Reduction of crude protein and amino acid supplementation of diets in the production of broilers

Este trabalho foi realizado para avaliar o efeito da formula??o de dietas que consideram o atendimento das exig?ncias de prote?na bruta, dietas com redu??o dos valores de prote?na bruta e atendimento das exig?ncias de amino?cidos digest?veis e dietas com atendimento das exig?ncias de amino?cidos sobre os par?metros de desempenho, consumo de energia, prote?na, amino?cidos, rendimento de carca?a e cortes, empenamento e custos na produ??o de frangos de corte nas diferentes fases de cria??o. Foram realizados cinco experimentos, conduzidos no setor de Avicultura da UFVJM, no Campus JK, em Diamantina ? MG. As aves usadas nos experimentos foram todas machos, da linhagem Cobb 500. No total, foram usadas 2.430 aves e consideradas as fases de 1 a 7, 8 a 21, 22 a 35, 36 a 42 e 42 a 49 dias de idade. Em todos os experimentos, as aves foram distribu?das segundo um delineamento experimental inteiramente casualizado, com seis tratamentos (T1 ? Dieta-controle formulada de acordo com recomenda??es das Tabelas Brasileiras para aves e su?nos (2011) para atender prote?na bruta e amino?cidos digest?veis; T2 ? Dieta com 5% de redu??o da prote?na bruta da dieta-controle; T3 - Dieta com 10% de redu??o da prote?na bruta da dieta-controle; T4 - Dieta com 15% de redu??o da prote?na bruta da dieta-controle; T5 - Dieta formulada para atender as exig?ncias de amino?cidos digest?veis da dieta-controle com o valor da prote?na bruta livre; T6 - Dieta formulada para atender o valor da prote?na bruta da dieta-controle deixando livre o atendimento dos amino?cidos digest?veis. Na fase de 42 a 49 dias foram utilizadas tr?s repeti??es, mas nas demais fases foram usadas quatro repeti??es por tratamento. Com rela??o ao desempenho das aves, foi observado que, com o atendimento das exig?ncias de amino?cidos digest?veis, ? poss?vel reduzir em at? 10% os valores da prote?na bruta nas recomenda??es nutricionais feitas por Rostagno et al. (2011) e, dessa forma, o desempenho das aves n?o ? afetado. No entanto, dietas formuladas para atender apenas as exig?ncias de amino?cidos digest?veis, pioram o desempenho das aves. De modo geral, n?o houve diferen?as no consumo de energia; por?m, o consumo de prote?na e de amino?cidos diferiu ? medida em que se alterou os n?veis de prote?na bruta e amino?cidos digest?veis das dietas. A redu??o dos valores de prote?na bruta das dietas em at? 15% n?o afetou o rendimento de carca?a e cortes, mas as dietas formuladas para atender apenas ?s exig?ncias de amino?cidos digest?veis causaram pioras no rendimento de carca?a e carne do peito das aves. O empenamento das aves n?o foi afetado pelas dietas avaliadas. As an?lises de custos realizadas mostraram que dietas formuladas para o atendimento da prote?na bruta apresentam menor custo; por?m, at? os 35 dias, a redu??o de at? 10% dos valores da prote?na bruta com suplementa??o de amino?cidos digest?veis melhoram o custo do ganho em peso das aves.Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Zootecnia, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2012.ABSTRACT This study was conducted to evaluate the effect of diet formulation considering the attendance of crude protein, diets with reduced crude protein values and requirements of digestible amino acids and diets to meet the amino acid requirements on parameters performance, energy consumption, protein, amino acids, carcass yield and cuts, feathering and costs in the production of broiler chickens at various stages of creation. We conducted five experiments, conducted in the experimental aviary of UFVJM on campus in JK Diamantina - MG. The birds used in the experiments were all male, the strain Cobb 500. In total 2430 birds were used and considered stages 1-7, 8-21, 22-35, 36-42 and 42-49 days of age. In all experiments, the birds were distributed according to a completely randomized design with six treatments (T1 - diet control and formulated in accordance with recommendations of Rostagno et al. (2011) to meet crude protein and digestible amino acids, T2 - diet 5% reduction in crude protein diet control, T3 - diet with 10% reduction of crude protein in the control diet; T4 - diet with 15% reduction of crude protein in the control diet; T5 - diet formulated to meet the requirements the digestible amino acids of diet control with the amount of crude protein free; T6 - diet formulated to meet the amount of crude protein diet control with the amount of digestible amino acids free). In the period from 42 to 49 days were three replicates, but in the other phases were used four replicates per treatment. The performance of the birds, it was observed that, with the assistance of digestible amino acid requirements can be reduced up to 10% of the crude protein nutritional recommendations made by Rostagno et al. (2011), that performance is not affected. However, diets formulated to meet only the requirements of digestible amino acids, decrease the performance of the birds. In general, no differences in energy consumption, however, the consumption of protein and amino acids differ as altered levels of crude protein and digestible amino acid diets. The decreased levels of dietary crude protein up to 15% did not affect carcass yield and cuts, but the diet formulated to meet only the requirements of digestible amino acids, caused decrease in carcass and breast meat of birds. The feathering of the birds was not affected by the diets evaluated. The cost analysis performed showed that diets formulated to meet crude protein have a lower cost, however, up to 35 days, a reduction of up to 10% of the crude protein supplementation with digestible amino acids, improve the cost of weight gain birds