Lysine level increases live performance and breast yield in male broilers

Recent data have clearly demonstrated that feeding starting broilers diets containing higher levels of lysine (Lys) than recommended by the NRC improv es broiler performance. In addition, there are data suggesting the Lys requ irement for meat yield is higher than the level considered adequate for fee d conversion. Two experiments evaluated the effects of adequate and supplem ental Lys levels (93 to 133% of the 1984 NRC for birds 1 to 48 days old in Experiment 1; 97 to 157% of the 1984 NRC for birds 21 to 52 days old in Exp eriment 2) on broiler performance and carcass muscle development. Body weight was maximized in birds fed 113% of the NRC in Experiment 1 and 109% of the NRC in Experiment 2. Feed conversions were optimized by feeding 103% and 121% of the NRC Lys recommendation in Experiments 1 and 2, respec tively. Breast meat weight and proportional yield were significantly increa sed in Experiment 1, with the greatest improvement achieved by feeding broi lers 113% of the NRC Lys recommendation. In Experiment 2, increasing dietar y Lys up to 121% of the NRC recommendation significantly increased breast m eat weight and proportional yield, with no improvement at higher levels. Th e results of this study indicate that male broiler performance and breast m eat yield are improved by feeding Lys levels well above what is considered adequate by the NRC.