An experiment was conducted aiming to verify the effect of different levels of available phosphorus (AP) in the diet on performance, egg quality, bone tissue and percentages of P, Ca and Mg in excreta produced by quails during the final third of the production cycle. A total of 300 Japanese quails, with 313 days of age, was assigned to 30 experimental units of ten birds. A completely randomized design was used, with five levels of AP (0.15, 0.25, 0.35, 0.45 and 0.55%), with six replicates per treatments. The experimental diets were isoproteic (20.0% CP), isocaloric (2.900 kcal ME/kg), isocalcium (3.0% Ca) and isoaminoacidic. The increasing levels of AP in the diet linearly increased the concentration of Ca and Mg in the tibia; however, it linearly reduced the height of eggs analyzed. There was quadratic effect for specific gravity, weight and shell percentage, shell percentage of Ca and P in the tibia, achieving maximum points with the use of 0.43, 0.41, 0.42, 0.27 and 0.42% AP, respectively. Quadratic effects were also observed for excretion of Ca, P and ash, yielding maximum values with the use of 0.34, 0.30 and 0.43% AP in the diet. For other parameters, there was no effect of dietary phosphorus. Diet containing 0.15% AP satisfactorily meets the performance and maintenance of the physical integrity of the egg, in addition to reducing P excretion, without any loss caused by problems with egg shell nor occurrence of cage fatigue by weakening of the bone system, although there is reduction in the mineralization of the shell and bone tissue of Japanese quail in the final third of the production cycle (45 to 57 weeks of age).
bone tissue; Coturnix coturnix japonica; egg quality; productive performance
