Theses and Dissertations

Issuing Body

Mississippi State University


Cathcart, Thomas

Committee Member

Rowe, Dennis

Committee Member

To, Filip

Committee Member

Kidd, Michael

Committee Member

French, Todd

Date of Degree


Document Type

Dissertation - Open Access


Biological Engineering

Degree Name

Doctor of Philosophy (Ph.D)


James Worth Bagley College of Engineering


Department of Agricultural and Biological Engineering


Loss of ammonia from broiler litter degrades air quality, decreases litter fertilizer value, and can have negative health consequences for birds and their caretakers. Rates of NH3 emission from broiler houses are complicated by interrelated management and environmental factors such as air temperature, humidity, house style, ventilation rate,bird age, litter conditions, litter characteristics, and cleanout schedule. Wide variations inemission rates necessitate further investigation of litter characteristics and abatement techniques. The research was designed to clarify the impact of moisture effects that are critical to emissions for poultry litter, in conjunction with bedding type and temperature. Experiments were conducted on litter samples in the laboratory using anacid trap method for determining NH3 losses. Statistical models were developed for predicting release from each bedding material and within the range of litter moistureand temperatures found in commercial broiler houses. This allowed development of relationships that describe the effects of bedding, moisture, time, and temperature on litter generation that have not been published previously. First, type of bedding material was investigated within a limited scope of moisture contents. The results indicated that increasing moisture increases generation from litter. Literature supports the phenomenon that greater litter moisture content up to apoint elicits greater release. At the original moisture content, sand and vermiculite litters generated the most, whereas wood shavings, commercial, and rice hull. Second, an extended range of litter moisture contents (20 – 55%) was investigated while including temperature (18.3 – 40.6 °C) effects. Experiments were conducted using built-up commercial broiler litter from multiple flocks. Response surfaces were parabolic cylinders, indicating maximum production was between 37.4 and 51.5% litter moisture depending on temperature. Comparing the temperature extremes, the maximum up to 7 times greater at 40.6 vs. 18.3 °C. This research defines intermediate critical moisture levels in broiler litter where NH3 is maximized, providing target areasfor researchers and the poultry industry to develop management scenarios to reduce from litter.