ABSTRACT 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 is less than or equal to 0.01) on blood gas parameters, with an estimated equilibrium at 0.19% dietary Cl–. No effect (P is more than or equal to 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 is less than or equal to 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.
(Key Words: acid-base balance, chloride requirements, sodium, tibial dyschondroplasia)
2001 Poultry Science 80:289-294
© 2001, by the Poultry Science Association. All rights reserved.