Effect of N-(n-butyl) Phosphoric Triamide (NPBT) and a Linalool or Pine Oil Extract on Urea Concentration, Odorants, and Coliform Bacteria in Cattle Feedlot Manure

Authors: Varel, Vincent; Wells, James - Jim; Berry, Elaine

Submitted to: American Society of Agri Engineers Special Meetings and Conferences Papers
Publication Type: Proceedings
Publication Acceptance Date: 7/1/2007
Publication Date: 9/16/2007
Citation: Varel, V.H., Wells, J., Berry, E.D. 2007. Effect of N-(n-butyl) Phosphoric Triamide (NPBT) and a Linalool or Pine Oil Extract on Urea Concentration, Odorants, and Coliform Bacteria in Cattle Feedlot Manure. In CDRom Proceedings: American Society of Agri Engineers Special Meetings, Sept. 15-19, 2007, Broomfield, CO. CDRom 701P0907cd.

Interpretive Summary: Pathogens, ammonia, odor, and greenhouse gas emissions are serious environmental concerns associated with livestock production. In the laboratory we have shown that these parameters can be controlled with plant oils such as thymol, and to a lesser extent with extracts of plant oils. The extracts are less expensive than thymol. The objectives of the current study were to evaluate two mixtures of plant oils; one, a linalool extract and the other a pine oil extract, in combination with a urease inhibitor for their ability to maintain urea in feedlot manure, control odorant production and reduce pathogens. The urease inhibitor significantly increased urea nitrogen in feedlot manure; however, after rainfall this effect was lessened. Both the linalool and pine oil extract reduced butyrate, a common odorant emitted from the feedlot surface, and reduced pathogens. However, these parameters were also affected by environmental conditions such as dry matter of the manure. This study suggests that it will be a challenge to treat an open feedlot surface with additives to control pathogens, nitrogen, and odor emissions.

Technical Abstract: The objectives of this study were to evaluate the influence of a urease inhibitor (NBPT) in combination with plant oils for their ability to maintain urea in feedlot manure, control odor production, and reduce pathogens. Initially, NBPT (40 ppm) and a linalool extract (LE; 4000 ppm) were sprayed once per week (Friday) on three pens (area 15 x 1.2 m behind concrete apron) for four weeks, while another three alternating pens were untreated. Each pen was 30 x 150 m and contained seventy 300 kg animals. After treatment, manure samples from six locations of the experimental area in each pen were collected twice weekly (Monday and Wednesday), analyzed, and results are expressed on a manure dry matter (DM) basis. Following this four-week treatment, NBPT and pine oil extract (POE) were applied for an additional four-week period at the same concentrations as in the first experiment. The NBPT increased (P < 0.01) manure urea concentration (1 to 6 g/kg) in pens treated with either LE or POE. There was a tendency for volatile fatty acid (VFA, odorants) to be reduced (P = 0.09) and L-lactate accumulation to be increased (P< 0.05), with concomitant numerically lower pH values with the POE treatment. Both LE and POE reduced (P < 0.01) butyrate concentrations and reduced (P < 0.01) total coliform bacteria and Eschericheria coli. It is concluded that these treatments applied once per week can conserve urea on the feedlot surface, and reduce odorant concentrations and pathogens in cattle manure; although the environment, especially manure DM, greatly influences these parameters.