Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: May 14, 2004
Publication Date: July 27, 2004
Citation: Varel, V.H., Wells, J., Miller, D.N. 2004. Combination of a urease inhibitor and a plant essential oil for control of fecal coliforms and emissions of odor and ammonia from cattle waste [abstract]. Journal of Animal Science 82(Suppl. 1):302. Interpretive Summary: No interpretive summary is required.
Technical Abstract: A 2002 report from the National Research Council of the National Academies ranked ammonia and odor as their highest concerns for emissions from confined animal feeding operations. Most of the ammonia emissions in livestock wastes originates from hydrolysis of urea, whereas odor emissions originate from microbial production of VFA from waste organic matter. The objectives of this work were to evaluate urea hydrolysis, VFA production (odor), and fecal coliforms in cattle waste slurries after a urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) and a plant oil (thymol) were added. Feces, urine and distilled water in the ratio 50:35:15 were blended for 1 min. Triplicate aliquots of 750 ml were amended with chemical additives and reblended for 1 min, and were poured into 1.6 L wide-mouth jars covered 90% with a lid. After 56 days, thymol (2000 mg/kg waste) in combination with NBPT (80 mg/kg waste) retained 5.2 g of the initial 8 g of urea in cattle waste slurries, compared to less than 1 g of urea retained when NBPT was the only additive (P < 0.05). Thymol by itself had no inhibitory effect (P > 0.05) on urea disappearance. However, thymol or thymol in combination with NBPT reduced VFA production (P < 0.01), but NBPT had no effect (P < 0.05) on VFA production. Thymol and thymol with NBPT also eliminated all fecal coliforms after one day. Fecal coliforms disappeared in the no addition treatment after 8 days; however, they were viable at 6.6 x 104 cfu/g waste beyond 35 days in the NBPT treatment. These results indicate thymol has an additive effect to NBPT by further inhibiting hydrolysis of urea in cattle waste slurries and increasing nitrogen retention in the waste. Also NBPT appears to interfere with the normal eradication of fecal coliforms in cattle waste slurries.