Is grass-fed beef from cattle grazing a diverse mixture of plants healthier for consumers?

View the project final report

Commodities

• Animal Products: meat

Practices

• Animal Production: feed/forage, free-range, meat product quality/safety
• Education and Training: farmer to farmer, on-farm/ranch research, participatory research
• Natural Resources/Environment: biodiversity
• Production Systems: integrated crop and livestock systems

To improve soil health in the North Central Region, a growing number of beef producers are finishing cattle and other livestock species on plant-species diverse forage and/or cover crops. While meat provides many essential nutrients in the American diet, pilot data from our research team indicated that when livestock are raised and finished on plant-diverse pastures, more omega-3 fatty acids and additional health-promoting phytonutrients such as terpenoids, phenols, carotenoids, and other anti-oxidants concentrate in meat. While linkages among the plant-animal-human health continuum (“healthy plants, healthy animals, healthy humans”) are often touted as the reason why grass-fed beef and other pasture-raised animal-based foods may have additional health benefits, no studies have systematically assessed this.

Using novel metabolomics approaches, the goal of our work was to detail the transfer of hundreds of biochemicals and phytochemicals from the forage/feed consumed by pasture-raised versus feedlot-fed animals, to their food products, and into the body of consumers and determine metabolic health biomarkers in response to consumption. 

Phytochemical richness of forage and total mixed ration samples was determined using metabolomics (Objective 1). Second, we compared the presence of phytochemicals and biochemicals in both types of beef (Objective 2). To provide insight into consumer health (plasma metabolomes, inflammation), we conducted a randomized controlled trial and obtain blood samples from participants before and after 16 weeks of weekly consumption of grass-fed beef, pasture-raised pork, chicken and chicken eggs versus conventional grain-fed beef, pork, chicken and chicken eggs (Objective 3). Our central hypothesis: consuming grass-fed beef and other pasture-raised animal-based foods results in metabolic signatures indicative of improved metabolic health.

Cooperating farmers/ranchers assisted with sample collection and provided knowledge on grazed plants. Findings are being shared with producers, consumers, and stakeholders in the North Central region and the US via workshops, tradeshows, articles in traditional and social media, and scientific publications.  Up to now, presentations related to this study have been given to over 1000 producers via six presentations in the states of South Dakota, Iowa, Illinois, Missouri, Kentucky and Oklahoma. Outreach partners include the ARS-Northern Great Plains Research Laboratory, grazing coalitions (South Dakota/North Dakota), and stakeholder groups including Understanding Ag, Thousand Hills Lifetime Grazed, Wisconsin Grass-fed beef Coop, and Carbon Cowboys. Project findings have potential for farmers and ranchers in the northcentral region to improve economic viability via more direct sales to consumers while potentially enhancing consumer health.

Ribeye steaks from grass-fed and grain-fed cattle were compared using targeted assays for phytonutrients, B-vitamins, and fat-soluble vitamins. Grain-fed beef showed 15–35% higher vitamin B₁, B₅, B₆, and B₇. Grass-fed beef contained ~88% more α-tocopherol and ~53% more β-carotene. Of 195 phytonutrients detected, 39 differed significantly: 30 elevated in grass-fed (e.g., hippuric acid +78%, p-cresol sulfate +37%, cinnamoylglycine +93%) and 9 in grain-fed (e.g., 4-hydroxyphenylacetic acid +275%, 3-phenyllactic acid +150%). Among 10 classes, carboxylic/hydroxy acids were 160% higher in grain-fed; flavonoids were 123% higher in grass-fed. Multivariate models and pasture survey data, including spatial “terroir” mapping, showed that botanically diverse, well-rested pastures enhanced α-tocopherol and phytonutrient concentrations. Thus, finishing diets and pasture conditions can be strategically managed to enrich beef in vitamins and phytonutrients.

The controlled human feeding trial demonstrated that consumption of pasture-raised beef, pork, chicken, and eggs significantly enhances red blood cell omega-3 fatty acid profiles and reduces the omega-6 to omega-3 ratio in healthy adults compared with conventionally-raised animal-source foods. These changes occurred independently of total energy intake and overall macronutrient distribution and suggest that pasture-raised animal products may represent a viable dietary strategy for improving population-level omega-3 status, particularly among individuals with low seafood consumption. Although no significant effects on traditional cardiometabolic risk markers were observed in this relatively healthy population, the improvements in omega-3 biomarkers—including a transition from high-risk to intermediate-risk omega-3 index values—support the potential for long-term cardiovascular and anti-inflammatory benefits.

The cooperating farmers/ranchers for this project already produce and sell grass-fed beef and pasture-based pork and/or chicken and/or chicken eggs.  However, we expect that the results from this project will have an influence on consumer purchases and on the management decisions of existing pasture-based meat and egg producers.

Project Objectives:

(a) Determine if eating grass-fed beef as well as pasture-raised pork, chicken and chicken eggs from animals that ate a plant species-diverse diet elicits more healthful inflammatory and metabolite profiles in adult people than eating conventional grain-fed beef, pork, chicken and chicken eggs.

(b) Translate this information back to producers and consumers by partnering with producer coalitions and stakeholder groups.

Learning Outcomes:

Farmers will learn how finishing cattle on biodiverse forage influences the phytochemical richness of beef.

Consumers will learn if consuming such grass-fed beef and other animal-based foods from pasture-raised animals impacts their metabolic health.

Action Outcomes:

Farmers can adopt biodiverse pastures and cover crops to increase healthfulness of their pasture-fed beef, pork, chicken and chicken eggs.

Consumers encouraged to seek out local grass-fed beef, pork, chicken and chicken eggs.