TYPE Review
PUBLISHED 23 February 2026
DOI 10.3389/fanim.2025.1710262

OPEN ACCESS

EDITED BY
Anusorn Cherdthong, Khon Kaen University, Thailand
REVIEWED BY
Mohamed E. Abd El-Hack, Zagazig University, Egypt Padsakorn Pootthachaya, Khon Kaen University, Thailand
*CORRESPONDENCE
Jules R. Siedenburg
j.siedenburg@uea.ac.uk
RECEIVED 08 October 2025
REVISED 24 December 2025
ACCEPTED 25 December 2025
PUBLISHED 23 February 2026
CITATION
Siedenburg JR, Attard E and Verschoor A (2026) Microalgae as futuristic feeds for securing chicken production while promoting human health.
Front. Anim. Sci. 6:1710262.
doi: 10.3389/fanim.2025.1710262
COPYRIGHT
© 2026 Siedenburg, Attard and Verschoor. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

Microalgae as futuristic feeds for securing chicken production while promoting human health
Jules R. Siedenburg 1,2*, Everaldo Attard 2 and Arjan Verschoor 1
1School of Global Development, University of East Anglia, Norwich, United Kingdom, 2Institute of Earth Systems, University of Malta, Msida, Malta
Livestock keepers face growing challenges, notably rising input prices and escalating biotic and abiotic stresses linked to environmental issues like climate change. These stresses pose problems for farmers but could also adversely affect wider society, including food security and the environment. Agricultural innovations are needed to help address such threats, and nature-based solutions are a promising locus of innovative farm inputs. The present paper reviews the available evidence on one species of microalgae – Arthrospira platensis – and its potential significance for chicken production given these challenges. It finds that this feed possesses multifaceted efficacy, namely boosting the production of meat and eggs, enhancing the resilience of production to biotic and abiotic stresses, and improving product quality. These effects could bolster the economic viability of chicken production. The observed quality effects also create scope for producing biofortified chicken products, with potentially major implications for public health. The paper summarises the evidence on these themes in non-technical language using intuitive metrics. It also frames its findings in terms of key target users of this innovative feed, namely farmers, farm advisors and policy makers. It concludes by discussing the potential significance of this agricultural innovation and highlighting key research and policy priorities.
KEYWORDS
Arthrospira, biofortified foods, chicken production, climate change, food systems transformation, microalgae, nature-based solutions, public health
1		Introduction
Livestock keepers face growing challenges, notably rising input costs and worsening biotic and abiotic stresses linked to environmental issues. Consequences can include lower production of meat, milk and eggs and higher morbidity and mortality, potentially jeopardising the viability of livestock production (Godde et al., 2021; Sommer et al., 2013). The difficulties facing these producers are a facet of wider food system challenges.
Several authoritative analyses have found that global food systems are facing profound problems. One aspect is farming. Many farmers are struggling economically due to input costs, land degradation and climate change, while their practices may also exacerbate
environmental problems. The other aspect is food. Some populations face health problems linked to processed foods and farm inputs like pesticides and hormones, while others are malnourished. Such problems impose huge costs on society ($12 trillion/year globally) (Food and Land Use Coalition, 2019; The UN Food Systems Summit, 2021; Ruben et al., 2021).
This state of affairs has led to high-level calls for food systems transformation to secure better outcomes for people and planet (Food and Land Use Coalition, 2019; Willett et al., 2019; The UN Food Systems Summit, 2021; Food and Agriculture Organization of the United Nations, 2024). To achieve this, farmers will have to adopt productive yet regenerative agricultural practices while consumers embrace healthier diets. Predicted benefits include higher agricultural production, better health outcomes and positive environmental impacts.
Making the needed changes to agriculture will require agricultural innovations, which offer new ways to produce food and meet farming challenges. Different types of agricultural innovations include new agrochemicals and improved seeds (Bilal, 2024), ‘advanced’ technologies like artificial intelligence and drones (Khan et al., 2021), and ‘nature-based solutions’ (NbSs) that harness natural processes to meet human needs (Iseman and Miralles-Wilhelm, 2021).
NbSs for agriculture involve using natural substances as farm inputs in ways that can support agricultural livelihoods while also having positive environmental impacts (Demozzi et al 2024). Those based on microorganisms like microalgae (Cmiková et al 2025; Mutale-Joan et al., 2023) microfungi (dos Santos et al., 2023; Vassilev and Mendes, 2024), and bacteria (Týskiewicz et al., 2022; Zin and Badaluddin, 2020), are attracting growing interest as promising options. Some species have shown remarkable technological promise as both livestock feeds (Saadaoui et al 2021) and crop inputs (Siedenburg et al 2022). Species choice is critical, however. Notably, some microorganisms are toxic to animals (Niccolai et al., 2017), while biotic or abiotic contamination of cultures can also pose a challenge (Siedenburg and Cauchi, 2022; Yu et al., 2019). Despite their potential, current use of microorganisms as farm inputs is believed to be limited (Chen et al 2016; Harman, 2024; Kumar et al 2025; Siedenburg et al., 2024).
An emerging literature examines the potential of microalgae as feed supplements for livestock like cattle, sheep, pigs and chickens, and finds they show promise in multiple ways (Orzuna-Orzuna et al., 2023; Madeira et al., 2017; Amorim et al., 2021). The present review focuses on the microalga Arthrospira platensis as a feed for chickens.
Arthrospira platensis are aquatic organisms rich in nutrients and bioactive compounds. This is the most studied, commercialised and affordable microalgae species, and has regulatory approval as a food and feed in various jurisdictions under the name spirulina (De Oliveira and Bragotto, 2022). These microalgae lack rigid cell walls and hence can be viable as farm inputs in their raw form. They grow fast and can be induced to adapt rapidly via applying selective pressures (Siedenburg et al., 2024). They possess characteristics that could facilitate their culture within farming communities, namely being extremophiles vis-à-vis alkalinity, salinity and temperature (Habib et al., 2008; Gerday and Glansdorff, 2009). Their use as feeds also offers scope to deliver biofortified livestock products that could help address key public health objectives, as explored below. While technically classified as cyanobacteria, Arthrospira are often grouped with microalgae in the academic (Mutale-Joan et al., 2020; Rachidi et al., 2020), policy (Habib et al., 2008; Lomas et al, 2022), and popular (Nutrients in Bulk, [[NoYear]]; BBC), literatures due to their similarities.
Chickens are a key livestock subsector and the most popular meat globally (Richie et al., 2023). They produce more edible product per unit feed than other livestock (Govoni et al., 2021), and can metabolise diverse feedstuffs, including agriculture residues, household wastes, and food processing byproducts (Grzinic et al., 2023). Raising chickens is widely accessible to farmers due to their modest cost (Korver, 2023), and they can produce marketable products fast thanks to their relatively small size (Upton, 2004). Chicken production nonetheless faces the same challenges as other livestock, notably high feed costs, disease pressures and environmental stresses.
The present paper examines the available literature on using microalgae as an innovative chicken feed. It looks at the various different ways this innovative feed can impact chicken production, thus revealing its multifaceted efficacy. It also sets this evidence in the context of the wider challenges facing chicken farmers. It finds that this innovative feed represents a practical and ‘futuristic’ solution to key challenges facing these farmers, one that supports sustainable production while also delivering health and environmental benefits. This includes enhancing the quality of eggs and chicken meat in ways that contribute to human health (e.g., enrichment in fatty acids, antioxidants, immune-boosting compounds). While it focuses mainly on Arthrospira biomass as a chicken feed, the paper also includes evidence from studies testing other microalgae (e.g., Nannochloropsis) and extracts of Arthrospira.
2		Methodology
A search of the academic literature on using Arthrospira as a feed supplement for chickens was conducted. Pertinent papers were identified via Google Scholar using search terms, notably ‘microalgae’ or ‘Arthrospira’ in conjunction with ‘chicken’ and ‘feed’. For each combination of terms the first 100 hits were examined, and relevant studies cited in these papers were likewise examined. Several studies on other microalgae were also included to bolster evidence on key themes. Papers that could not be accessed without paying were excluded.
Reviewing this literature revealed that using Arthrospira as a chicken feed showed several distinct types of technological efficacy. A critical question is how this technological profile fits with farmers’ priorities, given their status as the prospective users of any agricultural innovation. Five priorities were extrapolated from the authors’ reading of the literature and discussions with myriad farmers over the years. Table 1 flags these priorities and possible ways Arthrospira feed for chickens might help address them based
TABLE 1 Farmer priorities and corresponding efficacy pathways of Arthrospira feed for chickens.
Farmer priority	Efficacy pathway	
Reduce costs	Offering a protein substitute for livestock feed	
Increase production	Securing higher productivity	
Cope with biotic stresses	Enhancing resilience to various biotic stresses	
Cope with abiotic stresses	Enhancing resilience to various abiotic stresses	
Improve product quality	Improving quality of livestock products	

on the evidence reviewed. Each distinct way in which this feed may deliver on farmer priorities is termed an ‘efficacy pathway’.
Figure 1 posits a conceptual framework regarding “NbSs for agriculture” as a family of technologies. This framework extrapolates from the evidence on Arthrospira as a chicken feed, notably the remarkable finding that this NbS shows efficacy vis-a-vis all five farmer priorities, echoing the efficacy of Arthrospira on crops (Siedenburg et al., 2024).
The present paper is organised around the five efficacy pathways elaborated. Each study reviewed was categorised based on what was deemed its primary focus. Studies assessed efficacy by comparing treatments with controls. All statistically significant differences were reported, but the mechanisms underpinning these effects were not explored, since such mechanisms can be highly technical and not relevant to key target audiences like farmers and policymakers. Significant results were summarised in the paper then reported in full in the annex. With most variables beneficial effects were reflected in percentage increases but for some variables more negative findings represented improvements. For instance, in Kolluri et al. (2022) higher Newcastle disease inhibition titres and a lower foot-web index both showed evidence that Arthrospira feed had boosted vaccine efficacy. To simplify the paper’s narrative, summary findings vis-à-vis a given variable category used absolute values of percentage changes observed, and hence presented findings as a positive range. In our example, the summary data for vaccine efficacy reads +9-35%. The

FIGURE 1
Conceptual framework for “NbSs for agriculture” highlighting multifaceted efficacy. Reprinted from Siedenburg et al. 2024, Creative Commons CC BY 4.0.

significance of this body of evidence was then discussed, as were key caveats and outstanding research and policy priorities.
Since adoption of agricultural innovations ultimately depends on farmers, they are a key target audience of this paper. Other target audiences include farm advisors since they may influence farmers, policy makers since the policies and programmes they develop can create incentives for farmers, and researchers since their work can inform thinking and actions. These groups will largely determine whether this innovative feed is adopted at scale, and hence whether its potential benefits for people and planet are harnessed. Given its target audiences, this paper employs non-technical language; reports findings in terms of percentage change vs controls; and underlines ways this feed might help address problems facing farmers and society.
3		Results
Studies investigating Arthrospira as a chicken feed are divided into five categories based on their relevance to the five efficacy pathways framed above. In each section pertinent studies are summarised in a table then discussed.
3.1		Provide protein source
Various studies have investigated whether microalgal biomass could substitute for conventional protein sources like soymeal in the diet of chickens. Such work departs from the growing recognition that the sustainability of animal production is threatened by continued reliance on conventional protein sources, which are resource-intensive and can cause environmental problems. Meanwhile, the available evidence suggests that alternative protein sources like insects, microalgae and agro-industrial byproducts can enhance the sustainability and resilience of livestock production while delivering high-quality nutrition and positive environmental impacts (Keohavong, 2026).
Earlier studies narrowly focussed on growth parameters, but the breadth of observed effects has gradually broadened. Blum and Calet (1976) (Blum and Calet, 1976) substituted Arthrospira biomass for soybean or fishmeal in chick diets over 8 weeks. They observed comparable weight gain with 3% or 5% Arthrospira, but lower growth at higher dosages. Yoshida and Hoshii (1980) (Yoshida and Hoshii, 1980) substituted Arthrospira biomass for soymeal in chick diets. They reported comparable growth rates up to the highest level tested (20% of rations), and hypothesised this positive result was due to the quality of Arthrospira used. Venkataraman et al. (1994) replaced groundnut cake or fishmeal with Arthrospira in chicken diets at 14-17% of rations over 12 weeks and observed no differences from controls in chicken weight or health (Venkataraman et al., 1994). Bleakley and Hayes (2017) suggested that Arthrospira is comparable to established protein sources like soybean and egg (Bleakley and Hayes., 2017). Park et al. (2018) note that its essential amino acid composition meets the feed requirements of the Food and Agriculture Organization of the
United Nations (Park et al., 2018). Other researchers write about its high protein content of superior quality with high digestibility (Alvarenga et al., 2011; Spolaore et al., 2006; Plaza et al., 2009).
The findings of several recent studies on broiler chickens and laying hens are summarised in Table 2. This table shows both positive and adverse outcomes of substitution, as well as observed parameters that remained unchanged. This analysis focuses on biological effects relevant to chicken farming but not on economic factors, following the approach of the studies reviewed. Economic considerations relating to protein choice are, however, briefly explored in the discussion section.
Given their focus on protein substitution, such studies equalised protein content of treatments and controls. Since Arthrospira is high in protein, this typically meant reducing conventional proteins by a greater margin, sometimes accompanied by increasing carbohydrate ingredients.
The available data suggest that Arthrospira offers an effective substitute for soymeal, while also potentially delivering additional benefits like improved productivity, health and product quality. The efficacy of this feed generally increased with higher dosages, but the two studies that tested the highest dosages (20 and 21% of diet) found that such levels adversely affected outcomes.
3.2		Boost productivity
Another set of studies investigates Arthrospira feed for chickens as a means to boost productivity. Unlike the studies summarised above which substituted Arthrospira biomass for conventional proteins, these studies simply added it to feed rations then compared the outcomes to those achieved with untreated controls. Changes in productivity were assessed via variables like body weight gain and feed conversion ratio (FCR), which shows how efficiently an animal uses feed. FCR is the weight of feed intake divided by the animal’s weight gain, so a lower ratio shows greater efficiency. Table 3 presents key results from several relevant studies.

Studies	Dietary substitutions as a proportion of total diet	Observed outcomes relative to conventional diet
Improvements	Adverse effects	Comparable	
Mishra et al. (2023)	•		Add: Arthrospira (+3%)
•		Remove: Soymeal (-2%), soy oil (-.5%), corn (-.5%)	•		Body weight gain (+50%)
•		Gut health parameters (+100-300%)		•		Feed conversion ratio (FCR)
•		Intestinal morphology	
El-Hady et al. (2022)	•		Add: Arthrospira (+3-6%)
•		Remove: Soymeal (-3-6%)	• Antioxidant status (+21-54%)
•		Serum biochemistry (+14-47%)
•		Immune function (+7-8%)	---	•		Weight gain
•		FCR
•		Mortality rate
•		Other antioxidant & serum parameters	
Curabay et al. (2021)	•		Add: Arthrospira (+1-2%), wheat (2.5-3.5%)
•		Remove: Soymeal (-2%), sunflower meal (-.5-1.8%) vegetable oil (-.7-1%)	• Yolk colour index (+291-377%)		•		Weight gain
•		FCR
•		Egg yield
•		Shell thickness
•		Blood parameters	
Evans et al. (2015)	•		Add: Arthrospira (+6-21%), corn (+1-4.5%)
•		Remove: Soymeal (-5.5-22%), other (-.05-2.5%)	6-16% treatment
•		Weight gain (+2-3%)
•		8 amino acids (AAs) are more bioavailable	21% treatment
•		Weight gain (-3%)
•		4 AAs are less bioavailable	•		FCR
•		Mortality	
Ross and Dominy (1990)	•		Add: Arthrospira (+3-20%)
•		Remove: Soymeal (-6-26%)	-	20% of feed over 20 days
• Weight gain (-16%)	Arthrospira up to 15%
•		Body weight gain
•		FCR
•		Mortality	
Wu et al. (2019)	•		Add: Nannochloropsis (+1-8%)
•		Remove: Soymeal (-1.3-10.7%), soy oil (-0.3-1.6%)	Egg quality with 8%
•		Yolk colour (+131%)
•		Omega-3 PUFAs (+201%)
•		Omega-6 PUFAs (-34%)
•		Ratio of omega 6/3 (-62%)		•		Productivity: Laying rate, egg weight, FCR
•		Egg quality: Yolk percentage, protein	
Long et al. (2018)	•		Add: Schizochytrium (+1-2%)
•		Remove: Soymeal oil (-1-2%)	•		Daily weight gain (+3-11%)
•		Feed use efficiency (+5-10%)
•		Carcass traits (+26-66%)
•		Antioxidant capacity (+33-81%)
•		Serum LDL (-26-40%)
•		Omega-3: DHA (+700-1909%), EPA (+46-408%)	--	Quality: Meat colour, drip loss Other carcass traits: Percentage size of Fabricius & pancreas	

TABLE 2 Arthrospira and other microalgal feeds as alternative protein sources.

These productivity studies used much lower dosages of Arthrospira feed than the protein substitution studies (0.03-1.5% vs 1-21%). Four of the five studies gave the best results at the highest dose tested, but Shanmugapriya et al. (2015) found the highest dose performed less

Studies	Treatment (% of feed rations)	Observed outcomes relative to untreated controls	
		Improvements	Adverse effects	Comparable	
Shanmugapriya et al. (2015)	Arthrospira biomass (0.5, 1 or 1.5%)	•		Body weight gain (+12-17%)
•		More beneficial gut microbiota (+18-87%)
•		Less harmful gut microbiota (-16-31%)		• FCR	
Kaoud (2015)	Arthrospira biomass (0.1%)	•		Final body weight (+6%)
•		Carcass percentage (+6%)
•		Immune organs (+7-19%)		• FCR	
Fathi et al. (2018)	Arthrospira (0.03, 0.05, 0.07, 0.09%)	•		Body weight (+9-14%)
•		FCR (-6-9%)
•		Abdominal fat (-8-25%)
•		Immune organs (+12-50%)
•		Blood & serum parameters (+1-47%)
•		Beneficial gut microbiota (+2-5%)			
Park et al. (2018)	Arthrospira (0.25, 0.5, 0.75, 1%)	•		Body weight gain (+2-4%)
•		FCR (-1-3%)
•		Nutrient digestibility (+1-5%)
•		Antioxidant enzymes in serum (+12-41%)
•		Beneficial gut microbiota (+1-5%)
•		Greenhouse gas emission (-24-31%)		•		Mortality
•		Meat colour
•		Immune organ weight	
Selim et al. (2018)	Arthrospira (0.1%, 0.2%, 0.3%)	•		Body weight gain (+4-20%)
•		Egg mass/hen/day (+7-16%).
•		Improved yolk colour (+27-61)
•		Greater shell thickness (+2-12%)			

TABLE 3 Arthrospira feed as a means to boost productivity.

well. One conclusion is that testing higher dosages might give still better outcomes. Another conclusion is that small amounts of Arthrospira feed can powerfully support chicken health and performance.
All five studies found that Arthrospira boosted productivity. Other observed benefits include:
x Three studies examined impacts on chickens’ gut microbiota and all observed positive impacts. Namely, Arthrospira boosted beneficial species like Lactobacillus while suppressing pathogenic species like E coli. Such microbiota impact chickens’ intestinal wall, which absorbs nutrients, acts as a barrier to pathogens or toxins, and produces bodies that support immune system function. While stressors can undermine the wall’s efficacy, some foods/feeds can boost it via their impacts on intestinal microbiota (Shanmugapriya et al., 2015). These findings fit with those of earlier studies (Kabir et al., 2004; Kulshreshtha et al., 2008). Kaoud (201 5) suggests Arthrospira may have particularly strong effects on intestinal microflora under poor production conditions.
x Two studies observed improved carcass traits like higher carcass percentage or less abdominal fat. These show the proportion of usable meat in a bird, a key economic indicator. Carcass traits may also affect disease resistance and reproductive performance (Zhuo et al., 2015).
x Two studies observed positive impacts on immune organs. A larger bursa or thymus suggests better immune system function (Cazaban et al., 2015), while a larger liver or spleen can be a sign of infection, disease or inflammation (Zaefarian et al., 2019; Vali et al., 2023).,
x Two studies observed benefits to blood or serum parameters. Park et al., 2018 reported higher antioxidant enzyme activity, suggesting chicks have stronger defences against stressors like heat, diseases or poor quality diet (Alyileili et al., 2020). The findings of Fathi et al. (2018) suggest better immune function (lymphocytes, white blood cells), less risk of cardiovascular issues or metabolic syndrome (triglycerides (Hermier, 1997)), and better overall health (Abd El-Hack et al., 2019).
x Finally, one study reported lower ammonia emissions from chick excreta due to more efficient nutrient digestion, thus lowering their contribution to climate change.
While Arthrospira feed has been shown to enhance chicken productivity, the mechanisms at play remain unclear, with researchers postulating different factors. Kaoud (2015) suggests a rich array of nutrients foster beneficial gut microbiota that support digestion while enhancing immune system function. Sugiharto et al. (2020) suggest that essential amino acids support development and morphology of the digestive tract, gut microbial balance, and improved antioxidative status. Park et al. (2018) suggest that positive impacts on chicken microbiota can boost productivity via enhanced nutrient absorption while suppressing pathogens and detoxifying harmful substances. Alagawany et al. (2019) suggest that Arthrospira supports chicken health via greater intake of omega-3 fatty acids, which can improve their fertility and immune responses.

3.3		Build resilience to biotic stresses
Pests and diseases are key biotic stresses facing farmers. Such stresses may pose risks to the growth, health and even survival of livestock and crops. Finding ways to combat them is therefore a key priority of farmers. A growing body of evidence suggests Arthrospira can enhance the resilience of chickens to biotic stresses, mirroring the evidence suggesting it can do this for crops (Siedenburg et al., 2024).
Tables 4a–c summarise several studies investigating Arthrospira feed as means to help chickens cope with biotic threats like pathogenic bacteria, fungi and viruses. Examining the mechanisms by which Arthrospira may act on such threats falls outside this paper’s scope. The studies reviewed nonetheless suggest three broad impact pathways, namely direct effects on pathogens, boosting chickens’ immune system function, and substituting for synthetic antibiotics.
3.3.1		Direct effects on pathogens
Incorporating Arthrospira biomass into chicken feed can potentially counteract microbial pathogens directly. This follows because some microalgae are rich in bioactive compounds with potent antimicrobial efficacy, including antiviral, antibacterial and antifungal effects (Kaushik and Chauhan, 2008; Park et al., 2018; Fathi et al., 2018; Finamore et al., 2017) Relevant compounds from Arthrospira include phycocyanin, β-carotene, flavonoids, phycobiliproteins, and phenolic acids (Mishra et al., 2023). Table 4a summarises three pertinent studies.
Summary observations.
x Simply dissolving Arthrospira biomass in water can offer good efficacy against diverse pathogens, but some investigators do not consider this option, focussing instead on obtaining extracts using organic solvents
x Some solvents produce effective extracts while others do not x Conflicting findings like methanol extract being effective (Kaushik and Chauhan, 2008) or ineffective (Mala et al., 2009) may reflect methodological differences.
3.3.2		
Effects on immune system
Another pathway by which Arthrospira supplements may enhance the biotic resilience of chickens is by boosting their immune system function. For instance, they might impact relevant blood parameters and organs via compounds with antiinflammatory or immunomodulatory effects (Sugiharto, 2020). Another possibility is that consuming Arthrospira may foster gut microbiota associated with improved health and immune response to biotic threats (Sugiharto, 2016; Shanmugapriya et al., 2015; Finamore et al., 2017). Table 4b summarises three pertinent studies. Additional observations.
x Bhowmik et al: While the chemical antibiotic inhibited both beneficial and pathogenic bacteria, Arthrospira differentially inhibited pathogenic bacteria, albeit less powerfully than the antibiotic. Both stimulative and inhibitive effects of Arthrospira increased with higher doses and longer exposure.
x Lokapirnasari et al: Low lymphocyte counts reliably predict mortality risk since lymphocytes fight infections and diseases, whereas cardiac lesions due to Avian influenza can heighten risk of cardiac failure.
x Kumari et al: IBD impairs immune function, causing susceptibility to infections and diseases. Vaccination combats IBD but weakens chickens’ immune system. Arthrospira counteracts these immunosuppression effects.
3.3.3		Antibiotics substitute
Arthrospira may also impact the resilience of chickens to biotic stresses by substituting for chemical antibiotics.
Chemical antibiotics have been widely used on livestock as a means to reduce infection risk and promote growth.

Studies	Effects tested	Observed efficacy	
Mala et al. (2009)	Efficacy against 7 pathogenic bacteria, as a % of efficacy of a chemical antibiotic	•		Four treatments showed efficacy
o Microalgae biomass in water (25-52%)
o Extracts: Petroleum ether (28-59%), acetone (22-49%), diethyl ether (29-59%)
•		Two extracts were ineffective	
El-Baz et al. (2013)	Efficacy of an extract against viral, bacterial & fungal pathogens	•		Inhibited all viruses tested by 50-77%
•		Inhibited some bacteria but not others
•		Inhibited the one fungus tested	
Kaushik & Chauhan (2008)	Antibacterial activity of 4 Arthrospira extracts vs a chemical antibiotic	•		All extracts showed efficacy but only one was effective against most bacteria
•		The best extract inhibited bacteria growth ½ as much as chemical antibiotic
•		Arthrospira concentration needed for inhibition is >100x higher than antibiotic	

TABLE 4A Antimicrobial efficacy of Arthrospira feed vis-a-vis pathogens.

Unfortunately, this practice has led to development of antibiotic-resistant bacteria strains, resulting in reduced efficacy (Ritchie and Spooner, 2024; Antibiotic Use in the UK Poultry Sector, 2016)., Antibiotics can also leave residues and resistant bacteria in meat, potentially fostering antimicrobial resistance in people (Conceicao et al., 2023; Lima et al., 2023)., Growing public

Studies	Treatment	Observed efficacy relative to untreated controls	
Lokapirnasari et al. (2016)	Added dried Arthrospira (10 or 20%) to drinking water	Boosted immune response to Avian Influenza
•		Increased leukocyte numbers (+6-10%)
•		Lesions were linked to 30% mortality in control birds but 0% in treated birds	
Kumari et al. (2019)	Added Arthrospira (1%) to feed rations	Effectively counteracted the adverse effects of IBD vaccination, namely:
•		Lower body weight; smaller immune organs
•		Depression; reduced intake of feed & water	
Bhowmik et al. (2009)	Added dried Arthrospira (1, 5 or 10 g/L) to cultures	Positively impacted gut microbiome
•		Boosted growth of 3 species that promote health in humans/chickens (+223467%)
•		Inhibited 4 pathogenic species (-41-68%) & 2 species with ambiguous effects (36%)	

TABLE 4B Arthrospira feed and immune support vis-à-vis pathogens.

concerns with these issues have seen numerous governments restrict antibiotics use on farms (World Veterinary Association, 2020). These restrictions are followed in some countries but compliance remains an issue in others (World Animal Protection, 2022; Alabi et al., 2023). The net effect is that global antibiotics use still stands at 99,500 tonnes per year (Mulchandani et al., 2023), with three-quarters given to livestock (Ritchie, 2017). It is widely believed that limiting antibiotic use threatens livestock production due to higher infection risks (Sugiharto, 2020), but emerging evidence suggests this need not be the case.
Various natural substances have been investigated as possible substitutes for antibiotics, and the early evidence suggests some may offer safe and effective alternatives (Ritchie and Spooner, 2024; Jamil et al., 2015)., Examples include medicinal plants, prebiotics (non- digestible substances that benefit the host’s gut microbiota) and probiotics (living microorganisms that exert health benefits on the host) (Sugiharto, 2016; Halder et al., 2024; Maghsoudi et al., 2020). Arthrospira offer another possible solution due to its various bioactive agents (Sugiharto, 2020). Three relevant studies are summarised in Table 4c.
3.3.4		Counteracting oxidative stress
One of the key ways that biotic stresses manifest in the physiology of chickens and other animals is by inducing ‘oxidative stress’ in their bodies. This occurs when there is an imbalance between two types of molecules, free radicals and antioxidants, such that excess free radicals remain. Free radical spikes can damage cells and tissues (Lykkesfeldt and Svendsen, 2007). Biotic stressors can cause increased production of free radicals like reactive oxygen molecules within chickens. Other stressful circumstances can likewise cause free radical spikes, such as facing elevated ambient temperatures, exposure to heavy metal pollutants, and undergoing medical procedures like vaccinations (Rehman et al., 2018; Oke et al., 2014).

TABLE 4C Arthrospira feed as an antibiotic substitute.

Studies	Effects tested	Observed efficacy relative to control	
Ismita et al. (2022)	Arthrospira feed (1%) vs Enrofloxacin	Arthrospira & antibiotic gave comparable performance relative to untreated chicks
• Both improved body weight gain, feed use efficiency and a key blood parameter	
Sugiharto et al. (2018)	Arthrospira feed (1%) vs zinc bacitracin	Arthrospira & antibiotic gave mostly comparable results relative to untreated chicks
•		Comparable outcomes included weight gain, feed use efficiency, organ development and gut microbiota
•		One organ (caecum) weighed significantly more with Arthrospira feed, suggesting better gut health and digestive function (Akram et al., 2024).	
Jamil et al. (2015)	Arthrospira (2, 4 or 8 g/kg) vs untreated control, but framed as a substitute for using in-feed antibiotics as growth promoters	Observed improved outcomes across various performance and health parameters:
•		Body weight gain (+10-12%)
•		Feed use efficiency (+8-10%)
•		Haematological parameters like red and white blood cells (+13-50%)
•		Hepaprotective serum enzymes (-34-55%)	

Summary observations
• Alongside various positive impacts, Sugiharto et al. (2018) observed lower values for 4 of the 10 blood parameters examined, suggesting weaker immune system function. This finding contrasts with earlier studies (Jamil et al., 2015; Lokapirnasari et al., 2016), that reported positive effects on blood parameters. The authors suggested this discrepancy may be due to biotic contamination of the Arthrospira used, since it was grown in non-saline water unlike standard practice.
• All three authors submitted that Arthrospira feed offers a viable substitute to chemical antibiotics for chickens.
• Given the problems with chemical antibiotics, identifying and harnessing effective alternatives is important to both livestock production and food safety.

Approaches to reducing oxidative stress in chickens include minimising exposure to stressors, administering synthetic antioxidants, and dietary interventions (Oke et al., 2014). While desirable, reducing exposure to stressors like diseases or elevated ambient temperatures isn’t always feasible. This leaves chemical antioxidants or dietary changes. Key questions regarding such options include their efficacy, potential adverse effects, and possible co-benefits.
Synthetic antioxidants are widely used in the poultry industry to help chickens combat oxidative stress and hence maintain growth rates (Fellenberg and Speisky, 2006). A major drawback is that these products can leave carcinogenic and mutagenic compounds in treated chickens. These compounds may be passed on to consumers of chicken products, with potentially adverse health effects, especially if they were applied at elevated rates (Sugiharto, 2020; Fellenberg and Speisky, 2006).
Various natural dietary supplements can offer alternative means to deliver antioxidants to chickens and thus boost their capacity to combat oxidative stress. Options investigated that have shown promise include plant extracts, filamentous fungi and microalgae like Arthrospira (Oke et al., 2014; Sugiharto, 2020; Sugiharto, 2019). Various studies reviewed in the present paper provide evidence that Arthrospira feed can exert antioxidative activity in chickens. Critically, natural dietary supplements like Arthrospira may also deliver other benefits to chickens and perhaps also consumers of chicken products, as documented in this paper. Conversely, synthetic antioxidants may have adverse side-effects (Berghiche et al., 2020; Shanmugapriya et al., 2015).,
3.4		Build resilience to abiotic stresses
Like biotic stresses, abiotic stresses can pose major threats to livestock production and agriculture generally. Abiotic stresses that can adversely affect chicken production include heat stress, water scarcity (El Sabry et al., 2023; Usva et al., 2023) water salinity (Alahgholi et al., 2014; Biswas et al., 2024), and pollution of their feed, water or local environment by toxic substances like lead (Bakalli et al., 1995; Youssef et al., 1996), or arsenic (Zivkov Balos et al., 2019). All these stresses are growing concerns to farmers, with the first three exacerbated by climate change. Finding ways to combat or cope with such stresses is a key priority of farmers.
Heat stress is a key focus of the existing academic literature on abiotic threats to chicken production. This reflects the fact that high ambient temperatures are a critical stress factor for chickens that can jeopardise their productivity, health or even survival (Abdel- Moneim et al., 2022; Mirzaie et al., 2018; Kolluri et al., 2022). Low temperatures can also be stressful to chickens (Zhao et al., 2014; Regnier and Kelley, 1981), but this literature does not include studies investigating Arthrospira feed as a possible a response option.
Many chicken farms are sited in localities facing elevated temperatures. Heat stress is a historical problem for poultry production that has varied from year to year. For instance, the US poultry industry saw heat-related mortality rates of up to 10% in 2011 and 2012, causing large economic losses (Hester, 2017). This risk has grown in recent years due to climate change (Uyanga et al., 2023). It can be particularly problematic in areas with limited financial resources including wide swaths of the Global South, where it may threaten both farm livelihoods and food security (Sanou et al., 2022; Sithole et al., 2025).
Chickens can generally tolerate temperatures up to 25 °C. Anything above this can lead to heat stress with potentially serious consequences like decreasing body weight and egg production, lowering product quality like thinner eggshells, and increasing mortality. Elevated humidity exacerbates the stress to chickens caused by high temperatures. A heat stress index can be used to track risks to chickens. At very low humidity they experience high stress at 37C, but at 50% relative humidity this occurs at 32C (Hester, 2017; Chart taken from data developed by the Department of Agricultural and Biosystems Engineering).,
Chickens use several behaviours to cope with heat stress. Unlike humans and other mammals, birds lack sweat glands and hence cannot sweat. Panting nonetheless allows them to harness the cooling effects of evaporation. Other behavioural responses include finding shade, bathing in or splashing water, spreading their wings to increase exposure to fresh air, and burying into litter or soil (Dawson and Whittow, 2000). The feasibility or efficacy of these behaviours may however be constrained by local circumstances. Critically, the efficacy of evaporative cooling falls as humidity rises.
Heat stress induces various physiological changes in chickens that help them cope with this threat, yet these changes can also cause health problems. Excessive panting can cause respiratory alkalosis, which compromises nutrient utilisation and therefore performance and health (Teeter et al., 1985; Kim et al., 2025)., Release of corticosterone to redirect the body’s limited energy and protein resources to support critical systems (e.g., cardiovascular, respiratory) can mean fewer resources are available for systems not vital to immediate survival with consequences like poor skeletal health (Carsia and Harvey, 2000). Release of catecholamines can mobilise energy for stress responses, but these compounds can also bind to immune cell receptors, causing immunosuppression (Wurtman, 2002).
Farmers can use infrastructure measures to reduce heat stress to chickens. Examples include (i) providing housing with insulated roofing to minimise heat transfer during hot spells, (ii) housing ventilation systems that employ fans and/or capture prevailing winds, and (iii) increasing drinking facilities and/or providing colder water. Rollout of such measures may however be limited by costs (Gates and Timmons, 1988; Mirzaie et al., 2018), or uncertainty regarding economic benefits over time (Hester, 2017).
Another way farmers can address heat stress to chickens is by favouring heat-resistant breeds. For instance, Sithole et al. (2025) examined the capacity for indigenous chickens in Nigeria to cope with heat stress and found this option shows promise (Sithole et al., 2025). Conversely, breeds selected for rapid growth could be more vulnerable to heat stress (Abdel-Moneim et al., 2022).
Dietary interventions offer still another route for farmers to support chickens facing heat stress. A small but growing literature suggests such interventions can help chickens cope with hot weather by improving their heat tolerance. Identifying relevant feed innovations is a timely question given climate change, with
potentially major ramifications for farmers and global food security (Hester, 2017).
Diverse innovative feeds have been examined as possible options to help chicken face heat stress. Options that have shown promise include herbs (El-Hack et al., 2020), essential oils (Khosravinia, 2016), vitamins (Lin et al., 2002), electrolytes (Ahmed and Sarwar, 2006), probiotics like Lactobacillus (Zulkifli et al., 2000), and prebiotics like mannanoligosaccharide, which is derived from yeast (Houshmand et al., 2012). Some studies have investigated the scope for microalgae biomass to meet this need, often focussing on Arthrospira platensis.
Dietary changes can mitigate the physiological effects of heat stress on chickens in various ways. For instance, chickens facing heat stress pool blood to vessels near their body surface (skin, comb, feet) to foster conductive cooling, but this can compromise digestive function, nutrient absorption and appetite (Bonnet et al., 1997). Providing nutrient-rich diets can help compensate for such effects. Another example is that chickens facing heat stress may excrete vitamins and minerals, causing deficits in tissues and organs. Again, nutrient-rich diets can counteract this adverse physiological effect. Since chickens drink more when facing heat stress, incorporating nutrient-rich supplements into their water can be an effective way to deliver supplements believed to help them cope with heat stress (Hester, 2017).
Table 5 provides summary data for several studies testing Arthrospira feed as a means to help chickens cope with heat stress. These studies provide a snapshot of the available evidence on this question.
Summary observations
x All five studies reported multiple positive impacts of Arthrospira feed given heat stress, including modest gains in performance measures like body weight and larger gains in parameters linked to chickens’ health and immune system function like serum characteristics and immune organs.
x Mirzaie et al. (2018) compared untreated chicks under normal conditions with treated chicks facing heat stress and found many comparable outcomes, suggesting Arthrospira largely counteracted harm from heat stress.
x Two studies found that heat stress can compromise the efficacy of vaccines (e.g., reduced serum antibodies against key diseases) but Arthrospira feed mitigated these effects.
x All five studies concluded this feed enhanced chickens’ heat tolerance and could help manage heat stress.

Studies	Treatment; conditions	Observed efficacy relative to untreated control	
Abdel-Moneim et al. (2022)	Arthrospira (0.5 or 1% of rations); 34C	•		Performance: Body weight (+3-4%), FCR (-4-6%), carcass traits (+2-17%)
•		Immune organs (+8-45%)
•		Serum lipid profile: HDL (+8-13%), LDL (-12-29%), triglycerides (-7-8%)
•		Serum antibodies (+8-252%)
•		Serum antioxidant enzymes (+11-99%)	
Aboul-Zeid et al. (2015)	Arthrospira or Chlorella (0.1 or 0.2% of rations); 24-36C	Findings were strongest with Arthrospira
•		Body weight gain (+7-14%)
•		FCR (-10-14%)
•		Abdominal fat (-12-23%)
•		Net revenues (+12-21%)	
Khalek et al. (2019)	Arthrospira (0.00015% of rations); 38C at 55-65% relative humidity	•		Productivity: Egg production (+18%), hatchability (+13%)
•		Egg quality: Albumin (+9%)
•		Serum parameters linked to health & immune system function (+9-70%)	
Kolluri et al. (2022)	Arthrospira (5, 10, 15 & 20 g/L); 32-38C at 18-52% relative humidity	•		Body weight gain (+2-4%)
•		Haematological indices (+19-128%)
•		Serum cholesterol and triglycerides (-11-39%)
•		Serum enzymes associated with liver damage (-19-59%)
•		Vaccine efficacy (+9-35)	
Mirzaie et al. (2018)	Arthrospira (1-2% of rations); 36C	•		Humoral immunity (+24-25%)
•		Antioxidant parameters (+8-43%)
•		Serum lipid profile: HDL (+17-41%), triglycerides (-17%)
•		Stress indices (-6-43%)	

TABLE 5 Arthrospira feed and heat stress.

Other abiotic stresses besides heat stress can likewise constrain chicken production. The question of whether Arthrospira feed might offer an option to help farmers face these stresses remains neglected by researchers to date, however. Its efficacy vis-à-vis other abiotic stresses has however been investigated for laboratory animals, fish and humans, and positive effects were observed (Annex, Table A5), suggesting the possibility of similar benefits in the case of chickens. Examples of abiotic stresses to humans or animals for which Arthrospira was tested as a possible mitigation measure include elevated salinity, water stress, prolonged light exposure, chemical additives, chemical drugs, insecticides, arsenic poisoning and radiation. The efficacy of Arthrospira vis-à-vis diverse abiotic stresses facing crops has also been tested (Siedenburg et al., 2024).

3.5		Improve product quality
As demonstrated, incorporating Arthrospira biomass into the feed or water supply of chickens can boost their productivity, health and resilience. The available evidence additionally suggests this innovative feed can improve the quality of chicken products. This includes conventional quality indicators like the proportion of fat in chicken meat or the colour of meat or eggs. It also includes the prospect of producing biofortified chicken products, since various compounds in microalgal biomass appear to be able to transfer to the meat and eggs of chickens.
Table 6 summarises the findings of studies on microalgae as a chicken feed that emphasise the product quality impacts of this feed innovation.
3.5.1		Potential benefits for human health
Several potential benefits of microalgal chicken feed for human health are briefly considered, given the magnitude of observed biofortification effects and their potential significance for society. Three pathways are considered, namely how this innovative chicken feed could offer an effective means to deliver antioxidants, minerals, and polyunsaturated fatty acids to humans.
3.5.1.1		Oxidative stress and antioxidants
As discussed above, oxidative stress can contribute to health difficulties in chickens. It likewise contributes to health difficulties in humans. For instance, it is believed to play a role in the onset of chronic and degenerative conditions like cancers, cardiovascular diseases, asthma, kidney disease, rheumatoid arthritis, dementia, Parkinson’s and multiple sclerosis (Cleveland Clinic Website, 2024). It follows that finding dietary sources of antioxidants is important for both livestock and humans.
Incorporating Arthrospira biomass into feed could provide chickens with a potent source of antioxidants, benefitting both them and any people who consume their products. Various studies summarised above demonstrated how antioxidant levels in the muscles of treated chickens compared to those in control chickens (El-Hady et al., 2022; Park et al., 2018; Evans et al., 2015). Three studies from Table 6 found strong increases in the redness or yellowness of egg yolks. Such coloration reflects the accumulation of pigments like carotenoids and xanthophylls that have potent antioxidant and anti-inflammatory properties (Selim et al., 2018). By neutralising free radicals and limiting oxidative stress, these pigments can lower the risk of chronic diseases like cancers, improve cardiovascular health, and support healthy eyes and skin (Anthony, 2018; Stahl and Sies, 2003; Eroglu et al., 2023).

Studies	Treatment	Observed efficacy relative to untreated control	
El-Bahr et al. (2020)	Added Arthrospira platensis, Amphora coffeaformis and Chlorella vulgaris (0.1% of rations)	Findings for Arthrospira
•		Quantity: Body weight (+8%)
•		Conventional meat quality: Cooking loss (-33%), microbial growth (-15%)
•		Biofortification of breast meat
o Fatty acids: EPA (+141%), DHA (+116%), total omega-3s (+53%)
o Essential amino acids (+15 - 26%)
o Antioxidant status (+25-64%)	
Saeid et al. (2016)	Added Arthrospira maxima biomass (0.1% of rations), while enriching both treatments and controls with copper and iron.	•		Egg quality
o Yolk mass (+12%), reddish yolk (+23%), shell strength (+7%)
•		Key nutrients in egg whites
o Iron (+857%), zinc (+113%), manganese (+195%), calcium (+50%)
•		Bioavailability of key nutrients in
o Muscle: Copper (+56%), iron (+83%)
o Eggs: Copper (+28%), iron (+79%)	
Zahroojian et al. (2013)	Arthrospira (1.5, 2 and 2.5% of rations)	•		Yolk colour, specifically yellowness (+581-652%)
•		Other parameters not statistically significant
o Egg production, weight, shell thickness…	
Bonos et al. (2016)	Arthrospira (5 & 10 g/kg) to a maize-soy basal diet enriched with herring meal	•		Long-chain polyunsaturated fatty acids in thigh meat
o EPA (+40-86%)
o DHA (+17-107%)
o DPA (+34-118%)
•		Other parameters not statistically significant
o Weight gain, FCR, mortality rate, lipid oxidation of meat	
Manor et al. (2019)	Nannochloropsis oceanica in its defatted form (+2.85-23%)	•		Egg yolk
o Redness (+97-195%), omega-3 PUFAs (+52-180%), n6/n3 ratio (-39-68%)
•		Breast meat: Omega-3 PUFAs (+50-850%), n6/n3 ratio (-19-91%)
•		Thigh meat: Omega-3 PUFAs (+700%), n6/n3 ratio (-88%)
•		Other parameters not statistically significant
o Body weight, egg production, egg yolk percentage	

TABLE 6 Arthrospira feed and product quality.

Another benefit of dietary antioxidants is helping to safeguard chicken meat. This meat is susceptible to oxidative degradation, which causes nutrient losses and discoloration while reducing its shelf life. The pre-slaughter diet of animals greatly impacts the susceptibility of their meat to degradation, notably the degree to which it contains antioxidants. There is growing interest in using natural feed supplements rich in antioxidants like herbs (Hashemipour et al., 2013) or essential oils (Anjum et al., 2004) to enhance the oxidative stability of chicken meat. Critically, antioxidant-rich supplements can increase the market value of these products (Jimoh et al., 2024).
3.5.1.2		Minerals
Iron deficiency is the most widespread nutritional disorder in the world, underlining the importance of iron-rich foods. Iron is essential for human health but also for the growth, productivity and reproduction of chickens, yet can also be toxic at high levels (Isidori et al., 2018; Bost et al., 2016). Consuming iron-rich foods can alleviate iron deficiency, but iron from animal sources tends to be more bioavailable than that from plant sources (Schönfeldt and Hall, 2011). This fact underlines the potential significance of meat or eggs rich in iron to human health (Martınez-Navarrete et al., 2002). Arthrospira biomass possess naturally high iron content (353 to 1459 µg/g of dried biomass) (Isani et al., 2022). Some studies have nonetheless examined the scope to further enhance its levels of key minerals by altering their culture medium. This has been found to be effective as a way to obtain a feed supplement for chicken that delivers powerfully fortified meat and eggs (Saeid et al., 2016).
The findings of Saeid et al. (2016) suggest that microalgal feed may offer a highly effective pathway for mineral delivery to humans. The mineral content of products from treated chickens was much higher than products from the control chickens, and they were also deemed to be more bioavailable. This included both minerals that had been incorporated into the enriched basal feed for all chickens and other key minerals. These minerals are essential for human health but also for the growth, productivity and reproduction of chickens (Bost et al., 2016).
3.5.1.3		Essential polyunsaturated fatty acids
Omega-3 fatty acids are a class of polyunsaturated fatty acids (PUFAs) that is attracting growing attention due to their reported health benefits. These substances are called ‘essential’ PUFAs because they cannot be synthesised by vertebrates and must therefore be obtained from food. Of the three main types, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are especially important to human health and found only in oily fish like salmon or sardines and microalgae, with oily fish obtaining their omega-3s from microalgae. The third type, a-linolenic acid (ALA), is found in plants like walnut, flaxseed and hempseed (Schuchardt et al., 2024).
The health benefits of omega-3 PUFAs have been demonstrated by both clinical studies and experiments with laboratory animals. A recent meta-analysis found that omega-3 PUFAs improved cardiovascular outcomes and reduced cardiovascular mortality, with EPA having the strongest effects (Khan SU. et al., 2021). Based on biobank data for 250,000 people over 10 years, another study (Zhang et al., 2025) suggested that increasing intake of these PUFAs can reduce the risk of developing 19 different types of cancer. These PUFAs can also counteract neurodegeneration, including loss of grey and white matter in volume and integrity, while fostering improved cognitive function during aging and lowering risk of dementia (Cutuli, 2017; Lai, 2018; Ogluszka et al., 2022; Mora et al., 2022). Finally, a study on 3,376 human subjects found that DHA was strongly linked to slowing biological aging (Shan et al., 2025).
Despite mounting evidence on their benefits, many people remain deficient in omega-3 PUFAs (Bonos et al., 2016). Some 75% of countries lack data on their intake, while those that generate data mostly show low intake levels (Schuchardt et al., 2024).
Various of the studies summarised above demonstrated that Arthrospira feed can be a potent means of delivering these PUFAs to chickens, with benefits to aspects of their health like immune system function and fertility (Alagawany et al., 2019). Treated chickens typically showed sharply higher levels of key omega-3 PUFAs in their meat and eggs relative to untreated controls. Increasing farmer uptake of Arthrospira feed therefore also offers a way to deliver these essential fatty acids to humans via consuming chicken meat or eggs.
While higher levels of omega-3 PUFAs in meat or eggs are considered a type of biofortification with potent benefits for both livestock and human health, a lower ratio of omega-6 to omega-3 PUFAs is considered beneficial to human health. This follows because modern diets often contain high levels of omega-6 PUFAs from foods like vegetable oils coupled with low levels omega-3 PUFAs. This leads to high ratios of omega-6 to omega-3 PUFAs, which have been linked to health problems like cardiovascular disease, cancer and inflammation (Moore, 2025; Simopoulos, 2010; Simopoulos, 2016; Zhang et al., 2025). Manor et al. (2019) found that microalgal chicken feed can greatly reduce this ratio in thigh meat.
Current official recommendations on PUFA intake focus largely on oily fish. The World Health Organization recommends intake of PUFAs without specifying their source (WHO, 2023), but some other public health authorities do specify. The American Heart Association recommends eating two portions of oily fish per week, while the UK’s National Health Services suggests one. The European Food Safety Authority recommends 250mg per week of both EPA and DHA, then notes this is approximately 1/3 of a portion of salmon (Calder et al., 2026; Salmonfacts, 2019). One problem with this framing is that many people may not eat oily fish. For instance, an estimated 70% of Britons never do so (Moore, 2025).
Another problem with oily fish is that it can contain mercury, a toxic element that poses serious risks to human health, particularly foetuses and children. It can harm growth, nervous system development and birth outcomes (Stratakis et al., 2020; Naess et al., 2020). Studies in Spain found elevated mercury levels in the blood of children relative to reference values (Dıé z et al., 2009; Ramon et al., 2022).. Some scholars argue there is no safe level of exposure, while others suggest harmful levels are not well defined (Dragan et al., 2023) or that mercury isn’t a concern (Golding et al., 2022). Mercury levels in fish vary by species and location (Dragan et al., 2023; Le Donne et al., 2016), but this is rarely measured (Gribble et al., 2016). Worryingly, levels in some fish populations are still rising despite efforts across the globe to control mercury pollution (Gramling, 2019).
Given this reality, Cropotova and Popel (2013) stress the importance of finding alternative sources of omega-3 PUFAs (Cropotova and Popel, 2013). Possible alternatives that could boost omega-3 PUFAs in human serum include microalgae and several plants (Irawan et al., 2022). Like oily fish, microalgae provide EPA and DHA and are a good source of these PUFAs for humans (Saini et al., 2021). By contrast, foods like chia, flax and camelia seeds contain ALA, which is less effective as a source of omega-3 PUFAs for humans (Ryan and Symington, 2015).
Consuming Arthrospira could offer a solution but this has not been promoted by public health authorities, perhaps because some see microalgae as an unappealing food. A related option that merits greater attention is delivering EPA and DHA to people via biofortified meat and eggs, based on incorporating microalgae into feed rations. The bioavailability of omega-3 PUFAs from chickens given microalgal feed appears to be high, whether from eggs (Lemahieu et al., 2017; Khan et al., 2015), and meat (Prates, 2025; Dr et al., 2023)., Livestock-based foods like meat and milk also score high on likely lifelong adherence of consumers, while oily fish and related supplements score lower (Stanton, 2018). These observations suggest that fortifying livestock products via microalgae feed may offer an effective way for public health authorities to boost intake of omega-3 PUFAs across their jurisdictions.
4		Discussion
4.1		Significance
The evidence summarised shows that incorporating Arthrospira into chicken feed can support chicken production in five distinct ways: Partially substituting for conventional proteins, boosting productivity, enhancing resilience to biotic and abiotic stresses, and improving product quality. These findings showcase a small but growing body of evidence from studies on the technological potential of using Arthrospira biomass as chicken feed supplement, whether as a substitute for conventional protein sources or as an addition to rations.
Incorporating Arthrospira biomass into chicken diets may offer additional benefits to farmers beyond these five impacts. For ‘traditional’ farmers reliant on local natural resources like water and pastures, it could minimise morbidity and mortality linked to poor quality feed. The net effect is to make farming more economically viable and sustainable. For ‘modern’ farmers reliant on commercial inputs, it can substitute wholly or in part for inputs like imported soymeal and antibiotics, thus potentially lowering farm costs.
The cost of microalgal biomass is a key factor, since its affordability could be central to whether or not farmers end up embracing it as an input. This is particularly true in poorer parts of the Global South. Despite their importance, cost considerations remain largely unexplored in the literature. The main exception is that some researchers argue that using microalgae as a protein substitute remains uneconomic due to soymeal being cheaper (Holman and Malau-Aduli, 2013; Park et al., 2024; Keohavong, 2026). This perspective can lead to focusing on possible ways to address microalgae production costs, such as boosting algae productivity (Elshamy and Rösch, 2022; Saadaoui et al 2021) or valorising co-products (Keohavong 2026). While this argument has merit, it is also problematic. As detailed in this paper, one counterargument is that Arthrospira feed delivers multiple benefits, not just protein. Another is that Arthrospira can be grown in low-cost media like wastewater or livestock slurry (Otto and Malau-Aduli 2017; Greene et al 2022; Abdel-Aal and Mofeed 2020) and sourced locally (Saadaoui et al., 2021). Meanwhile, reliance on soymeal entails large hidden costs like deforestation in the Amazon and greenhouse gas emissions from being transported vast distances (Elshamy and Rösch, 2022). Conversely, meeting the protein needs of livestock with microalgae instead of soybeans could sharply reduce land and water use (Tzachor, 2019). For all these reasons, this price comparison is misleading and an example of ‘comparing apples and oranges’. Such positive and negative impacts of competing protein sources are not typically reflected in market prices at present, yet they could be in future if governments delivered subsidy reform and policy measures to internalise externalities, as advocated by economic theory (Pieper et al., 2020; Buttel, 2023; Nacimento et al., 2023). Such steps could help ensure market prices reflect the true costs of food.
Arthrospira feed could also deliver benefits to wider society, including both national priorities and the UN Sustainable Development Goals. By boosting the profitability and resilience of farming, it could help secure agricultural jobs. Biofortified foods could improve consumers’ health. More abundant food could enhance food security while minimising ‘human security’ problems like refugee flows (Siedenburg, 2021). Microalgal feeds could lower demand for imported soy, thus reducing its adverse impacts on deforestation, biodiversity and climate change (Walsh et al., 2015) (Figure 2).
Of the five efficacy pathways explored above, two could prove particularly significant in the coming years, namely the scope for Arthrospira feed to enhance stress resilience and deliver biofortified foods.
Risks to chicken production are mounting, with various biotic and abiotic stresses exacerbated by climate change. Technologies that mitigate these risks are thus increasingly important. Each of the stresses elaborated above can undermine chicken production. Any biotic or abiotic stress can also leave chickens more vulnerable to other stresses. For instance, heat stress compromises their immune system function, leaving them vulnerable to infections (Abdel-Moneim et al., 2022) and undermining the efficacy of vaccines (Kolluri et al., 2022). Similarly, those with a disease are more vulnerable to heat or water stress. Stresses can thus lead to cascading adverse effects that threaten the viability of chicken farming. Conversely, any feeds that enhance stress resilience may help farmers avoid this vicious circle. A related benefit is that farms which continue producing when others struggle may be able to sell their products at higher prices while others miss this opportunity. These observations underline the potential significance of Arthrospira feed for farmers facing climate change, given its multiple benefits and the risks of foregoing them.
The fact that biofortified chicken products may be able to deliver key compounds to humans has profound implications for human health. It opens up the possibility that fostering wider use of Arthrospira feed by farmers could offer a pathway to deliver such compounds to consumers at scale. If the compounds thus delivered addressed deficiencies or otherwise met health needs of these

FIGURE 2
Significance of Arthrospira feed to farmers, health and wider societal goals. Reprinted with permission from David Punchard, "'Tiny Mighty Anna', an unpublished story about algae by Punchard and Edwards (2012).

consumers, the net effect could be to achieve key public health priorities. For instance, such foods could potentially lower the risk of chronic diseases and support healthy aging (Research and Markets, 2025; Global nutraceuticals market to grow by USD 668 billion by 2033, driven by innovation, consumer demand and preventative health trends, says astute analytica, 2025; Borowitzka, 2013).
If this prospect were embraced by public health authorities, it might provide a powerful impetus for wider uptake of Arthrospira feed by farmers, with the myriad benefits that seems to promise. This follows due to the centrality of health as a concern to families and governments and the magnitude of healthcare spending. If Arthrospira feed offered scope to reduce such spending, this could represent a compelling argument for governments to foster its wider use among farmers.
The present paper seeks to maximise impact on its target audiences by (i) summarising this evidence in non-technical language and intuitive metrics, (ii) considering the multifaceted efficacy of this feed in an integrated manner and (iii) setting its technological potential in the context of key problems facing farmers and society.
4.2		Caveats
This body of evidence had several shortcomings. One is that many relevant studies were conducted under unrealistic conditions (Abou-Zeid et al., 2015; Mirzaie et al., 2018; Abdel-Moneim et al., 2022; Sugiharto et al., 2018). For instance, studies examining the capacity of Arthrospira feed to help chickens cope with heat stress or biotic pathogens typically provided them with feed and water ad libitum. Yet in practice stress conditions may occur together, notably given environmental degradation and climate change. Studies also typically provided optimised control diets, contrasting with the realities on many farms. Some control diets were unusually rich, which could reduce the pertinence of Arthrospira feed as a nutrient source (Bonos et al., 2016; Ross and Dominy, 1990). Another issue was that many studies only examined low dosages of Arthrospira feed yet found that benefits increased as dosages rose, raising the question of whether results might have been still stronger if additional dosages were tested. Finally, many studies only tested this feed over short periods, e.g., 18 days (Evans et al., 2015), yet chickens’ lifespan is 3–7 years, albeit it may be shorter on farms (Spindler, 2021). Such shortcomings could lead to underestimating the impacts of Arthrospira feed, since its impacts appear greatest under suboptimal conditions, while longer treatments allow time for effects to be revealed.
Most of the studies reviewed only focus on one or a few types of efficacy while ignoring others. Yet researchers may only observe effects if they look for them. The resulting situation recalls the proverbial ‘blind men and the elephant’, where different observers report different effects. This fact underlines the need for a holistic perspective when dealing with NbSs for agriculture.
Some authors suggest that use of microalgae as a chicken feed remains very limited (Selim et al., 2018), while others suggest its use as animal feed is increasing steadily (Kolluri et al., 2022). United Nations data suggest that its use as a feed remains low and skewed to aquaculture (FAO, 2024). One barrier to its use is cost considerations, as discussed. Another factor is knowledge gaps regarding its different types of efficacy and application modalities. Given such constraints, Arthrospira has not generally been advocated as a farm input by governments, charities or international organisations (Siedenburg et al., 2024).
4.3		Research and policy priorities
Priorities were selected based on their potential significance to harnessing the technological potential of microalgal feeds and maximising their impact. They are grouped based on their relation to the review’s findings.
Finding: Microalgal feeds show promise but the evidence base is thin, notably on efficacy in real world contexts.
x Conduct farm trials in various agricultural contexts to (i) flesh out the evidence base on this innovative feed in diverse scenarios including facing multiple stresses, and (ii) determine its scope to substitute for conventional inputs alongside delivering its other effects. Organise data using the ‘NbSs for agriculture’ framework.
x Clarify the modalities for using Arthrospira as a chicken feed, including dosages and comparing intact biomass with extracts. Given its multifaceted efficacy, clarify the best dosages for favouring different target outcomes.
x In localities where an indigenous microalgae species is believed to have potential to serve as an effective feed supplement, conduct trials comparing the efficacy of Arthrospira and this indigenous species.
Finding: Microalgal feed could positively impact the health of consumers.
x Conduct rigorous studies to deepen the evidence base on how microalgal feeds can impact human health.
x Generate rough estimates of the possible impacts on human health if ever farmer use of Arthrospira feed became widespread. Include estimates of economic impacts, notably those linked to improved health status and possible reductions in medical and pharmaceutical expenditures. Do this for one or more jurisdictions based on existing documentary evidence and key informant interviews. Run this analysis using different plausible assumptions about health impacts and their economic consequences.
x Investigate whether Arthrospira feed could help chickens and perhaps also those who consume their meat and/or eggs to cope effectively with rising risks from environmental toxins like microplastics and pesticides.
Finding: Possible pathways to harness the technological promise of microalgal feeds merit greater attention
x Examine how Arthrospira’s status as a natural product may constrain its use as a feed, notably how the fact that this biomass is non-proprietary might incentivise researchers and businesses to focus instead on microalgae extracts or genetically modified microalgae. Explore possible ways to overcome this constraint.
x Investigate low cost, appropriate tech options to produce Arthrospira for use as a farm input based on the premise that this might enhance its accessibility to farmers, including the prospect of producing it using waste products like livestock slurry.
x Examine the market prices of competing protein sources for chickens in one or more jurisdictions, including how they are affected by subsidies and by externalities that have not been internalised via policy measures. Alternative price signals given possible policy reforms to deliver economically optimal outcomes could be generated as a means to inform policy.
x Elucidate the key barriers preventing public health authorities from advocating that governments foster wider use of microalgal feed as a means to improve public health via biofortified livestock products.
x Assess the scope for this feed to help deliver key national priorities and UN Sustainable Development Goals.
x Assess the scope to secure cashflows from payments for ecosystem service schemes to support this innovation, including schemes at EU level and those involving private sector actors.
x Conduct outreach to relevant institutions (governments, civil society, international institutions) to explore the scope for them to incorporate this feed and other microalgal farm inputs into their policies & programmes
x Conduct outreach to agribusiness firms to discuss the prospect of them devoting R&D resources to develop improved “++” versions of what Arthrospira biomass offers as a farm input, for those who can afford them.
x Investigate possible ways for these technological prospects and this analysis to secure greater prominence in the answers to pertinent questions asked of AI search tools like ChatGPT, DeepSeek and Perplexity.
5 Conclusions
This paper reviews the available academic literature on the technological prospect of incorporating Arthrospira biomass into the diet of chickens. It finds that this feed can support farming by boosting productivity, enhancing stress resilience and improving product quality thanks to being rich in readily digestible nutrients and bioactive compounds. The net effect is that this agricultural innovation could enhance the viability of chicken farming despite growing threats like climate change and antimicrobial resistance, thus bolstering farm livelihoods and food security. The prospect of this feed delivering health benefits via biofortified chicken products is also explored. Possible future adoption pathways for microalgal chicken feed include growing recognition of resilience effects as critical, policy initiatives to ensure that price signals of competing farm inputs reflect their true costs, and health authorities embracing biofortified foods as a public health measure.
The paper sets this technological prospect in the context of key problems facing farmers and society, discussing its potential significance and priority actions. It also posits a conceptual framing suited to NbS technologies that demonstrate multifaceted efficacy. Given its aim to maximise impact, the paper uses non-technical language and intuitive metrics to make this evidence accessible to potential users like farmers, farm advisors and policymakers.
Author contributions
JS: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Writing – original draft, Writing – review & editing, Visualization. EA: Conceptualization, Funding acquisition, Methodology, Project administration, Supervision, Writing – review & editing, Validation, Visualization. AV: Conceptualization, Methodology, Project administration, Supervision, Validation, Writing – review & editing.
Funding
The author(s) declared that financial support was received for this work and/or its publication. This research was funded by the Maltese government’s Ministry for Education, Sport, Youth, Research and Innovation under the project “Agri-food applications of microalgae: Learning from experience about their capacity to foster agricultural sustainability and food security despite climate change,” grant number UM REF:2023_048_UM_MSUN.
Conflict of interest
The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Generative AI statement
The author(s) declared that generative AI was not used in the creation of this manuscript.
Any alternative text (alt text) provided alongside figures in this article has been generated by Frontiers with the support of artificial intelligence and reasonable efforts have been made to ensure accuracy, including review by the authors wherever possible. If you identify any issues, please contact us.
Publisher’s note
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Supplementary material
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fanim.2025.1710262/ full#supplementary-material

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