This study was performed to investigate the effects of dietary threonine (Thr). level on performance, metabolizable energy, intestinal morphology, and immune system in coccidian–infected broiler chickens. The diets contained: 88%, 100% (Non challenged (NC) and challenged control (PC)), 112%, 124%, and 136% of Thr requirement according to Cobb 500 recommendation and fed during grower (pre challe...