عنوان مقاله [English]
This study was conducted to evaluate the effects of different levels of urea and energy in diets on performance, egg quality traits and blood parameters of laying hens. This experiment was conducted with two hundred and eighty eight Hy Line- W36 laying hens from 35 to 46 weeks of age as 3*2 factors with 3 levels of urea (0, 0.25%, and 0.5%) and 2 levels of metabolizable energy (ME) (2800 and 2900 kcal/kg) in 6 treatments, 4 replicates and 12 hens in each replicate in a completely randomized design. In diet with 2900 kcal/kg ME egg production percentage, egg mass, feed conversion ratio, eggshell weight, albumin weight and Haugh unit in contrary with diet contained 2800 kcal/kg ME improved. Laying hens had the best performance, egg quality traits and the lowest feed price/per kilogram of egg with diet contained 0.25% urea. Using different levels of ME and urea in diets did not have any significant effects on blood parameters of laying hens, however in interaction effects of ME and urea in diets, the lowest level of cholesterol was observed in diet contained 2900 kcal/kg ME without urea using and the lowest amount of blood albumin obtained in diet contained 2900 kcal/kg ME and 0.25% urea. The overall results indicated that in laying hens from 35 to 46 weeks of age, using diet with 2900 kcal/kg metabolizable energy and 0.25% urea improve the performance and egg quality traits and reduce the production price.