Further, gene and protein markers of intestinal integrity and stress were assessed. Irrespective of d of heat stress exposure, plasma endotoxin levels increased 45% (P < 0.05) in HS compared to TN pigs, while jejunum TER decreased 30% (P < 0.05) and LPS APP increased two-fold (P < 0.01). Furthermore, d 7 HS pigs tended (P = 0.06) to have increased LPS APP (41%) compared to PFTN controls. Lysozyme and alkaline phosphatase activity decreased (46 and 59%, respectively; P < 0.05) over time in HS pigs, while the immune cell marker, myeloperoxidase activity, was increased (P < 0.05) in the jejunum at d 3 and 7. These results indicate that both heat stress and reduced feed intake decrease intestinal integrity and increase endotoxin permeability.