Desempenho, carca？a e cortes de frangos caipira Francês Barré (Gris Barré Cou Plumé)

this study aimed to analyze the effects of metabolizable energy levels and the age at slaughter on growth performance, carcass yield and cuts broilers caipira french barré. the experiment was conducted in parauapebas, pa. we used 192 one day chicks reared in intensive system. the experimental design was completely randomized with three treatments. each treatment consisted of four replications, the experimental unit being a box of 16 birds. the treatments were defined according to the levels of metabolizable energy diets (1 to 28 days) and late (29 to 90 days),respectively: t1 - 3000 and 3100 kcal of me/kg, t2 - 3100 and 3200 kcal/kg, t3 - 3200 and 3300 kcal of me/kg. the variables studied were initial weight, final weight, feed intake and feed conversion, protein consumed, metabolized protein consumed, energy efficiency and protein efficiency. the characteristics of carcasses of birds, analyzed with 77, 84 and 91 days of age were the carcass, breast, thigh, drumstick, wing, back, wings, feet, head and neck. the statistical analysis was performed using the anova procedure for a completely randomized model with the system for statistical analysis and genetics (saeg, 2007). differences between means of variables were performed by tukey's test at a level of 5%. the energy levels in the diets did not affect on the performance and carcass yield, breast, thighs, drumsticks, wings, feet and head + neck in birds. the level of 3200 kcal/kg provided better yield back. the protein and metabolic energy consumed by the birds improved with higher energy content of feed during the fattening stage. age at slaughter did not affect carcass yield, however the birds slaughtered at 90 days of age showed higher breast yield.