Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/10/1997
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: Air endotoxin (ET) concentrations were measured at 4 large feedyards (30,000 to 50,000 head). The kinetic quantitative limulus lysate method was used to assay the ET. The collection of ET was facilitated by trapping it in glass Petrie plates (90 mm x 15 mm) each containing 20 ml of reverse osmosis water. Andersen two-stage air impactors were used to hold the Petrie plates and measure the quantity of feedyard air moved through the sampler (1 cu ft / min.). Three impactors were used simultaneously for 30 minutes. Impactor positions, relative to the feedyard, were 1 upwind, 1 on site, and 1 downwind. Plate 0 contained the non-respirable size particles (7 micron and above) and Plate 00 contained the respirable particles (0.65 to 1.1 micron). Considerable variation in ET concentration occurred between Petrie plates (0 and 00) and between positions in the feedyard. A downwind sampler collected the highest concentration of ET (1.4 ng ET/20 ml/30 cu ft of air). The average ng ET (SD) per the 4 feedyards, impactor positions and pore size are as follows: upwind Plate 0 = 0.208 (35), Plate 00 = 0.083 (.077); on site Plate 0 = 0.173 (.11), Plate 00 = 0.393 (.33); downwind Plate 0 = 0.079 (.04), Plate 00 = 0.736 (.75). The concentration of ET laden dust in the air, exposure time, amount of stress and susceptibility are potentially important factors in animal and human health. These initial data appear to present a minimal ET concentration in feedyard air and should not contirbute to calf morbidity.