New study explores the difference between grass-fed and pen-finished bison meat
With rising concerns regarding the effects of red meat on humans and the environment, a growing number of livestock producers are exploring ways to improve animal well-being and human health. Additionally, growing consumer interest in grass-fed meat has raised several questions about its nutritional quality.
In a previous article, we explored the difference between Grass-fed and Grain-fed beef from a butcher’s point of view, which brought an original opinion on this topic.
A preliminary study¹ produced in September 2022 (preprint) from a collective of authors based at Utah State University and other research institutes² attempted to determine the impact of two common finishing systems in the North American red meat industry – pasture-finished or pen-finished (in confinement) on metabolomic, lipidomic, and fatty acid profiles.
“Retail sales of bison meat have more than doubled in the past decade”
The study chose to narrow down the research to Bison. Bison are a quintessential symbol of the North American Great Plains. Once considered as the main source of red meat in the American diet in pre-industrial times³ and after near-extinction, bison meat is again growing in popularity with North American consumers. Retail sales of bison meat have more than doubled in the past decade and reached US $350 million in 2017, and continued increases in sales are predicted over the coming years⁴.
Plus, if previous studies in cattle, goats, and sheep have been published and have reported that pasture finishing can improve animal welfare and transfers phytochemicals – with potential antiinflammatory and anti-oxidant effects – from forage to animal⁵, it is not largely undocumented whether or not finishing bison using such practices confers benefits to the nutritional compounds found in their meat.
“For this particular study, 1570 bison bulls were used”
For this particular study, 1570 bison bulls were used. After grazing rangeland pastures during the weaning and stocker phase, the herd was split during the 146-day finishing phase: a group of bulls were placed in a pen (with approximately 275 m2/hd of space per animal) and provided ad libitum access to meadow hay, alfalfa hay bales, and whole-shell corn prior to harvest, while pasture-finished bulls continued to rotationally graze native rangeland pasture until harvest (pastures averaging ∼27 hectares with a stocking density of ∼16,812 kg/ha).
On average, pen-finished bulls consumed 7.3 kg/day of corn, 5.1 kg/day of alfalfa and 2.0 kg/day of meadow hay. The pen-finished bulls also had free-choice access to a vitamin/mineral formulation. Pasture-finished bulls had access to a salt block on pasture but did not consume a vitamin/mineral formulation. The average daily gain of the pen- and pasture-finished bulls was 0.75
kg/d and 0.67 kg/d, respectively. Dry matter intake for the pen- and pasture-finished bulls was estimated by the ranch supervisors to be ∼3.2% of body weight and ∼3% of body weight, respectively.
“All bulls were harvested at approximately 30 months of age”
All bulls were harvested in USDA-inspected slaughter facilities at approximately 30 months of age. Striploins were removed from one side of each carcass approximately 24 hours post-harvest.
Relative to pasture-finished animals, the muscle of pen-finished animals displayed markers of excess glucose, triglycerides, oxidative stress and proteolysis. In contrast, pasture-finished animals displayed improved mitochondrial metabolism and higher levels of various Krebs cycle metabolites and carnitine metabolism.
Pasture-finishing also concentrated higher levels of phenolics, alpha-tocopherol, carotene and very long-chain fatty acids in meat, while having lower levels of common advanced lipoxidation and glycation end products.
In contrast, vitamins B5, B6, and C, and gamma-tocopherols are higher in the grain-fed animals suggesting some concentrate feeding, or grazing plants rich in those compounds, may be beneficial.
“Pasture finishing enriches several very long-chain saturated and mono-unsaturated fatty acids (omega-3s)”
The primary findings of this study indicate that:
- pasture-finishing improves the metabolic health pathways of bison and the presence of potentially health-promoting compounds in their meat. Several of these metabolic pathways are interrelated and outcomes may be the result of both reduced physical activity and/or grain-feeding of bison in confinement.
- pasture-finished animals concentrated higher levels of phenolic metabolites, alpha-tocopherol, and carotene in their meat. Besides well-established effects on enriching very-long chain polyunsaturated fatty acids (omega-3s).
- pasture finishing enriches several very long-chain saturated and mono-unsaturated fatty acids. These findings are arguably directly related to the forage consumed by the pasture-finished bison.
- The differences in fatty acids and phenolic metabolites in grass vs. pen-finished bison are not as substantial as those often observed in pasture- vs. feedlot-finishes
cattle. The likely explanation is that bison were in loose confinement (more space to roam in the pen) and had the ability to partially self-select their diet (free choice arrangement of corn, alfalfa, and meadow hay).
Red meat, irrespective of whether animals are feedlot- or pasture-finished, contributes important nutrients in the diet. The data in the study do not per se indicate that bison meat from animals finished in pens is unhealthy to consume. However, as compared to pen-finishing on corn and hay, pasture-finishing of bison improves various markers of animal metabolic health and nutritional compounds in meat with purported human health benefits. Whether this has an appreciable effect on human health remains to be studied in future controlled feeding trials.
“Pen/feedlot-finished meat requires additional time, labour and feed than pasture-finished meat”
Additional considerations not elaborated in the study:
- pasture-finished meat takes longer to finish than pen/feedlot-finished meat
- pen/feedlot-finished meat requires additional time, labour and feed than pasture-finished meat
- the authors expect that agroecological approaches in livestock systems, such as the rotational grazing practices employed in this work, will continue to gain traction. These practices are highlighted in the most recent report of the Intergovernmental Panel on Climate Change⁶ as part of “nature-based” solutions to address the impact of food production on climate change.
- future studies should, therefore, also attempt to make direct connections between the environmental and human health impacts of various production systems, thus linking the health of soils, plants, animals, and humans.
Here at Hustler, farming sustainably is at the heart of everything we do.
Our belief in sustainable farming practices underpins our range of world-leading livestock feeding solutions. If you are looking for farming equipment near you or buying livestock feeding equipment, contact our friendly team today!
You may also like to take a look at some of these great resources:
- The Art of Sustainable Hay Feeding in a Tough Economy
- Benefits of feeding long-stem hay, especially when weaning calves
- Does it really make sense to ground-feed onto mud?
- Increasing Soil Fertility and Forage Production through Pasture Management
- How to deal with hay shortage in drought conditions
- Improve your pasture for free with your bale feeding routine
- 8 Benefits to rotational grazing
¹ Pasture-finishing of Bison Improves Animal Metabolic Health and Potential Health-Promoting Compounds in Meat. https://www.researchsquare.com/article/rs-2066449/v1 (accessed on 24 November 2022). 2022.
² Authors are from Utah State University, South Dakota State University, Turner Institue of Ecoagriculture, Louis Bolk Institute and USDA-ARS Northern Great Plains Research Laboratory
³ Lueck D: The Extermination and Conservation of the American Bison. The Journal of Legal Studies 2002, 31(S2):S609-S652.
⁴ Association NB: Current Status. Available online: https://bisoncentral.com/current-status/ (accessed on 24 November 2022). 2020.
⁵ A few examples of these studies:
Provenza FD, Villalba JJ, Dziba LE, Atwood SB, Banner RE: Linking herbivore experience, varied diets, and plant biochemical diversity. Small Ruminant Research 2003, 49(3):257-274
Manteca X, Villalba JJ, Atwood SB, Dziba L, Provenza FD: Is dietary choice important to animal welfare? Journal of Veterinary Behavior 2008, 3(5):229-239
Crump A, Jenkins K, Bethell EJ, Ferris CP, Kabboush H, Weller J, Arnott G: Optimism and pasture access in dairy cows. Scientific Reports 2021, 11(1):4882
van Vliet S, Provenza FD, Kronberg SL: Health-Promoting Phytonutrients Are Higher in Grass-Fed Meat and Milk. Frontiers in Sustainable Food Systems 2021, 4(299)
Delgadillo-Puga C, Cuchillo-Hilario M: Reviewing the Benefits of Grazing/Browsing Semiarid Rangeland Feed Resources and the Transference of Bioactivity and Pro-Healthy Properties to Goat Milk and Cheese: Obesity, Insulin Resistance, Inflammation and Hepatic Steatosis Prevention. Animals 2021, 11(10):2942.
⁶ IPCC: Intergovernmental Panel on Climate Change. AR6 Climate Change 2022: Mitigation of Climate Change. https://www.ipcc.ch/assessment-report/ar6/ (accessed on 24 November 2022). 2022.