A whole-genome assembly of the domestic cow, Bos taurus, was completed using a combination of hierarchical and whole-genome shotgun sequencing methods. The assembly, named UMD2, consists of 2.86 billion base pairs and includes 2.61 billion base pairs placed on 30 chromosomes. It is more complete and accurate than previous assemblies, with thousands of gaps closed and many errors corrected. The assembly was evaluated using independent metrics and found to be significantly more accurate than alternative versions. The assembly includes a large portion of the B. taurus Y chromosome and provides a high-quality resource for annotation and research in cattle genomics. The UMD2 assembly was compared to the BCM4 assembly, which was produced by the Baylor College of Medicine. The UMD2 assembly is larger and has a higher N50 contig size, indicating better assembly quality. The UMD2 assembly also has more accurate gene mapping and fewer segmental duplications. The assembly was validated using independent mapping data and showed a higher accuracy in gene mapping. The UMD2 assembly was also compared to the human genome and showed a high level of synteny between the cow and human genomes. The assembly includes a detailed synteny map between the cow and human genomes, which was used to identify homologous synteny blocks. The UMD2 assembly was also compared to six finished BAC sequences and showed a higher accuracy in mapping. The assembly was deposited in GenBank and is available for further research. The study highlights the importance of accurate genome assemblies for future research in cattle genomics and comparative mammalian genomics.A whole-genome assembly of the domestic cow, Bos taurus, was completed using a combination of hierarchical and whole-genome shotgun sequencing methods. The assembly, named UMD2, consists of 2.86 billion base pairs and includes 2.61 billion base pairs placed on 30 chromosomes. It is more complete and accurate than previous assemblies, with thousands of gaps closed and many errors corrected. The assembly was evaluated using independent metrics and found to be significantly more accurate than alternative versions. The assembly includes a large portion of the B. taurus Y chromosome and provides a high-quality resource for annotation and research in cattle genomics. The UMD2 assembly was compared to the BCM4 assembly, which was produced by the Baylor College of Medicine. The UMD2 assembly is larger and has a higher N50 contig size, indicating better assembly quality. The UMD2 assembly also has more accurate gene mapping and fewer segmental duplications. The assembly was validated using independent mapping data and showed a higher accuracy in gene mapping. The UMD2 assembly was also compared to the human genome and showed a high level of synteny between the cow and human genomes. The assembly includes a detailed synteny map between the cow and human genomes, which was used to identify homologous synteny blocks. The UMD2 assembly was also compared to six finished BAC sequences and showed a higher accuracy in mapping. The assembly was deposited in GenBank and is available for further research. The study highlights the importance of accurate genome assemblies for future research in cattle genomics and comparative mammalian genomics.