The Optimal Dietary Sodium or Chloride Level of Broilers Fed a Corn–Soybean Meal Diet from 22 to 42 Days of Age

The objective of this study was to assess the ideal dietary Na or Cl level for chickens from 22 to 42 d of age, utilizing a corn-soybean meal diet that maintains a 1:1 ratio of Na to Cl. At 22 d of age, a total of 288 male broilers of Arbor Acres were selected and randomly divided into one of six treatments. Each treatment contained eight replicates, with six chicks in each replicate. The control chicks were given a basic diet including 0.02% Na and 0.07% Cl without added Na or Cl, while the birds in other treatments were given diets containing different Na or Cl levels (0.13%, 0.19%, 0.25%, 0.31%, and 0.37%). With increasing dietary Na or Cl levels, linear (<i>p</i> < 0.0001) and quadratic (<i>p</i> < 0.0001) increases occurred in ADG, ADFI, and average daily water consumption, while F/G exhibited a linear (<i>p</i> < 0.0001) and quadratic (<i>p</i> < 0.0001) decrease from 22 to 42 d of age in broilers. Linear (<i>p</i> < 0.02) and quadratic increases (<i>p</i> < 0.03) were found in the heart indicator, serum Cl^- concentrations, and blood Na⁺ and Cl^- concentrations, whereas the kidney indicator, blood K⁺ concentrations, and serum K⁺, UA, and glucose (GLU) concentrations showed a linear (<i>p</i> < 0.04) and quadratic (<i>p</i> < 0.004) decrease with an increase in dietary Na or Cl levels. The excreta water content, liver indicator, and jejunal crypt depth also showed a linear increase (<i>p</i> < 0.02). The ideal levels of dietary Na or Cl were estimated to be 0.07% to 0.12%, based on the most suitable broken-line and asymptotic models (<i>p</i> ≤ 0.0002) using those sensitive indicators mentioned above. It was suggested that the suitable dietary Na or Cl level of 0.12% would adequately fulfill the Na or Cl metabolic demands of chickens from 22 to 42 d of age.