RESUMO -Dois experimentos foram conduzidos para avaliar o desempenho, o balanço e a retenção de MS, EE e PB e os parâmetros biométricos do trato gastrintestinal de frangos de corte recebendo diferentes níveis de proteína na ração pré-inicial (1 a 7 dias). No experimento 1, 560 pintos Avian Farms foram distribuídos em baterias segundo um delineamento inteiramente casualizado, em esquema fatorial 5 x 2 (cinco níveis de proteína, 18, 20, 22, 24 e 26%, e dois sexos), com dez tratamentos, cada um com quatro repetições de 14 aves. No experimento 2, 1.860 pintos machos e fêmeas Ross foram distribuídos em boxes de 2,0 x 2,5 m, em um delineamento em blocos casualizados, com cinco tratamentos (níveis de proteína, 18, 20, 22, 24 e 26%), cada um com seis repetições de 62 aves. No experimento 1, os níveis crescentes de PB da dieta não afetaram significativamente os dados de desempenho, mas o balanço e a quantidade retida do EE promoveram efeito linear positivo. O balanço de proteína não foi afetado, mas a retenção de proteína apresentou efeito linear positivo. A biometria dos órgãos não foi significativamente influenciada aos quatro dias. Nos períodos seguintes, os níveis crescentes de proteína afetaram positivamente o peso relativo do pâncreas. No experimento 2, observou-se, com base nos resultados de desempenho, que os mais altos níveis de proteína na ração pré-inicial atenderam às necessidades nutricionais das aves.Palavras-chave: balanço nutricional, desempenho, dietas, órgãos digestivos Performance, nutrient balance and retention and biometrical measures of digestive organs of broilers fed different dietary protein levels in the prestarter period AB STRACT -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 4 th 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.

-Two experiments were carried out (pre-starter and starter phases) to evaluate the effect of feather and blood meal on performance, organ development and digestibility and retention of nutrients in broilers. In the first experiment, it was used 280 birds and in experiment 2, it was used 240 birds. The experimental diets were formulated with four levels of feather and blood meal (0%, 2%, 4% and 6%) all of them isonutritive and isoenergetic. A metabolic assay was developed on the 4 th and 7 th days of age in experiment 1 and on the 14 th and 17 th days of age in experiment 2. In these periods, one bird per experimental unit was sacrificed for determination of morphometry of the digestive organs. In experiment 1, in which it was evaluated the pre-starter phase, there was a negative linear effect of the levels of feather and blood meal on weight gain and intake in 1-21 day of age period. By using feather and blood meal in the diet, it was observed a linear effect on digestibility coefficient of dry matter, nitrogen and ether extract; there was a quadratic effect on retention of dry matter and nitrogen and linear effect on the retention of ether extract. However, performance of birds in the starter phase (experiment 2) was not affected by levels of feather and blood meal used in the diet. Coefficient of digestibility of dry matter and ether extract and retention of ether extract were affected. In both phases, mortality and morphometric data of digestive organs were not influenced by the levels of meal in the diet. Formulation of diets with up to 6% feather and blood meal for chickens in the pre-starter phase (from 1 to 7 days) is not a good alternative because it worsens performance of birds. However, from the initial phase (from 8 to 21 days), the use of feather and blood meal in the diet is viable. Feather and blood meal can be used at levels 3.0 or 4.0% for broilers in the pre-starter and starter phase.

RESUMORealizaram-se dois experimentos com 1008 pintos machos Ag-Ross 508 em cada um deles. No primeiro, avaliou-se o desempenho de frangos de corte alimentados com diferentes níveis de gérmen integral de milho (GIM) na dieta de um a sete dias de idade (fase pré-inicial). No segundo, avaliou-se o desempenho e o rendimento de carcaça no período de oito a 47 dias. As aves foram alojadas em 16 unidades, divididas em quatro tratamentos, de acordo com os níveis de GIM, em substituição ao milho na dieta (0%, 33%, 67% e 100%), e quatro repetições de 63 aves cada. Utilizou-se o delineamento inteiramente ao acaso, e os dados foram analisados por regressão polinomial. O GIM não foi um bom alimento para a fase pré-inicial. A inclusão recomendada do GIM foi de 21,9% e 22,5% nos períodos de oito a 21 dias e de 22 a 38 dias, respectivamente. Não houve restrição do uso do GIM na fase final.

RESUMO -Um experimento foi conduzido com o objetivo de avaliar níveis de energia metabolizável em rações para frangos de corte na fase pré-inicial de crescimento. Foram alojados 280 pintos de 1 dia de idade, linhagem Avian Cobb em baterias aquecidas e distribuídas em um delineamento inteiramente casualizado com cinco tratamentos (2.850, 2.950, 3.000, 3.050, 3.150 kcal/kg de EM na ração) e quatro repetições de 14 aves por unidade experimental. Foram medidos os pesos das aves e das rações fornecidas e as sobras nos 1, 4, 7, 10, 14, 18 e 21 dias de idade e as características de desempenho determinadas (ganho de peso médio, consumo de ração e conversão alimentar) nos períodos de 1 a 7 e de 1 a 21 dias de idade. Realizou-se um ensaio de digestibilidade durante a primeira semana entre o quarto e o sétimo dias. Metabolizable energy levels in broiler pre-starter dietsABSTRACT -This experiment was carried out to evaluate the dietary metabolizable energy levels for broilers in the preinitial growth phase. A total of 280 Avian × Cobb one day old chicks was allotted to warm cages as a completely randomized design with five treatments (2,850, 2,950, 3,000, 3,050, and 3,150 kcal/kg of ME in the diet) and four replicates of 14 birds per experimental unit. Bird weight and diet and orts weights were measured at 1, 4, 7, 10, 14, 18 and 21days old and the performance characteristics determined (average weight gain, feed intake, feed-to-gain ratio) from 1 to 7 and 1 to 21 days.A digestibility assay was performed during the first week between the 4 th and 7 th days. The results showed that the evaluated ME levels influenced the performance of the birds from 1 to 21 days old, however, the lowest level of ME resulted in worst DM digestibility values. The lowest levels, 2,850 kcal ME/kg, provided better broiler performance, while the 3,115 kcal ME/kg provided better DM digestibility in corn-soybean based diets.

-The use of viscera and bone meal in poultry pre-starter and starter diets and its effects on performance, digestive organ development and digestibility and nutrient retention were evaluated. In the first assay, 280-day-old Avian Cobb ® chicks were allotted in four experimental groups with five replicates of 14 birds each, in the pre-starter phase; in the second assay, 280 eight-day-old Avian Cobb 48 ® chicks were allotted in four experimental groups with five replicates of 12 birds each. The experimental diet consisted of increasing levels of viscera and bone meal: 0% (control diet), 3%, 6% and 9% in pre-starter (Assay 1) and starter (Assay 2) diets, to meet nutritional requirements and feed composition proposed by the Brazilian Tables, all of them isonutritive and isoenergetic. A metabolic assay was developed and the total excreta collection was performed from the 4 th to the 7 th days in Assay 1 and from the 14 th to the 17 th days in Assay 2. On these days, one chick per experimental unit, representing the mean body weight of the parcel, was euthanized to perform digestive organ