Digestible Arginine Requirements in Hy-Line W-۳۶ Laying Hens: Effects on Performance, Egg Characteristics, and Plasma Parameters During ۴۰ to ۴۶ Weeks of Age

This study was conducted to estimate digestible arginine (Arg) requirements for performance and egg quality parameters in Hy-Line W-۳۶ laying hens from ۴۰ to ۴۶ weeks of age. A total of ۱۵۰ laying hens were arranged in a completely randomized design with ۵ treatments, ۵ replicates and ۶ hens in each. These treatments included ۰.۸۱, ۰.۸۶, ۰.۹۱, ۰.۹۶, and ۱.۰۱ % digestible Arg. At the end of experiment, data were obtained in performance, egg quality, and quantity parameters as well as plasma levels of cholesterol, uric acid, globulin, and insulin-like growth factor (IGF-۱). Results have shown that feed conversion ratio, egg production, and egg mass improved by supplementing ۰.۸۶ digestible Arg in the diet compared to other treatments (P < ۰.۰۵). Moreover, these items significantly affected by the interaction of treatments and weeks. In the last three weeks of this experiment, the use of ۰.۸۶, ۰.۹۱, ۰.۹۶, and ۱.۰۱ % digestible Arg significantly increased egg mass and egg roduction. Plasma concentrations of globulin, cholesterol, and uric acid were not affected by dietary Arg levels. However, a significant increase in plasma IGF-۱ was shown by supplementation of % ۰.۹۱ Arg (P < ۰.۰۵). Based on quadratic equations, the optimum levels of digestible Arg for egg production, egg mass, feed conversion ratio, and IGF-۱ were ۰.۹۱۷, ۰.۹۱۷, ۰.۹۰۸, and ۰.۹۷۰%, respectively.