Selenium is an essential micro element in vertebrates’ nutrition including birds. There are organic and inorganic forms of selenium which the latter form; Sodium Selenite (SS), is widely used in broiler diets. Organic form of selenium; Selenomethinin (SM), is different in terms of absorption, metabolism and storage. An experiment with a complete random design with a 2×3×2 factorial arrangement and 3 replicates per each treatment was conducted to compare organic and inorganic selenium (SS Vs SM) at three different levels of diet energy by adding 3 different levels of soybean oil (0 , 2.5 and 5 percent) and two levels of vitamin E (normal and +200 IU) on male broiler performance, breast yield, carcass traits, drip loss and thyroid hormones. 900 Ross308 mail broilers were placed in 36 pens (25 chicks per pen). An increase in diet energy caused higher body weight (BW) and lower feed conversion ratio (FCR) but did not affect daily feed intake (DFI). Vitamin E level of +200 IU increased FCR and decreased BW in comparison with the control surprisingly. Se source significantly increased DFI in starter diets. BW increased smoothly by SM comparing with SS although it was not significant. FCR was not affected by Se source. Breast yield was not affected by Se source or diet energy but significantly improved by vitamin E level. Se source and diet energy level had a significant interaction on drip loss. T3 and T4/T3 ratio were significantly affected by Se source and energy level interaction.
