Eugenol stimulates lactate accumulation yet inhibits volatile fatty acid production and eliminates coliform bacteria in cattle and swine waste.
OBJECTIVE
To determine how eugenol affects fermentation parameters and faecal coliforms in cattle and swine waste slurries stored anaerobically.


RESULTS
Waste slurries (faeces:urine:water, 50:35:15) were blended with and without additives and aliquoted to triplicate 1-l flasks. Faecal coliforms were eliminated in cattle and swine waste slurries within 1 or 2 days with additions of eugenol at 10.05 mm (0.15%) and 16.75 mm (0.25%). At these concentrations volatile fatty acids (VFA) were reduced ca 70 and 50% in cattle and swine waste, respectively, over 6-8 weeks. Additionally, in cattle waste, eugenol stimulated the accumulation of lactate (>180 mm) when compared with thymol treatment (20 mm lactate). In swine waste, lactate accumulation did not occur without additives; eugenol and thymol stimulated lactate accumulation to concentrations of 22 and 32 mm, respectively.


CONCLUSIONS
Eugenol added to cattle waste may be more beneficial than thymol because not only does it effectively control faecal coliforms and odour (VFA production), it also stimulates lactate accumulation. This in turn, causes the pH to drop more rapidly, further inhibiting microbial activity and nutrient emissions.


CONCLUSIONS
Plant essential oils have the potential to solve some of the environmental problems associated with consolidated animal feeding operations. Thymol and eugenol reduce fermentative activity, thus, have the potential to reduce emissions of greenhouse gases and odour, and curtail transmission of pathogens in cattle and swine wastes.
Varel
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Roman L. Hruska US Meat Animal Research Center, United States Department of Agriculture, Agricultural Research Service, Clay Center, NE 68933, USA. varel@email.marc.usda.gov
Miller
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D000818:Animals; D002417:Cattle; D015169:Colony Count, Microbial; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D005054:Eugenol / Q000494:pharmacology*; D005232:Fatty Acids, Volatile / Q000096:biosynthesis*; D005285:Fermentation / Q000187:drug effects; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D019344:Lactic Acid / Q000378:metabolism*; D008372:Manure / Q000382:microbiology*; D009812:Odorants / Q000032:analysis / Q000517:prevention & control; D012037:Refuse Disposal / Q000379:methods; D013552:Swine
D005232:Fatty Acids, Volatile; D008372:Manure; D019344:Lactic Acid; D005054:Eugenol