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, a survey of grass-finishing production systems throughout the USA was conducted, and beef finished on the participating farms was analyzed for its nutritional composition, including fatty acid (FA), mineral and fat-soluble vitamin contents. Samples were analyzed from 12 producers and annual production capacity of farms ranged from 25 to 5,000 cattle, with a mean age of cattle at harvest of 26.8 ± 2.30 mo. An array of finishing diets included grazing exclusively in perennial pasture, incorporating annual forage crops, and feeding a variety of harvested forages with supplementation of non-starch feed byproducts. Beef muscle tissue FA content was analyzed by gas chromatography-mass spectrometry (GC–MS). The mean ratio of omega-6 (n-6) to omega-3 (n-3) FA in samples varied significantly by producer, ranging from 1.80 to 28.3 (P < 0.0001), with an overall sample set median of 4.10. A selection of minerals including iron, magnesium, and potassium were analyzed by ICP emission spectroscopy and mineral content significantly differed by producer for all minerals (P < 0.001). Mean α-tocopherol and β-carotene content was 610.6 µg/100 g beef and 32.2 µg/100 g, respectively. The amount of these antioxidants also varied between producers (P < 0.0001), but tended to be greater in beef finished solely on fresh forages. This survey indicates that commercially available GFB can vary in nutritional composition due to the diverse practices used to grass-finish cattle.

There is increased consumer interest in grass-finished beef (GFB) with retail sales reaching $272 million in 2016. GFB contains higher omega-3 fatty acid levels compared to grain-finished beef, but variations in fatty acid (FA), mineral, and antioxidant content by producers and season is poorly documented. Hence, GFB samples from cattle finished in both fall and spring were obtained from four producers representing several US sub-regions. FAs were extracted using microwave-assisted extraction, derivatized to methyl-esters, and quantified using gas chromatography-mass spectrometry. Mineral content was quantified using coupled plasma mass-spectrometry and antioxidants were quantified via UV-absorption. Overall, total omega-3 FA content was greater in beef from cattle finished in the spring (13.4 mg/ 100g beef) than the fall (10.3; P<0.001). Additionally, α-tocopherol was present in greater amounts in spring-finished beef (259 vs. 223 ug/100g beef, P<0.001) as was the micromineral selenium (18.2 vs. 17.3ug/100g beef, P = 0.008). Despite using the same feed in fall and spring, cattle from producer 4 had higher total omega-3, omega-6, and total polyunsaturated fatty acids in spring compared to fall (P<0.010). These results suggest there are seasonal differences in omega-3 and omega-6 fatty acids, minerals and antioxidants in grassfinished beef independent of finishing diet.

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, a survey of grass-finishing production systems throughout the United States was conducted, and beef finished on the participating farms was analyzed for its nutritional composition, including fatty acid (FA), mineral and fat-soluble vitamin contents. Samples were analyzed from 12 producers and annual production capacity of farms ranged from 25 to 5,000 cattle, with a mean age of cattle at harvest of 26.8 ± 2.30 mo. An array of finishing diets included grazing exclusively in perennial pasture, incorporating annual forage crops, and feeding a variety of harvested forages with supplementation of non-starch feed byproducts. Beef muscle tissue FA content was analyzed by gas chromatography-mass spectrometry (GC–MS). The mean ratio of omega-6 (n-6) to omega-3 (n-3) FA in samples varied significantly by producer, ranging from 1.80 to 28.3 (P &lt; 0.0001), with an overall sample set median of 4.10. A selection of minerals including iron, magnesium, and potassium were analyzed by ICP emission spectroscopy and mineral content significantly differed by producer for all minerals (P &lt; 0.001). Mean α-tocopherol and β-carotene content was 610.6 μg/100 g beef and 32.2 μg/100 g, respectively. The amount of these antioxidants also varied between producers (P &lt; 0.0001), but tended to be greater in beef finished solely on fresh forages. This survey indicates that commercially available GFB can vary in nutritional composition due to the diverse practices used to grass-finish cattle.