These data support the notion that clinically inapparent chlamydial infection elicits an inflammatory response that is detrimental to growth in calves, consistent with the growth stunting effects of bacterial infections or LPS of gram-negative bacteria that is mediated by circulating inflammatory cytokines such as IL-1, IL-6, and TNF-α [41], [42]. Here, IL6 is linked to chlamydia trachomatis infectious disease.