effects of alcoholic extract thyme on the performance, antioxidant status and blood gas indices of broiler chickens received sodium nitrate in drinking water

an experiment was conducted with two hundred and twenty day-old male broiler chicks (ross 308) in five groups to investigate the effects of different levels of 0, 0.2, 0.4 and 0.6% thyme extract in drinking water (including 27.4 mg sodium nitrate per liter) on broiler performance and antioxidantstatus and blood gas indices. no significant differences were observed between the treatments for body weight gain and feed consumption during the starter, grower, finisher and whole the experimental periods (p˃0.05). nitrate consumption had no effect on feed conversion ratio during the starter period, but consumption of highest thyme level increased it (p˃0.05). there was no significant difference between the treatments for feed conversion ratio during the grower, finisher and whole the experimental periods (p˃0.05). none of the experimental treatments affected the blood uric acid, creatinine, total protein, malondialdehyde, total antioxidant capacity and blood gas indices at day 42 of age (p˂0.05). nitrate consumption increased the blood urea whereas thyme extract supplementation decreased it (p˂0.05). it was concluded that consumption of 27.4 mg nitrate per liter drinking water causes the kidney injuries and higher blood urea in the end of the experimental period (day 42 of age) as a consequence but does not changes the performance, antioxidant indices and blood gas indicates, that shows the lack of induced methemoglobinemia and peroxidation. the thyme extract consumption in drinking water of broiler chicken decreases the blood urea through the diminished kidney injuries.