Algae as a sustainable feed resource: revolutionizing animal nutrition

Abstract

Algae, including microalgae and macroalgae, are gaining prominence as a transformative solution for sustainable animal nutrition across ruminant, poultry, and aquaculture systems. Their exceptionally diverse nutritional profile ranges approximately from 5 to 70% protein content (dry matter) across species, such as brown seaweed Ascophyllum nodosum (5–15% protein) and the microalgae Spirulina and Chlorella spp. (50–70% protein). This profile includes essential ω-3 fatty acids (ALA, EPA, DHA), a comprehensive spectrum of vitamins (A, B, C, D, E, K), and valuable bioactive compounds such as astaxanthin, fucoidan, and phycocyanin, which collectively enhance livestock growth performance, immune function, and disease resistance. Remarkably, algae cultivation in non-arable environments such as seawater, brackish water, or wastewater not only reduces pressure on freshwater and fertile land but also contributes to carbon sequestration, offering dual environmental benefits. However, several key challenges including significant nutrient variability between species and cultivation conditions, anti-nutritional factors like polyphenols in some macroalgae, and high production costs associated with harvesting and processing limit large-scale adoption. Despite their potential, these challenges hinder widespread adoption. This comprehensive review summarizes current information on historical use, documented nutritional benefits, and environmental advantages. It then critically assesses these aspects through evidence-based analysis. It also identifies priority future research directions to optimize algae’s integration into animal feed systems, including genetic improvement of algal strains and development of cost-effective cultivation technologies. By bridging these gaps, the review aims to advance algae’s role in fostering an innovative, resilient, and truly sustainable agricultural industry for the future.