Use of microalgae in poultry farming: an alternative to reduce antibiotic dependence and improve meat and egg quality

SUMMARYPoultry farming plays a key role in the global and Brazilian economies, providing a significant source of animal protein and contributing to food security. However, the sector is facing increasing challenges due to restrictions on the use of antimicrobials, which have traditionally been used to promote growth and prevent infections. These restrictions are driven by the alarming rise in antimicrobial resistance, which poses serious risks to public, animal, and environmental health. In this context, microalgae have emerged as a promising functional ingredient due to their antimicrobial, antioxidant and immunomodulatory properties. This integrative review analysed 26 articles published between 2013 and 2023 that investigated the use of microalgae in poultry nutrition and health. Most studies focused on Spirulina platensis, with additional evaluations of Chlorella vulgaris and Dunaliella salina. Reported benefits included improvements in zootechnical performance, feed conversion, immune modulation, lipid profile, and meat and egg quality. However, only ten of the studies directly assessed antibacterial activity and modulation of the intestinal microbiota, indicating that, while promising, evidence in this area remains limited. The conclusions highlight a dual impact: microalgae supplementation has the potential to reduce antibiotic dependence in poultry production while opening up opportunities to develop a national microalgae production chain that could drive innovation, add value and strengthen competitiveness. Nevertheless, the current body of research is insufficient compared to the scale of Brazilian poultry farming. The scarcity of applied, large-scale clinical studies highlights the need for further research into bioprospecting of native species, investment in field trials and supportive public policies. Advancing this line of research is essential to consolidate the role of microalgae, particularly Spirulina and Chlorella, as natural antimicrobial agents and performance enhancers.