Two experiments were carried out to estimate sodium requirements for brown-eggs laying hens in the late first and during second egg-production cycle. A completely randomized design was used, with seven sodium levels (0.08, 0.13, 0.18, 0.23, 0.28, 0.33 and 0.38%), six replications of six birds in the late first egg-production cycle and five replications of six birds in the second egg-production cycle. In the late first egg-production cycle, sodium levels (SL) had no effect on feed intake (FI), egg weight (EW), egg dozen feed conversion (EDC) and egg-shell specific gravity (SG). The SL showed quadratic effect on egg production (EP), egg mass (EM) and egg mass feed conversion (EMC), that resulting in sodium requirements (SR) of 0.21, 0.22 and 0.21%, respectively. In the second egg-production cycle, SL had no effect on EW and SG. However, EP, EM, EMC and EDC improved when the levels of sodium were 0.20, 0.19, 0.18 and 0.19%, respectively. Considering the estimates of sodium requirements to egg production and egg mass feed conversion, could be suggests 0.22% e 0.20% as maximum sodium levels, respectively, to late first and second egg-production cycle.
eggshell quality; mineral; performance; sodium bicarbonate
