A Sustainable Approach to Managing Invasive Macroalgae: Assessment of the Nutritional Profile and the Potential for Enteric Methane Mitigation of <i>Rugulopteryx okamurae</i>
2024
Helder P. B. Nunes | Cristiana Maduro-Dias | Joana Carvalho | Alfredo Borba
The expansion of the invasive Asian macroalgae <i>Rugulopteryx okamurae</i> along the coasts of the Azores represents a significant challenge for local marine biodiversity. A promising approach to managing the biomass produced by this alien alga is to valorize it in the context of the blue economy. This study characterizes and evaluates the potential of <i>R. okamurae</i> biomass for incorporation into cattle feed, with a focus on mitigating enteric methane production. The nutritional value of <i>R. okamurae</i>, its digestibility, and its potential as a mitigating agent for enteric methane production were analyzed in vitro. The results indicate that the inclusion of 5% <i>R. okamurae</i> in the diet significantly (<i>p</i> < 0.05) reduced accumulated methane production by 98% after 24 h of incubation. The addition of 1% algae over the same period resulted in a 38% reduction in methane production. However, a significant decrease (<i>p</i> < 0.05) in gas production of 57.02% and 73.5% was also observed in relation to control, with the inclusion of 1% and 5%, respectively, during 96 h. Nutritionally, <i>R. okamurae</i> was found to have a crude protein content of 18.68% and fiber (NDF) of 55.71% of DM. It is also worth highlighting the high content of ash (31.86%) that was identified in these brown macroalgae. In conclusion, the fresh biomass of <i>R. okamurae</i> could serve as a functional ingredient in cattle feed to mitigate enteric methane production, provided it is used in low percentages. However, it is important to emphasize that high concentrations in the first 12 h did not produce methane, which is also not recommended for enteric fermentation. However, before including it in animal feed, in vivo tests are needed to assess its toxicity.
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