- Animals: bovine
- Animal Production: feed/forage, grazing management, meat product quality/safety
- Education and Training: participatory research
- Sustainable Communities: local and regional food systems, partnerships, consumer health
Many Southern farmers/ranchers are seeking ways to improve health from the ground up. One way they are doing that is by using pasture-based livestock systems to enhance the health of soils, animals, and presumably that of consumers. Beef, irrespective of rearing practices, provides many essential nutrients such as bioavailable protein, zinc, iron, and B12. Emerging data indicate that raising livestock on pasture concentrates additional health-promoting metabolites—vitamins/minerals, terpenoids, phenols, carotenoids, antioxidants, peptides, and other bioactive compounds—compared to meat from animals fed grain-based diets in conventional systems. Preliminary studies also show potential for additional anti-inflammatory effects in people after eating pasture-raised meat.
While the connections among soil-plant-beef-consumer health are often touted for why grass-fed beef has additional health benefits, no studies have systematically tested these links using a bottom-up approach. To bridge this gap, we have forged a consortium of pasture-based farmers and interdisciplinary researchers from leading agricultural (NC State University) and medical (Duke University) schools.
Using a systems approach, we will compare forage and soil metabolomes of grazed pastures in three regional grass-fed beef systems to total mixed rations and soil samples from a grain-fed beef system (Objective 1). Second, we will compare health-promoting compounds in grass-fed beef from three regional systems to grain-fed beef (Objective 2). We will then compare metabolite and inflammatory profiles of adults consuming grass-fed versus grain-fed beef to provide insight into consumer health (Objective 3). For objective 3, we propose a randomized-crossover design where participants consume each source of beef (grass-fed vs grain-fed) during separate test-days. Blood samples will be obtained before and several hours after. We hypothesize that grass-fed beef results in higher amounts of health-promoting metabolites—terpenoids, phenolics, and other antioxidants—in the metabolome of consumers and induces additional anti-inflammatory effects compared to grain-fed beef.
Metabolomics is the biological marker common to all three objectives to link shared metabolites from soil, to forage/feed, to meat, and into the body of consumers; an approach we describe as ‘from Farm to Table to Us’. The proposed study will provide a critical, and largely unstudied, link between land ecology, livestock systems, and human health—key priority areas of SARE’s Systems Research for Agriculture. Farmers will have crucial roles by assisting with sample collection, monitoring and reporting on cattle grazing habits, linking research findings back to pasture botanical composition, and disseminating findings to peers.
Findings will be shared (Objective 4) with producers, consumers, and stakeholders through NC Cooperative Extension (e.g., Amazing Grazing/NC Choices), Build-Up Dietitians, the Appalachian Sustainable Agriculture Project, Understanding Ag, and farmer cooperators (workshops/farm tours). Findings will be presented at local meetings (e.g., Carolina Meat Conference) and published in scientific journals, farm press, and social media outlets. Our work is vital to Southern pasture-based producers who work hard to nourish local communities, but lack scientific evidence on the healthfulness of their beef. Having such justification can result in tremendous “brand building” opportunities for local pasture-based producers to improve economic viability whilst enhancing human and environmental health.
Project objectives from proposal:
Our project includes the following four objectives:
Objective 1: Compare forage and soil metabolomes of grazed pastures in three regional grass-fed beef systems to total mixed rations and soil samples from a grain-fed beef system.
Hypothesis 1a: The forage consumed by grass-fed cattle will contain higher amounts and a wider variety of phytochemicals—terpenoids, phenols, carotenoids, amines, and other organic acids— compared to total mixed rations (corn and hay) consumed by grain-fed cattle.
Hypothesis 1b: The phytochemical richness of forage and feed (TMR), as determined by metabolomics, is correlated with nutrient levels and metabolomes of the soils.
Objective 2: Compare the presence of health-promoting compounds in grass-fed beef from three regional systems to grain-fed beef.
Hypothesis 2a: Grass-fed beef contains higher amounts and a wider variety of health-promoting metabolites—terpenoids, phenols, carotenoids, phenols, peptides, unsaturated fatty acids, and other bioactive compounds—compared to grain-fed beef.
Hypothesis 2b: The metabolomes of grass-fed and grain-fed beef correlate with the metabolome profiles of consumed forage/feed by cattle.
Objective 3: Compare metabolite and inflammatory profiles of adults consuming grass-fed versus grain-fed beef to provide insight into their impact on consumer health.
Hypothesis 3a: Consuming grass-fed beef provides the body with higher amounts and a wider variety of health-promoting metabolites— terpenoids, phenols, carotenoids, phenols, peptides, unsaturated fatty acids, and other bioactive compounds—and induces anti-inflammatory effects compared to eating grain-fed beef during the postprandial period (i.e., for several hours after consumption).
Hypothesis 3b: The post-meal metabolomes of consumers correlate with the metabolomes of grass-fed and grain-fed beef.
Objective 4: Develop outreach and education efforts to translate findings to farmers, consumers, and industry through Extension programs, and regional farmer and consumer partnerships.
Expected outcomes from this project are that:
1) soil nutrient levels and metabolomes of grazed pastures and row-crop fields relate to the phytochemical richness of forage/feed consumed by grass-fed cattle and grain-fed cattle—an expectation solidly supported by work linking soil health to the phytochemical richness of plants/crops (Rajashekar et al., 2009;Reeve et al., 2016);
2) greater phytochemical richness of forage consumed by pasture-raised cattle will increase the phytochemical richness of beef compared to grain-finished animals—an expectation solidly supported by previous work from our group (Van Vliet et al., 2020a;Van Vliet et al., 2020c) and others (Larick et al., 1987;Agabriel et al., 2007);
3) these biochemicals will become available in the plasma of consumers within hours after consumption and share a resemblance to the metabolome profiles of the ingested food source (grass-fed vs grain-fed beef)—an expectation solidly supported by work from us (van Vliet et al., 2017;Van Vliet et al., 2019) and others (Pimentel et al., 2018);
4) higher post-meal circulating levels of phytochemicals/biochemicals in the plasma of grass-fed beef consumers will induce acute anti-inflammatory effects—an expectation solidly supported by previous studies on meat consumption and acute changes in inflammatory markers (Arya et al., 2010;Li et al., 2010). For example, comparable work by Pimentel et al. (2018) found that acute changes in the circulating metabolome after single meals of yogurt or milk (both from grain-fed systems) already reflected many of the changes that were observed with chronic (2-week intake) intake of yogurt or milk, respectively. While acute findings will need to be followed up with temporally longer trials, it will be critical to obtain preliminary insight into potential human health responses of grass-fed vs grain-fed beef and to establish a ‘proof of principle’ of the transfer of phytochemicals from forage into beef and the consumer before moving on to temporally longer studies.
Metabolomics has a high potential to contribute to sustainable agriculture by providing a deep understanding of linkages between soil health, agricultural production practices, the nutrient densities of foods, and their impact on human metabolism. We expect this project to result in data that can inform management practices that emphasize finishing cattle on diverse pastures to enhance the phytochemical richness of beef and consumer health outcomes. We expect that metabolomics will reveal that, despite differences in management strategies on the three pasture-based farms, high-quality forage ingestion by pasture-raised cattle with result in phytochemically-rich beef that is distinct from the feedlot finished beef, but similar to each other.
Recent research with forage-based beef production systems in LA, SC, NC, and GA showed consistency in performance and carcass quality between pasture-raised beef produced from systems provided a high level of forage management was maintained (Poore et al., 2020). Our data is expected to reinforce the notion that, as long as management practices stimulate soil health and forage quality, practices can be tailored to the individual farm (i.e., multiple pasture-based production methods can lead to nutrient-dense beef). Evidence on high-quality beef from different pasture-based management practices is important for bringing local grass-fed beef with consistent quality to wholesale markets.
The objectives and expected outcomes of this project are solidly in line with Southern SARE’s program objectives, which are based on the 1990 Farm Bill. First, we expect our results to enhance understanding of linkages between soil health, livestock production systems, and human health, which is in line with Priorities #1; “Satisfy human food and fiber needs” and #3; “Make the most efficient use of nonrenewable resources and on-farm resources and integrate, where appropriate, natural biological cycles and controls”. Second, our work will generate results directly usable by consumers and producers, which can help Southern grass-fed beef producers improve profitability in a growing market and consumers enhance health, which is in line with Priorities # 4; “Sustain the economic viability of farm operations; and 5; “Enhance the quality of life for farmers and society as a whole”. Finally, by having an evidence-based justification on the healthfulness of grass-fed beef as a result of grazing nutrient-rich pastures we expect our findings will re-enforce Priority #3: “Enhance environmental quality and the natural resource base upon which the agricultural economy depends”.