Effect of dietary supplemental sodium chloride on growth, blood or serum parameters, and related aspects of broilers aged 22 to 42 days

We aimed to explore the effect of different dietary supplemental sodium chloride (NaCl) levels on growth performance, organ indexes, blood gases, serum biochemical indicators, jejunal morphology, and tibial traits in broilers aged 22 to 42 days in order to estimate the ideal dietary supplemental NaCl level. A total of 288 22-day-old male broilers with similar weight were randomly allotted to 6 treatments with 8 replicates per treatment, and were respectively fed diets containing 0.0 %, 0.1 %, 0.2 %, 0.3 %, 0.4 %, or 0.5 % of added NaCl for 21 days. As dietary added NaCl levels raised, among the affected parameters (P < 0.05), the average daily gain (ADG), average daily feed intake (ADFI), tibial ash Na content, as well as blood Cl^- and Na⁺ contents increased linearly and quadratically (P < 0.05), whereas the feed/gain (F/G), K⁺ content in blood, the contents of serum uric acid (UA), glucose (GLU) and K⁺, exhibited linear and quadratic (P < 0.01) decreases. Based on the best-fitted models (asymptotic or broken-line models, R² = 0.42-0.96, P < 0.0001) from the above indices, the corresponding estimates for dietary supplemental NaCl levels that could optimize ADG, ADFI, F/G, blood Na⁺, blood Cl^-, blood K⁺, serum GLU, serum UA, serum K⁺, and tibial ash Na, were calculated to be 0.18 %, 0.12 %, 0.16 %, 0.14 %, 0.14 %, 0.12 %, 0.10 %, 0.13 %, 0.10 %, and 0.21 %. In conclusion, the ideal dietary supplemental NaCl level for broilers aged 22 to 42 days is recommended to be 0.18 % for maximum growth performance or 0.21 % for Na or Cl metabolism. They are not only lower than that (0.24 %) suggested by our previous study on broilers aged 1 to 21 days, but also lower than that (0.30 %) added in the current Chinese broiler production.