Genome-wide discovery of SNPs in candidate genes related to production and fertility traits in Sahiwal cattle

Genome-wide selection signatures address trait specific candidate genes in cattle indigenous to arid regions of India

The peculiarity of Indian cattle lies in milk quality, resistance to diseases and stressors as well as adaptability. The investigation addressed selection signatures in Gir and Tharparkar cattle, belonging to arid ecotypes of India. Double digest restriction-site associated DNA sequencing (ddRAD-seq) yielded nearly 26 million high-quality reads from unrelated seven Gir and seven Tharparkar cows. In all, 19,127 high-quality SNPs were processed for selection signature analysis. An approach involving within-population composite likelihood ratio (CLR) statistics and between-population FST statistics was used to capture selection signatures within and between the breeds, respectively. A total of 191 selection signatures were addressed using CLR and FST approaches. Selection signatures overlapping 86 and 73 genes were detected as Gir- and Tharparkar-specific, respectively. Notably, genes related to production (CACNA1D, GHRHR), reproduction (ESR1, RBMS3), immunity (NOSTRIN, IL12B) and adaptation (ADAM22, ASL) were annotated to selection signatures. Gene pathway analysis revealed genes in insulin/IGF pathway for milk production, gonadotropin releasing hormone pathway for reproduction, Wnt signalling pathway and chemokine and cytokine signalling pathway for adaptation. This is the first study where selection signatures are identified using ddRAD-seq in indicine cattle breeds. The study shall help in conservation and leveraging genetic improvements in Gir and Tharparkar cattle.

Genome-wide mining of diversity and evolutionary signatures revealed selective hotspots in Indian Sahiwal cattle

The Sahiwal cattle breed is the best indigenous dairy cattle breed, and it plays a pivotal role in the Indian dairy industry. This is due to its exceptional milk-producing potential, adaptability to local tropical conditions, and its resilience to ticks and diseases. The study aimed to identify selective sweeps and estimate intrapopulation genetic diversity parameters in Sahiwal cattle using ddRAD sequencing-based genotyping data from 82 individuals. After applying filtering criteria, 78,193 high-quality SNPs remained for further analysis. The population exhibited an average minor allele frequency of 0.221 ± 0.119. Genetic diversity metrics, including observed (0.597 ± 0.196) and expected heterozygosity (0.433 ± 0.096), nucleotide diversity (0.327 ± 0.114), the proportion of polymorphic SNPs (0.726), and allelic richness (1.323 ± 0.134), indicated ample genomic diversity within the breed. Furthermore, an effective population size of 74 was observed in the most recent generation. The overall mean linkage disequilibrium (r2) for pairwise SNPs was 0.269 ± 0.057. Moreover, a greater proportion of short Runs of Homozygosity (ROH) segments were observed suggesting that there may be low levels of recent inbreeding in this population. The genomic inbreeding coefficients, computed using different inbreeding estimates (FHOM, FUNI, FROH, and FGROM), ranged from -0.0289 to 0.0725. Subsequently, we found 146 regions undergoing selective sweeps using five distinct statistical tests: Tajima's D, CLR, |iHS|, |iHH12|, and ROH. These regions, located in non-overlapping 500 kb windows, were mapped and revealed various protein-coding genes associated with enhanced immune systems and disease resistance (IFNL3, IRF8, BLK), as well as production traits (NRXN1, PLCE1, GHR). Notably, we identified interleukin 2 (IL2) on Chr17: 35217075-35223276 as a gene linked to tick resistance and uncovered a cluster of genes (HSPA8, UBASH3B, ADAMTS18, CRTAM) associated with heat stress. These findings indicate the evolutionary impact of natural and artificial selection on the environmental adaptation of the Sahiwal cattle population.

Phenotypic and genetic characterization of unexplored, potential cattle population of Madhya Pradesh

Bawri or Garri, a non-descript cattle population managed under an extensive system in Madhya Pradesh state of India, was identified and characterized both genetically and phenotypically to check whether or not it can be recognised as a breed. The cattle have white and gray colour and are medium sized with 122.5 ± 7.5 cm and 109.45 ± 0.39 cm height at withers in male and female, respectively. Double-digest restriction site associated DNA (ddRAD) sequencing was employed to identify ascertainment bias free SNPs representing the entire genome cost effectively; resulting in calling 1,156,650 high quality SNPs. Observed homozygosity was 0.76, indicating Bawri as a quite unique population. However, the inbreeding coefficient was 0.025, indicating lack of selection. SNPs found here can be used in GWAS and genetic evaluation programs. Considering the uniqueness of Bawri cattle, it can be registered as a breed for its better genetic management.

Genomic clues of association between clinical mastitis and SNPs identified by ddRAD sequencing in Murrah buffaloes

The total milk production of India is 209.96 MT out of which 45% is contributed by the indigenous buffalo and due to their high producing virtue, the prevalence of mastitis is 5-20%. Despite the increasing level of technological advancement, mastitis is still an issue of concern for dairy industry in India as well as across the world. Therefore, the present study aimed to identify the SNPs and associate them with the incidence of clinical mastitis in Murrah buffalo using the ddRAD sequencing approach taking mastitis incidence data of 96 Murrah buffaloes. A total of 246 million quality controlled reads were obtained with an average alignment rate of 99.01% and at a read depth of 10, quality controlled SNPs obtained were 18,056. The logistic regression model was used and a total of seven SNPs were found significantly associated (p < 0.001) with mastitis incidence and seven genes were identified viz., NCBP1, FOXN3, TPK1, XYLT2, CPXM2, HERC1, and OPCML. The majority of them were having tumor suppressing action, related to immunogenetics or glycolytic and energy production. Conclusively, the SNPs identified in this study may be useful for future studies on mastitis incidence in Murrah buffalo and the SNP associations can be further validated.

Genome wide mining of SNPs and INDELs through ddRAD sequencing in Sahiwal cattle

The study was conducted in Sahiwal cattle for genome wide identification and annotation of single nucleotide polymorphisms (SNPs) and insertions and deletions (INDELs) in Sahiwal cattle. The double digest restriction-site associated DNA (ddRAD) sequencing, a reduced representation method was used for the identification of variants at nucleotide level. A total of 1,615,211 variants were identified at RD10 and Q30 consisting of 1,480,930 SNPs and 134,281 INDELs with respect to the Bos taurus reference genome. The SNPs were annotated for their location, impact and functional class. The SNPs identified in Sahiwal cattle were found to be associated with a total of 26,229 genes. A total of 1819 SNPs were annotated for 209 candidate genes associated with different production and reproduction traits. The variants identified in the present study may be useful to strengthen the existing bovine SNP chips for reducing the biasness over the taurine cattle breeds. The diversity analysis provides the insight of the genetic architecture of the Sahiwal population Studied. The large genetic variations identified at the nucleotide level provide ample scope for implementing an effective and efficient breed improvement programme for increasing the productivity of Sahiwal cattle.

Genome-wide genetic variation and population structure of native and cosmopolitan cattle breeds reared in Türkiye

This is the first comprehensive study to reveal genetic variation and population structure at genome level in six Anatolian (Anatolian Black, East Anatolian Red, South Anatolian Red, South Anatolian Yellow, Turkish Grey Steppe, and Zavot) and two cosmopolitan (Brown Swiss and Holstein Friesian) cattle breeds reared in Türkiye. Being 20 samples from each population, a total of 160 blood samples retrieved from representative herds were utilized to generate genomic libraries by ddRADseq method. Genomic libraries sequenced by Illumina HiSeq X Ten instrument revealed a total of 211,119 bi-allelic SNPs with high call rate. Compared to cosmopolitan cattle breeds, a higher genetic variation was observed in native Turkish cattle with an average of 0.380 observed heterozygosity. Genetic distances were comparatively low between native cattle breeds, whereas the highest genetic distance (0.064) was detected between South Anatolian Yellow and Brown Swiss. Population structure analyses showed that the native Turkish and cosmopolitan cattle breeds were clearly different from each other according to their phylogenetic origin. Besides, a high level of genetic admixture was detected among Anatolian Black, Turkish Grey Steppe, South Anatolian Red, and South Anatolian Yellow, whereas East Anatolian Red and Zavot were distinct from the other native and cosmopolitan cattle breeds. TreeMix algorithm under the assumption of one and two migration events revealed a migration route from Anatolian clade to Anatolian Black, while a second migration edge was drawn from Brown Swiss to East Anatolian Red. This study demonstrates the importance of national conservation studies in the native breeds whose population size has dramatically decreased. In addition, SNP arrays and next-generation sequencing platforms are recommended for future studies to reveal the genetic variation of other local Turkish livestock species to arrange effective conservation programs.

Genetic variants of TORC1 gene promoter and their association with carcass quality and body measurement traits in Qinchuan beef cattle

In the present study, sequencing of TORC1 prompter region explored three SNPs at loci g.80G>T, g.93A>T, and g.1253G>A. The SNP1 produced GG, GT and TT, SNP2 AA, AT and TT, and SNP3 produced GG, GA and AA genotypes. Allelic and genotypic frequencies analysis exhibited that SNP1 is within Hardy-Weinberg equilibrium (HWE). All three SNPs were found highly polymorphic as PIC value (0.25 < PIC < 0.50). At loci g.80G>T the cattle with genotype GG showed significantly (P <0.01) larger body length (BL), Wither height (WH), Hip height (HH), Rump length (RL), Hip width (HW), Chest depth (CD), and Chest circumference (CC). The genotype AA at g.93A>T showed significantly (P< 0.01 and 0.05) Larger body length (BL), Wither height (WH), Hip height, Rump length (RL), Hip width (HW), Chest depth (CD), and Chest circumference (CC). Interestingly, the carcass quality parameters such as Ultrasound loin area (ULA) and Intramuscular fat percentage (IF%) was highest in genotype GG at loci g.1253G>A. These findings conclude that genotype GG at loci g.80 G>T and AA at loci g.93A>T could be used as genetic markers for body measurement and genotype GG at loci g.1253G>A for carcass quality traits of TORC1 gene in Qinchuan beef cattle.

Landmarks in the history of selective sweeps

Half a century ago, a seminal article on the hitchhiking effect by Smith and Haigh inaugurated the concept of the selection signature. Selective sweeps are characterised by the rapid spread of an advantageous genetic variant through a population and hence play an important role in shaping evolution and research on genetic diversity. The process by which a beneficial allele arises and becomes fixed in a population, leading to a increase in the frequency of other linked alleles, is known as genetic hitchhiking or genetic draft. Kimura's neutral theory and hitchhiking theory are complementary, with Kimura's neutral evolution as the 'null model' and positive selection as the 'signal'. Both are widely accepted in evolution, especially with genomics enabling precise measurements. Significant advances in genomic technologies, such as next-generation sequencing, high-density SNP arrays and powerful bioinformatics tools, have made it possible to systematically investigate selection signatures in a variety of species. Although the history of selection signatures is relatively recent, progress has been made in the last two decades, owing to the increasing availability of large-scale genomic data and the development of computational methods. In this review, we embark on a journey through the history of research on selective sweeps, ranging from early theoretical work to recent empirical studies that utilise genomic data.

Bioinformatics and genetic variants analysis of FGF10 gene promoter with their association at carcass quality and body measurement traits in Qinchuan beef cattle

The fibroblast growth factor 10 (FGF10) gene regulates adipogenesis and myogensis. In this study, sequencing of FGF10 prompter region identified three SNPs at loci g.78G > A, g.116C > T and g.201A > T. Each SNP yields three genotypes as GG, GA and AA at loci g.78G > A, CC, CT and TT at loci g.116C > T and AA, AT and TT at loci g.201A > T. Allelic and genotypic frequencies of all three SNPs deviated from the Hardy-Weinberg equilibrium (HWE) (P < 0.05) and were found highly polymorphic as PIC (0.25 < PIC < 0.50). Moreover, we found highest LD (D'/γ2) between SNP2 and SNP3 (0.989/0.909), followed by SNP1 and SNP3 (0.944/0.796). Moreover, three variants of FGF10 gene promoter exhibited significant (P < 0.05) association with body measurement and carcass quality traits in Qinchuan beef cattle. At loci g.78G > A, the genotype GG showed significantly (P < 0.01) larger body length (BL), rump length (RL), chest depth (CD), chest circumference (CC) and ultrasound loin area (ULA). The genotype TC at loci g.116C > T showed significantly (P < 0.01 and 0.05) larger body measurement and intramuscular fat, and ultrasound loin area (ULA). In addition to that, at loci g.201A > T, genotype TT showed significantly (P < 0.01 and P < 0.05) larger body length (BL), rump length (RL), hip width (HW), chest circumference (CC) and ultrasound loin area (ULA). Additionally, screening of promoter sequence of FGF10 gene explored loss of four TFs binding sites (KLF3, ZNF37α, GLIS2 and BCL11A) at g.116C > T because of SNP2. However, a single TF binding site was lost at g.202A > T due to SNP3. Interestingly, none of TF binding site was lost at g.78G > A in SNP1; however, one new TF binding site was gained at this location due to SNP1. These findings conclude that genotype GG, TC and TT could be used as genetic markers of FGF10 gene for body measurement and carcass quality traits in Qinchuan beef cattle.

Progress and future perspectives of livestock genomics in India: a mini review

The field of genetics has evolved a lot after the emergence of molecular and advanced genomic technologies. The advent of Next Generation Sequencing, SNP genotyping platforms and simultaneous reduction in the cost of sequencing had opened the door to genomic research in farm animals. There are various applications of genomics in livestock, such as the use of genomic data: (i) to investigate genetic diversity and breed composition/population structure (ii) to identify genetic variants and QTLs related to economically important and ecological traits, genome-wide association studies (GWAS) and genomic signatures of selection; (iii) to enhance breeding programs by genomic selection. Compared to traditional methods, genomic selection is expected to improve selection response by increasing selection accuracy and reducing the generation interval due to early selection. Genomic selection (GS) in developed countries has led to rapid genetic gains, especially in dairy cattle, due to a well-established genetic evaluation system. Indian livestock system is still lagging behind developed nations in adopting these technologies. This review discusses the current status, challenges, and future perspectives of livestock genomics in India.

Genetic variation in the OPN gene affects milk composition in Chinese Holstein cows

The aim of this study was to investigate the association between genotypes and haplotypes of OPN, and milk composition in dairy cows. A total of 317 Chinese Holstein cows were genotyped via DNA sequencing in this study. Three single nucleotide polymorphisms (SNPs), g.2916G > A, g.58675C > T and g.58899C > A, and eight haplotypes were identified. Of the eight possible haplotypes, four haplotypes i.e., Hap2 (ACC; 55.30%), Hap6 (GCC, 15.6%), Hap1 (ACA, 13.6%) and Hap4 (ATC, 5.70%), were considered to be major with a cumulative estimated frequency of >90%. Single markers (g.2916G > A and g.58899C > A) and Haplotype Hap6/4 were found to be associated with an increase in butter-fat percentage (p < 0.05). Taken together, our results provided evidence that polymorphisms in OPN are associated with milk composition, and could potentially be used for marker-assisted selection in Chinese Holstein cows.

Genome-wide identification and annotation of SNPs for economically important traits in Frieswal™, newly evolved crossbred cattle of India

The Frieswal™ is a crossbred cattle evolved by ICAR-Central Institute for Research on Cattle utilizing more than 15,000 cattle maintained at more than 37 military farms spread all over the agro-climatic regions of the country. The ddRAD sequencing method was used to identify and annotate the SNPs and INDELs. The results of variant calling revealed 1,487,851 SNPs and 128,175 INDELs at a read depth of 10. A total of 3,775,079 effects were identified, and majority (66.41%) of the effects were in the intron region of the genome followed by intergenic (21.87%). Majority (99.18%) of the variants had the modifier effect. The results revealed a higher magnitude of transitions as compared to the transversion. The classification of SNPs by functional class revealed a majority of missense (43%) and silent (56%) effects. Out of 26,278 genes identified, 1841 SNPs were annotated in 207 candidate genes responsible for various milk production and reproduction traits. The observed heterozygosity was 0.2804 against the expected heterozygosity value of 0.2978. The overall average inbreeding coefficient (FIS) was 0.0604. The pathway analysis revealed that the prolactin signaling pathway (GO:0038161) was significant biological process complete for both milk production and reproduction traits. The SNP variations can be effectively used as markers for early and accurate identification of the QTLs and for formulating an efficient and effective breed improvement program in Frieswal™ cattle.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03701-0.

ddRAD sequencing based genotyping of six indigenous dairy cattle breeds of India to infer existing genetic diversity and population structure

The present investigation aimed to identify genome wide SNPs and to carry out diversity and population structure study using ddRAD-seq based genotyping of 58 individuals of six indigenous milch cattle breeds (Bos indicus) such as Sahiwal, Gir, Rathi, Tharparkar, Red Sindhi and Kankrej of India. A high percentage of reads (94.53%) were mapped to the Bos taurus (ARS-UCD1.2) reference genome assembly. Following filtration criteria, a total of 84,027 high quality SNPs were identified across the genome of 6 cattle breeds with the highest number of SNPs observed in Gir (34,743), followed by Red Sindhi (13,092), Kankrej (12,812), Sahiwal (8956), Tharparkar (7356) and Rathi (7068). Most of these SNPs were distributed in the intronic regions (53.87%) followed by intergenic regions (34.94%) while only 1.23% were located in the exonic regions. Together with analysis of nucleotide diversity (π = 0.373), Tajima's D (D value ranging from - 0.295 to 0.214), observed heterozygosity (HO ranging from 0.464 to 0.551), inbreeding coefficient (FIS ranging from - 0.253 to 0.0513) suggested for the presence of sufficient within breed diversity in the 6 major milch breeds of India. The phylogenetic based structuring, principal component and admixture analysis revealed genetic distinctness as well as purity of almost all of the 6 cattle breeds. Overall, our strategy has successfully identified thousands of high-quality genome wide SNPs that will further enrich the Bos indicus representation basic information about genetic diversity and structure of 6 major Indian milch cattle breeds which should have implications for better management and conservation of valuable indicine cattle diversity.

Genome-wide identification and annotation of SNPs and their mapping in candidate genes related to milk production and fertility traits in Badri cattle

This study was conducted in Badri cattle using a double digest restriction-site associated DNA sequencing approach. The study aimed to identify and annotate high confidence single nucleotide polymorphisms (SNPs) and their mapping in candidate genes related to production and fertility in dairy cattle. A total of 7,168,552 genome-wide SNPs were initially identified in Badri cattle by alignment with the Bos indicus reference genome. After filtration of SNPs, 65,483 high confidence SNPs were retained and further used for downstream analysis. Annotation of high confidence SNPs revealed 99.197% SNPs had modifier impact, 0.326% SNPs were low impact, 0.036% were high impact, and 0.441% were moderate impact SNPs. Most SNPs in Badri cattle were found in intergenic, transcript and intronic regions. The candidate genes for milk production PRKCE, ABCG2, GHR, EPS8, CAST and NRXN1 were found to harbour maximum high confidence variants. Among candidate genes for fertility in cattle, ATP2B1, SOX5, WDR27, ARHGAP12, CACNA1D, ANKRD6, GRIA3, ZNF521 and CAST822 have maximum high confidence variants mapped in them. The SNPs found mapped in the candidate genes will be important genetic tools in the search for phenotype-modifying nucleotide changes and will aid in formulating relevant genetic improvement programmes for dairy cattle.

Trajectory of livestock genomics in South Asia: A comprehensive review

Livestock plays a central role in sustaining human livelihood in South Asia. There are numerous and distinct livestock species in South Asian countries. Several of them have experienced genetic development in recent years due to the application of genomic technologies and effective breeding programs. This review discusses genomic studies on cattle, buffalo, sheep, goat, pig, horse, camel, yak, mithun, and poultry. The frontiers covered in this review are genetic diversity, admixture studies, selection signature research, QTL discovery, genome-wide association studies (GWAS), and genomic selection. The review concludes with recommendations for South Asian livestock systems to increasingly leverage genomic technologies, based on the lessons learned from the numerous case studies. This paper aims to present a comprehensive analysis of the dichotomy in the South Asian livestock sector and argues that a realistic approach to genomics in livestock can ensure long-term genetic advancements.

A Post-GWAS Functional Analysis Confirming Effects of Three BTA13 Genes CACNB2, SLC39A12, and ZEB1 on Dairy Cattle Reproduction

In our previous GWAS of Chinese and Nordic dairy cattle, genes CACNB2, SLC39A12, and ZEB1 locating on BTA 13 were suggested as candidate genes for reproduction. In this study, validation of these associations was performed in an independent population with records of nine reproductive traits. More importantly, functions of these genes in the reproductive process were verified by employing the expression data of ovarian follicles. The potential variants within the three genes were firstly detected in 68 Chinese Holstein bulls, and then screened in 1,588 Chinese Holstein cows using the KASP (Kompetitive allele-specific PCR) method. There were nine variants with polymorphisms in CACNB2, five in SLC39A12, and four in ZEB1, respectively, of which one SNP was in the upstream regulatory region, two in exon region, four in downstream regulatory region, and 11 SNPs in intronic regions. Amongst the 18 variants, g.33267056T/G in CACNB2 explained the largest phenotypic variance for age at first calving (0.011%), interval from first to last insemination (0.004%), and calving ease (0.002%), while g.32751518G/A in SLC39A12 contributed the most to stillbirth in heifers (0.038%). Two haplotype blocks were constructed for CACNB2 while one each for SLC39A12 and ZEB1, which were significantly associated with five reproductive traits, including age at the first service, age at the first calving, calving ease in heifers and cows, and the interval from calving to the first insemination. We then studied the profile of gene expression in granulosa cells isolated from four developmental stages of ovarian follicles from eight dairy cows. All three genes were differentially expressed between ovarian follicles with different sizes (p < 0.05), indicating their potential roles in the reproductive process of dairy cows. This study successfully demonstrated the associations of three BTA 13 genes CACNB2, SLC39A12, and ZEB1 with reproduction and further examined their expression levels in ovarian follicles directly. These findings can be beneficial for the ongoing genomic selection program for reproductive traits which have long been considered as traits that are difficult to achieve genetic improvement due to the lack of efficient genetic markers.

Within- and between-Breed Selection Signatures in the Original and Improved Valachian Sheep

This study explored the genomic diversity and selection signatures in two Slovakian national breeds, the Original Valachian and the Improved Valachian sheep. As they are an important animal genetic resource within the country, but with decreasing population size, our aim is to identify potentially valuable genomic regions. A total of 97 sheep (18 male and 79 female) from the Original Valachian, and 69 sheep (25 male and 44 female) from the Improved Valachian populations were genotyped using the GeneSeek GGP Ovine 50 K chip. The inbreeding levels were assessed with runs of homozygosity (ROH). The selection signatures within breeds were identified based on the top 1% of most homozygous regions within the breed, the so-called ROH islands. The selection signatures between breeds were assessed based on variance in linkage disequilibrium. Overall, we have identified selection signatures with quantitative trait loci (QTL) and genes pointing towards all three production purposes of the Valachian sheep, milk, meat, and wool, including their quality characteristics. Another group with apparent large importance was the various traits related to health and resistance to parasites, which is well in line with the sturdy nature of this breed.

Comparative Signatures of Selection Analyses Identify Loci Under Positive Selection in the Murrah Buffalo of India

India is home to a large and diverse buffalo population. The Murrah breed of North India is known for its milk production, and it has been used in breeding programs in several countries. Selection signature analysis yield valuable information about how the natural and artificial selective pressures have shaped the genomic landscape of modern-day livestock species. Genotype information was generated on six buffalo breeds of India, namely, Murrah, Bhadawari, Mehsana, Pandharpuri, Surti, and Toda using ddRAD sequencing protocol. Initially, the genotypes were used to carry out population diversity and structure analysis among the six breeds, followed by pair-wise comparisons of Murrah with the other five breeds through XP-EHH and F _ST methodologies to identify regions under selection in Murrah. Admixture results showed significant levels of Murrah inheritance in all the breeds except Pandharpuri. The selection signature analysis revealed six regions in Murrah, which were identified in more than one pair-wise comparison through both XP-EHH and F _ST analyses. The significant regions overlapped with QTLs for milk production, immunity, and body development traits. Genes present in these regions included SLC37A1, PDE9A, PPBP, CXCL6, RASSF6, AFM, AFP, ALB, ANKRD17, CNTNAP2, GPC5, MYLK3, and GPT2. These genes emerged as candidates for future polymorphism studies of adaptability and performance traits in buffaloes. The results also suggested ddRAD sequencing as a useful cost-effective alternative for whole-genome sequencing to carry out diversity analysis and discover selection signatures in Indian buffalo breeds.

A SNP within the PMCH gene as a molecular marker associated with fertility traits in Angus and Brangus beef heifers raised under a desert environment

Components of the GH/IGF1 endocrine axis regulate growth and reproductive traits in cattle. The pro-melanin-concentrating hormone (PMCH) gene located within chromosome 5 belongs to this axis. Objective herein was to evaluate PMCH single-nucleotide polymorphisms (SNPs) as molecular markers associated with age at first calving, calving interval, and age at second calving in Angus and Brangus beef heifers raised in desert conditions. Five SNPs within the PMCH gene were included in the study. Three of these SNPs had minor allele frequency > 10% and only one SNP did not deviate from Hardy-Weinberg equilibrium. A genotype to phenotype association analyses was performed using a mixed-effects model which included phenotype as the response variable, SNP genotype, breed, year of birth and age of dam as fixed terms, and sire as a random effect. Genotypes from the SNP rs135033882 were found to be associated (P < 0.05) with all evaluated fertility traits, and the term breed resulted as a significant source of variation only for age at second calving. The allele A was the favorable allele because it decreased the age at first calving 98.6 days, the calving interval 85.3 days, and the age at second calving 183.1 days, in Angus and Brangus heifers. In conclusion, we proposed a SNP within the PMCH gene as a potential candidate marker associated with reproductive performance in Angus and Brangus beef heifers raised in a desert climate.