Effects of Rosemary (Rosmarinus officinalis) Extract on Performance, Antioxidant Ability and Blood Gas Indices of Broiler Chickens Treated with Sodium Nitrate in Drinking Water

A total of 220 broiler chicks in five groups were used to reveal the effects of different levels of 0.0, 1.5, 3.0 and 6.0 mL/L rosemary extract along with sodium nitrate (27.4 mg/L) in drinking water as compared to the control (without any supplement in water) on performance and antioxidant potential of treated broiler chickens. Body weight gain and feed conversion ratio were negatively affected by nitrate during finisher period and was compensated by all the rosemary levels. Both the blood uric acid and total antioxidant capacity were diminished by nitrate while consumption of 3.0 mL/L rosemary extract returned it to the control level. Nitrate decreased venous blood pO2, and rosemary extract levels of 3.0 and 6.0 mL/L increased pO2 to the same level as the control. Venous blood pCO2 was affected in an opposite way to pO2 by nitrate and rosemary extract. It is concluded that rosemary extract supplementation in drinking water can improve antioxidant ability and performance functions of broiler chickens treated with sodium nitrate.