Consumer demand for milk and meat from grass-fed cattle is growing, driven mostly by perceived health benefits and concerns about animal welfare. In a U. S.-wide study of 1,163 milk samples collected over 3 years, we quantified the fatty acid profile in milk from cows fed a nearly 100% forage-based diet (grassmilk) and compared it to profiles from a similar nationwide study of milk from cows under conventional and organic management. We also explored how much the observed differences might help reverse the large changes in fatty acid intakes that have occurred in the United States over the last century. Key features of the fatty acid profile of milk fat include its omega-6/omega-3 ratio (lower is desirable), and amounts of total omega-3, conjugated linoleic acid, and long-chain omega-3 polyunsaturated fatty acids. For each, we find that grassmilk is markedly different than both organic and conventional milk. The omega-6/omega-3 ratios were, respectively, 0.95, 2.28, and 5.77 in grassmilk, organic, and conventional milk; total omega-3 levels were 0.049, 0.032, and 0.020 g/100 g milk; total conjugated linoleic acid levels were 0.043, 0.023, and 0.019 g/100 g milk; and eicosapentaenoic acid levels were 0.0036, 0.0033, and 0.0025 g/100 g milk. Because of often high per-capita dairy consumption relative to most other sources of omega-3 fatty acids and conjugated linoleic acid, these differences in grassmilk can help restore a historical balance of fatty acids and potentially reduce the risk of cardiovascular and other metabolic diseases. Although oily fish have superior concentrations of long-chain omega-3 fatty acids, most fish have low levels of α-linolenic acid (the major omega-3), and an omega-6/omega-3 ratio near 7. Moreover, fish is not consumed regularly, or at all, by ~70% of the U. S. population.
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We appreciate the “job well done” by the CROPP Cooperative regional pool staff in collecting the bulk-tank samples and getting them to the laboratory. We thank the technical staff at Silliker, Inc., for their attention to detail and help working through technical details. We also acknowledge and honor the commitment and skill of the grassmilk farmers in CROPP, all of whom faced a raft of challenges in converting their operations to nearly 100% forage-based feed. The authors are grateful for funding from CROPP Cooperative, Lafarge, Wisconsin; LowInputBreeds, Sixth Framework Programme for Research, Technological Development and Demonstration Activities, European Community (grant no. 222623); and the Sheepdrove Trust, UK.
Sheepdrove Trust, UK; CROPP Cooperative, Lafarge, Wisconsin; LowInputBreeds, Sixth Framework Programme for Research, Technological Development and Demonstration Activities, European Community, Grant/Award Number: Grant no. 222623
This study does not involve any human or animal testing. Regarding conflicts of interest, CROPP Cooperative sells grassmilk via its Organic Valley brand. MAL is the Executive Director of Research & Development and Quality Assurance at CROPP Cooperative. LP and SA-C are on the research and technical services staff of CROPP Cooperative. BJH is faculty supervisor of the University of Minnesota West Central Research and Outreach Center’s organic dairy, which markets its milk through CROPP Cooperative and Organic Valley. CMB was Chief Scientist of The Organic Center, 2005–2012, funded in part by CROPP Cooperative; DRD was a consultant to same center, 2011–2012. CMB was program leader for the Measure to Manage
- dairy farming
- dairy fatty acids
- grass milk
- omega-6/omega-3 ratio
- organic milk