An experiment was carried out to evaluate different formulated feeds for broilers from 43 to 49 days of age. Six hundred male Cobb broilers were distributed in a completely at random experimental design with 3 treatments (3 different criteria of feed formulation) and 4 repetitions per treatment, with 50 birds each. Diets were formulated with different criteria of digestible amino acid inclusion (methionine, methionine+cystine, lysine and threonine), according to the profiles recommended by Baker and Chung (1992), Degussa (1997) and Rostagno (2000) Live performance and carcass yield were evaluated in birds fed the different diets from 43 to 49 days of age). The profile established by Degussa (1997) resulted in best live performance. All profiles supplied the nutritional requirements of the birds for adequate carcass yield, but Degussa (1997) profile resulted in highest breast yield.

O objetivo do experimento foi avaliar os efeitos do tamanho da partícula do fosfato bicálcico (fina ou granulada) e dos níveis de fósforo total sobre o desempenho de frangos de corte e sobre os teores de cálcio, fósforo e magnésio dos ossos. O delineamento experimental utilizado foi o inteiramente casualizado em esquema fatorial 3x2 com 3 níveis de fósforo total (0,5%; 0,6% e 0,7%) e duas granulometrias de fosfato bicálcico (fina e granulada). Foram utilizados 300 pintos de corte com um dia de idade, machos, da linhagem Cobb, alojados em baterias metálicas em 6 tratamentos com 5 repetições de 10 aves, totalizando 30 gaiolas dispostas em 6 baterias de 5 andares cada. Os resultados demonstraram que o uso do fosfato granulado resultou em melhor desempenho dos animais. Aves alimentadas com o nível de 0,5% de fósforo total apresentaram o pior desempenho, sendo que o nível de 0,6% proporcionou melhor desempenho das aves. As diferentes granulometrias do fosfato, não diferiram estatisticamente quanto a percentagem de matéria mineral, cálcio, fósforo e magnésio nos ossos.

The objective of the experiment was to evaluate the effects of particle size of dicalcium phosphate (fine or granulated) and of the levels of total phosphorus on the performance of broilers and levels of calcium, phosphorus and magnesium of the bones. Three hundred one-day chicks, males, Cobb strain, were used in an experimental design involving six treatments in a factorial arrangement 2x3 (2 particles size of dicalcium phosphate and 3 phosphorus levels of 0,5%, 0,6% e 0,7%). It was concluded that the addition of granulated dicalcium phosphate resulted in a better performance. The level of 0,5% total phosphorus depressed body weight gain, feed intake and feed conversion and level 0,6% showed better performance. Total bone ash and bone calcium were not affected by treatments, however, better bone phosphorus was found when the broilers received the diet with 0,7% total phosphorus. Particle size did not influence the content of ash, calcium, phosphorus and magnesium levels of the bone.