Microalgae provide preformed long chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA), particularly docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). Their inclusion in cattle diets may increase the nutritional value of beef, but responses vary according to microalgal species, fatty acid composition, processing method, dietary inclusion level, feeding duration, basal diet and animal characteristics. Ruminal lipolysis and biohydrogenation substantially limit the transfer of dietary unsaturated fatty acids into muscle, while excessive lipid supplementation may reduce feed intake or compromise ruminal function. Although beef studies generally demonstrate increased muscle EPA, DHA or total LC n-3 PUFA following microalgal supplementation, the magnitude of deposition is inconsistent and may not always be sufficient to support nutrition content claims. Enrichment may also increase susceptibility to lipid oxidation, colour deterioration or undesirable flavour, although these effects depend on antioxidant protection, postmortem ageing, packaging, retail display and product format. Genetic variation contributes to intramuscular fat, fat melting point and fatty acid composition. Associations involving FASN, SCD, FABP4, FADS2, FADS3 and THRSP genes provide a biological basis for genetic improvement, but candidate gene effects can be population specific and should increasingly be complemented by genome wide prediction. Direct evidence that genotype modifies the response to microalgal supplementation remains scarce. Integrating microalgal nutrition, rumen protection technologies, repeated phenotyping, genomics, metabolomics and microbiome analysis therefore appears promising rather than established. Commercial translation will require adequately powered multibreed studies, standardised reporting of fatty acids in edible portions, comprehensive meat quality assessment, validated genomic predictions and evidence of economic return across feedlot and supply chain settings.