The aim of this experiment was to verify the sodium levels and electrolyte balance of diets for commercial laying hens on the first and second production periods. Two experiments with 112 days each, divided in four periods of 28 days, were carried out. One hundred and sixty Lohmann laying hens (25 weeks old) and 160 Babckok forced molting laying hens (80 weeks old), in the first and second experiments, respectively, were used. The laying hens were assigned to a completely randomized design, with five treatments, four replicates and eight birds each. The diets were formulated based on corn and soybean meal and the values of chemical and energy feeds composition were calculated according to Rostagno et al. (1985) and the electrolyte balance of diet was calculated according to Mongin (1980). Five sodium levels, from common salt and sodium bicarbonate, were used. For the first experiment, the sodium levels were 0.12; 0.15; 0.18; 0.21; 0.24% and the calculated electrolyte balance was 205, 218, 231, 243, 246 mEq/kg and for the second one 0.13; 0.15; 0.17; 0.19; 0.21% and 174, 183, 192, 200, 209 mEq/kg, respectively. At the end of each experimental period, data of productive performance, eggshell quality and excreta moisture were evaluated, and the last one was evaluated only in the first trial. The evaluated variables, in all experiments, were not influenced by sodium levels and dietary electrolyte balance. Therefore, it can be concluded that sodium level of .12%, for 205 mEq/kg diets, for laying hens in the first production period and the sodium level of 0.13%, for 174 mEq/kg diets, for laying hens in the second production cycle, were sufficient to provide a good productive performance and good egg shell quality.
electrolyte balance; forced molting; laying hens; sodium
