Investigation on BRCA1 SNPs and its effects on mastitis in Chinese commercial cattle

The main objective of this study was to investigate whether the bovine breast cancer 1 (BRCA1) gene was associated with mastitis resistance in Chinese commercial cattle. A total of 51 SNPs were screened from public data resources and DNA sequencing. Three SNPs (c.5682G>C,c.26198C>T and c.46126G>T) were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and created restriction site PCR (CRS-PCR) methods and 21 combinations of these SNPs were observed. The single SNP and their genetic effects on somatic cell score (SCS) were evaluated and a significant association with SCS was found in c.46126G>T. The mean SCS of individuals with genotype KK was significantly lower than those of genotypes KL and LL. The results of combined genotypes analysis of three SNPs showed that HHLLNN genotype with the highest SCS was easily for the mastitis susceptibility, whereas GGKKMM genotype with the lowest SCS was favorable for the mastitis resistance. The information provided in the present study will be very useful for improving mastitis resistance in dairy cattle by marker-assisted selection (MAS).     

Single nucleotide polymorphisms,haplotypes and combined genotypes of lactoferrin gene and their associations with mastitis in Chinese Holstein cattle

Lactoferrin (Lf) is naturally produced by the mammary gland, having biological functions of antibacterial and anti-inflammatory activities. To investigate whether the Lf gene is associated with mastitis in dairy cattle, a DNA sequencing approach was used to identify single nucleotide polymorphisms (SNPs) in the gene. Three previously reported SNPs in the 5′ flanking region and one novel SNP in exon1 of Lf gene were identified. A total of 353 individuals from Holstein cattle populations were genotyped for their SNPs using Created Restriction Site PCR (CRS-PCR) and PCR-RFLP methods. Twenty-two and nineteen combinations of three SNPs (g.3440T>G, g.3879_3880insG, and g.4432T>C) and another three SNPs (g.3429G>A, g.3440T>G, g.3879_3880insG) were observed, respectively. The result of haplotype analysis of four SNPs showed that fourteen different haplotypes were identified. Two major haplotypes (GECB and GECA) occurred with a frequency of 22.5 and 18.5% in the study population, respectively. Statistical analyses revealed no significant association between one single SNP of Lf gene and SCS, whereas significant associations between their combined genotypes of three SNPs, haplotype and SCS. Combined genotype EFCDBB and GGEFDD with the lowest SCS were favorable for the mastitis resistance. They may be used as a possible candidate for marker-assisted selection in dairy cattle breeding program.     

Haplotype analysis of TLR4 gene and its effects on milk somatic cell score in Chinese commercial cattle

Bovine mastitis is a very complex and common disease of dairy cattle and a major source of economic losses to the dairy industry worldwide. In this study, the bovine TLR4 was taken as a candidate gene for mastitis resistance. This study aimed to analyze the associations of single nucleotide polymorphisms (SNP) or haplotype and somatic cell score (SCS) in 404 Chinese commercial dairy cattle including Chinese Holstein, Sanhe cattle and Chinese Simmental breeds. The polymerase chain reaction and sequencing methods were used for detecting genotype and allele frequency distribution of the two SNPs (rs8193062, rs8193064), statistical results showed that T allele at rs8193062 and C allele at rs8193064 were the predominate alleles. Moreover, six SNPs, including two SNPs (rs8193062, rs8193064) and four SNPs (rs8193060, rs8193069, rs29017188, rs8193046) which were chosen according the polymorphism level for the same cattle populations in previous studies, were used for haplotype analysis, the results revealed that twenty-one haplotypes were found in the mentioned animals, of which, Hap1 (30.5 %) and Hap2 (30.4 %) were the most common haplotypes. Hap2, Hap4 and Hap12 might negatively effect on milk SCS, whereas Hap13 might positively effect on milk SCS. The results in this study might assist in marker assisted selection and provided some reference to be implemented in breeding programs to improve the mastitis resistance of dairy cattle.     

Polymorphisms in MX2 Gene Are Related with SCS in Chinese Dairy Cows

Viral infections can play direct or indirect roles in the etiology of the bovine mastitis. Mx dynamin-like GTPase 2 (MX2) gene is a main effector of the antiviral innate immune defense mediated by type I interferon (IFN I), which was demonstrated to confer positive antiviral responses to many viruses. Given the importance of the MX2 in modulating the host immune response, MX2 gene may be a suitable candidate gene for studying disease resistance in dairy cattle. Here, we scanned the sequence variation of the MX2 gene in Chinese indigenous cattle breeds. Twenty-three previously reported SNPs were identified. To further analyze the effects of SNPs detected on mastitis disease, analysis of two SNPs (g.787527 C?>?T and g.787610 T?>?C) from 297 Chinese Holstein cows revealed a significant association with somatic cell score (SCS). Although functional studies are necessary to ascertain whether these two SNPs are causal polymorphisms or merely in linkage with the true causal SNPs, implementation of these two SNPs as genetic markers in the dairy industry may be beneficial in selecting individuals with lower SCS.     

SNPs of CXCR1 gene and its associations with somatic cell score in Chinese Holstein cattle

Mastitis is one of the most prevalent diseases in dairy cattle; CXCR1 plays a key role in mastitis resistance via IL8 signaling pathway, with the CXCR1 SNPs showing a different degree of mastitis resistance. To investigate the situation of CXCR1 polymorphisms in Chinese Holstein cattle and determine the relationship between the CXCR1 SNPs and mastitis resistance, the CXCR1 SNPs in 610 Chinese Holstein cattle of 30 families were investigated using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique. The results showed that four SNPs, -1830A > G, -1768T > A, -344T > C, and 783C > A were detected at 5' upstream and coding region. The correlation analysis demonstrated that -1830AA, -1768TT, and -344TT correlated significantly with the lowest SCS for each site, respectively. Haplotype analysis revealed Haplo2 (ATTA) correlated significantly with the lowest SCS. These findings indicated a prospect genetic marker of mastitis resistance in dairy cattle.     

Polymorphisms of the <Emphasis Type="Italic">IL8</Emphasis> gene correlate with milking traits,SCS and mRNA level in Chinese Holstein

To explore the relation of Interleukin-8 (IL8) gene polymorphism with immunity against mastitis in dairy cow, the polymorphism of IL8 gene was investigated in 610 Chinese Holstein cow from 30 bull families in a dairy farm in Shanghai using polymerase chain reaction–single strand conformation polymorphism (PCR–SSCP) technique, and milk yield, milk fat percentage, milk protein percentage, 305 day corrected milk yield, 305 day milk fat yield, 305 day milk protein yield and somatic cell score (SCS) were measured and analyzed, and the mRNA levels of IL8 genotypes in blood were detected by real-time PCR. The results showed that three genotypes, KK, KA and AA were detected with frequencies of 0.187, 0.451, and 0.362, respectively. The gene frequencies of K and A were 0.412 and 0.588, respectively. The significant association of the IL8 mutations with milk yield, 305 day milk protein yield, 305 day corrected milk yield and 305 day milk fat yield, SCS, and significant association with milk protein percentage were identified, while their association with milk fat percentage were not significant. KK had higher milk yield, 305 day milk protein yield, 305 day corrected milk yield and 305 day milk fat yield than AA or KA, and the least square mean of SCS of KK was significantly lower than that of AA or KA. AA had significant lower milk protein yield than KK or KA. The relative IL8 mRNA level of KK in blood was the highest. These findings demonstrated that IL8 genotype significantly correlated with mastitis resistance and the locus could be a useful genetic marker for mastitis resistance selection and breeding in Chinese Holstein.     

Toll-Like Receptor 2 Gene Polymorphism and its Relationship with SCS in Dairy Cattle

Toll-like receptor 2 (TLR2) plays an important role in the innate immune response to a variety of pathogens. In this study, bovine TLR2 gene was taken as a candidate gene for mastitis resistance. Through PCR-SSCP analysis and sequencing, three missense mutations at T385 G, G398A, and G1884A were detected in the coding region that encoded extracellular domain. Altogether 240 dairy cattle of three breeds (Holstein, Simmental, and Sanhe cattle) were genotyped and allele frequencies were determined. The effects of TLR2 polymorphisms on somatic cell score (SCS) were analyzed and significant association was found between T385 G and SCS. The mean of genotype GG was significantly lower than those of genotype TT and TG. No significant associations were found with SCS for G398A and G1884A. Information provided in this research will be useful in further studies to determine the role of TLR2 gene in the mastitis resistance.     

奶牛乳铁蛋白基因5′侧翼区遗传多态性及其与乳腺炎关联性分析

牛乳铁蛋白(Lactoferrin, LF)是保护乳腺组织的防御因子之一, 是具有多种功能的糖蛋白。关于牛LF基因的多态性研究的报道较多, 但其多态性与奶牛乳腺炎相关性的研究较少。文章采用PCR-RFLP、CRS-PCR对268头中国荷斯坦牛LF基因启动子区的-926(G/A)、-915(T/G)、-478(/G)、+72(T/C)突变进行基因型分型, 应用最小二乘线性模型分析LF基因多态性与体细胞评分(Somatic cell score, SCS)的相关性。结果表明, 新发现+72(T/C)和-478(/G)对SCS有显著影响, 而其他两个位点对SCS影响不显著(P>0.05)。+72(T/C)的AB基因型是优良基因型, 其个体的SCS值均显著低于AA型(P<0.01)、BB型个体(P<0.05)。-478(/G)位点的C等位基因是优良的等位基因, CC基因型个体的SCS值极显著低于CD、DD基因型个体(P<0.01)。因此, LF基因+72(T/C)的AB基因型和-478(/G)位点的CC基因型均是奶牛乳腺炎抗性的优良基因型, 可作为分子标记应用于奶牛乳腺炎抗性筛选。     

Polymorphism of exon 2 of <Emphasis Type="Italic">BoLA</Emphasis>-<Emphasis Type="Italic">DRB3</Emphasis> gene and its relationship with somatic cell score in Beijing Holstein cows

In the present study, the exon 2 and 3′ end sequence of intron 1 of BoLA-DRB3 gene of 211 Beijing Holstein cows was amplified and a uniform fragment of 284 bp was obtained. The genetic polymorphism was investigated by PCR-RFLP using two restriction endonucleases HaeIII and BstYI. Seven genotypes were detected by digesting the PCR products with HaeIII. The frequency of AA, AB, AC, AD, BB, BC and BF genotypes was 0.4638, 0.0193, 0.0193, 0.3478, 0.0290, 0.0386 and 0.0822, respectively. Three genotypes were found by digesting the PCR products with BstYI. The frequency of AA, AB and BB genotypes was 0.0569, 0.2844 and 0.6587, respectively. The relationship between the polymorphisms in exon 2 of BoLA-DRB3 gene and somatic cell score (SCS) in Beijing Holstein cows was analyzed by least squares linear model. No significant difference was detected among least squares means of SCS for seven HaeIII-RFLP genotypes (P > 0.05). As for BstYI-RFLP analysis, least squares mean of SCS for AA was significantly lower than that for AB (P < 0.05) or BB (P < 0.05), and no significant difference was detected between AB and BB genotypes (P > 0.05). BstYI AA was the most favorable genotype and BstYI BB was the most unfavorable genotype for mastitis resistance. The information found in the present study is very important for improving mastitis resistance in dairy cattle by marker assisted selection.     

Association of IL8 -105G/A with Mastitis Somatic Cell Score in Chinese Holstein Dairy Cows

The single nucleotide polymorphisms (SNPs) in the 5′ upstream of bovine IL8 gene were investigated in 810 Chinese Holstein cows from 35 bull families in a dairy farm in Shanghai using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique. The Real-time PCR and Western blot were used to detect the mRNA and protein levels of genotype Chinese Holstein dairy cows. The results showed that one SNP -105G>A was detected, designating three genotypes (GG, GA and AA) with respective frequencies of 0.38, 0.46, and 0.16. The significant association of the SNP -105G>A with somatic cell score (SCS) was identified. Genotype GG had a significantly lower SCS than genotype GA or AA (P < 0.01), and the relative mRNA expression and protein level of GG was found to be the highest. These results suggest that the genotype GG may be a useful genetic marker for mastitis resistance selection and breeding in Chinese Holstein dairy cows.     

荷斯坦牛Nramp1基因遗传多态性及其与乳房炎相关性的研究

利用PCR-SSCP技术检测了344头中国荷斯坦牛Nramp1基因exon 11的基因多态性, 并分析了其不同基因型与乳房炎及产奶量性状的关系。结果表明: 实验群体发现3种基因型AA、AB、BB, 其中A等位基因为优势等位基因, 等位基因频率为0.767, 而B等位基因频率则为0.233。经χ2适合性检验, 群体处于Hardy-Weinberg平衡状态(P>0.05)。测序结果显示: 扩增片段分别在200 bp(C/G)和254 bp(T/G)存在碱基突变, 并导致了氨基酸改变, 分别为丙氨酸替换为脯氨酸(Ala356Pro)、亮氨基酸替换为蛋氨酸(Leu374Met)。通过构建最小二乘线性模型, 进行Nramp1基因多态性与产奶量、体细胞评分(SCS)的相关性分析表明, AA型个体的SCS最小二乘均值显著低于BB﹑AB型(P<0.05), 而AA型﹑AB个体的产奶量最小二乘均值显著高于BB型(P<0.01, P<0.05), AA基因型可作为乳房炎抗性的优良基因型。因此, 可将Nramp1作为奶牛乳房炎候选基因应用于分子标记辅助选择育种。     

Candidate SNP of CACNA2D1 Gene Associated with Clinical Mastitis and Production Traits in Sahiwal (Bos taurus indicus) and Karan Fries (Bos taurus taurus × Bos taurus indicus)

The present study was conducted to identify polymorphisms in CACNA2D1 gene and their association with clinical mastitis and production traits. Exon 18 and its flanking regions were screened for the presence of SNPs. Statistical analysis was performed to identify association of period of birth, breed, and genotype with mastitis incidence on randomly selected 103 Sahiwal and 102 Karan Fries cattle. PCR-RFLP analysis revealed that g.38819398G?>?A mutation in exon 18 (269?bp amplicon) of CACNA2D1 gene resolved into AA, AG, and GG genotypes in Sahiwal and Karan Fries cattle. Wald chi-square analysis revealed that the period of birth, breed, and genotype were significantly associated with mastitis incidence. GG genotyped cattle were found to be less susceptible to mastitis. Least square analysis revealed that GG and AG genotype animals of G38819398A SNP of CACNA2D1 gene in Sahiwal as well as in Karan Fries cattle were associated with higher average milk yields during 1st, 2nd, and 3rd lactations (P?<?0.01). These observations and their differential association with the incidence of mastitis and production traits can be utilized as an aid to selection for simultaneous improvement of both antagonistic traits; however, validation of results on large number of animals is warranted.     

SNPs in the bovine IL-10 receptor are associated with somatic cell score in Canadian dairy bulls

Altering the balance between pro- and anti-inflammatory responses can influence an animal’s susceptibility to acute or chronic inflammatory disease; bovine mastitis is no exception. Genetic variation in the form of single nucleotide polymorphisms (SNPs) may alter the function and expression of genes that regulate inflammation, making them important candidates for defining an animal’s risk of developing acute or chronic mastitis. The objective of the present study was to identify SNPs in genes that regulate anti-inflammatory responses and test their association with estimated breeding values (EBVs) for somatic cell score (SCS), a trait highly correlated with the incidence of mastitis. These genes included bovine interleukin-10 (IL-10) and its receptor (IL-10R), and transforming growth factor β1 (TGF-β1) and its receptor (TGF-βR). Sequencing-pooled DNA allowed for the identification of SNPs in IL-10 (n = 2), IL-10Rα (n = 6) and β (n = 2), and TGF-β1 (n = 1). These SNPs were subsequently genotyped in a cohort of Holstein (n = 500), Jersey (n = 83), and Guernsey (n = 50) bulls. Linear regression analysis identified significant SNP effects for IL-10Rα 1185C>T with SCS. Haplotype IL-10Rα AAT showed a significant effect on increasing SCS compared to the most common haplotype. The results presented here indicate that SNPs in IL-10Rα may contribute to variation in the SCS of dairy cattle. Although functional studies are necessary to ascertain whether these SNPs are causal polymorphisms or merely in linkage with the true causal SNP(s), a selection program incorporating these markers could have a beneficial influence on the average SCS and productivity of a dairy herd.     

中国荷斯坦牛IL8基因遗传多态性与泌乳性状以及体细胞评分的关联

以上海某奶牛场30个公牛家系的610头中国荷斯坦牛为试验材料,采用聚合酶链式反应-单链构象多态性(PCR-SSCP)技术对Interleukin-8(IL8)基因的遗传多态性进行了分析,采用混合动物模型分析了IL8基因突变位点与测定日产奶量、测定日乳脂率、测定日乳蛋白率、305d校正产奶量、305d乳脂量、305d乳蛋白量及测定日体细胞评分7个性状的相关性,寻找可用于生产实际的分子标记。共检测到KK、KA和AA3种基因型,频率分别为0.187、0.451和0.362,等位基因K和A的频率分别为0.412和0.588。该位点突变对测定日产奶量、305d乳蛋白量、305d校正产奶量和305d乳脂量以及体细胞评分影响达到极显著水平(P0.01),对测定日乳蛋白率的影响达到显著水平(P0.05),对测定日乳脂率影响不显著(P0.05)。多重比较表明:KK基因型对测定日产奶量、305d校正产奶量、305d乳蛋白量和305d乳脂量极显著高于AA和KA基因型(P0.01)。KK基因型的体细胞评分(SCS)最小二乘均值极显著低于KA、AA基因型(P0.01)。对于测定日的乳蛋白率AA基因型显著低于KA、KK型(P0.05)。IL8基因遗传突变对中国荷斯坦牛泌乳性状和乳房炎抗性有较大的遗传效应,可用于中国荷斯坦牛的分子标记辅助选择。     

Mannose-binding lectin 1 haplotypes influence serum MBL-A concentration,complement activity,and milk production traits in Chinese Holstein cattle

Mannose-binding lectin (MBL) is a member of the collectin protein family that binds a broad range of microorganisms and activates the lectin-complement pathway of innate immunity. MBL deficiency is associated with an increased risk for various infections and arises from five polymorphisms in the promoter and first exon of the MBL gene in humans. In this study, three novel single-nucleotide polymorphisms (SNPs) in the promoter region and two previously reported SNPs in exon 2 of the MBL1 gene were detected using PCR single-strand conformation polymorphism, restriction fragment length polymorphism, and DNA sequencing in 537 cattle from three Chinese breeds. Analysis of the genotypes and haplotypes was used to investigate the polymorphisms and their possible implications, especially their association with serum MBL-A levels, complement activity (CH50 and ACH50), and milk production traits was investigated. The g.2651G>A SNP in exon 2 affected the serum MBL-A concentrations and the serum CH50 values, whereas the g.−1330G>A SNP significantly affected CH50 and the somatic cell scores (SCSs). Statistical analysis revealed that cows with the ATGGC/ACAAC combined genotype and those with the AAGGT/ACGGT combined genotype exhibited the lowest and highest SCSs, respectively. Serum antibacterial activities were also conducted to verify the effect of the SNPs on resistance to mastitis pathogens. Results of real-time PCR showed that the liver of cows with clinical mastitis exhibited a higher MBL1 expression compared with healthy ones (P < 0.05). Findings of this study indicate that the MBL1 gene possibly contributes to bacterial infection resistance and can be used as a molecular marker of milk production traits to control mastitis.     

Single nucleotide polymorphism of CACNA2D1 gene and its association with milk somatic cell score in cattle

The objective of the present study was to identify polymorphisms of the CACNA2D1 gene, and to analyze associations between these polymorphisms and mastitis in several cattle breeds. Through PCR-RFLP methods and DNA sequencing, an allelic variant corresponding to the A→G mutations and Aspartic (Asp) to Glycine (Gly) amino acid replacement at positions 526745 in the exon 25 of bovine CACNA2D1 gene could be detected. Two alleles, A and G, and three genotypes, AA, AG and GG were defined. Genetic character in the studied populations indicated that the A526745G loci of CACNA2D1 gene was moderate polymorphism and fitted with Hardy-Weinberg equilibrium (P > 0.05). The effects of CACNA2D1 polymorphisms on somatic cell score (SCS) were analyzed and significant association was found between A526745G and SCS. The mean of genotype GG was significantly lower than those of genotype AG and AA (P = 0.0469). Information provided in this research could be useful in further studies to determine the role of CACNA2D1 gene in the mastitis resistance.     

Association study of single nucleotide polymorphisms in JAK2 and STAT5B genes and their differential mRNA expression with mastitis susceptibility in Chinese Holstein cattle

The JAK–STAT pathway plays a key role in mediating immune responses. The genetic effects of single nucleotide polymorphisms (SNPs) in JAK2 and STAT5B were investigated for serum cytokines, mastitis indicators and productions traits in a population of 468 Chinese Holstein cattle. Pooled DNA sequencing revealed one SNP (BTA8:g.39645396A>G) in JAK2 and two SNPs (BTA19:g.43673888A>G and BTA19:g.43660093T>C) in STAT5B. A fixed effect model considering the effects of SNPs, parity, herd, season and year of calving was used by way of the general linear model procedure of sas . Genotype frequencies of these SNPs in the population were in Hardy–Weinberg equilibrium (P > 0.05). A novel SNP (g.39645396A>G) in JAK2 was predicted to change the amino acid from lysine to asparagine and was significantly associated with the somatic cell count (SCC) and somatic cell score (SCS), whereas g.43673888A>G in STAT5B was significantly associated with SCC, SCS and interleukin‐4 (IL‐4) (P < 0.05). The dominant effect of g.39645396A>G in JAK2 was significant for SCS, and its additive effect was significant for SCC, whereas the dominant effect of g.43673888A>G in STAT5B was significant for SCS and IL‐4 (P < 0.05). The combination of g.39645396A>G in JAK2 and g.43673888A>G in STAT5B showed a significant effect on SCC, SCS, IL‐4 and TNF‐α (P < 0.05). As for mRNA expression analysis, the AA genotype g.39645396A>G and GG genotype g.43673888A>G indicated higher mRNA expression level and were significantly different from other genotypes (P < 0.05). The results imply that JAK2 and STAT5B genes could be useful candidate genes, and the identified polymorphisms might potentially be strong genetic markers for selection of dairy cattle against mastitis development.     

Associations of polymorphisms in the promoter I of bovine acetyl‐CoA carboxylase‐α gene with beef fatty acid composition

The objectives of this study were to identify single nucleotide polymorphisms (SNPs) in the promoter I (PI) region of the bovine acetyl‐CoA carboxylase‐α (ACACA) gene and to evaluate the extent to which they were associated with lipid‐related traits. Eight novel SNPs were identified, which were AJ276223:g.2064T>A (SNP1), g.2155C>T (SNP2), g.2203G>T (SNP3), g.2268T>C (SNP4), g.2274G>A (SNP5), g.2340A>G (SNP6), g.2350T>C (SNP7) and g.2370A>G (SNP8). Complete linkage disequilibrium was observed among SNP1, 2, 4, 5, 6 and 8. Phenotypic data were collected from 573 cross‐bred steers with six sire breeds, including Hereford, Angus, Brangus, Beefmaster, Bonsmara and Romosinuano. The genotypes of SNP1/2/4/5/6/8 were significantly associated with adjusted backfat thickness. The genotypes of SNP3 were significantly associated with triacylglycerol (TAG) content and fatty acid composition of longissimus dorsi muscle (LM) in Brangus‐, Romosinuano‐ and Bonsmara‐sired cattle. Cattle with g.2203GG genotype had greater concentrations of TAG, total lipid, total saturated fatty acid and total monounsaturated fatty acid than did cattle with g.2203GT genotype. The genotypes of SNP7 were significantly associated with fatty acid composition of LM. Cattle with genotype g.2350TC had greater amounts of several fatty acids in LM than did cattle with genotype g.2350CC. Our results suggested that the SNPs in the PI region of ACACA gene are associated with variations in the fatty acid contents in LM.     

Polymorphism of the <Emphasis Type="Italic">BoLA-DRB3</Emphasis> gene in the Mongolian,Kalmyk, and Yakut cattle breeds

Polymorphism of the BoLA-DRB3 gene was studied with the use of the PCR-RFLP technique in three cattle breeds (Mongolian, Kalmyk, and Yakut) representing the Bos taurus turano-mongolicus group. 35 BoLA-DRB3.2 alleles were detected in the Mongolian breed and 34 alleles in the Kalmyk breed. The frequencies of alleles in both populations are distributed rather evenly: the frequencies of the most widely represented alleles (*18, *20, and *28) in the Mongolian cattle varied from 7.75 to 8.45%. The most frequent alleles in the Kalmyk cattle were *28 (14.52%), *24 (7.26%), and *12 (6.45%). Only five alleles were identified in the Yakut cattle breed. The prevailing allele was *29 (77.3%); a relatively frequent allele was *1 (13.1%), and the remaining three alleles constituted only 9.6%. Such a low level of diversity of BoLA-DRB3 gene alleles was not observed earlier in any other cattle breed. The Mongolian and Kalmyk breeds showed a wide diversity of BoLA-DRB3 genotypes (56 and 51 genotypes, respectively) and a high level of expected heterozygosity (H _e = 0.953 and 0.946, respectively). Both breeds had a deficiency of heterozygotes (Mongolian cattle: H _o = 0.775, D = −0.187; Kalmyk cattle: H _o = 0.708, D = −0.252). A low level of genotypic diversity for the BoLA-DRB3 locus (only seven genotypes; the frequency for the genotype *29/*29 is 71.4%) and a very low level of observed heterozygosity (H _o = 0.12) were revealed in the Yakut breed. BoLA-DRB3.2 alleles associated with resistance to persistent lymphocytosis caused by the bovine leukemia virus (total frequencies 15.49 and 24.19%) and to various forms of mastitis (total frequencies 12.68 and 20.96%, respectively) were identified in the Mongolian and Kalmyk animals. In the Yakut breed, alleles associated with resistance to diseases are represented only by the BoLA-DRB3.2 allele *7 (1.2%). Thus, the Mongolian and Kalmyk cattle breeds are characterized by a wide diversity of alleles and genotypes for the BoLA-DRB3 gene. In contrast, the population of Yakut cattle from the Verkhoyanskii region of the Republic of Sakha has a poor diversity of alleles and genotypes for the BoLA-DRB3 gene and a very low level of heterozygosity, suggesting an unfavorable state of the population that is probably caused by inbreeding depression due to a long-term isolation and a small number of animals.