Amino acid reduction in broiler diets supplemented with phytase and elaborated according to different nutritional plans

Abstract

The need for suitable diets in chickens, considering the ideal protein concept associated with phytase, is important in order to improve the productivity of birds. The aim of this study was to assess the need for the correction of amino acid levels in the diets of broilers, by using different combinations of crude protein (CP) supplemented with phytase. For performance, eight days old Cobb 875 broiler chicks, with initial body weights of 155 ± 1.4g were used. The birds were distributed in a completely randomised design with seven treatments (nutritional plans) and five replicates of 25 birds. For the metabolism trial, 300 birds were selected which were also distributed using the same design, but with five, four and three birds per experimental stage: 8-21 days, 22-35 days and 36-42 days. The nutritional plans consisted of different combinations of CP in diets with reduced calcium and phosphorus, supplemented with phytase and amino acids. The reduction of amino acids in diets with reduced levels of CP resulted in an increased intake, feed conversion and abdominal fat level, and decreased the yield of thigh + drumstick. The inclusion of phytase reduced the excretion of calcium and phosphorus, but increased nitrogen excretion when the CP was not reduced. As a result, this study concluded that the reduction of amino acids to 3.5%, supplemented with phytase and prepared according to a nutritional plan does not improve the performance and carcass characteristics of broilers, although it may reduce the emission of polluting elements by excreta. Index terms: Carcass characteristics, ideal protein, nutrition, performance RESUMOA necessidade de dietas adequadas para frangos, considerando o conceito de proteína ideal associada à fitase, é importante para melhorar a produtividade das aves. Objetivou-se avaliar a necessidade de correção dos níveis de aminoácidos em rações para frangos de corte, formuladas em diferentes combinações de proteína bruta (PB) e suplementadas com fitase. Para o desempenho, foram utilizados 875 pintos de corte Cobb, com oito dias de idade e peso inicial de 155±1,4g. As aves foram distribuídas em delineamento inteiramente casualizado, com sete tratamentos (planos nutricionais) e cinco repetições de 25 aves cada. Para o ensaio de metabolismo, foram selecionadas 300 aves que foram também distribuídas no mesmo delineamento, porém com cinco, quatro e três aves por parcela experimental nas fases de 8 a 21, 22 a 35 e 36 a 42 dias. Os planos nutricionais consistiram em diferentes combinações de PB em rações com cálcio e fósforo reduzidos, suplementadas com fitase e aminoácidos. A redução de aminoácidos em dietas com teores reduzidos de PB aumentou o consumo, a conversão alimentar e a gordura abdominal e diminuiu o rendimento de coxa + sobrecoxa. A inclusão de fitase reduziu a excreção de cálcio e de fósforo, porém aumentou a de nitrogênio quando a PB não foi reduzida. Conclui-se que a redução de aminoácidos em 3,5% em rações para frangos de corte suplementadas com fitase e elaboradas segundo um plan...

Protease Supplementation under Amino Acid Reduction in Diets Formulated with Different Nutritional Requirements for Broilers

“…In order to meet broiler's requirements, different nutritional recommendations can be used in association with enzymes added to diets (Oliveira et al, 2012). Crude protein and digestible lysine levels are the variables with highest variation among nutritional plans, as they are among the most expensive components and an excess or deficiency will lead to amino acid imbalance.…”

Phytase and amino acids for broilers from 36 to 42 days of age

“…Similarly, an effective way to decrease the N excretion is to reduce the crude protein (CP) rate from the diet and use synthetic amino acids to meet the nutritional requirements of the broilers (Oliveira et al, 2012). However, the CP minimum level necessary to allow good results with broiler chickens from 36 to 42 days old is not well established yet.…”