Figure 1.

Schematic illustration of the experimental periods and related procedures. (A) Age of the animals in weeks and experimental periods (Pre: preliminary period; D1: first calcium depletion period; R1: first recovery period; D2: second calcium depletion period; R2: second recovery period; D3: third calcium depletion period). (B) Dietary calcium supply and experimental procedures. Control groups were fed with adequate calcium diet (Ca+) continuously. Calcium deficient groups were fed alternatingly with low calcium diet (Ca−) (black sections) and adequate Ca+ feed. Egg quality analysis was performed on all eggs laid within the last three consecutive days of periods Pre, R1 and R2 (blue striped sections), as well as during the entire phases of Ca− (blue sections). Body weighing (BW) was performed directly prior to each change of diet.