BISON were once a quintessential symbol of the North American Great Plains and a main source of red meat in the pre-industrial American diet. But bison meat is once again growing in popularity in North America, with sales of bison meat more than doubling in the past decade.
Much like beef, bison meat can be from animals finished on grains in confinement or on pasture, though bison are typically provided with less grain and more space to roam in confined finishing operations.
With increasing concern regarding the effects of red meat on human and environmental health, a growing number of livestock producers are exploring ways to improve production systems.
Agroecological practices such as rotational grazing of locally adapted ruminants can deliver favourable outcomes for climate and nature, but growing consumer interest in pasture-finished meat has raised questions about its nutritional composition.
A study from a joint team of researchers from the USA and The Netherlands has determined the impact of two common finishing systems in North American bison—pasture-finished or pen-finished.
They found that pasture-finishing broadly improves bison metabolic health and therefore accumulates additional potential health-promoting compounds in their meat.
The researchers found that 671 out of 1570 profiled compounds (43%) differed between pasture- and pen-finished conditions.
Relative to pasture-finished animals, the muscle of pen-finished animals displayed elevated glucose metabolites (~ 1.6-fold), triglycerides (~ 2-fold), markers of oxidative stress (~ 1.5-fold), and proteolysis (~ 1.2-fold).
In contrast, pasture-finished animals displayed improved mitochondrial (~ 1.3-fold higher levels of various Krebs cycle metabolites) and carnitine metabolism (~ 3-fold higher levels of long-chain acyl carnitines).
Pasture-finishing also concentrated higher levels of phenolics (~ 2.3-fold), alpha-tocopherol (~ 5.8-fold), carotene (~ 2.0-fold), and very long-chain fatty acids (~ 1.3-fold) in their meat, while having lower levels of a common advanced lipoxidation (4-hydroxy-nonenal-glutathione; ~ 2-fold) and glycation end-product (N6-carboxymethyllysine; ~ 1.7-fold).
By contrast, vitamins B5, B6, and C, gamma/beta-tocopherol, and three phenolics commonly found in alfalfa were ~ 2.5-fold higher in pen-finished animals (all P < 0.05); suggesting some concentrate feeding, or grazing plants rich in those compounds, may be beneficial.
The research shows that pasture-finishing broadly improves bison metabolic health and accumulates additional potential health-promoting compounds in their meat compared to concentrate finishing in confinement.
The data, however, does not indicate that meat from pen-finished bison is therefore unhealthy. The studied bison meat—irrespective of finishing practice—contained favourable omega 6:3 ratios (< 3.2), and amino acid and vitamin profiles.
The study represents one of the deepest meat profiling studies to date (> 1500 unique compounds), having revealed previously unrecognized differences in animal metabolic health and nutritional composition because of finishing mode. Whether observed nutritional differences have an appreciable effect on human health remains to be determined.