The aim of thiswork was to evaluate the effects of the reduction on nutritional levels of dietsfor semi-heavy hens during the laying peak on performance, egg quality and boneparameters. A total of eight diets were evaluated, each one with five repetitionsof eight birds: 1) control: formulated to supply requirements by the birds;2) control + 0.03% or 600 FTU; 3) 15% crude protein; 2,800 kcal ME; 3.8% Caand 0.28% aP; 4) diet 3 + 0.03% or 600 FTU; 5) 14% crude protein; 2,750 kcalME; 3.4% Ca and 0.23% aP; 6) diet 5 + 0.03% or 600 FTU; 7) 13% crude protein;2,700 kcal ME; 3.0% Ca and 0.18% aP; and 8) diet 7 + 600 FTU. The reductionof the nutritional levels harmed the performance of the birds, particularlyegg production and egg mass, which improved by the inclusion of phytase in thediets. However, the parameters for egg quality did not change as the level wasreduced down to 15% crude protein; 2,800 kcal ME/kg; 3.80% Ca and 0.280% aP,which was not repeated in the levels with lower nutritional density. Reductionof nutritional levels did not affect the evaluated bone parameters, except forresistance, which improved as phytase was added at the level 600 FTU. Reductionon the diet nutritional levels to 15% crude protein; 2,800 kcal ME/kg; 3.80%Ca and 0.280% aP with the addition of 600 FTU of phytase does not impair eggproduction neither egg mass and improve the bone health of birds.
