Food production needs to grow to meet the needs of a growing human population, which is expected to reach 9 billion by 2050. With more terrestrial and aquatic livestock production comes more greenhouse gas emissions from the production of feed like soy, maize (corn), and fish oil/meal (World Bank, 2023). As of 2020, the agriculture sector is responsible for roughly 2.5 gigatons of CO₂e per year, in addition to 64 million tons CO₂e per year emitted by the aquaculture sector (Cao et al., 2026; Zhang et al., 2026). Including seaweed in animal feed for both terrestrial and aquatic livestock production could reduce the carbon footprint of food systems and the associated pressure on land and water use (Balasse et al., 2019; Cottrell et al., 2020; DeAngelo et al., 2023; Morais et al., 2020; Michalak et al., 2022). Seaweed in feed can also improve livestock health and growth, decreasing overreliance on chemical antibiotics; Figure 1 summarizes the benefits for different types of livestock (Gabrielsen & Austreng, 1998; Morais et al., 2020; M. G. Mustafa & Nakagawa, 1995; Wassef et al., 2013).

Elements of seaweed-based animal feed production

This section presents an overview of the workstreams involved in producing seaweed-based animal feed for livestock consumption. After cultivation and harvest, seaweed biomass is pre-processed to stabilize it and remove undesirable components (e.g., impurities, excess salts, heavy metals, and some polysaccharides) so the material meets quality, safety, and shelf-life requirements under regional standards (Ozogul et al., 2024; Hofmann et al., 2025). This can occur with or without dewatering/drying. The biomass is then processed to refine it and release, isolate, or purify the compounds needed for animal-feed performance, ranging from minimal handling (e.g., using semi-fresh seaweed, Hansen et al., 2003) to more intensive extraction approaches (Øverland et al., 2019). Post-processing further stabilizes and concentrates the resulting biomaterial (often emphasizing the liquid fraction) and prepares it for distribution. Finally, the product is packaged into market-ready formats such as pellets or meal for use as a feed ingredient (e.g., Certified Organic Irish Seaweed Meal), or as a dry or liquid feed additive to supplement existing feed (e.g., Olmix MFeed+).

Species Selection

There are over 10,000 species of seaweed whose nutritional profiles vary with lifecycle, seasonality, and processing approach. Animal feed product producers select species based on their nutritional profile, target livestock, and existing regional seaweed supply; they use either individual species or species blends (Ozogul et al., 2024; Stedt et al., 2022). Table 1 summarizes seaweed groups’ nutritional composition, limitations, and how they are used.

Table 1. Examples of seaweed groups’ nutritional composition for animal feed, limitations, and example species and products. Sources: Cian et al. (2015), Valente et al. (2015), Garcia-Vaquero and Hayes (2016), Øverland et al. (2019), Morais et al. (2020), Schleder et al. (2020), Costa et al. (2021)

Wild harvest and cultivation practices

Harvesting wild seaweed for animal feed occurs in nations such as Norway, but this industry needs large volumes of biomass so leading companies achieve this by sourcing raw material from large-scale cultivated seaweed producing economies such as Indonesia (World Bank, 2023). While cultivation can occur in a range of locations (onshore vs offshore) and scale of farms, the approach of choice will vary according to end-product specifications and the level of inclusion in livestock diet (Costa et al., 2021). For cross-cutting information about seaweed cultivation and harvest, refer to the “Cultivation and Dewatering/Drying” chapter.

Dewatering/drying

Animal feed must be dewatered/dried before further processing. Commercial-scale drying methods include air drying on net frames, or freeze or heated drying in temperature-controlled rooms (Garcia-Vaquero & Hayes, 2016; Jönsson et al., 2020; Grabež et al., 2023). Conventional methods can degrade heat-sensitive target compounds (e.g., polyphenols, antioxidants), meriting R&D on how to dry seaweed without jeopardizing downstream product quality (Costa et al., 2021). See the “Cultivation and Dewatering/Drying” chapter for more information.

Preprocessing

Seaweed polysaccharides (e.g., cellulose, alginate, carrageenan, ulvan) and heavy metals interfere with adequate nutrient absorption in most livestock diets (e.g., Terry et al., 2023; Sumana et al., 2026). To address this, conventional pre-processing methods include blanching, washing and boiling biomass (e.g., Hanaoka et al., 2001; Stévant et al., 2018; Ownsworth et al., 2019; Blikra et al., 2021; Hofmann et al., 2025). Pre-treating seaweed biomass with microbial fermentation and ensiling is being studied as one innovative solution to improve digestibility, with observed co-benefits like increased antioxidant potential and immune system health (Usmani et al., 2020; Yen et al., 2024; Khan et al., 2025). Enzymatic hydrolysis pre-treatment is also being explored, as it breaks down polysaccharides into oligosaccharides, improving nutrient absorption and feed efficiency (Kulshreshtha et al., 2020; Mota et al., 2023; Bikker et al., 2016). In addition to increasing digestibility, simple fermentation methods (e.g., salt brine) are being tested to extend the seaweed’s shelf life (Stévant and Rebours, 2021; Ozogul et al., 2024; Sumana et al., 2026).

Processing

Conventional methods to extract proteins and other valuable compounds use high temperatures, water, acid, and/or salt solutions over time to break down seaweeds’ cell walls to reach desirable compounds (Dobrinčić et al., 2020). Methods include mechanical or enzymatic cell rupture, centrifugation, and advanced separation techniques (e.g., chromatography, electrophoresis; reviewed in Kumar and Sharma, 2017, Jönsson et al., 2020). The result of each method is a solid and liquid fraction of seaweed biomaterial, the latter of which contains desirable soluble protein and other compounds used in feed production. Novel extraction methods are being developed to cut down on extraction time, solvent usage, and energy needs and to maximize protein extraction while maintaining their functional and nutritional properties (reviewed in Naseem et al., 2024). Pre-processing and processing is summarized in Figure 2 while Table 2 summarizes the novel techniques, the benefits of their use in producing seaweed-based animal feed, and technological readiness.

Table 2. Emerging pre-/processing techniques and claimed benefits. Sources: de Moura et al. (2008), Yuan and Macquarrie (2015), Zollmann et al. (2019), Bordoloi and Goosen (2020), Dobrinčić et al. (2020), Naseri et al. (2020), Matos et al. (2021), Sharma and Zalpouri (2022), Lewandowska et al. (2023), Choulot et al. (2025), Gaiero et al. (2025), Sumana et al. (2025)

Technology Readiness Level 7-9

Animal feed from seaweed is already in market at commercial scale with companies having products for multiple livestock sectors.

Table 3. Examples of commercial-size companies and target livestock. Table adapted from Kulshreshtha et al., 2020. 

Context

Adding seaweed to livestock feed could reduce agriculture’s carbon footprint by partially replacing conventional feed ingredients (like soy and corn) and/or improving feed conversion ratios so animals need less feed to reach market weight (Costa et al., 2021; Hofmann et al., 2025).

Studies have flagged feed conversion ratios (FCRs) as a key driver in mitigating emissions due to animal feed. The Seaweed Company has stated that their products can improve FCR by 3–10% in swine farms, reducing the carbon footprint of 100,000 pigs by up to 18,000 tons CO₂e per year (as stated in World Bank, 2023). If applied worldwide in 2024, it could have mitigated approximately 191,003 tons CO₂e. More studies have been done replacing soy protein with seaweed for fish feed and that will be the basis for the calculations below.  The global aquaculture sector generates approximately 64 Mt CO₂e per year, with feed production — particularly soy protein concentrate — representing a dominant emissions driver. Seaweed-based protein offers a partial substitution pathway for soy in fish feed.

Key Findings and Limitations of Existing Life Cycle Assessments

Multiple life cycle assessments (LCAs) have flagged energy consumption in seaweed drying and pelletizing and resourcing wild harvest versus cultivated seaweed as climate impact drivers (e.g., Halfdanarson et al., 2019; Coelho et al., 2022; Koesling et al., 2021; Wu et al., 2025).

However, LCAs to date are incomplete in several respects. First, they do not cover the full end-to-end product lifecycle, including emissions in the cultivation process, and product end-use (Chaurasiya et al., 2026). Second, indirect land use change may not be fully incorporated: for example, when seaweed replaces soy protein, there is less pressure to clear forests to grow soybeans, thus creating an additional mitigation benefit. Third, seaweed products are increasingly marketed as alternatives to synthetic antibiotics in livestock, but the upstream emissions from antibiotic manufacture and the downstream benefits of antibiotic reduction are absent from available LCAs, making direct like-for-like comparison impossible with regards to climate impact.

Emissions Reduction Potential

Note: The mitigation potential estimates presented here are screening-level calculations to establish order-of-magnitude plausibility under specific adoption scenarios. Each estimate is derived by combining published or estimated values for current or forecasted seaweed-based product emissions performance in currently available LCAs (e.g., methane reduction per animal, GHG intensity relative to a displaced product) with assumptions about adoption rates and addressable market size.

Evidence Base

(Seghetta et al., 2017), working with Danish cultivation systems on a predominantly renewable grid, find that substituting soy with Saccharina latissima protein reduces emissions by 300 kg CO₂e per hectare of cultivation per year; using Laminaria digitata the emissions reduction rises to 1,230 kg CO₂e/ha/yr, reflecting that species’ higher protein yield.

(Koesling et al., 2021) however shows that under the scenario of a Norwegian grid with fossil inputs, S. latissima protein generates +28.8 kg CO₂e per kg crude protein — a net emissions increase versus soy. The majority of global seaweed production occurs in China, Indonesia, and the Philippines where grid electricity is substantially more carbon-intensive than Norway, meaning the (Koesling et al., 2021) base case is closer to current reality for most global production than the (Seghetta et al., 2017) Danish renewable scenario.

Three systematic omissions mean current figures are conservative even when conditions are met. First, indirect land-use change (iLUC): when seaweed replaces soy, reduced demand decreases pressure on land clearing in Brazil and Southeast Asia; Brazilian soy iLUC emissions are estimated at 4–12 t CO₂ee per hectare of soy displaced which is a benefit absent from current LCAs. Second, antibiotic avoidance: seaweed-based feed additives reduce synthetic antibiotic use, whose upstream production carries its own emissions footprint. Third, feed conversion ratio improvement: a 10% FCR reduction in aquaculture reduces environmental impacts by up to 24%, but this is not considered.

Calculation

A theoretical long-term anchor is total cultivation area:

Animal feed product performance and livestock impacts

Farmers have tight margins and are resistant to changing management practices that run a risk of further reducing these margins; therefore, seaweed-based animal feed products must be able to consistently meet or exceed competitor products’ performance. Key performance metrics still lag behind conventional alternatives. For example, studies have found that current seaweed-based protein concentrate contains roughly half of the protein found in soy protein concentrate, increasing the amount of feed (and cost) required to meet livestock growth targets (e.g., Hognes et al., 2012; Seghetta et al., 2016). However, seaweed-based products deliver bioactive compounds beyond macronutrients that can function as organic antibiotics and prebiotics, reducing reliance on synthetic inputs while supporting a broader set of nutritional needs (Makkar et al., 2016; Ozogul et al., 2024; Terry et al., 2023; Costa et al., 2021; Reddy et al., 2024). This is particularly advantageous in aquaculture, where nutrition requirements are not met by terrestrial plant-based protein sources (Cottrell et al., 2020; Schleder et al., 2020). Table 6 summarizes studies of seaweed-based animal feed and livestock impacts.

Table 6. Summary of impacts on livestock health from seaweed-based animal feed and feed additives, grouped by species type. FCR: feed conversion ratio; ns: no significant difference between treatment and control; ↑: improvement; ↓: reduction; ↑/↓: outcome depends on inclusion level. Each study count (n) refers to distinct experimental papers reviewed. Sources: Ergün et al. (2009), Soler-Villa et al. (2009); Güroy et al. (2010), Güroy et al. (2013), Hernández et al. (2009), Viera et al. (2011), Erickson et al. (2012), Bach et al. (2008), Marín et al. (2009), Hansen et al. (2003), Ventura et al. (1994), Kulshreshtha et al. (2017), O’Doherty et al. (2010), Antaya et al. (2015, 2019)

Table 5. State of the Market of global seaweed production and seaweed-based animal feed and blue food, including its value and growth. Values taken from Global Seaweed New and Emerging Markets Report (2023). 

Seaweed-based animal feed products are currently not cost-competitive with terrestrial plant-based feed products (e.g., soy, corn) as protein replacements (Emblemsvåg et al., 2020; see Table 7). However, seaweed is already cost-competitive as a functional feed additive (immune support, FCR improvement, antibiotic reduction), which is the primary current market.  In order to compete in the commodity protein feed market, seaweed producers must have facilities capable of processing over 10,000 tons of fresh seaweed/year to reduce costs of production (World Bank, 2023). Maximizing valorization of seaweed compounds through cascading biorefineries is also being explored to reduce cost of production and increase profit margins; more information is available in the “Biorefineries” roadmap chapter.

Table 7. Market price of soybean, corn, and seaweed per ton. Data taken from, Statista (2026), Kite-Powell et al. (2022) and World Bank (2023). 

Benefits

• Growing seaweed requires no arable land, high-carbon chemical fertilizers or freshwater resources (Morais et al., 2020; Reddy et al., 2024)

Risks

• Changing an animal’s diet can alter the digestion and nutrient content of its waste, potentially adversely impacting local terrestrial/marine environments; this specific occurrence and the magnitude of its impact from seaweed-based animal feed requires further research to confirm (Hempel et al., 2022)

Benefits

• Seaweed-based animal feed can help improve feed conversion ratios, immune system function, and overall health for terrestrial and aquatic livestock, indirectly reducing operating costs for farmers and sustaining livelihoods (Kebreab et al., 2016; Seghetta et al., 2017; Bampidis et al., 2019; Chaurasiya et al., 2026)
• Seaweed-based animal feed and feed additives relieve pressure on land-use for global food security, fulfilling Sustainable Development Goals (SDG):
  • SDG 2: Zero Hunger
  • SDG 12: Responsible Consumption and Production

Risks

• Consuming food products fed with seaweed can risk bioaccumulation of heavy metals, pathogens, organic pollutants, and marine biotoxins in livestock, though studies have characterized inclusion levels within regulatory limits for adult consumption and beneficial for specific conditions (e.g., iodine and pregnancy, Antaya et al., 2019, Brito, 2020; (FAO, 2024; Jarvis & Bielmyer-Fraser, 2015; Stedt, Steinhagen, et al., 2022).

Livestock-only products have been seen to enhance consumer support by aligner with growing consumer demand for sustainable meat and dairy (World Bank, 2023; see chapter “Livestock methane inhibitors” for more information). Public perception is generally positive when these feeds are marketed as natural alternatives to synthetic additives, but maintaining a long-term license depends on building public trust through transparent data and rigorous safety standards (World Bank, 2023; Ozogul et al., 2024).

Regulations governing seaweed-based animal feed focus on limiting biocontaminants in feed and animal products (e.g., meat, milk, eggs), but differing national thresholds and limited seaweed-specific safety data create a fragmented compliance landscape for producers (Hofmann et al., 2025; summarized in Table 7 below). There is a lack of food safety data and discussion regarding seaweed-based animal feed products and alignment on international and national regulations (FAO, 2022; Cottier-Cook et al., 2023). Furthermore, there is currently no Codex standard or guidelines that address food safety for seaweed production, processing and utilization (reviewed in Hofmann et al., 2025). The most consequential policy development for seaweed as a feed ingredient may be the European Union’s EC 1831/2003’s 2006 ban on antibiotic growth promoters in livestock feed, creating direct regulatory demand for non-antibiotic alternatives.

Table 7. Feed-relevant policies and regulations governing seaweed-based animal feed in key markets.