Performance of laying hens on diets with different levels of protein

There is little information on the use of low-protein diets with the ideal protein profile for laying hen. An experiment was conducted to evaluate the layer performance of hen with low crude protein diets with the ideal protein profile. 240 hens Hy-Line W36 were used from 26 to 44 weeks of age, and the treatments were distributed among the experimental units in four treatments with five replicates of 12 birds each. The experimental design was completely random. The hens were fed sorghum plus soybean meal diets and synthetic amino acids formulated to 13, 14, 15 and 16% crude protein with similar levels of digestible amino acids lysine 0.725% (100), 0.596% methionine and cystine (82), threonine 0.509% (70) and tryptophan 0.179% (25). The variables studied were feed intake, egg production, egg weight, egg mass per bird d(-1) and feed conversion. An analysis of repeated observations and a regression analysis with quadratic transformation was determined with each level of crude protein. Furthermore, we calculated the value of protein to maximize performance using the derivative of the regression formula. There was a quadratic effect (P <= 0.05) for egg production, egg weight, egg mass ave d(-1) and feed consumption. The data analysis suggests that for better bird egg mass d(-1) of laying hen Hy-Line W36, 15.3% crude protein is required in the diet. The relationship lysine-arginine and lysine-valine could be limiting for diets with 13% crude protein.