Populations of (A) monocytes/macrophages, (B) CD1.1+ antigen presenting cells, (C) CD3+ T cells, (D) CD3+CD4+ helper T cells, (E) CD3+CD8α+ cytotoxic T cells, and (F) CD3+TCRγδ+ cells in the spleen of 14, 28, and 42-day-old Ross 308 broilers fed corn- or wheat-based diets ± 0.175% algae ingredient. Data represent the mean cell population with each marker identified within the (A–C) live cell gate or (D–F) CD3+ T cell gate from 10 birds/ treatment/ timepoint ± SEM. Bars with different letter labels are significantly different, P ≤ 0.05.