Lysine requirements of growing turkeys in various temperature environments

The lysine requirement of Large White male turkeys (Nicholas strain commercial cross) was determined in two experiments at different environmental temperatures for two age periods (8 to 12 and 16 to 20 wk of age). Response curves (segmented and exponential) were obtained by regressing body weight gain (grams/day) on dietary lysine concentration (percentage) or lysine intake (grams/day). Varying levels of dietary lysine were obtained by supplementing a corn-sesame meal diet with L-lysine.HCl. Temperature affected percentage lysine requirement as determined by the segmented (broken line) regression model during 8 to 12 wk of age in Experiment 1 (P less than .05) and in Experiment 2 (P less than .10). The requirements (mean +/- SE) by broken line regression for the 8 to 12-wk age period were: Experiment 1, 1.13 +/- .02 and 1.25 +/- .02% at 6 and 23 C, respectively, and Experiment 2, 1.10 +/- .03, and 1.23 +/- .04% at 7, 20, and 26 C, respectively. For the 16 to 20 wk age period the requirements for Experiment 1 were .75 +/- .02 and .77 +/- .03% at 8 and 24 C, respectively. For Experiment 2, requirements were .74 +/- .03, .72 +/- .02, and .78 +/- .02% at 7, 16, and 24 C, respectively. Percentage requirements by the exponential model showed the same patterns relative to temperature. Multiple regression analysis of gain on lysine intake and temperature indicated that variability in gain was primarily explained by intake (R2 ranged from .82 to .97) with deficient lysine intakes. Temperature environment also affected the gain response to lysine intake, resulting in different response curves at the different environmental temperatures.