Digestible lysine requirement of female turkeys during the starter period

Three experiments were conducted to determine the digestible lysine requirement of female turkey poults during the starter period. Birds were fed a standard corn-soybean meal diet until the onset of each trial and were then randomly assigned to treatments that were fed for 2 wk. Dietary treatments included titrated levels of digestible lysine (1.18 to 1.72%) added to a basal corn-soybean meal diet with an intact crude protein content of either 21% (Experiment 1) or 18.4% (Experiments 2 and 3). All diets contained 3,100 to 3,200 kcal MEn/kg. True digestible lysine contents of the basal diets were 1.42% (Experiment 1) and 1.18% (Experiments 2 and 3), based on digestibility assays of corn and soybean meal with cecectomized turkeys. A positive control diet (28% CP, 3,175 kcal MEn/kg) was also included in the treatments for comparison. Other amino acids were maintained at levels in relation to lysine based on previous research and the Illinois Ideal Chick Protein. Broken-line analysis suggests that the digestible lysine requirement is 1.32% for optimum body weight gain and 1.34% for optimal feed:gain at the energy levels used in these studies.