Influence of Added Synthetic Lysine in Low-Protein Diets with the Methionine Plus Cysteine to Lysine Ratio Maintained at 0.75

Abstract

Two studies were conducted to determine the influence of added synthetic lysine to low-protein diets. The purpose of experiment 1 was to determine the correct Met+Cys/Lys ratio in low-protein diets. The objective of experiment 2 was to determine the influence of added synthetic lysine in low-protein diets with the Met+Cys/Lys ratio maintained at 0.75. In both experiments, there were 8 replicates per treatment with 15 Hy-Line W-36 hens (37 wk old) in each replicate. Experiment 1 had 4 Met+Cys/Lys ratios (0.75, 0.80, 0.85, and 0.90), and experiment 2 was a 2 × 4 factorial arrangement of treatments with 2 protein levels (14.3 and 13.6%) and 4 added synthetic lysine levels (0.000, 0.025, 0.050, and 0.075%). The results of experiment 1 showed no difference (P > 0.05) in performance among 4 Met+Cys/Lys ratios from 0.75 to 0.90, indicating a Met+Cys/Lys ratio of 0.75 was adequate. The results of experiment 2 showed that beneficial effects (P < 0.05) of added synthetic lysine were obtained for feed consumption, egg production, egg mass and egg weight at 13.6% protein level, and for feed conversion at 14.3% protein level, indicating that the quality of low-protein diet can be improved by added lysine when the Met+Cys/Lys ratio is maintained at 0.75.