Biorefined grass-clover protein is emerging as a promising, locally sourced alternative to imported soybean cake in organic pig diets. Recent research evaluating its effects on pork quality and storage stability shows that this novel feed ingredient can improve the fatty acid profile of pork without compromising meat quality.
Study methodology overview
The study, led by scientists at the Department of Veterinary Science at the University of Aarhus, Denmark, compared 5 dietary treatments using soybean cake or biorefined grass-clover protein, combined with either fresh grass-clover or silage.
The grass-clover protein significantly increased the alpha-linolenic acid content in pork, reducing the n‑6/n‑3 ratio—a shift widely recognised as beneficial from a human health perspective. Soy-based diets generally produced higher levels of linoleic acid, whereas grass-clover protein enhanced the presence
of omega‑3 fatty acids. This nutritional gain did not come at the expense of carcass traits or growth performance, both of which remained consistent across treatments.
Oxidative stability and antioxidants
Despite concerns that a higher proportion of unsaturated fatty acids might lead to increased oxidation, the study found no detrimental effects on overall meat stability. Although pigs fed grass-clover protein experienced greater oxidative stress during growth—evidenced by lower levels of alpha‑tocopherol in muscle—the natural antioxidants in the grass-clover protein appeared sufficient to mitigate negative impacts on meat quality. Importantly, measurements of lipid oxidation (TBARS values) showed no significant differences between dietary treatments.
These findings provide reassurance to producers and feed formulators that grass-clover protein is a robust and valuable option for future pig production systems.”
Sensory evaluation and storage
Sensory evaluation revealed only minor differences between treatments. Meat from pigs fed grass-clover protein tended to appear slightly paler and less red when fresh grass was included, but panelists reported no major changes in flavour, tenderness or juiciness. Storage for 6 months did predictably increase rancid and acidic notes and reduce tenderness in all groups, but these effects were unrelated to the type of protein source. Crucially, grass-clover protein did not heighten susceptibility to quality deterioration during frozen storage.
Diet flexibility and key drivers
The study also assessed the effect of reducing lysine levels in one of the grass‑clover protein diets. Lowering lysine by 10% did not negatively influence meat quality, suggesting flexibility in formulation for producers aiming to optimise cost or reduce environmental impact. Roughage type—whether fresh grass-clover or silage—had minimal influence overall, reinforcing that the key nutritional driver in this study was the biorefined protein ingredient.
Sustainability and industry implications
The results have important implications for both sustainability and supply chain resilience. With growing pressure to reduce reliance on imported soy, particularly in organic systems, grass-clover protein offers a viable, environmentally favourable alternative that supports regional feed autonomy. Its favourable fatty acid profile also aligns with consumer interest in healthier meat products.
Conclusion: Future feeding systems
In conclusion, biorefined grass-clover protein can successfully replace soybean cake in organic pig diets without compromising meat quality, sensory attributes or storage stability. Its inclusion improves the nutritional profile of pork by increasing omega‑3 fatty acids and reducing the n‑6/n‑3 ratio, while maintaining acceptable levels of oxidative stability. These findings provide reassurance to producers and feed formulators that grass‑clover protein is a robust and valuable option for future pig production systems.
