fat Percentage and Daily Milk Production in Sheep Milk

[0095] The experiment examined the polymorphism of 460 dairy sheep during lactation, determined their genotypes, and used a general linear mixed-effects model in SPSS 16.0 to analyze the correlation between genotypes, alleles, and haplotypes of FABP3 gene SNPs and sheep lactation traits. The results are expressed as mean ± standard error.

[0096] To determine the fixed and random effects included in the model, we analyzed the influence of age, number of lambs, and parity on the sheep's lactation trait. The results showed that the number of lambs and parity had no significant effect on lactation, but age had a highly significant effect. We used a general linear mixed-effects model in SPSS 16.0 to analyze the correlation between the FABP3 genotype (allele or haplotype) and the sheep's lactation trait.

[0097] The model is Y = μ + Genotype (Allele or Haplotype) + Population + Age + e, where Y represents the lactation trait, 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.

[0098] 2. Experimental Results

[0099] The embodiments of the present invention have achieved some positive results during the research and development or use process, and have indeed great advantages compared with the prior art. The following content describes them in conjunction with the data, charts and other information of the experimental process.

[0100] (1) The results of sheep FABP3 genotyping are shown in Table 2:

[0101] Table 2: Analysis of milk production traits corresponding to genotypes at SNP loci of the FABP3 gene in sheep

[0102]

[0103] The results showed that at the SNP1 locus, the milk fat percentage of individuals with the AG and GG genotypes was 0.99% and 1.01% higher than that of individuals with the AA genotype, respectively (P<0.05), with no significant difference in milk fat percentage between individuals with the AG and GG genotypes. At the SNP2 locus, the milk fat percentage of individuals with the TC and TT genotypes was 1.18% and 1.23% higher than that of individuals with the CC genotype, respectively (P<0.05), with no significant difference in milk fat percentage between individuals with the TC and TT genotypes; the daily milk production of individuals with the TC and TT genotypes was 1.97% and 1.27% higher than that of individuals with the CC genotype, respectively (P<0.01), with no significant difference in daily milk production between individuals with the TC and TT genotypes.

[0104] PARMS genotyping results of two SNP sites in the FABP3 gene are as follows: Figure 2 As shown, there are two alleles, A and G, at the SNP1 (c.246+20 G / A) locus, forming three genotypes: AA, AG, and GG; and there are two alleles, C and T, at the SNP2 (c.348+12 C / T) locus, forming three genotypes: CC, CT, and TT.

[0105] (2) Association analysis between FABP3 genotype and lactation trait

[0106] Table 3 shows that the milk fat percentage of individuals with the AG and GG genotypes was 0.99% and 1.01% higher than that of individuals with the AA genotype, respectively (P<0.05), while there was no significant difference in milk fat percentage between individuals with the AG and GG genotypes. These three genotypes had no significant effect on the remaining lactation traits.

[0107] Table 3: Association analysis between FABP3 SNP1 genotype and lactation trait in sheep

[0108]

[0109] Table 4 shows that the milk fat percentage of individuals with the TC and TT genotypes was 1.18% and 1.23% higher than that of individuals with the CC genotype, respectively (P<0.05), with no significant difference in milk fat percentage between TC and TT individuals. The daily milk yield of individuals with the TC and TT genotypes was 1.97% and 1.27% higher than that of individuals with the CC genotype, respectively (P<0.01), with no significant difference in daily milk yield between TC and TT individuals. These three genotypes had no significant effect on the remaining lactation traits.

[0110] Table 4: Association analysis between FABP3 SNP2 genotype and lactation trait in sheep

[0111]

[0112] (3) Effects of the FABP3 allele on lactation traits

[0113] 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 a higher milk fat percentage (present: 5.449±0.092; absent: 4.455±0.326) (P=0.003) (Table 5).

[0114] Table 5: Correlation between FABP3 SNP1 alleles and lactation traits in sheep

[0115]

[0116] In SNP2, the presence of allele T was associated with a higher milk fat percentage (present: 5.453±0.093; deleted: 4.267±0.409) (P=0.006), while the presence and deletion of allele C had no significant effect on lactation traits (Table 6).

[0117] Table 6: Correlation between FABP3 SNP2 alleles and lactation traits in sheep

[0118]

[0119] (4) Association analysis between FABP3 haplotype and lactation traits

[0120] Four haplotypes were established between SNP1 and SNP2 sites of the FABP3 gene: CA (6.63%), TA (1.26%), TG (91.93%), and CG (0.18%). After removing haplotype combinations CG and TA with frequencies below 5%, association analysis revealed that individuals with the CA haplotype had significantly higher daily milk production than those with the TG haplotype (P<0.05) (Table 7).

[0121] Table 7: Correlation between sheep FABP3 gene haplotypes and lactation traits

[0122]

[0123] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. Application of reagents for detecting genotypes of the following SNP loci in identifying milk production traits in sheep; The SNP site corresponds to the positive strand of chromosome 2 in the sheep reference genome ARS-UI_Ramb_V 3.0 version sequence information. FABP3 The guanine G at position c.246+20 of the gene is replaced with adenine A; Alternatively, the SNP site may be the positive strand of chromosome 2 corresponding to the sequence information of sheep reference genome ARS-UI_Ramb_V 3.0 version. FABP3 The cytosine C at position c.348+12 of the gene is replaced with thymine T; The milk production trait is milk fat percentage.

2. Application of reagents for detecting genotypes of the following SNP loci in identifying milk production traits in sheep; The SNP site corresponds to the positive strand of chromosome 2 in the sheep reference genome ARS-UI_Ramb_V 3.0 version sequence information. FABP3 The cytosine C at position c.348+12 of the gene is replaced with thymine T; The milk production trait refers to the daily milk production.

3. A method for identifying milk production traits in sheep, characterized in that, The method is any one of the following 1)-2): 1) Includes the following steps: testing the test sheep FABP3 The genotype of the SNP site c.246+20G / A in the gene as described in claim 1; the genotype of the SNP site c.246+20G / A is AG , GG or AA ; The FABP3 The SNP site c.246+20G / A in the gene has the following genotype: AG or GG The milk fat percentage of the tested sheep was better than that of the SNP locus c.246+20G / A genotype. AA The sheep used in the experiment; 2) Includes the following steps: testing the test sheep FABP3 The genotype of the SNP site c.348+12C / T in the gene as described in claim 1; the genotype of the SNP site c.348+12C / T is TC , TT or CC ; The FABP3 The SNP site c.348+12C / T in the gene has the following genotype: TC or TT The tested sheep exhibited better milk fat percentage and daily milk yield than those with the C.348+12C / T genotype at the stated SNP locus. CC The sheep used for testing.

4. The application of the method described in claim 3 in sheep screening or sheep breeding.

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