The Efficiency of Energy and Protein of Broiler Chickens Fed on Diets with Different Lysine Concentrations

An experiment was conducted to evaluate the performance and carcass yield of broilers fed diets (starter and grower) with different levels of lysine requirements, very high lysine (120% NRC), high lysine (110% NRC), standard (100% NRC) and low lysine (90% NRC) in a completely randomized experimental design. All diets were isocaloric and isonitrogenous. In broilers receiving very high lysine (120% NRC), body weight in 42 days significantly increased by 248 g compared with standard lysine diet. Feeding broilers with very high lysine diets (120% NRC) significantly increased protein and energy intake (starter, grower and 0- 42 days of age) compared with others treatments (p<0.05). Lysine efficiency was significantly difference in all of periods of trail (p<0.05) and very high lysine levels was significantly greater than standard treatment. Protein Efficiency Ratio (PER) and Energy Efficiency Ratio (EER) were unaffected by dietary treatments. Lysine levels had significantly effect on Production Efficiency Factor (PEF). This study showed that increasing lysine level (120% NRC) in diet significantly increased carcass percentage and abdominal fat pad, gizzard and heart weight compared with standard group (p<0.05). The results of this study suggest that additional lysine at the level of 120% of NRC in starter (1.32%) and grower (1.22%) diets significantly improved body weight and PEF.