An experiment was conducted to determine nutritional calcium requirement of 360 Japanese female quails averaging initial weight of 121.5 g during the initial production phase (from 56 to 171 days of age). A complete randomized design with a 6 x 4 factorial arrangement (six Ca levels: 1.6, 2.0, 2.4, 2.8, 3.2, and 3.6% and four experimental periods of 28 days each) was used. Each treatment consisted of six replicates and a cage with ten birds, that was the experimental unit. No significant effect of Ca levels ' periods interaction on any variable was detected. However, it was observed linear increase on egg production, egg weight and eggshell thickness and linear decrease on feed:egg mass ratio and Ca percentage in the tibia, and quadratic effect on egg mass, bird weight gain, egg specific weight, eggshell weight and ash percentage in the tibia. It was observed that egg production and mass obtained with the 3.2% Ca level was 3.3 and 3.8% greater, respectively, in absolute values, than the 3.6% Ca level. The estimated Ca requirement of Japanese laying quails during the initial production phase ranged from 3.0 to 3.6% in the diet, depending on the evaluated parameters. It is recommended the dietary Ca level of 3.2%, that corresponds to a daily intake of 882 mg Ca/bird or 87 mg Ca/g of egg, to obtain better production and feed efficiency (feed:egg mass and feed:egg dozen ratios) and to maintain egg quality.
calcium levels; Coturnix coturnix japonica; egg quality; productive performance
