Antibiotic-free broiler production has increased interest in natural feed additives such as dried Chlorella vulgaris (DCV) and cinnamon oil (CO). This study evaluated DCV, CO, and their combination (DCV amylase was higher with DCV; protease was higher only with DCV&CO ( P < 0.05). Supplemented diets upregulated mRNA expression of nutrient transporters ( EAAT3, GLUT2, SGLT1, PEPT1, CAT-1 ) and tight junction markers ( MUC2, ZO-2, OCLN, CLDN1, TJP1 ). Cytokines were modulated: IL-1β increased in DCV, IL-8 in DCV&CO, and TNF-α decreased in all supplemented groups ( P < 0.05). DCV and CO, alone or combined, improved growth, intestinal morphology, digestive enzyme activities, and gut barrier function while modulating pro-inflammatory cytokines, supporting their use as natural alternatives to antibiotic growth promoters.
Kewan et al. (Sun,) studied this question.