BACKGROUND: The application of medicinal herbs with high anti-oxidant properties could reduce the detrimental effects of oxidative stress and free radicals under heat stress and improve the performance of broilers. OBJECTIVES: The effects of rosemary powder and extract on growth performance, carcass characteristics and blood parameters of broilers were evaluated under heat stress. METHODS: For studying the effect of experimental treatments including control, different levels of rosemary powder (5, 10 and 15 g/kg), rosemary extract (3.5,7 and 10.5 g/kg) and Vit-Asp (1 g/L) on growth performance (feed intake, body weight and feed conversion ratio), carcass characteristics and blood parameters (cholesterol, triglyceride, hematocrit, glucose and heterophil to lymphocyte ratio), 160 one-day old chicks (Ross male-308) were used applying a randomized complete block design with 8 treatments, 4 replicates and 5 chicks per replicate during a 42-day period. Heat stress schedule was 32±2ºC as cyclic from 10.00 AM to 6.00 PM. RESULTS: Rosemary had significant effects on feed intake and final live weight of chicks (p<0.05) but not on feed conversion ratio (p>0.05). Significant effects from rosemary on glucose and heterophil to lymphocyte ratio were found (p<0.05). The effects of rosemary on carcass characteristics, cholesterol, triglyceride and hematocrit were not significant (p>0.05). CONCLUSIONS: In general, inclusion of rosemary in broilers diet under heat stress improved the performance because of anti-oxidant effects.Keyword: Rosemary, performance, blood parameters, heat stress, broilers

BACKGROUND: Salmonella Enteritidis in poultry is one of the main causes of illness that can be controlled effectively by some plant compounds, antibiotics and probiotics. OBJECTIVES: This study compares the effect of rosemary, thyme, propolis, antibiotic and probiotic on the immune system and blood parameters of broilers challenged with Salmonella Enteritidis.  Methods: Four hundred and twenty 1-day- old male broiler chicks Cobb strain were divided into seven groups: including rosemary ethanol extract, ethanol extract of propolis, ethanol extract of thyme, and probiotics, virginiamycin (10%) and positive and negative controls, and were reared for 6 weeks. At the end of experiment chickens were sampled and slaughtered. RESULTS: The results showed that plant extracts with probiotics can improve the immune system, reduce serum lipids, reduce harmful bacteria such as Salmonella and E.coli and increase the beneficial bacteria such as lactic acid bacteria. CONCLUSIONS: This study showed that the herbal extracts and probiotics can be used as an alternative to antibiotics in broiler diets.