Agroecological practices in United States North Central dairy systems enhance omega-3 and phytonutrient levels in cow's milk

This study evaluated the impact of agroecological (“regenerative”) practices on milk nutritional quality and soil health in U.S. dairy systems. Five North Central dairy farms employing rotational grazing and diverse forage feeding were compared to a conventional total mixed ration (C-TMR) control. Milk and forage were analyzed for fatty acids by gas chromatography and for phytonutrients by high-performance liquid chromatography–tandem mass spectrometry. Soil indicators included total organic carbon (SOC), microbial mass, fungi-to-bacteria ratio, and organic-to-inorganic nitrogen ratio. Milk from regenerative farms contained higher omega-3 fatty acids: eicosapentaenoic acid (C20:5n3) was 122–144% higher in farms 1 and 4, and docosapentaenoic acid (C22:5n3) was 800–1000% higher in farms 1, 3, and 4 versus the control. Forages averaged 217% more alpha-linolenic acid (C18:3n3), whereas the control feed contained 148% more linoleic acid (C18:2n6). Regenerative milk was also enriched in phytonutrients including p-cresol sulfate (117%), hippuric acid (49.5%), and catechol (48.5%). Cluster analysis highlighted farm-level variation in compounds such as formononetin (20.6% higher) and genkwanin (225% higher). Soils from regenerative farm 1, with the most plant diversity, showed elevated SOC (up to 420 mg/kg) and a balanced nitrogen ratio (1.0).Overall, regenerative practices—including rotational grazing and diverse forage feeding—were associated with enhanced milk fatty acid and phytonutrient profiles, alongside improved soil health indicators. Further research is needed to assess long-term impacts across a broader range of farms.