The objective of this study was to evaluate the monoammonium phosphate (MAP) as a source of phosphorus and Paraíso limestone (CP) with higher magnesium levels (1.92%) as a source of calcium for commercial layers. A total of 280 white Dekalb chickens were housed in individual cages during the period from 46 to 58 weeks old. A completely randomized experimental design, with four diets, seven replicates and ten birds per experimental unit were used. The diets were: FBC/CB - dicalcium phosphate and Barroso limestone (gray); FBC/CP - dicalcium phosphate and Paraíso limestone (white); MAP/CB - monoammonium phosphate and Barroso limestone; MAP/CP - monoammonium phosphate and Paraíso limestone. Egg production, mean weight and egg mass; feed intake and feed conversion were evaluate, and also shell percentage and thickness. Egg production, mean egg weight and mass improved with the use MAP with both evaluated limestone. Feed intake and feed conversion improved with utilization of MAP as source of phosphorus. Egg shell percentage and thickness were not affected by calcium source in the diet, hence, the higher level of Mg and finer particles of Paraíso limestone did not impaired egg shell quality. No alterations were observed in feces consistency and survival rate of the layers. The nitrogen excretion was 10% higher for birds that received MAP as a phosphorus source. Monoammonium phosphate could be used as an alternative source of phosphorus replacing dicalcium phosphate; and Paraíso limestone is technically viable for feeding commercial layers without problems for egg production and shell quality.
egg production; limestone; monoammonium phosphate; shell quality
