Unlocking the feed supplement potentials of blue-green alga (spirulina) in broiler nutrition: a comprehensive review.

Presently, spirulina, a cyanobacterium, is gaining attention as a safe feed supplement in livestock and poultry production due to its rich nutritional and medicinal benefits. Spirulina grows well in highly alkaline environments with a pH range of 9.5–11 such as pond, fresh and marine water. It is an excellent source of proteins, vitamins (ascorbic acid, tocopherol, and B-complex), minerals (iron and magnesium), and fatty acids (gamma linoleic acid, capric acid, palmitic acid, omega-3 and omega-6). It has a higher essential amino acid profiles than soybean meal, which usually is the main protein source in poultry diets. In addition, spirulina contains phytopigments (carotenoids and phycocyanins) and bioactive compounds (polyphenols and flavonoinds), which have a wide range of biological activities, including antimicrobial, hypolipidemic, hypocholesterolemic, antioxidant, and anti-inflammatory effects. There has been variable results on growth-promoting effects of spirulina in broilers. Knowledge and detailed understanding of spirulina’s nutritional composition, (i.e., proximate, amino acid, vitamins, minerals, and fatty acid), mechanisms of action, and its supplementation value in broilers are critical to fully maximize its use in broiler nutrition. However, while most of these findings are valuable, they are scattered throughout the literature, making it difficult to use them in evidence-based decision-making in the poultry industry. The present review therefore attempts to pool current published evidence on spirulina’s chemical composition, and the effect of its supplementation on production indices and health status of broilers to enhance the adoption of these findings in decision support system in the poultry industry, as well as to identify knowledge gaps and fashion out new research directions. The phytochemical composition and mechanisms by which spirulina enhances broiler performance will also be reviewed.