Background: Organic acids and ammonium salts added to drinking water can optimize productivity of broiler chickens. Objective: To evaluate the effect acidifying on productive performance, blood intestinal pH, morphology broilers. Methods: 1,400 one-day-old chicks were used two pH levels (4 6) during three periods (1-21, 1-28, 1-42 days age). The treatments consisted with a blend formic acid (31...