RESUMEN
Two experiments were conducted in order to evaluate the effects of different dietary amino acid and calcium profiles on the bone characteristics of two chicken strains (Avian Farms and Cobb) during the starter phase. At the end of each experiment, 2 chickens of each replicate were sacrificed and their tibiae were collected for analysis of following bone characteristics: bone measurements (weight, length and thickness of the compact and spongy layers) and bone density (bone densitometry). A total of 540 birds were used in each experiment, divided into fully randomized blocks with a 3 x 2 factorial schemes, i. e., 3 amino acid profiles (methionine, lysine and threonine ¡ 100 per cent, 125 per cent and 150 per cent of NRC recommendations, 1994) and 2 calcium levels (75 per cent and 100 per cent of NRC recommendations, 1994), with 30 birds per replicate. Birds of the Cobb strains fed 75 per cent of the recommended calcium allowance showed lower bone density. Calcium level significantly affected the weight and thickness of the spongy layer of the tibia. In birds of the Avian strain, bone density and measurements were not affected by any of the experimental treatments.