Pasture-finishing of cattle in Western U.S. rangelands improves markers of animal metabolic health and nutritional compounds in beef

Authors: Kronberg, Scott; EVANS, NIKIA - Oregon Health & Science University; VAN VLIET, STEPHAN - Utah State University; CLOWARD, JENNIFER - Utah State University; WARD, ROBERT - Utah State University; PROVENZA, FREDERICK - Utah State University; VAN WIETMARSCHEN, HERMAN - Louis Bolk Institute; VAN EEKEREN, NICK - Louis Bolk Institute

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/2024
Publication Date: 8/30/2024
Citation: Kronberg, S.L., Evans, N., Van Vliet, S., Cloward, J., Ward, R., Provenza, F., Van Wietmarschen, H., Van Eekeren, N. 2024. Pasture-finishing of cattle in Western U.S. rangelands improves markers of animal metabolic health and nutritional compounds in beef. Scientific Reports. 14:20240. https://doi.org/10.1038/s41598-024-71073-3.
DOI: https://doi.org/10.1038/s41598-024-71073-3

Interpretive Summary: There is a growing interest in beef from animals finished on pasture. This research conducted three types of chemical analyses relevant to nutrition to study more than1500 compounds in the meat of Black Angus cattle from two common commercial US beef finishing systems (grass-fed on pasture and grain-fed in a feedlot). We found that 907 out of 1575 profiled compounds differed in abundance between grass-fed and grain-fed beef samples. Grass-fed beef had higher levels of potentially beneficial compounds , while grain-fed beef had higher levels of other potentially beneficial compounds. This indicates that feeding some grain (by-products) could be beneficial. Grass-fed beef samples also had lower markers of oxidative stress and improved mitochondrial function compared to grain-fed animals. Two potential metabolites of antibiotics, were only observed in grain-fed beef. Pasture-finished cattle displayed improved markers of metabolic health and potentially beneficial compounds for consumers. Our findings, however, do not indicate that grain-fed beef is unhealthy. It remains to be determined in randomized controlled human feeding trials whether observed differences have an appreciable effect on human health.

Technical Abstract: As environmental and health concerns of beef production and consumption mount, there is growing interest in agroecological production methods, including rotationally grazing and finishing beef cattle on pastures with phytochemically diverse grasses, forbs, and/or shrubs. The goal of this metabolomics, lipidomics, and fatty acid methyl ester profiling study was to compare meat (pectoralis profundus) of Black Angus cattle from two common commercial US beef finishing systems (pasture-finished on rangeland; n=18 and grain-fed in a feedlot; n=18). 907 out of 1575 compounds differed in abundance between pasture-finished and grain-fed beef samples (all, false discovery rate adjusted P<0.05). Pasture-finished beef contained higher levels of phenolic antioxidants (2.6-fold), alpha-tocopherol (3.1-fold), nicotinate/vitamin B3 (9.4-fold), choline (1.2-fold), myo-inositol (1.8-fold), and omega-3 fatty acids (4.1-fold). Grain-fed beef contained higher levels of gamma-tocopherol (14.6-fold), nicotinamide/vitamin B3 (1.5-fold), panthothenate/vitamin B5 (1.3-fold), pyridoxine/vitamin B6 (1.3-fold); indicating that feeding some grain (by-products) could be beneficial. Pasture-fed beef samples also displayed lower markers of oxidative stress (homocysteine, 0.6-fold; 4-hydroxy-nonenal-glutathione, 0.4-fold) and improved mitochondrial function (1.3-fold) compared to grain-fed animals. 2,8-quinolinediol and 2,8-quinolinediol sulfate, two potential metabolites of fluoroquinolone antibiotics, were only observed in grain-fed beef. Pasture-finished cattle displayed improved markers of metabolic health and many potentially beneficial compounds for consumers. Our findings, however, do not necessarily indicate that grain-fed beef is unhealthy. Randomized controlled trials with people fed different diets are required to further assess whether these observed differences have an appreciable effect on human health.