Macroalgae (algae) fed to ruminants – cattle, buffaloes and camelids – can reduce their enteric emissions of greenhouse gases (methane, CO4). (1)
It is therefore appropriate to investigate their potential contribution to the sustainable development of animal husbandry, in line with the FAO recommendations (2019). (2)
An excerpt of the scientific review (Beauchemin et al., 2022) devoted to options to mitigate enteric methane emissions from farmed animals. (3)
1) Blue bioeconomy. Algae, agriculture and aquaculture
Blue bioeconomy it is the concept that best expresses research and innovation on the most unexplored treasures of the oceans and fresh waters, algae. Macroalgae and microalgae can perform ecosystem functions, from carbon sequestration to water phytoremediation and environmental remediation. In addition to supplying biomass with high nutritional value with various applications. Human and animal nutrition, medicine and cosmetics, agriculture, biofuels.
The European Commission acknowledged the need to develop this productive sector – still marginal in the Old Continent – in the communication 'Towards a Strong and Sustainable EU Algae Sector' (4,5). The 23 actions envisaged in Brussels, as we have seen, include:
- as of 2023, the evaluation of market potential, efficiency and safety of seaweed-based materials such as fertilizers and/or biostimulants (action 5. See note 6),
- by the end of 2024, also on the basis of good practices and indicators on feed, promote the replacement of fish-based feed with algae-based feed (action n. 7).
2) Algae and animal husbandry
The role of macroalgae and microalgae and phlorotannins in animal husbandry has already been successfully demonstrated in Italy, thanks to the research and experience of Algatan, in strengthening the microbiota of animals. To the point of reducing - even eliminating, where possible - the use of coccidiostatics and antibiotics in poultry farming. (7) A major innovation to mitigate the phenomenon of antibiotic resistance (AMR, Anti-Microbial Resistance).
Important results have also been achieved in pig farming, where it has also been possible to develop lines of meatantibiotics-free', as well as on cattle and sheep. (8) Up to now, however, little attention has been paid by institutions and animal husbandry operators to the innovation described above. As well as the potential of algae to reduce enteric methane emissions from ruminants. Essential by the way also in a logic of carbon farming e carbon credits. (9)
3) Role of algae in the reduction of methane emissions from ruminants
Algae they have a chemical composition that varies significantly depending on the species, the harvest period and the growth environment. The scientific review in question (Beauchemin et al., 2022) reports the studies published so far on some macroalgae that contain bioactive compounds capable of inhibiting methanogenesis in ruminants. (1)
3.1) Macroalgae examined
'Red algae such as Asparagopsis taxiformis and Asparagopsis armata they accumulate halogenated compounds, among which bromoform abounds (Machado et al., 2016). Halogenated methane analogs react with vitamin B12 to block the last step of methanogenesis in methanogenic archaeans (Wood et al., 1968).
More algae they contain polysaccharides, proteins, peptides, bacteriocins, lipids, phlorotannins, saponins and alkaloids. In turn known to reduce methane production by killing archaea and protozoa. Causing however. in some cases, an undesirable decrease in nutrient degradability (Abbott et al., 2020)'. (1)
3.2) Studies in vivo
'In vivo studies on sheep, steers and dairy cows reported a dose- and ration-dependent reduction of methane (CH4) production, ranging from 9 to 98%, by integrating Asparagopsis in the diet (Li et al., 2018; Roque et al ., 2019a, 2021; Kinley et al., 2020; Stefenoni et al., 2021).
A substantial reduction of CH4 production for cattle was confirmed in a meta-analysis (Lean et al., 2021). The efficacy of asparagopsis for CH4 mitigation depends on its bromoform concentration, which ranges from 3,0 to 51,0 mg/kg DMI (Kinley et al., 2020; Roque et al., 2019a, 2021; Stefenoni et al., 2021)'. (1)
3.3) Asparagopsis
'The Asparagopsis may be more effective in reducing CH4 production with high-concentrate diets than high-forage diets (Roque et al., 2021). Although it is feared that Asparagopsis may lose efficacy in the long term (Hristov et al., 2022). Studies on the efficacy of other algae on CH4 production are mostly limited to in vitro conditions (Abbott et al., 2020), although interest is growing.
Food supplementation with Asparagopsis reduced feed intake in a dose-dependent manner in most, but not all, experiments. (…). Asparagopsis supplementation has been reported to increase feed efficiency in some small-scale studies (Kinley et al., 2020; Roque et al., 2021). The inclusion of Asparagopsis in the diet had no effect on carcass quality, meat quality, or taste (Kinley et al., 2020; Roque et al., 2021), (…). ' (1)
3.4) Elements of attention
The valuable scientific review (Beauchemin et al., 2022) also indicates some elements of attention. From the point of view of food safety, it is necessary to check the possible presence of contaminants in the algae. In addition to the concentrations of minerals such as iodine, so that the transfer to products of animal origin (e.g. milk) does not exceed the Acceptable Daily Intakes (ADI) of the various consumer groups.
It's also important 'sustainably cultivate the seaweed in aquaculture or marine systems with a constant concentration of active compounds, which must be maintained during transport, handling, storage and feeding of the animals. (…)
The inclusion of other algae in ruminant diets may be acceptable to consumers if there is no risk of toxicity and if there are no off-flavors in the meat or milk'. (1)
Provisional conclusions
'More research is needed in vivo to determine CH4 mitigation and productivity changes under different diet and management conditions for both bromoform-containing algae and other algae (Lean et al., 2021).
The use of macroalgae as an antimethanogenic strategy it may be feasible in confined and mixed systems, but is likely to be difficult to implement in extensive systems.
For integration of animals in extensive systems it is necessary to design delivery mechanisms that do not reduce the efficacy of the bioactive compounds of the macroalgae.(1)
Dario Dongo
Cover image from Toki™Asparagopsis taxiformis Feed (Zhejiang, China) https://asparagopsistaxiformisfeed.com/
Footnotes
(1) Antonio Gattuli. Algae against the greenhouse effect. GIFT (Great Italian Food Trade). 22.5.18
(2) Dario Dongo, Marina De Nobili. Animal husbandry, FAO proposes 5 intervention areas to reduce greenhouse gas emissions. GIFT (Great Italian Food Trade). 29.8.20
(3) Karen A. Beauchemin, Emilio M. Ungerfeld, Adibe L. Abdalla, Clementina Alvarez, Claudia Arndt, Philippe Becquet, Chaouki Benchaar, Alexandre Berndt, Rogerio M. Mauricio, Tim A. McAllister, Walter Oyhantçabal, Saheed A. Salami , Laurence Shalloo, Yan Sun, Juan Tricarico, Aimable Uwizeye, Camillo De Camillis, Martial Bernoux, Timothy Robinson, Ermias Kebreab (2022). Invited review: Current enteric methane mitigation options. Journal of Dairy Science, Volume 105, Issue 12, 2022, Pages 9297-9326. ISSN 0022-0302. https://doi.org/10.3168/jds.2022-22091
(4) European Commission Communication to the European Parliament and the Council. Towards a Strong and Sustainable EU Algae Sector. https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=COM:2022:592:FIN COM (2022) 592 final
(5) Marta Strinati. The European Commission proposes 23 actions for the seaweed industry. GIFT (Great Italian Food Trade). 23.11.22
(6) Dario Dongo, Andrea Adelmo Della Penna. Biostimulants in olive growing, the organic revolution. Scientific review. GIFT (Great Italian Food Trade). 14.5.21
(7) Dario Dongo, Andrea Adelmo Della Penna. Antibiotic-free poultry farming, the Italian way. GIFT (Great Italian Food Trade). 14.12.20
(8) Dario Dongo, Andrea Adelmo Della Penna. Animal husbandry, algae and microalgae to prevent the use of antibiotics. Algatan. GIFT (Great Italian Food Trade). 9.9.20
(8) Dario Dongo, Giulia Pietrollini. Carbon farming, green light from the Council for EU certification of carbon credits in agriculture. GIFT (Great Italian Food Trade). 21.12.22
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
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