Polymorphism of Bovine Prolactin Gene: Microsatellites,PCR–RFLP

In the samples of Russian Ayrshire and Gorbatov Red cattle breeds, distribution of frequencies of prolactin (PRL) gene alleles generated due to the presence of polymorphic RsaI site in exon 3 were studied. In the breeds, the frequencies of the Ballele of the PRLgene (with RsaI(+) site) detected by the PCR–RFLP method were 14.1 and 8.6%, respectively. In Black Pied, Ayrshire and Gorbatov Red cattle breeds, variation of the microsatellite dinucleotide repeat in the regulatory region of the gene PRLwas also studied. Gorbatov Red breed was monomorphic at the microsatellite locus with the only allele 164 bp in length. Two alleles (164 bp and 162 bp) were detected in the other breeds studied. The frequencies of 164-bp allele of the microsatellite locus were 93.7 and 90.0% in Black Pied and Ayrshire breeds, respectively. In Gorbatov Red breed of dairy type with good beef qualities and low milk-fat yield, lower level of heterozygosity for PRLgene was demonstrated compared to Ayrshire and Black Pied breeds that have high milk-fat yield. In three cattle breeds, higher mean estimate of polymorphism information content of PCR–RFLP in exon 3 (PIC = 0.21) was revealed compared with the same estimate (PIC = 0.09) for the microsatellite locus variability in the regulatory region of the PRLgene. Characteristics of allele Bdistribution of thePRLgene in the representatives of the Bovidae family are considered.     

Comparative analysis of Ayrshire and Black Pied cattle breeds by histocompatibility markers

Distribution of BoLA-A antigens and BoLA-DRB3 alleles was studied by means of the microlymphocytotoxic test (BoLA-A) and the PCR-RFLP method (BoLA-DRB3) using restriction endonucleases RSAI, HaeIII, and XhoII in Ayrshire (n = 127) and Black Pied (n = 129) cattle breeds. Comparative analysis of profiles for class I antigens revealed significant differences in the frequencies of antigens W2, W6, W10, W31, W44, W15, and W19 (P > 99%). The studied breeds also differ in the spectrum of BoLA-DRB3 alleles and distribution of their frequencies. Heterogeneous allele frequency profile was detected in Ayrshire cattle: five of 18 detected alleles (DRB3.2*7, *8, *10, *24, and *28) accounted for 77%. Allele DRB3.2*7 (37.6%), which is classed with rare alleles in Black Pied cattle is the most common in Ayrshire cattle. The observed heterozygosity level in the combined sample of Black Pied breed (0.836) is higher than in Ayrshire breed (0.070). In both breeds, the heterozygosity level was studied in the groups of healthy and ill with persistent lymphocytosis (caused by bovine leukemia virus) animals and in the group of virus carriers in Ayrshire breed. In ill animals, a decrease in the observed heterozygosity level was detected, as compared to healthy animals and the expected heterozygosity level. The observed heterozygosity level exceeds the expected one in virus carriers. The detected features of the heterozygosity level in the studied groups allow the heterozygosity level for locus BoLA-DRB3 to be considered a nonspecific factor of resistance to leukemia and are heterozygous animals to have higher resistance to bovine leukemia. The presence of a larger proportion of highly productive animals (the annual productivity of more than 7000 kg) in the group of ill Ayrshire cattle animals, as compared to healthy animals to established. To increase resistance to bovine leukemia, the obtained data indicate the importance of the control of heterozygosity level and genetic diversity for gene BoLA-DRB3 in cattle herds.     

Analysis of Genetic Variation at the Prolactin-RsaI (PRL-RsaI) Locus in Indian Native Cattle Breeds (Bos indicus)

This study assessed the distribution pattern of allelic variants at the prolactin-RsaI locus in 23 Indian native cattle breeds (Bos indicus). PCR-RFLP genotyping of a 156?bp fragment of prolactin (PRL) in exon 3 revealed the predominance of the heterozygous AB genotype (mean frequency 0.58) irrespective of utility type (dairy, dual, draft), geographic region (northern, central, southern), and coat color (red, gray) of the breeds analyzed. The overall frequencies of homozygous AA (0.22) and BB (0.20) genotypes were in a similar range. The PRL (A) and PRL (B) alleles exhibited similar gene frequencies (means 0.52 and 0.48, respectively). The existing profile of the PRL-RsaI gene locus in a large set of Indian native cattle breeds was different from that of Bos taurus and cattle breeds of other countries, where either the BB genotype and PRL (B) allele or the AA genotype and PRL (A) allele have been reported to be more prevalent.     

Association of DNA polymorphisms of the growth hormone and prolactin genes with milk productivity in Yaroslavl and black-and-white cattle

Polymorphisms of the prolactin (bPRL) and growth hormone (bGH) genes were studied comparatively in the Russian and German Black-and-White and Yaroslavl cattle breeds. Two polymorphisms were studied for each gene. In the case of the bPRL gene, the polymorphism of the 5'-untranslated region was examined by microsatellite analysis and the RsaI polymorphism of exon 3, by RFLP analysis. In the case of the bGH gene, the MspI polymorphism of intron III and the AluI polymorphism of exon 5 were assessed by RFLP analysis. Differences in allele and genotype frequencies were observed both between and within breeds. The heterozygosity at the RsaI marker was low (9.4%) in the Russian Black-and-White breed; that at the microsatellite of the bPRL gene was low (3.2-24%) in all breeds examined. Homozygotes BB at the bPRL gene, which had not been reported earlier for European cattle breeds, were detected in the German Black-and-White and Yaroslavl breeds (at frequencies 0.16 and 0.13, respectively). The frequency of allele MspI(-) of the bGH gene in the Yaroslavl breed was extremely low (0.02), comparable only with that of the Holstein cattle (0.02). The heterozygosity at the AluI polymorphism was higher than at the MspI polymorphism of the bGH gene and reached 55% in the Yaroslavl breed. Genotype BB of the RsaI polymorphism of the bPRL gene tended to show a negative association with the fat content in milk. The genotypes of the AluI polymorphism of the bGH gene were associated with the fat content in milk in the Yaroslavl (F = 4.56, P = 0.013) and German Black-and-White (F = 4.1, P = 0.014) breeds: the highest fat content in milk was observed in the subsample of cows with heterozygous genotype VL.     

微卫星标记对12个中外牛品种群体遗传结构的研究

选用联合国粮农组织(FAO)和国际动物遗传学会(ISAG)推荐的12对微卫星引物, 采用荧光标记–多重PCR技术, 检测了9个中国地方黄牛品种和3个外来牛品种的遗传多样性。利用等位基因频率计算出各群体的平均遗传杂合度(H)、多态信息含量(PIC)和群体间的DA及DS遗传距离。基于DA遗传距离, 用UPGMA法进行聚类分析, 结果12个中外牛品种被聚为4类: Ⅰ类属于南方黄牛品种, 包括恩施牛、黎平牛、昭通牛和川南山地牛; Ⅱ类属于中原黄牛品种, 包括郏县红牛、早胜牛和平陆山地牛; Ⅲ类属于北方黄牛, 包括延边牛和长白地方牛; Ⅳ类属于外来牛品种, 包括西门塔尔牛、夏洛来牛和德国黄牛。研究结果为中国地方牛品种的保护和利用提供了理论依据。     

Allelic polymorphism of kappa-casein gene (CSN3) in Russian cattle breeds and its informative value as a genetic marker

The frequencies of the kappa-casein gene (CSN3) alleles and genotypes have been determined in five Russian cattle breeds (Bestuzhev, Kalmyk, Russian Black Pied, Yaroslavl, and Yakut breeds) by means of PCR-RFLP analysis using two independent restriction nucleases (HinfI and TaqI) and by allele-specific PCR. Typing alleles A and B of CSN3 is of practical importance, because allele B is correlated with commercially valuable parameters of milk productivity (protein content and milk yield) and improves the cheese yielding capacity. The frequencies of the B allele of CSN3 in the breeds studied vary from 0.16 to 0.50; and those of the AB and BB genotypes, from 0.27 to 0.60 and from 0.02 to 0.23, respectively. The Yaroslavl breed had the highest frequencies of CSN3 allele B and genotype BB (0.50 and 0.23, respectively). The frequencies of the B allele and BB genotype in other breeds studied varied from 0.25 to 0.32 and from 0.03 to 0.09, respectively. In none of the breeds studied have the observed and expected heterozygosities been found to differ from each other significantly. However, the observed genotype distributions significantly differ from the expected one in some herds (in most such cases, an excess of heterozygotes is observed). Two herds of the Yaroslavl breed dramatically differ from each other in the heterozygosity level: a deficit (D = -0.14) and an excess (D = 0.20) of heterozygotes have been observed at the Mikhailovskoe and Gorshikha farms, respectively. In general, however, the heterozygosity of the Yaroslavl breed corresponds to the expected level (D = 0.04). Analysis of breeds for homogeneity with the use of Kulback's test has shown that all cattle breeds studied are heterogeneous, the CSN3 diversity within breeds being higher than that among different breeds, which is confirmed by low Fst values (0.0025-0.0431). Thus, a DNA marker based on CSN3 gene polymorphism is extremely important for breeding practice as a marker of milk quality; however, it is inapplicable to marking differences between breeds or phylogenetic relationships between cattle breeds because of the high diversity with respect to this locus within breeds.     

Genetic structure of Eurasian cattle (Bos taurus) based on microsatellites: clarification for their breed classification1

We pool three previously published data sets and present population genetic analyses of microsatellite variation in 48 Bos taurus cattle breeds from a wide range of geographical origins in Eurasia, mostly its northern territory. Bayesian model‐based clustering reveals six distinct clusters: besides a single‐population cluster of the Yakutian Cattle from Far Eastern Siberia and a cluster of breeds characteristic of an early origin, the other four major clusters largely correspond to previously defined morphological subgroups of Red Lowland, Lowland Black‐Pied, Longhorned Dairy and North European Polled cattle breeds. The results highlighted past expansion events of the productive breeds such as Danish Red, Angeln, Holstein‐Friesian and Ayrshire in northern and Eastern Europe. Based on genetic assignment of the breeds and the availability of breed information, we provide a preliminary classification of the five breeds that were to date undefined. Furthermore, in the analysis of molecular variance, despite some correspondence between geographical proximity and genetic similarity, the breed classification appears to be a better predictor of genetic structure in the cattle populations (the among‐group variance component: breed classification, 2.47%, P < 0.001; geographical division, 0.77%, P < 0.001).     

Genetic mechanisms of resistance and susceptibility to leukemia in Ayrshire and black pied cattle breeds determined by allelic distribution of gene Bola-DRB3

In the herds of Ayrshire and Black Pied cattle breeds of Russian selection, comparative analysis of allelic distribution of BoLA-DRB3 was performed in animal groups with different status of persistent lymphocytosis (PL) caused by the bovine leukemia virus (BLV). Alleles were typed by PCR-RFLP. Different spectra of BoLA-DRB3 alleles mediating susceptibility and resistance to leukemia were detected in the studied breeds. The role of amino acid motives in beta 1 domain of BoLA-DRB3 antigens was confirmed: ER (in positions 70-71), in resistance to leukemia and VDTY and VDTV (75-78), in susceptibility to leukemia. The nucleotide sequence of allele BoLA-DRB3.2*7 with deletion of codon 65, which resulted in the changed conformation of the corresponding antigen molecule, was associated with resistance to PL. Cows of Black Pied and Ayrshire breeds with genotypes coding VDTY/VDTV (RR = 11.67, P = 0.014) and VDTY/VDTY (RR = 4.71, P = 0.022), respectively, were shown to be susceptible to PL. The role of heterozygosity level was demonstrated (estimated by BoLA-DRB3 alleles and by amino acid motives in positions 75-78 of the antigen) as an unspecific factor of resistance to PL. The lowest heterozygosity level by amino acid motives (75-78) was revealed in PL animals, for which sample inbreeding coefficients were detected: F = 0.324 and F = 0.084 in Ayrshire and Black Pied breeds, respectively.     

Diversity of the TLR4 Immunity Receptor in Czech Native Cattle Breeds Revealed Using the Pacific Biosciences Sequencing Platform

The allelic variants of immunity genes in historical breeds likely reflect local infection pressure and therefore represent a reservoir for breeding. Screening to determine the diversity of the Toll-like receptor gene TLR4 was conducted in two conserved cattle breeds: Czech Red and Czech Red Pied. High-throughput sequencing of pooled PCR amplicons using the PacBio platform revealed polymorphisms, which were subsequently confirmed via genotyping techniques. Eight SNPs found in coding and adjacent regions were grouped into 18 haplotypes, representing a significant portion of the known diversity in the global breed panel and presumably exceeding diversity in production populations. Notably, the ancient Czech Red breed appeared to possess greater haplotype diversity than the Czech Red Pied breed, a Simmental variant, although the haplotype frequencies might have been distorted by significant crossbreeding and bottlenecks in the history of Czech Red cattle. The differences in haplotype frequencies validated the phenotypic distinctness of the local breeds. Due to the availability of Czech Red Pied production herds, the effect of intensive breeding on TLR diversity can be evaluated in this model. The advantages of the Pacific Biosciences technology for the resequencing of long PCR fragments with subsequent direct phasing were independently validated.     

Restriction Fragment Length Polymorphism (RFLP) in Exon 2 of the BoLA-DRB3 Gene in South American Cattle

The Bola-DRB3 gene participates in the development of the immune response and is highly polymorphic. For these reasons, it has been a candidate gene in studies of the genetic basis of disease resistance and in population genetic analysis. South American native cattle breeds have been widely replaced by improved exotic breeds leading to a loss of genetic resources. In particular, South American native breeds have high levels of fertility and disease resistance. This work describes genetic variability in the BoLA-DRB3 gene in native (Caracu, Pantaneiro, Argentinean Creole) and exotic (Holstein, Jersey, Nelore, Gir) cattle breeds in Brazil and Argentina. PCR-RFLP alleles were identified by combining the restriction patterns for the BoLA-DRB3.2 locus obtained with RsaI, BstY and HaeIII restriction enzymes. Allelic frequencies and deviations from the Hardy-Weinberg equilibrium were also calculated. Analysis of the 24 BoLA-DRB3 PCR-RFLP alleles identified showed differences in the allele distributions among breeds.     

Nucleotide sequence polymorphism within exon 4 of the bovine prolactin gene and its associations with milk performance traits

Prolactin plays an important regulatory function in mammary gland development, milk secretion, and expression of milk protein genes. Hence the PRL gene is a potential quantitative trait locus and genetic marker of production traits in dairy cattle. We analysed the sequence of the PRL gene to investigate whether mutations in this sequence might be responsible for quantitative variations in milk yield and composition. Using SSCP and direct sequencing, we detected six single-nucleotide polymorphisms within a 294-bp prolactin gene fragment involving exon 4. All detected mutations were silent with respect to the amino acid sequence of the protein. PCR-RFLP genotyping of SNP 8398 R (RsaI) was used to assess allele frequencies in 186 Black-and-White cows (0.113 and 0.887 for A and G, respectively) and in 138 Jersey cows (0.706 and 0.294 for A and G, respectively). Black-and-White cows with genotype AG showed the highest milk yield, while cows with genotype GG showed the highest fat content.     

Analysis of STAT5A/AvaI Gene Polymorphism in Four Italian Cattle Breeds

The STAT5A/AvaI polymorphism was investigated with PCR-RFLP in a sample of 339 cattle belonging to four breeds: Italian Friesian, Jersey, Italian Brown, and Podolica reared in south Italy. All three possible genotypes for the C/T polymorphism were identified. In these breeds, PCR-RFLP showed the predominance of the TT genotype in Italian Brown and Jersey cows; in Podolica and Italian Friesian CT is the most frequent genotype. The frequency of the T allele ranged from 0.55 to 0.81 in the analyzed populations. The distribution of genotypic and allelic frequencies at this locus was significantly different among the four populations based on a χ² test (P < 0.001), suggesting that the molecular characteristics of the STAT5A gene could be significantly affected by the breed selection. Gene heterozygosity, gene homozygosity, effective allele number, fixation index, and polymorphism information content (PIC) were calculated. The observed heterozygosity, as well as the N _e and PIC values, indicates high genetic variability in the Podolica breed. Podolica could be considered an interesting reservoir of genetic diversity for a species under high selective pressure elsewhere.     

DNA typing of Pakistani cattle breeds Tharparkar and Red Sindhi by microsatellite markers

Microsatellite markers are used for any individual identity and breed characterization in animals that is an efficient and successful way of investigation. They are used for multiple purposes as genetic detectors including, rapid mutation rate, high level of polymorphism, and range of variety of microsatellite markers available. A panel of 19 microsatellite markers was developed for breed characterization in Tharparkar and Red Sindhi breeds of cattle in Pakistan. Forty four blood samples of cattle (each breed) were collected from Department of Livestock Management, Sindh Agriculture University, Tandojam, Tando Qaiser, Tharparkar Cattle Farm Nabi sar Road, Umer Kot, Sindh, and Govt. Red Sindhi Cattle Breeding Farm, Tando Muhammad Khan Pakistan. Breed characterization was 100% successful. Average PIC, He and Power of Exclusion values were found to be 0.91, 0.62 and 13.28, respectively. Pattern of allelic frequencies of most of the microsatellite markers were clearly distinct between two breeds. As a result of present study a reliable, efficient and very informative panel of microsatellite markers was successfully developed which was capable to interpret individual identity, forensic cases and breed characterization in cattle. This facility is ready to be provided to local cattle breeder at commercial level for DNA testing of cattle. This study will also be highly helpful for breed conservation of cattle. In addition this study can also become a basis to open up new disciplines of animal forensics in Pakistan.     

湖北省三品种猪27个微卫星座位的遗传变异

采用国际动物遗传学会（ISAG）和联合国粮农组织（FAO）共同推荐的27个微卫星标记,对湖北省3个主要地方猪种（通城猪、清平猪和阳新猪）的遗传变异进行了检测。计算出各个品种的基因杂合度、各个座位的多态信息含量及品种间的遗传距离。结果表明,3个地方猪种的平均基因杂合度分别为0.7489、0.6987和0.6273,遗传多样性比较丰富;通城猪和清平猪亲缘关系较近,而两者与阳新猪亲缘关系略远。     

Polymorphism of intron 2 of the SDF1 gene in Galloway, Hereford, and Russian Black Pied cattle

The region of intron 2 of the SDF1 gene encoding a chemokine of the CXC subfamily has been resequenced in Galloway, Hereford, and Black Pied cattle. Five of the single-nucleotide polymorphisms (SNPs) that were earlier detected by other authors in various breeds of cattle in North America (99C/G, 128T/C, 206C/T, 267C/G and 313C/T) have been found. The 270insC polymorphic marker has proved to be monomorphic in Russian cattle breeds. Hereford cattle significantly differ from Galloway and Black Pied cattle in the frequencies of some SNP variants and their combinations. The number of SNP combinations in Hereford and Galloway cattle exceeds that in Black Pied cattle.     

Polymorphism of intron 2 of the <Emphasis Type="Italic">SDF1</Emphasis> gene in Galloway,Hereford, and Russian Black Pied cattle

The region of intron 2 of the SDF1 gene encoding a chemokine of the CXC subfamily has been resequenced in Galloway, Hereford, and Black Pied cattle. Five of the single-nucleotide polymorphisms (SNP) that were earlier detected by other authors in various breeds of cattle in North America (99C/G, 128T/C, 206C/T, 267C/G and 313C/T) have been found. The 270insC polymorphic marker has proved to be monomorphic in Russian cattle breeds. Hereford cattle significantly differ from Galloway and Black Pied cattle in the frequencies of some SNP variants and their combinations. The number of SNP combinations in Hereford and Galloway cattle exceeds that in Black Pied cattle.     

Association of a missense mutation in the bovine leptin gene with carcass fat content and leptin mRNA levels

Previously, we have shown that alleles of the BM1500 microsatellite, located 3.6 kb downstream of the leptin gene in cattle, were associated with carcass fat measures in a population of 154 unrelated beef bulls. Subsequently, a cytosine (C) to thymine (T) transition that encoded an amino acid change of an arginine to a cysteine was identified in exon 2 of the leptin gene. A PCR-RFLP was designed and allele frequencies in four beef breeds were correlated with levels of carcass fat. The T allele was associated with fatter carcasses and the C allele with leaner carcasses. The frequencies of the SNP alleles among breeds indicated that British breeds have a higher frequency of the T allele whereas the continental breeds have a higher occurrence of the C allele. A ribonuclease protection assay was developed to quantify leptin mRNA in a separate group of animals selected by genotype. Animals homozygous for thymine expressed higher levels of leptin mRNA. This may suggest that the T allele, which adds an extra cysteine to the protein, imparts a partial loss of biological function and hence could be the causative mutation.     

Evaluation of genetic differentiation in Bos indicus cattle breeds from Marathwada region of India using microsatellite polymorphism

Elucidation of genetic variability and genetic relationship among breeds has direct relevance with the issues of sustainable use of domestic animal genetic resources. In the present study, genetic polymorphism was evaluated using 22 microsatellite loci in unrelated samples of Red Kandhari and Deoni cattle breeds inhabiting the same geographical area of Marathwada region in Maharashtra state (western India). This work was mainly aimed at assessing the current genetic diversity to understand whether the two zebu populations in question are genetically differentiated. A total of 164 alleles were detected with an average of 5.82 and 5.86 alleles per locus (MNA) in Red Kandhari and Deoni breeds, respectively. The estimated mean observed (Ho) and expected (He) heterozygosity were 0.47 and 0.64 in Red Kandhari vs. 0.57 and 0.69 in Deoni cattle, respectively, demonstrating considerable level of genetic variation in both the populations. Mean estimates of F statistics were: F (FIT) = 0.315 +/- 0.035, f(FIS) = 0.231 +/- 0.031, theta(FST) = 0.110 +/- 0.022, with both the breeds exhibiting significant deficit of heterozygotes (FIS = 0.179 in Deoni; 0.278 in Red Kandhari). The multilocus FST values implied that 11.0% of the total genetic variation corresponds to breed and were statistically greater than zero for the two populations, suggesting population division. The evaluation of exact test also indicated that allele frequencies across all the loci differed significantly (P < 0.001) between two zebu breeds, further supporting population differentiation. Different genetic distance measures showed considerable levels of distances between the two cattle breeds (0.318 = Nei's standard DS; 0.250 = Nei's DA; 0.416 = Cavalli-Sforza and Edwards's Dc; 0.164 = Reynold's, and 2.64 = Delta mu square (dmicro)2. Bayesian statistical approach to assign each individual to the population also supported considerable differentiation between the two cattle breeds, possibly reflecting the limited gene flow between the two Marthwada cattle populations. The existence of cohesive breeding structure of both the breeds was further substantiated by allele-sharing distance measures (DAS) among individual animals. The results of this study thus revealed that the two Bos indicus breeds sharing the common breeding tracts are genetically differentiated enough as separate breeds.     

Evaluation of Genetic Differentiation in Bos indicus Cattle Breeds from Marathwada Region of India Using Microsatellite Polymorphism

Elucidation of genetic variability and genetic relationship among breeds has direct relevance with the issues of sustainable use of domestic animal genetic resources. In the present study, genetic polymorphism was evaluated using 22 microsatellite loci in unrelated samples of Red Kandhari and Deoni cattle breeds inhabiting the same geographical area of Marathwada region in Maharashtra state (western India). This work was mainly aimed at assessing the current genetic diversity to understand whether the two zebu populations in question are genetically differentiated. A total of 164 alleles were detected with an average of 5.82 and 5.86 alleles per locus (MNA) in Red Kandhari and Deoni breeds, respectively. The estimated mean observed (Ho) and expected (He) heterozygosity were 0.47 and 0.64 in Red Kandhari vs. 0.57 and 0.69 in Deoni cattle, respectively, demonstrating considerable level of genetic variation in both the populations. Mean estimates of F statistics were: F (FIT) = 0.315±0.035, f(FIS) = 0.231±0.031, θ(FST) = 0.110±0.022, with both the breeds exhibiting significant deficit of heterozygotes (FIS = 0.179 in Deoni; 0.278 in Red Kandhari). The multilocus FST values implied that 11.0% of the total genetic variation corresponds to breed and were statistically greater than zero for the two populations, suggesting population division. The evaluation of exact test also indicated that allele frequencies across all the loci differed significantly (P < 0.001) between two zebu breeds, further supporting population differentiation. Different genetic distance measures showed considerable levels of distances between the two cattle breeds (0.318 = Nei's standard DS; 0.250 = Nei's DA; 0.416 = Cavalli-Sforza and Edwards's DC; 0.164 = Reynold's, and 2.64 = Delta mu square (dμ)2. Bayesian statistical approach to assign each individual to the population also supported considerable differentiation between the two cattle breeds, possibly reflecting the limited gene flow between the two Marthwada cattle populations. The existence of cohesive breeding structure of both the breeds was further substantiated by allele-sharing distance measures (DAS) among individual animals. The results of this study thus revealed that the two Bos indicus breeds sharing the common breeding tracts are genetically differentiated enough as separate breeds.