effects of rosemary extract on growth, some blood parameters and carcass characteristics of broilers consuming sodium nitrate in drinking water

two hundred and twenty one-day male chicks (ross 308) were used in a completely randomized design with 5 treatments and four replicates each to investigate the effects of the different levels of 0.15, 0.3 and 0.6 percent rosemary extract along with nitrate (27.4 mg sodium nitrate/liter water) in drinking water on growth, some blood parameters and carcass characteristics of broiler chickens. no different difference was observed between the treatments for feed consumption and body weight gain (p˃0.05). nitrate consumption increased the feed conversion ratio which was removed by rosemary extract (p<0.05). rosemary extract had no effect on alanine aminotransferase (alt) but nitrate increased the aspartate aminotransferase (ast) activity (p<0.05). consumption of 0.3 and 0.6 percent rosemary extract deducted the blood hdl of nitrate consumed birds (p<0.05). liver weight was decreased by the highest rosemary level (p<0.05). totally rosemary extract consumption lowers the liver and lung damages through its antioxidant effects in broiler chickens under nitrate treatment. hence it diminishes the liver and lung weights and aspartate aminotransferase activity and as a consequence improves the feed conversion ratio