The use of practical diets and regression analyses to determine the utilization of lysine and phosphorus in corn distillers dried grains and solubles using Cobb 500 male broilers

Abstract

Two experiments were conducted to evaluate the utilization of lysine (experiment 1) and phosphorus (experiment 2) in corn distillers dried grains and solubles (DDGS). In these experiments, we used a 5 × 3 factorial analysis with variations in diet formulations for digestible lysine (DLys) and available phosphorus (AP) with increasing DDGS levels. Common performance metrics observed in both experiments 1 and 2 were average BW, average live weight gain, feed intake (by pen), and FCR. On d 43 of experiment 1, two birds per pen were chosen for analysis of carcass characteristics, and on d 21 of experiment 2, tibias were excised to obtain tibia ash measurements. For both experiments 1 and 2, performance metrics improved with increasing levels of DLys and AP, respectively. In experiment 1, there was a DLys × DDGS interaction where performance was best for diets containing high DLys and low levels of DDGS, and in experiment 2, DDGS inclusion had no effect on performance. Regression equations were derived for each performance metric across DLys or AP levels and solved 2 ways: (1) using the observed metric resulting from each DDGS inclusion at the lowest DLys or AP level in the equation derived from no DDGS inclusion; and (2) selecting a common performance metric and comparing DLys or AP predictions across DDGS inclusions. Based on these data, the original DLys and AP coefficients for DDGS are justified, but may underestimate availability by up to 0.08 and 0.02 percentage points, respectively. © 2013 Poultry Science Association, Inc.