Requirements of digestible methionine + cystine for broiler chickens at 1 to 42 days of age

C.C Goulart,J.G Souza,C.F.S Oliveira,F.G.P Costa,V.P Rodrigues,J.H.V Silva

doi:10.1590/s1516-35982011000400013

C.C Goulart, J.G Souza + Show 4 more

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https://doi.org/10.1590/s1516-35982011000400013

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Abstract

The objective of this work was to estimate requirements of digestible methionine + cystine for broiler chickens from 1 to 42 days of age. It was carried out four experiments for each one of the following phases: pre-initial, initial, growing and final. The birds were distributed in a completely randomized experimental design, with six treatments and six replicates. Treatments consisted of a basal feed for each phase, deficient in digestible methionine + cystine and supplemented with DL-methionine to supply six levels of digestible methionine + cystine, resulting in different digestible methionine + cystine:digestible lysine ratios. In the pre-initial phase, levels of digestible methionine + cystine did not influence feed intake and feed conversion. However, weight gain responded in a quadratic way. In the initial phase, levels of digestible methionine + cystine had decreasing linear effect on feed intake whereas weight gain and feed conversion were influenced in a quadratic manner. In the growth and final phases, feed intake was not influenced by levels of digestible methionine + cystine, but weight gain and feed conversion presented quadratic response. The levels of 0.873; 0.755; 0.748 and 0.661% of digestible methionine + cystine in the diet or the daily intake of 183; 575; 1,104 and 1,212 mg of digestible methionine + cystine are recommended for the pre-initial, initial, growth and final phases, respectively, which corresponds to the ratios of 71; 70; 76 and 72% of digestible methionine + cystine to digestible lysine.

Highlights

Protein is a key nutrient in poultry nutrition and has a significant share in the cost of the diet formulation, directly influencing feed conversion, carcass quality, and weight gain of animals
In the growth and final phases, feed intake was not influenced by levels of digestible methionine + cystine, but weight gain and feed conversion presented quadratic response
The levels of 0.873; 0.755; 0.748 and 0.661% of digestible methionine + cystine in the diet or the daily intake of 183; 575; 1,104 and 1,212 mg of digestible methionine + cystine are recommended for the pre-initial, initial, growth and final phases, respectively, which corresponds to the ratios of 71; 70; 76 and 72% of digestible methionine + cystine to digestible lysine

Summary

Introduction

Protein is a key nutrient in poultry nutrition and has a significant share in the cost of the diet formulation, directly influencing feed conversion, carcass quality, and weight gain of animals. A better understanding of the nutritional requirements of individual amino acids allows a more precise nutrition, offering the possibility for the formulator to partially replace the requirement of at least minimum levels of crude protein by essential amino acids requirements, generating lower costs for the producer and lower emissions to the environment (Suida, 2001). The sulfur amino acids methionine and cystine are limiting in diets for commercial broilers (Fatufe & Rodehutscord, 2005), making it essential to supplement the diet with synthetic methionine for best performance and economic results. According to Al-Mayah (2006), methionine can be economically added in most diets for broilers, which reduces the levels of crude protein and, the quantities of soybean meal in those diets. The requirements of these amino acids are usually considered together as requirements for methionine + cystine

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