“Effect of Swine Manure Pit Additives and Facility Disinfectants on the Fate of Antibiotics and Manure Composition During Simulated Swine Manure Slurry Storage”

Advisor: Dr. Shannon Bartelt-Hunt

This thesis investigates the effect of time and of swine manure slurry treatment on the physical properties, nutrient content, and the fate of antibiotics chlortetracycline, lincomycin, and tiamulin. Slurry was collected from the deep pit of a swine finishing facility near Dorchester, Nebraska. In one experiment the slurry was treated with a set of additive products, including Coban 90, Manure Magic, MOC-7 More Than Manure, Sludge Away, and Sulfi-Doxx. In a second experiment a set of disinfectant products, Chlorine Bleach, Tek Trol, Pi-Quat, and Virkon was used. Control consisted of unamended slurry. Manure stored in 60 liter stainless steel bioreactors to simulate deep pit storage and was sampled 7 times over a 40 day incubation.

Results were analyzed with ANOVA for completely randomized design with repeated measures over time. From this analysis it was concluded evaporation may be contributing a significant effect in concentration change of the manure constituents. With this in mind, each time series was normalized by its final time point and a second ANOVA was performed along with a growth curve analysis on the means and slopes over time of the normalized data. An LSD was used to differentiate treatment means and slopes. This further analysis resulted in a large decrease in treatment effects in the additives experiment but demonstrated no reduction in treatment effects in the disinfectants experiment.

With the additives experiment the Coban 90 treatment was shown to produce an increase in mean total suspended solids relative to control. Manure Magic, MOC-7, More Than Manure, Sludge Away, and Sulfi-Doxx all produced a slower decrease in electrical conductivity relative to the control. The Coban 90 treatment was found to produce a greater mean tiamulin concentration relative to the control over the course of the experiment. With the disinfectants experiment, Pi-Quat and Tek Trol treatments were found to result in increased total nitrogen mean concentrations. Chlorine bleach and Pi-Quat treatments resulted in an increase in mean phosphorus concentration. The Virkon treatment produced an increase in mean tiamulin concentrations. The antibiotics concentrations reported in both experiments were highly variable and could not be fit accurately to decay models.