Abstract
The experiment was conducted to estimate dietary requirements of sodium and chloride for Lingnan yellow chickens from 43 to 63 days of age. A total of 750 broiler males were randomly divided into 5 treatments, and each had 6 replicates with 25 birds per replicate. The control diet was formulated without supplemented NaCl. Dietary treatments 2 to 5 were the control diet supplemented with NaCl and contained equal levels of Na and Cl, 0.1%, 0.2%, 0.3%, and 0.4% of the diets, respectively. The results showed that NaCl supplementation increased body gain, feed and water intake, while improved FCR (P < 0.001). Body gain, serum sodium, and osmolality (OSM) presented a quadratic broken-line regression (R2 = 0.975, P < 0.05) at 0.09%, 0.1%, and 0.1%, respectively. Serum level of potassium decreased linearly (P = 0.033) with increased dietary sodium and chloride. Feeding a diet with 0.1% sodium and chloride resulted in higher thigh muscle (P < 0.01). The color lightness (L*) of the breast meat decreased linearly (P = 0.009), while the redness increased linearly (P = 0.038) at 0.4 % sodium and chloride. Dripping loss decreased at 0.4% sodium and chloride (P = 0.003). In conclusion, by quadratic broken-line regression model, dietary sodium and chloride requirements to optimize body gain, serum sodium and potassium levels and OSM were 0.09%, 0.10%, 0.10%, and 0.10%, respectively, for Lingnan broiler males as an example for slow-growing broiler breeds from 43 to 63 days of age.