Digestible sulfur amino acid requirement of starting turkeys

Department of Animal Science, University of Missouri-Columbia 65211, USA.

Three experiments (a total of 1,020 poults) were conducted to determine the digestible sulfur amino acid (SAA) requirement for female turkey poults during the starter period. Poults were fed a standard corn-soybean meal diet (PC) that met or exceeded NRC recommendations (28% CP, 3,172 kcal MEn/kg) for 1 wk and were then randomly assigned to treatments until 22 d (Experiment 2 and 3) or 23 d (Experiment 1) of age. Dietary treatments included the PC diet and seven or nine titrated levels of methionine added to a basal corn-soybean meal diet, for a total of 0.50 to 1.33% total digestible SAA. The basal diet contained 18.4% intact crude protein. All diets contained 3,171 kcal MEn/kg. The true digestible SAA content of the basal diet without methionine additions was 0.50% based on digestibility assays of the corn and soybeans with cecectomized turkeys. Diets were formulated to contain 1.40% digestible lysine. Other amino acids were maintained at levels in relation to lysine based on previous research with turkeys and the Illinois Ideal Chick Protein. Broken-line analysis suggests that the digestible SAA requirement for female turkeys during the starter period is 0.76% for optimum body weight gain and 0.75% for optimal feed:gain at the energy levels used in these studies.