Seaweed-Derived Extracts as Natural Alternatives to Antibiotics
Swine farming relies on antibiotics to prevent infections, but their overuse contributes to antimicrobial resistance (AMR), posing risks to both animal and human health. As regulations increasingly restrict antibiotic use in livestock, researchers are exploring sustainable alternatives. Seaweeds, rich in bioactive compounds, have demonstrated antibacterial and antioxidant properties that could make them viable substitutes.
In their study, Assessment of the Antibacterial and Antioxidant Activities of Seaweed-Derived Extracts, Monika Hejna and colleagues examine the effects of three seaweed species—Ascophyllum nodosum (AN), Palmaria palmata (PP), and Ulva lactuca (UL)—on bacterial inhibition and oxidative stress reduction. Funded by the European Union’s Horizon 2020 Research and Innovation Programme, this research highlights the potential of seaweed extracts as functional feed additives for livestock.
Combating Bacterial Infections in Livestock
Pathogenic Escherichia coli strains, particularly F4⁺ and F18⁺, are a major cause of post-weaning diarrhea in pigs. These bacteria not only disrupt gut health but also reduce animal growth and survival rates. Researchers tested seaweed extracts for their ability to inhibit E. coli growth, with AN and UL showing the most significant antibacterial effects. The study found a dose-dependent relationship—higher concentrations of these extracts resulted in stronger bacterial inhibition. However, PP did not exhibit the same antibacterial activity, and seaweed extract combinations did not enhance bacterial suppression, indicating potential antagonistic interactions between certain compounds.
The Role of Seaweed in Reducing Oxidative Stress
Oxidative stress, caused by an excess of free radicals, leads to cellular damage and negatively impacts livestock health. Seaweeds contain antioxidants that neutralize free radicals, protecting tissues from damage. The researchers evaluated the antioxidant potential of seaweed extracts using two chemical assays: DPPH radical scavenging activity and reducing power assay (RPA). AN demonstrated the strongest antioxidant response, followed by PP and UL. When combined, AN-based extracts exhibited synergistic effects, enhancing antioxidant activity.
Challenges and Considerations
While seaweed extracts offer promising benefits, several challenges must be addressed before widespread implementation in animal feed:
Digestibility: Seaweeds contain polysaccharides like alginates and fucoidans that can hinder nutrient absorption. PP demonstrated higher digestibility than AN, suggesting differences in nutritional bioavailability.
Heavy Metal Accumulation: Seaweeds naturally absorb minerals from seawater, but they can also accumulate heavy metals like mercury and lead. Cultivating seaweed in controlled environments or using processing methods such as water blanching can reduce these risks.
Extraction Efficiency: The method used to obtain bioactive compounds influences their effectiveness. Ethanol extraction may not recover all antibacterial components, highlighting the need for optimized extraction techniques.
Implications for Sustainable Agriculture
The study underscores the potential of seaweed-derived extracts as natural additives for animal feed, reducing reliance on antibiotics while improving gut health and oxidative stress resistance. AN and UL extracts, in particular, show promise for combating E. coli infections and enhancing antioxidant defenses. However, further research is needed to refine extraction methods, assess in vivo effects, and ensure safety for long-term use in livestock production.
References:
Hejna, M., Dell’Anno, M., Liu, Y. et al. (2024). Assessment of the antibacterial and antioxidant activities of seaweed-derived extracts. Sci Rep 14, 21044.