Date Full Report Received05/03/2017
Date Abstract Report Received05/03/2017
InvestigationInstitution: ARS, Southern Plains Area, USDA
Primary Investigator: Ross Beier
Co-Investigators: Robin C. Anderson, Branko Petrujkic
Funded ByNational Pork Board
New technologies are needed to help livestock producers maintain health and wellbeing of their animals while minimizing risks of disseminating antimicrobial resistant bacteria to humans or animals. Thymol, the active ingredient of many mouthwashes such as Listerine®, is an attractive candidate for development as an antibiotic alternative for swine because it is a potent biocide against Salmonella, E. coli and Campylobacter and as a natural product may more likely be viewed favorably by regulatory agencies. However, thymol and low molecular weight conjugated forms of thymol are rapidly absorbed in the stomach and small intestine which consequently prevents their delivery to the cecum and large intestine where many pathogenic bacteria primarily reside. In order to make thymol more resistant to absorption, we chemically linked thymol to larger molecular weight oligosaccharide complexes using a chemical bond like that used by plants to link glucose units into cellulose. The result was that certain of these high molecular weight thymol-conjugates exhibited potential as antibiotic-alternatives in benchtop laboratory studies but further work is needed to elucidate their pharmacokinetic properties in fed pigs. In a parallel investigation, we tested an extract of a Middle Eastern plant named Nigella sativa which contains natural bioactive constituents of thymol such as thymoquinone. Extracts of this plant have been found to enhance immune function, improve performance and reduce enteropathogen colonization in poultry and small ruminants but until now studies with swine had been lacking. Presently, we found that Nigella sativa extract exhibited modest anti-E. coli K88 and anti-Salmonella Typhimurium in benchtop studies. Furthermore, we found that when orally administered to recently weaned pigs the Nigella sativa extract helped reduce intestinal carriage of wildtype E. coli but had little if any observable effect on carriage of endogenous Campylobacter spp. or a challenge Salmonella Typhimurium strain. Cumulative feed conversion efficiency after 9 days feed administration of the Nigella sativa extract was improved significantly (> 60%) compared to that observed with control pigs (6.1 gram dry matter intake/ gram of live weight gain), due largely to early performance of the weaned pigs indicating that the Nigella sativa extract may hasten transition of the piglets to nursery diets.