Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: March 10, 2003
Publication Date: July 1, 2003
Citation: VAREL, V.H., MILLER, D.N., BERRY, E.D. SLOW-RELEASE THYME OIL GRANULES FOR CONTROL OF ODOR AND PATHOGENS IN FEEDLOT CATTLE WASTE. JOURNAL OF ANIMAL SCIENCE. 2003. v. 81(SUPP.1): ABSTRACT P. 77. Technical Abstract: Confined animal feeding operations can be a source of odor emissions, global warming gases, water pollution, and food contamination. Laboratory studies have indicated plant oils with antimicrobial activity can be used to control pathogens and odor emissions from cattle and swine wastes. However, these oils are volatile and were ineffective when topically applied to a feedlot surface. Our objective was to evaluate the effectiveness of topically applying thyme oil incorporated into corncob granules, added once per week, to control odor emissions and fecal coliforms in feedlot manure. Manure samples from six locations in each pen were collected from three control and three treated pens (15 x 150 m; 50 400-kg cattle/pen), three times per week for eight weeks. Samples were analyzed for thyme oil concentration, VFA and branched-chain VFA (odor), and number of Escherichia coli and total coliform bacteria. Over the eight weeks, with the exception of wk 7, the desired concentration of 0.15 to 0.2% thyme oil was maintained in the manure. Concentrations of VFA and branched chain-VFA increased over time in control and treated pens. However, production of VFA in treated pens, 7.5 ± 1.3 µmol/g DM/wk, was less than the rate of production in control pens, 18.0 ± 2.1 µmol/g DM/wk (P < 0.01). Likewise, production of branched-chain VFA in treated pens, 0.31 ± 0.04 µmol/g DM/wk, was less than control pens, 0.55 ± 0.06 µmol/g DM/wk (P < 0.01). Treatments did not differ in time for concentrations of E. coli and coliforms; although the concentrations of E. coli in treated pens, 2.9 ± 1.2 cfu x 10**5/g DM, were 91% less than control pens, 31.1 ± 4.0 cfu x 10**5/g DM (P < 0.04). Similarly, concentrations of coliforms in treated pens, 3.7 ± 1.3 cfu x 10**5/g DM, were 89% less than control pens, 35.3 ± 4.2 cfu x 10**5/g DM (P < 0.04). These results indicate odor emissions and fecal coliforms can be reduced in feedlot manure with a once per week application of thyme oil in a granular form.