Abstract
The objective of this study was to evaluate the performance and the pollutant excretion of broilers from 1 to 21 days of age fed diets with different levels of metabolizable energy (MEn), crude protein (CP) and available phosphorus (aP), supplemented with amino acids and phytase. To evaluate the performance, 1,350 Cobb broilers at one day of age (weight of 45.5 ± 0.9g) were distributed in a completely randomized design in a 4x2+1 factorial arrangement (four levels of MEn – 2,850; 2,950; 3,050 and 3,150 kcal/kg – and two of CP and aP – 17 with 0.34% and 19 with 0.25%, respectively, all with phytase, and an additional treatment – control, without phytase, with 21% PB, 3,000 kcal/kg MEn and 0.46% aP), in six replications with 25 birds. To evaluate the excretion of pollutants, 270 broilers at 14 days of age were allotted in metabolic cages in groups of five during seven days, using the same statistical design. Although the use of phytase reduced phosphorus and copper excretion, it decreased weight gain and increased feed conversion ratio in all studied nutritional plans. In phytase-diets, the energetic levels linearly reduced feed intake and improved feed conversion ratio and calcium and potassium excretion. Energy reduced the nitrogen, phosphorus and zinc excretion only in 17% CP and 0.34% aP diets. Crude protein reduction in phytase-diets improved feed conversion ratio and reduced nitrogen and potassium excretion. It was concluded that phytase decreases broiler performance until the third week of age when combined with reduced levels of CP and aP in diets. KEYWORDS: additive; enzyme; excrement quality; ideal protein; nutrition.
Highlights
Weight gain and increased feed conversion ratio in all studied nutritional plans
Existem relatos de que essa enzima também pode disponibilizar carboidratos, aminoácidos e íons, como fosfato, cálcio, potássio, zinco e cobre (SILVA et al, 2006), podendo, nesse caso, alterar o balanço energético, eletrolítico e de aminoácidos
A inclusão de fitase reduziu (P
Summary
A velocidade de expansão da avicultura vem acompanhada da assimilação contínua de moderna tecnologia, colocando o Brasil no grupo dos três maiores produtores mundiais de carne de frango. Objetivou-se avaliar o fornecimento de dietas com níveis reduzidos de proteína bruta e fósforo disponível, formuladas com diferentes níveis de energia metabolizável aparente corrigida (EMAn), suplementadas com aminoácidos e fitase, sobre o desempenho e excreção de poluentes por frangos de corte de um a 21 dias de idade. Paralelamente, foi conduzido um ensaio de metabolismo no qual foram utilizados 270 pintos da mesma linhagem aos 14 dias de idade, distribuídos em baterias metálicas (50 x 50 x 50cm) providas de bebedouro tipo “copo de pressão” e comedouro tipo calha com bordas de madeira para evitar desperdício, além de bandejas coletoras de excretas, colocadas em sala de metabolismo com ambiente controlado, recebendo luz artificial por 24 horas. Para os cálculos dos valores de EMAn das rações, foram utilizadas as equações descritas por MATTERSON et al (1965) e, para os coeficientes de retenção aparente do nitrogênio, fósforo, cálcio, potássio, zinco e cobre, a seguinte fórmula: Tabela 1 - Composição centesimal das rações experimentais
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