Two experiments were carried out to investigate the calcium (Ca):available phosphorus (aP) ratio and the level of phytase in the first and second posture cycle. In the first posture cycle, 128 birds were distributed to a 3 × 2 + 1 factorial arrangement, composed of three Ca:aP ratio [14:1 (4.2% Ca and 0.30% aP), 12:1 (3.5% Ca and 0.30% aP), and 9:1 (3.5% Ca and 0.38% aP)], two levels of phytase (0 and 600 Phytase Units - PU) and a Ca:aP control [11:1 (4.2% Ca and 0.38% aP)]. In the second posture cycle, 240 birds were distributed to a 2 × 2 × 2 factorial arrangement, composed of two Ca (3.5 and 4.2%), two aP (0.30 and 0.38%) levels and two phytase levels (0 and 600 PU). In the first posture cycle, among birds fed diets without phytase, the greater eggs weight was obtained with 9:1 Ca:aP ratio and the smaller, with 12:1 Ca:aP ratio. The best eggs mass and feed conversion by eggs mass (FCEM) were observed in birds fed a diet with 14:1 Ca:Pd ratio and worse, with the ration with 12:1 Ca:aP ratio. In birds fed diet with phytase, the best FCEM was obtained with 12:1 Ca:aP ratio and worse, with 9:1 Ca:aP ratio. In the second posture cycle, the diet consumption decreased with increasing levels of calcium (3.5 to 4.2%), available phosphorus (0.30 to 0.38%) and phytase (0 to 600 PU). Feed conversion by eggs mass or per dozen eggs improved, respectively, with increasing levels of available phosphorus and phytase, while specific gravity improved with the increase of dietary calcium level. For laying hens in the first posture cycle, it is recommended 14:1 (4.2% Ca:0.30% Pd) ratio without phytase and 12:1 (3.5% Ca:0.30% Pd) ratio with 600 PU and, for birds in the second posture cycle, it is recommended 14:1 (4.2% Ca and 0.38% Pd) ratio. The supplementation of diets deficient in available phosphorus with 600 PU improves egg weight in the second posture cycle.
brown laying hens; egg production; enzyme
