Dynamic immune and molecular responses to chronic heat stress in blood and peripheral blood mononuclear cells of dairy cows

The results suggest that heat stress induces dynamic changes of the red blood cell and lymphocyte profiles but only transiently activating the leukocytic NF-κB p65 signaling pathway while suppressing T cell signaling, both likely in response to the increased circulating endotoxin concentration. The activation of platelets and the coagulation cascade were likely due to heat-stress-induced microvascular injuries, altered hematocrit, or vasodilatation. Altered blood coagulation and immune responses need to be considered in the management of heat-stressed dairy cows.