The objective of this work was to determine the nutritional value of corn of four different qualities, obtained by stratification in densimetric table, for broilers at different ages. The corns were designed as: MDA - high density corn; MDI - medium density corn; MDB - low density corn and MDO - original density corn, composed of 25% MDA, 50% MDI and 25% MDB. Three biological assays were carried out by using the traditional total excreta collection method for determination of nitrogen corrected apparent metabolizable energy (AMEn). The first metabolism assay was carried out with Cobb chicks at 14 to 17 days of age, the second assay with chicks at 25 to 28 days of age and the third with chicks at 38 to 41 days of age. Chemical analyses were made for determination of the nutritional profile, classification of the grains according to density and comparison by estimates of energy value prediction equations. The values of AMEn of corns of different qualities (MDA, MDI, MDB and MDO) determined in broilers in initial phase were: 3562, 3382, 3198 and 3357 kcal/kg for growth phase and for final phase they were 3576, 3555, 3229 and 3416 kcal/kg and for the finish phase they were 3610, 3554, 3354 and 3585 kcal/kg, respectively. These results prove that significant energy losses of the lowest quality corns and the efficiency of the densimetric table to stratify the grains. The different AMEN values among ages of the birds suggest better energy use efficiency as age increases. The prediction equations can be used to estimate energy value of corn by its classification and by chemical analyses as well. However, the systematic error associated to each prediction equation can compromise the accuracy of the nutritional value.
gravity table; metabolizable energy; prediction equation
