The effect of different dietary potassium and chloride levels on performance and excreta dry matter in broiler chickens

The aim of this 3 × 3 factorial experiment on broilers was to investigate the effect of different dietary levels of potassium and chloride on chicken performance, carcass composition and dry matter content in excreta. 360 one-day-old Ross 308 chickens were allocated to 9 groups, in 5 replications of 8 birds (4 ♂ and 4 ♀). Chickens from 1 to 42 days of age were kept in cages with wire floors to enable excreta collection, and were administered water and feed ad libitum. The basal starter (days 1-14) and grower (days 15-42) diet contained in 1 kg, as analysed, 2.11 g and 2.10 g chloride, 8.6 g and 7.8 g potassium and 2.04 g and 1.93 g sodium, respectively. Basal diets were supplemented with potassium and chloride containing, as analysed, 11.1 g or 10.6 g and 11.8 g or 11.9 g K and 2.95 g or 2.58 g and 3.16 g or 2.70 g/kg Cl, for the starter or grower periods of feeding, respectively. The sum of cations (K + Na) in diets used in the experiment ranged from 309 mEq to 390 mEq in the starter diet and from 283 mEq to 388 mEq/kg in the grower diet; the dietary electrolyte balance (DEB) values varied from 219 mEq to 331 mEq and from 207 mEq to 329 mEq/kg, respectively. During the starter feeding period the body weight gain (BWG) and feed conversion (FCR) were positively affected by increasing the chloride supplement and decrease of DEB values from 298 to 274 mEq/kg (P ≤ 0.001). In the grower period and throughout the feeding period, the positive effect of chloride supplementation on BWG and FCR was not confirmed but a negative effect of potassium was found out. The interaction between dietary levels of chloride and potassium found for BWG and FCR suggests a reciprocal relationship for both electrolytes. Dry matter in excreta was decreased when the K level in the diet was increased to 11.9 g/kg and DEB value to 319 mEq/kg (P ≤ 0.001) but breast meat yield (P ≤ 0.01) and relative mass of heart in carcass (P ≤ 0.05) were increased. Dietary chloride content elevated from 2.2 to 2.58 g/kg reduced pH in breast meat after 24 h (P ≤ 0.001), whereas elevated potassium content (7.8 vs. 10.6 g/kg) reduced drip loss in 24 (P ≤ 0.01) and 48 h stored meat (P ≤ 0.05).