Sodium and chloride requirements of growing broiler chickens (twenty-one to forty-two days of age) fed corn-soybean diets.

Two trials were conducted to determine Na+ and Cl- nutritional requirements and dietary electrolyte balance (DEB) and its effects on acid-base balance, litter moisture, and incidence of tibial dyschondroplasia (TD) in broiler chickens during the growing period. Cobb broilers were distributed in a completely randomized design (30 pens) with six treatments, five replicates, and 50 birds per experimental unit at 21 d of age. Treatments used in both trials were a basal diet with 0.10% Na+ (Trial 1) or Cl- (Trial 2) supplemented to result in diets with Na+ or Cl- levels of 0.10, 0.15, 0.20, 0.25, 0.30, and 0.35%. In the first trial, the results indicated an optimum Na+ requirement of 0.15%. The Na+ levels, obtained with supplemental NaHCO3, did not affect blood gas parameters and TD incidence. Litter moisture increased linearly with Na+ levels. In the second trial, the Cl- requirement was estimated at 0.23%. Increasing Cl- levels, provided by NaCl with NaHCO3 to balance Na+, caused a linear effect (P < or = 0.01) on blood gas parameters, with an estimated equilibrium at 0.19% dietary Cl-. No effect (P > or = 0.05) of Cl- levels on litter moisture was observed. The hypertrophic area of growth plate in the proximal tibiotarsus increased with Cl- levels (P < or = 0.001). A nonlinear model describes this response. The best dietary electrolyte balance (DEB) was between 250 to 261 mEq/kg in Trial 1 and 249 to 257 mEq/kg in Trial 2. We concluded that the Na+ requirement was 0.15%, and the Cl- requirement was 0.23% for maximum performance of growing chickens between 21 and 42 d of age, and the best DEB was between 249 and 261 mEq/kg.