Níveis de metionina+cistina digestíveis para aves leves na fase de reposição e seus efeitos residuais

Abstract

The objective was to determine the nutritional requirement of methionine and cystine (ASF) digestible for replacement light pullets 1 to 6 weeks and 7 to 12 weeks of age and evaluate the effects on egg production phase. Were developed eight experiments, divided into four experiments from 1 at 6 weeks and four experiments in phase 7 to 12 weeks of age, at different production stages: initial (1 to 6 weeks), create (7 to 12 weeks), pre laying (18 to 29 weeks), posture I (33 a 49 weeks) and posture II (54 to 70 weeks). It was used a completely randomized design with six levels of methionine and cystine, six replicates and 30 birds per experimental unit (UE) for the initial phase, six replicates and 15 birds/UE for the create phase, eight replicates and 10 birds/UE in pre laying phase, six replicates and 8 birds/UE for posture I phase, and seven replicates and 4 birds/UE for posture II. The dietary treatments consisted of a positive control that met requirements of ASF according to the NRC (1994), and five other diets with levels of digestible ASF formulated based Brazilian tables nutritional requirements, equivalent to 80, 90, 100, 110 and 120% of the nutritional requirements for initial and create phases. Were evaluated performance data and serology in the initial and create phases, and performance and egg quality in pre laying and posture phases. For initial phase there was a quadratic effect on feed intake, feed conversion, lysine intake, enzymatic activity of alanine aminotransferase, gamma-glutamyltransferase, serum creatinine and albumin due to levels of ASF digestible, and the requirements for these characteristics 89.78% (0.575%), 114.33% (0.732%), 89.37% (0.572%), 100% (0.640%), 100.40% (0.643%), 104.30% (0.668%) and 111.88% (0.716%), respectively. For create phase there was a quadratic effect on final body weight, weight gain, feed conversion and enzymatic activity of gamma-glutamyltransferase due to levels of ASF digestible, and the requirements for these characteristics 110.60% (0.550%), 111.22% (0.553%), 104.83% (0.521%) and 99.47% (0.494%), respectively. Based on the results obtained and the xxi biological responses of birds during the study, is recommended to use of 0.516% methionine and cystine digestible, which corresponds to an intake of 104.21 mg/bird/day, and a relationship with lysine of 83%, for replacement light pullets with 1 at 6 weeks of age, and the use of 0.521% methionine and cystine digestible, which corresponds to an intake of 234.15 mg/bird/day, and a relationship with lysine of 84%, for replacement light pullets with 7 at 12 weeks of age.