Livestock and poultry producers face increasing challenge to reduce the negative impacts of their operations on the environment. Ammonia (NH3) released from animal manure to the atmosphere is one of the major environmental concerns associated with poultry production. There have been growing research efforts toward documenting or improving the inventory of NH3 emissions from animal production systems. Efforts also continue to develop process-based models for predicting gaseous, particularly NH3, emissions from animal feeding operations. In this thesis research, an environmentally -controlled dynamic gas emission chambers system was used to investigate the dynamic gaseous emissions, ingestion, and defecation activities of laying hens. Chapter 2 of this thesis describes the dynamic emissions of NH3 and carbon dioxide (CO2) relative to feeding and defecation activities of W-36 laying hens. Results presented include average daily feed consumption, manure production, relation of manure surface area to manure weight, daily NH3 and CO2 emission rates, and relations of NH3 and CO2 emissions to manure accumulation. The study revealed an inverse relationship between dynamic NH3 emissions and defecation events of the hens as manure accumulates. Results from this study will contribute to development and validation of process-based emission models for predicting NH3 emissions from laying-hen houses. The dynamic nature of NH3 emissions vs. defecation event of the hen may help guide the application timing of manure treatment agents to reduce NH3 emissions from laying-hen houses.

Chapter 3 assesses the effect of a diet containing corn distiller's dried grain with solubles (DDGS, 15% by weight) vs. control diet (no DDGS added) on NH3 emission and production performance of W-36 laying hens. Compared with hens fed the control diet, hens fed the DDGS diet had 16% higher manure mass production (P<0.001) and 13% higher egg mass production (P<0.05). After 6 days of manure accumulation, NH3 emissions for the DDGS diet regimen showed considerable reduction, as expressed in the units of g/hen-d (26%, P<0.1), g/kg manure-d (32%, P<0.05), g/kg egg-d (38%, P<0.01), or g/kg N intake-d (31%, P<0.01), when compared to the control diet regimen. Results of this study involving manure accumulation from live hens support previous findings of the NH3 emission-lowering effect of corn DDGS as observed in lab-scale studies involving static manure storage. Hence, corn DDGS (at 15% inclusion rate) seems to be a viable feed ingredient for laying hens that will lead to reduced NH3 emissions without negatively affecting the hen production performance. However field verification of hen production performance is warranted.