Dietary microalgae Schizochytrium spp and Nannochloropsis gaditana modulate antioxidant and immune-related gene expression in ewes’ monocytes and neutrophils

Lay Summary Microalgae are gaining attention as natural feed ingredients that can improve animal health and the nutritional quality of livestock products. In this study, dairy sheep were fed diets containing two types of microalgae, Schizochytrium (a source of docosahexaenoic acid, DHA) and Nannochloropsis gaditana (a source of eicosapentaenoic acid, EPA), for 90 days. The animals maintained normal feed intake, but their diets provided higher levels of n-3 fatty acids. The study examined how these supplements affected the animals’ natural defense and immune systems by measuring how certain biological pathways responded in blood cells. Moderate inclusion of the microalgae blend strengthened gene networks related to antioxidant defenses, while higher levels downregulated the expression of genes encoding enzymes that help reduce oxidative stress. At the same time, genes involved in inflammatory responses were decreased, suggesting that microalgae might have helped attenuate low-grade pro-inflammatory responses. Overall, feeding these n-3-rich microalgae was associated with transcriptional changes related to antioxidant and immune pathways, suggesting a potential role of microalgae supplementation in modulating cellular responses in dairy sheep under intensive farming conditions.