Pasture-finishing enhances phytonutrients and fat-soluble vitamin profiles while grain-finishing enhances B-vitamins in beef from North American commercial operations.

Consumers and producers are increasingly interested in how finishing practices impact beef nutrient density. This study compared ribeye steaks from grass-fed cattle (n = 237) and grain-fed cattle (n = 71) sourced from 112 North American operations and retailers using targeted metabolomics. Grain-fed beef contained 15-35% higher vitamins B₁, B₅, and B₆ (all p ≤ 0.05), reflecting vitamin-mineral premixes and/or enhanced microbial synthesis under amylolytic rumen conditions. In contrasts, grass-fed beef contained ∼88% higher α-tocopherol and ∼ 53% higher β-carotene (both p ≤ 0.01). Of 195 detected phytonutrients and related metabolites, 43 differed significantly between systems; 35 were higher in grass-fed beef, including hippuric acid (+78%), p-cresol sulfate (+37%), and cinnamoylglycine (+93%; all, p < 0.001), while 8 were higher in grain-fed beef, including 4-hydroxyphenylacetic acid (+275%) and 3-phenyllactic acid (+150%; both p < 0.001). Correlation analyses indicate that botanically diverse and well-rested pastures were associated with higher α-tocopherol and total phytonutrient concentrations in grass-fed beef, while higher phenylpropanoic/phenyllactic compounds associated with grain finishing.