Year of Publication


Document Type





Animal Science

First Advisor

Melissa C. Newman


Feeding sub-therapeutic levels of antibiotics to livestock has been associated withdevelopment and spread of antibiotic resistant bacteria. The present experiment was conductedto investigate the effect of antibiotic alternatives (caffeic acid, chlorogenic acid, and carbadox)on the microbial ecology of swine feces in vitro.Minimum inhibitory concentrations of caffeic and chlorogenic acids were determined forseveral pathogens using macrobroth and agar dilution techniques. Gram-negative bacteria werenot inhibited. Caffeic acid inhibited four Staphylococcus aureus strains at 200 ppm or less, andtwo Clostridium perfringens strains at 300 ppm. Chlorogenic acid inhibited all S. aureus strainsat 500 ppm, and one C. perfringens strain at 400 ppm.Effects of antibiotic alternatives on fecal microbial ecology were determined using an invitro incubation. Caffeic acid lowered total anaerobes, Bifidobacteria, Escherichia coli, andpercent E. coli (pandlt;0.01). Chlorogenic acid lowered total anaerobes, Bifidobacteria, andlactobacilli (pandlt;0.01), and increased acetate concentration (pandlt;0.0001). Carbadox lowered totalanaerobes, Bifidobacteria, E. coli, and coliforms (pandlt;0.01), and lowered acetate, propionate,butyrate, valerate, and total volatile fatty acid concentrations (pandlt;0.01). It can be concluded thataddition of caffeic acid, chlorogenic acid, or carbadox effected bacterial and chemicalcomponents of the microbial ecology of swine feces.