Performance traits of seven genetic groups (M1C1, C1C1, C2C2, M1C2, C2F1, C1F1, M1F1) of broilers obtained from crosses of two genetic groups developed by UFV (M1 and F1) and two commercial lines (C1 and C2) was studied. The birds were randomly allotted in 84 boxes (15 birds/box) whith 12 replicates. In the first period (1 to 21 days) the birds were fed on diet with 3000 kcal of EM/kg, and in the second period (22 to 42 days) they were fed on diets with four different levels of energy (2900, 3050, 3200 and 3350 kcal EM/kg). The following traits were analyzed: feed intake, weight gain and feed:gain ratio in the first (1 to 21 days), and second (22 to 42 days) periods and in total period (1 to 42 days of age). In the first period, significant differences among the genetic groups for weight gain and feed intake were observed, but no significant differences among the groups for feed:gain ratio were found. In the second period and in the total period, significant differences among the genetic groups and levels of energy for feed intake, weight gain and feed:gain ratio were observed. The effect of the levels of energy was linear for all traits studied.
Broiler; genetic group; energy level; performance
