The genetic improvement of livestock species is a very effective and sustainable method for enhancing the quality of livestock and their products. Selective breeding can be used to induce genetic changes that are both permanent and cumulative. Gene marker tests are now being used by seed stock and commercial cattle breeders to identify the specific alleles that are present within candidates for selection. Genetic Solutions (Brisbane, Australia), a leading biotech company focused on genetic information technology for the livestock industries globally offers such genetic tests. The GeneSTAR marbling and GeneSTAR tenderness tests marketed by Genetic Solutions are based on an SNP-based (single nucleotide polymorphism, a single DNA base sequence variation) genotyping (measuring DNA sequence variations) assay that uses the Luminex suspension array technology. Luminex xMAP microsphere technology and the Luminex100 flow analyzer is a system designed specifically for microsphere suspension arrays and is capable of performing both protein and nucleic acid analyses. SNP genotyping can be accomplished through a variety of assay formats. A solution-based allele-specific enzymatic step can be used to determine the genotype followed by capture onto the solid microsphere surface for detection. The process involves incorporation of a specific capture sequence during the enzymatic step that allows hybridization to a complementary address sequence on the microsphere surface. Alternatively, alleles can be discriminated by direct hybridization of a labeled PCR-amplified target DNA to microsphere sets bearing oligonucleotide capture probes specific for each SNP allele. The design, development, and optimization of a direct hybridization assay for SNP detection in the bovine calpastatin gene using the Luminex xMAP platform has been completed. The SNP has been associated with improved tenderness and eating quality of beef and is marketed as GeneSTAR tenderness.