Date of Award
Doctor of Philosophy
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 NH3 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.
Stacey Ann Roberts
Roberts, Stacey Ann, "Effects of dietary corn distiller's dried grains with solubles on ammonia emission, production performance, manure characteristics, and economic efficiency for laying hens" (2009). Graduate Theses and Dissertations. 10736.