A total of 252 one-day-old Ross broilers were randomly allocated to one of six treatments in a 2 × 3 factorial arrangement with respective Eimeria challenges (non-infection and infection) and three different selenium (Se) diets. Dietary treatments were as follows: (1) Se un-supplemented control (CON), (2) inorganic Se treatment (SS; 0.3 mg/kg as sodium selenite), and (3) organic Se treatment (SY; 0.3 mg/kg as selenized yeast). Six replicate cages were allocated per treatment. Chickens in the respective Eimeria infection groups were infected with an E. acervulina, E. tenella, and E. maxima oocyst mixture (15,000 oocysts/chicken) on day 16. Growth performance was measured on days 16, 22, and 24. On day 22, intestinal samples were collected from randomly selected chickens to evaluate gut lesion scores, antioxidant enzymes, and tight junction gene expression. Blood, breast, and liver samples were collected to analyze the Se concentrations on day 24. Dietary SY supplementation improved (p < 0.05) the growth performance of the chickens regardless of the Eimeria challenge. Moreover, independent of Eimeria infection, Se supplementation elevated (p < 0.05) the heme oxygenase 1 (HMOX-1) expression in jejunal mucosa at 6 days post-infection (dpi). Duodenal junctional adhesion molecule 2 (JAM-2) expression and jejunal occludin (OCLN) were elevated (p < 0.05) with dietary SY supplementation at 6 dpi. Among Se sources, broiler chickens fed with the SY diet showed higher (p < 0.05) Se concentrations in breast muscle and serum on 8 dpi. These results confirmed the beneficial effects of dietary Se and the efficiency of organic Se compared with inorganic Se for growth improvement and muscle Se enrichment in broiler chickens regardless of coccidiosis infection.
Keywords: antibiotic alternative; broiler; coccidiosis; gut health; oxidative stress; selenium.