Comparison the Effects of Nano-selenium and Sodium Selenite on Production traits and Antioxidant Status in Broiler Chickens under Thermal Stress Conditions

In this research total of 288 one- day old Ross 308 broiler chickens were used in a completely randomized design with 6 treatments and four replications for 5 weeks. The experimental treatments included 1) Basal diet without additive and normal temperature conditions (negative control) 2) Basal diet without additive and heat stress conditions (positive control) 3) Basal diet with 0.18 mg/kg sodium selenite and normal temperature conditions 4) Basal diet with 0.18 mg/kg sodium selenite and heat stress conditions 5) Basal diet with 0.18 mg/kg nano-selenium and normal temperature conditions and 6) Basal diet with 0.18 mg/kg nano-selenium and heat stress conditions. The results showed that in normal temperature conditions, nano-selenium caused decrease in feed intake in comparison to sodium selenite however in heat stress conditions, both nano-selenium and sodium selenite increased feed intake when compared with control treatment (P<0.01). Also, the results of feed conversion ratio showed that the highest and lowest feed conversion ratios in all rearing periods were related to the control in heat stress conditions and nano-selenium under normal temperature conditions, respectively (P<0.01). The highest and lowest blood serum malondialdehyde, aspartate transaminase and alanine transaminase, concentrations were observed in control treatment under heat stress conditions and treatment containing nano-selenium in normal temperature conditions, respectively. Generally the results of the present study showed that the utilization of nano-selenium in heat stress conditions in diet of broiler chickens improved feed conversion ratio, increased growth and increased cellular oxidation inhibitory enzymes.