Effect of Using L-Threonine and Reducing Dietary Levels of Crude Protein on Egg Production in Layers

This experiment was conducted to determine the effect of using l-threonine and reducing dietary levels of crude protein (cp) on egg production criteria in layers. three hundred of hy-line w36 laying hens were used in this experiment. this experiment consisted of three experimental treatments with five replications in each. experimental treatments included 3 diets with different levels of cp which were 15, 16 and 17% with 0.1, 0.05 and 0.02% l-threonine supplementation, respectively. experimental period lasted for 5 weeks. in this experiment quantitative factors such as egg mass, egg weight, egg production percentage, feed conver-sion ratio (fcr), body weight and feed intake were measured. measured data were analyzed by completely randomized design (crd). results indicated that reducing dietary levels of cp to 15% and using l-threonine supplementation had no significant effect (p>0.05) on laying criteria. according to economic analysis, the treatment containing 15% cp and 0.1% l-threonine was the most beneficial treatment.