1. This study was conducted to determine the effects of heat stress on fearfulness, leucocyte components, oxidative stress and lipid peroxidation in two commercial broiler strains, Cobb (C) and Ross (R). 2. At 36 and 37 d of age birds were exposed to 38 +/- 1 degree C for 3 h. Rectal temperatures, duration of tonic immobility (TI), haematocrit values, proportions of leucocyte components (heterophil, lymphocyte, basophil, eosinophil, monocyte), malondialdehyde (MDA) concentrations and antioxidant enzyme activities (CAT, SOD, GPx) of all the birds were determined, before and after heat treatment. 3. Rectal temperatures increased and haematocrit values decreased in birds exposed to heat stress. Heat stress caused a significant increase in heterophil/lymphocyte and in basophil ratios. 4. Exposing birds to heat stress increased duration of TI, suggesting heat-stressed birds tended to be more fearful. 5. Heat stress resulted in a significant Genotype x Treatment interaction for MDA concentration. CAT, SOD and GPx activities; MDA concentrations in heat-stressed R strain birds were greater than in heat-stressed C strain birds.

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1. This study was conducted to determine metabolic and physiological responses of 2 commercial broiler strains, Hubbard (H) and Cobb (C), exposed to an ambient temperature of 38 degrees +/- 1 degree C for 2 h at 14 and 15 d of age. 2. Exposure to high temperature at an early age resulted in weight loss in strain C, which was not compensated for by 35 d of age but there was no weight loss in strain H. 3. Exposure of broilers to heat stress (38 degrees +/- 1 degree C) at 35 d of age resulted in an increase in rectal temperature, regardless of previously high temperature experience but acid-base balance and haematocrit values were not affected by heat stress. 4. Malondialdehyde concentration was higher in unexposed birds than in previously exposed ones and did not significantly differ between strains.

Extracts obtained from aerial parts of eight Centaurea L. (Asteraceae) species (C. calolepis, C. cariensis subsp. maculiceps, C. cariensis subsp. microlepis, C. hierapolitana, C. cadmea, C. ensiformis, C. depressa and C. urvillei subsp. urvillei), were tested for their free radical scavenging activity (FRSA) in the DPPH screening assay, for their in vitro antiinflammatory activity in the reporter gene assay for inhibition of transcription factor NF-kappaB and for their total phenolic content. Methanol extracts (0.25 mg/4 mL) of C. urvillei, C. cadmea and C. ensiformis showed strong antioxidant activity with 90.41 +/- 2.98%, 86.66 +/- 2.67% and 86.19 +/- 2.94% FRSA, respectively. Antioxidant capacity results were consistent with the total phenolic content. Chloroform extracts of C. hierapolitana, C. calolepis and C. cadmea showed strong in vitro antiinflammatory activity with IC(50) values of 2.5, 4.4 and 6.2 microg/mL, respectively.