Consumer interest in the source of their food, its environmental footprint, and the impact of diet on health has supported the growth of the grass-finished beef (GFB) industry. Studies have concluded that GFB has distinct nutritional differences from conventionally-finished beef. As the GFB industry continues to expand, it is vital to continue to explore the nutritional complexities and variation in the product. To achieve this aim, a survey of grass-finishing production systems throughout the U.S. was conducted, and the beef finished on participating farms was analyzed for its nutritional composition, including fatty acid (FA), mineral and fat-soluble vitamin content. Annual production capacity of farms ranged from 25 to 5,000 cattle, with a mean age of cattle at harvest of 26.8 ± 2.3 months. An array of finishing diets included grazing exclusively perennial pasture, the incorporation of annual forage crops, as well feeding a variety of harvested forages and supplementation of non-starch feed byproducts. The ratio of omega-6 (n-6) to omega-3 (n-3) FA in beef samples averaged by producer ranged from 1.8 to 28.3, with an overall sample set median of 4.1. Only n-3 FA varied between harvest season, with a greater amount found in beef harvested in the spring. Mineral content was highly variable by season and producer, due to the inherent variation of soil and forage mineral content. Mean α-tocopherol content was 610.6 μg/100 g beef, and mean β-carotene content was 32.2 μg/100 g. The amount of these antioxidants also varied between producers, but tended to be greater in beef finished solely on fresh forages. This survey indicates that commercially available GFB can vary in its nutritional composition due to the diverse practices used to grass-finish cattle.
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