Feasibility of utilising natural products in animal production for the control of animal diseases and food pathogens

Widespread outbreaks of animal diseases have become more common, while foodborne diseases are a growing public health problem worldwide. The new European legislation banning traditional antimicrobial growth promoters has stimulated the search for suitable alternatives to chemical drugs that will help control animal diseases. Current research involves investigation of a range of products including naturally occurring compounds, medicinal plants and traditional herbs for their antimicrobial effects. Natural compounds were provided by an American research group and indigenous medicinal plants were obtained from Cameroon. Anti-mycobacterial effect of the natural compounds against Mycobacterium avium subspecies paratuberculosis (Map) was examined using a macrobroth susceptibility test to determine the minimum inhibitory concentration (MIC). Antimicrobial effect of medicinal plants against Escherichia coli and Listeria monocytogenes were evaluated using a modified microbiological procedure of Friedman et al. [1] on plant extracts. Six out of 19 tested natural compounds were found to inhibit the growth of Map for up to 42 days with MIC ranged from 24.7µg/ml to 74µg/ml. Currently, there is no drug approved to treat paratuberculosis in farm animals. The identified anti-Map natural compounds may have the potential to be included in animal therapeutics and as food additives for dairy products. A number of plant extracts showed potent inhibitory effects on Listeria with MIC as low as 2.4µg/ml as compared with 29.5µg/ml of Ampicillin (positive control). Similar effects as compared with Gentamicin on E. coli were observed with a number of plant extracts.

Acknowledgements: Western Regional Research Centre, U.S. Department of Agricultural, California, USA (provision of natural compounds), Catholic Private School of Nursing, Midwifery and Laboratory Technology Shisong, Cameroon (provision of medicinal plants).

References: 1. Friedman, M. et al. (2002)J. Food Protection 65: 1545–1560.