Abstract
Four experiments, involving 3060 broiler chickens, were conducted to estimate the lysine requirements of an imported Cobb European strain raised in the humid lowland tropics. Lysine, 1.10 and 0.9(Lo, maximized liveweight gain and feed/gain ratios for broiler starters (period 1) and finishers (period 2). Calculated lysine intakes were 0.63 and 1.11 g bird-1 d-1 at the 1.10 and 0.90% dietary lysine levels, respectively. Lysine requirements (% diet) remained respectively at 1.16 and 1.06% during periods 1 and Z in Experiment 3, when dietary protein was increased from 18 to 21%. However, when requirement was expressed as g intake bird-1 d-1, lysine intake increased from 0.65 to 0.76 g during period 1 and from 1.54 to 1.69 during period 2 as dietary protein was increased from 18 to 21%. In Experiment 4, lysine requirement remained at 1.06% diet when dietary energy increased from 11.7 to 15.1 MJ kg diet during period 1. Only birds fed on 11.7 and 13.4 MJ kg-1 diet required 1.06% lysine during period 2. The lysine requirement (g. bird 1 d "') decreased from 0.58 to 0.47 when dietary energy increased from 11.7 to 13.4 MJ kg diet during period 1, with a corresponding increase from 1.67 to 1.74 during period 2. Although the respective requirements of 1.10 and 0.90% dietary lysine by broiler starters and finishers were lower than the 1.16 and 1.02% reported (NRC, 1971; Scott eta/., 1976) for their counterparts raised in temperate environments, the lysine intake (g bird-1 d-1 ) between 1.10 and 1.16% dietary levels was similar for broiler starters. The intake of 0.90-1.02% dietary lysine for broiler finishers was also similar, suggesting that broiler chickens raised under widely different environmental conditions have similar requirements for lysine if expressed on a daily intake basis.
