Two trials were carried out to evaluate performance, balance and retention of EE, DM and CP and biometrical measures of digestive organs of broiler chicks fed different dietary CP levels in the pre-starter period (1 - 7 d). In the first experiment, 560 one-day-old Avian Farms chicks were allotted to a complete randomized design with ten treatments, with a 5 x 2 (protein levels: 18, 20, 22, 24, and 26% x sex) factorial arrangement and four replicates of 14 birds each. In the second experiment, 1,860 one-day-old Ross chicks were assigned to 2.0 x 2.5 m experimental pens. This experiment was analyzed as a complete randomized design, with five treatments (protein level - 18, 20, 22, 24, and 26%) and six replications of 62 birds each. In the first experiment, increasing dietary CP levels in the pre-starter period did not affect performance, but balance and retention of EE had linear and positive effects according to the treatments. No treatment effect on protein balance was observed, but protein retention showed linear and positive effect. No significant differences were observed for biometrical measures on 4th fday of experiment, but increasing CP levels improved the pancreas relative weight. In the experiment 2, it was possible to conclude that the higher protein levels are indicated for better results in performance.
digestive organs; nutritional balance; performance; pre-starter
