Effects of Dietary Metabolizable Energy and Protein on Early Growth Responses of Broilers to Dietary Lysine

摘要: Abstract Two studies evaluated effects of metabolizable energy (ME), digestible Lys (dLys), and amino acid (AA) balance on broiler performance. In experiment 1 diets contained 3 levels ME (3,000, 3,100, 3,200 kcal/kg) in combination with 4 dLys (1.05, 1.13, 1.21, 1.29%). A fixed proportion relative to CP key indispensable AA was maintained graded increments from 21.9 26.9%. There no interaction for 21 d BW gain or adjusted feed conversion ratio, which improved linearly dietary dLys. Increasing the had effect intake, linear improvement performance attributed a step-wise increase when CP. Experiment 2 response 20 age while maintaining (balanced CP), increased by supplementing synthetic l -Lys basal 22.0% (low CP) 27.0% (high without adjusting concentrations other The broilers fed low diet series followed quadratic response, requirement estimated be 1.19 ± 0.03% (1.30% total Lys). By contrast, both high balanced linearly. higher continued above 1.19% were confirmed that dependent When ratio applied dispensable not limiting, responded positively incremental up at least 1.32% (27.2% independent over range 3,000 kcal/kg.