A series of experiments was designed to evaluate the mechanisms and effects of dietary corn distiller's grains with solubles on NH₃ emission from laying hens. A diet containing 15% DDGS was fed to laying hens in high-rise houses on a farm in central Iowa. Hens in three houses were fed the DDGS treatment diet while hens in the other three houses were fed a 0% control diet. Emission, egg production, and economic parameters as well as manure characteristics were measured over the course of a one-year period (between fall manure clean-out). The manure pH was lower for the DDGS than the control regimen (7.10 vs. 7.42 y 0.08, respectively; P = 0.01). Contrary to the hypothesis, the lower manure pH did not lead to a decrease in NH3 emission (1.24 vs 1.32 y 0.08 g/hen-d for the DDGS and control, respectively; P = 0.54). However, higher N consumption by the DDGS hens did not lead to increased NH_{3 emission. The DDGS diet did not cause any adverse effects on production performance. Economic analyses revealed lower diet cost for the DDGS regimen than the control (10.8 vs. 11.2 y 0.1 y/hen-wk, respectively; P = 0.10 and 34.2 vs. 31.3 y 0.5 y/kg egg, respectively; P = 0.06). In a separate study, no change in pH or short-chain fatty acid contents of the laying-hen ceca could be detected between a 15% DDGS and control regimen. Because the DDGS treatment was expected to impact manure nutrient values, a study was conducted to determine which sampling strategies yielded the most precise nutrient values. The variation in dry-matter content was greater than the variation in nitrogen or phosphorus. Sampling strategies that accurately measure dry-matter content must be used, including collection of samples near the sidewall and in the center manure rows under high-rise houses. Diets containing 15% DDGS yielded lower feed cost while supporting egg production. However, no decrease in NH3 emission was detected.}