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: Using commercial antioxidants in the diet of chicken may cause cancer, liver swelling and changes in the activity of enzymes, hence their use is limited. Alternative herbal materials with antioxidant and antimicrobial properties can increase palatability, improve gastrointestinal function, improve the immune system and the performance of birds. OBJECTIVES: The purpose of the experiment was to study the effect of pomegranate peel extract (PPE) to a soybean oil diet on broiler performance and other related parameters. METHODS: This research was conducted as completely randomized design arranged in a 2×2×2 factorial experiment using pomegranate peel extract (PPE), antioxidant Nutriad® (AN) and soybean oil (SO). Three hundred and twenty 11 day-old Ross 308 broiler chicks were assigned to eight treatments of four replicates each (ten chicks per replicate). Data were analyzed using the GLM procedure of the SAS software, and the LSM of groups compared at 5% significance level. RESULTS: Soybean oil increased growing and overall feed conversion ratio (FCR) and harmful gastric micro flora. The overall ADG and feed intake were increased by PPE. Inclusion of PPE in the diet had no effect on FCR. Inclusion of PPE in the diet increased nutrient digestibility, beneficial gastric micro flora, lactobacillus, and the antibody titer in 39-day broilers, whereas AN had no effect on any of the performance parameters and decreased the beneficial gastric micro flora. CONCLUSIONS: The overall results showed that PPE in fat and non-fat containing diets might have the potential to increase the daily gain by enhancing feed intake, nutrient digestibility, beneficial gastric micro flora and immune system of broilers with  no deleterious effect on overall FCR.