The optimal dietary sodium and chloride level for broiler chicks fed a corn-soybean meal diet between 1 and 21 d of age.

The experiment was conducted to estimate the ideal dietary sodium (Na) and chloride (Cl) level for broilers during day 1 to 21 using a corn-soybean meal diet under a dietary Na:Cl ratio of 1:1. A total of 490 1-d-old Arbor Acres male broilers were randomly allotted by body weight to one of seven treatments in a completely randomized design. Each treatment consisted of seven replicate cages with 10 chicks per cage. Broilers were fed a Na and Cl-unsupplemented corn-soybean meal basal diet (control, containing 0.02% Na and 0.08% Cl) and the Na and Cl-supplemented basal diets containing 0.14%, 0.20%, 0.26%, 0.32%, 0.38%, and 0.44% Na and Cl levels, respectively for 21 d. The results indicated that average daily gain, average daily feed intake, blood partial pressure of CO2 and concentrations of HCO3-, total CO2, Na+, Cl-, base excess and anion gap, tibial ash, and ash Na contents of broilers were affected (P < 0.001) by dietary Na and Cl level, and increased linearly (P < 0.001) and quadratically (P < 0.001) with increasing Na and Cl levels. Feed/gain ratio, mortality, blood K+ concentration, serum osmotic pressure and K+, glucose and uric acid concentrations as well as heart, liver, and kidney indices of broilers were affected (P < 0.01) by dietary Na and Cl level, and decreased linearly (P < 0.001) and quadratically (P < 0.001) with increasing Na and Cl levels. The estimates of dietary optimal Na and Cl levels were 0.07% to 0.16% according to the best-fitted broken-line or asymptotic models (P < 0.001) of the above sensitive indicators. Therefore, the optimal dietary Na and Cl level was suggested to be 0.16% to support all of the above Na and Cl metabolic requirements of broilers fed the corn-soybean meal diet during day 1 to 21, which is lower than the 0.20% recommendation by the Chinese Feeding Standard of Chicken (2004).