Master of Science / Department of Grain Science and Industry / Cassandra Jones / Salmonella contamination in animal food production facilities is a growing concern. The bacteria has been the cause of 40% of pet food recalls in the past 5 years, and there are potential human health implications because pet food is a direct human contact food. A potential method to reduce Salmonella contamination in pet food is through the use of acidifiers and desiccants to destroy and inhibit growth of bacteria. The objective of this thesis was to quantify Salmonella contamination in livestock feed and pet food manufacturing facilities, and propose mitigation measures to mitigate the presence of pathogens in animal food. Therefore, the objective of Experiment 1 was to investigate sources of Salmonella contamination throughout livestock feed (n = 2) and pet food (n = 2) manufacturing facilities on a specific sampling day. Salmonella was present in all four facilities. However, one of the livestock feed manufacturing facilities had more than double the Salmonella-positive locations than all other facilities. This experiment demonstrated that surface type and location should be taken into consideration when controlling Salmonella contamination. In Experiments 2 and 3, the use of a commercial powdered dry acidulant, sodium bisulfate, was studied as a coating of dog kibble to reduce and prevent Salmonella growth over time. The coating reduced Salmonella concentration, and its efficacy was not impacted by altering the bulk density or surface area of the kibble. Experiment 4 was conducted to determine the efficacy of sodium bisulfate added to poultry mash to reduce or prevent Salmonella growth over time. The inclusion of the dry acidulant did not reduce Salmonella concentration; however, storage time reduced Salmonella contamination in poultry feed. In summary, Salmonella contamination exists in manufacturing facilities, but the location and magnitude of contamination differs. Furthermore, sodium bisulfate effectively reduces Salmonella contamination when applied as a pet food coating, but not in poultry feed.

Ammonia (NH₃) emissions from animal manure, such as poultry litter, can cause air quality problems. These emissions also result in excessive nitrogen (N) loading into aquatic environments which can lead to water quality problems where N is the limiting nutrient for eutrophication, such as the Chesapeake Bay. Poultry litter treatment (PLT, sodium bisulfate) is an acidic amendment that is applied to litter in poultry houses to decrease NH3 emissions, but currently it can only be applied before birds are placed in the houses. This project analyzed the effect of multiple PLT applications on litter properties and NH₃ release in a controlled and field environment. Volatility chambers with acid traps were used to compare multiple, single, and no applications of PLT to poultry litter. Both single and reapplied PLT caused a greater moisture content and lower pH in litter. Additionally, the E.coli in litter was decreased significantly with both single and reapplied PLT. After 15 days, NH₃ released from litter treated with reapplied PLT was significantly less than litter with both single and no applications. Furthermore, NH₄⁺-N content of litter was greatest in litter treated with reapplied PLT increasing its fertilizer value. The efficacy of a new farm scale system capable of applying several additions of PLT to poultry litter throughout the growth of a flock was also evaluated. Though litter pH, E.coli, and NH₃ volatilization were temporarily decreased with PLT application, the overhead reapplication auger system is not recommended at this time due to moisture and corrosion problems. / Ph. D.