Responses of growth performance, antioxidant function, small intestinal morphology and mRNA expression of jejunal tight junction protein to dietary iron in yellow-feathered broilers

This study aimed to investigate the dose-effect of iron on growth performance, antioxidant function, intestinal morphology, and mRNA expression of jejunal tight junction protein in 1- to 21-d-old yellow-feathered broilers. A total of 720 1-d-old yellow-feathered male broilers were allocated to 9 treatments with 8 replicate cages of 10 birds per cage. The dietary treatments were consisted of a basal diet (contained 79.6 mg Fe kg–1) supplemented with 0, 20, 40, 60, 80, 160, 320, 640, and 1,280 mg Fe kg–1 in the form of FeSO4·7H2O. Compared with the birds in the control group, birds supplemented with 20 mg Fe kg–1 had higher average daily gain (ADG) (P