Assessing the threonine-to-lysine ratio of female broilers from 14 to 28 days of age

Diets for straight-run broiler flocks are often formulated to meet the nutrient requirements of male broilers, assuming this will cover the nutrient needs of the females. Delineating the nutrient needs of female broilers may allow for a more precise formulation and may lead to a reduction in associated feed cost, particularly when feeding sexes separately. A study was designed to simultaneously evaluate the dietary needs of Lys and Thr of a high-yielding female broiler from 14 to 28 d of age. Dose-response diets were accomplished via the diet-dilution technique, and were formulated to provide a range from 0.84 to 1.24% and 0.46% to 0.86% standardized digestible Lys and Thr, respectively. Requirement estimates ranged from 1.06 to 1.11% for standardized digestible Lys, depending on the parameter and the statistical method used, whereas Thr requirement estimates ranged between 0.73 and 0.79%. In addition to the aforementioned requirement estimates, Thr-to-Lys ratios of 69 for BW gain and 70 for FCR were calculated.