Submitted to: Small Ruminant Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2002
Publication Date: 7/26/2002
Citation: Purdy, C. W., Straus, D. C., Parker, D. B., Ayers, J. R., Hoover, M. D. Treatment of feedyard dust containing endotoxin and its effect on weanling goats. Small Ruminant Research. 2002. v. 46. p. 123-132.
Interpretive Summary: Manure organic dust is a nuisance problem to feedyards and to downwind neighbors. This dust contains particles of all sizes. Recently small particles under 2.5 m have been associated with a disease called toxic organic dust syndrome. The particles which form feedyard dust also contain endotoxins which are very biologically active and cause inflammation of the respiratory system. Thus, feedyard dust may pose a potential health problem to both animals and humans. The endotoxin originates from the cell walls of Gram-negative bacteria found in the manure. This study provided evidence that endotoxin was the most toxic part of feedyard dust and that sufficient endotoxin survived steam sterilization to induce acute respiratory inflammatory disease in goats. Steam sterilization killed all of the microbes in the dust. This research indicates that ruminants are susceptible to endotoxin contained in dust administered as an aerosol in a closed tent. The ruminant responds to endotoxin like humans with an elevated body temperature and increased white blood cell count. Information gained from this study is important to the public, feedyard owners, veterinarians, and public health officials.
Technical Abstract: Thirty mixed-sex, weanling goats were randomly allotted to 4 treatment groups: principal autoclaved dust (n=6), control non-autoclaved dust (n=6), principal dry-heat dust (n=6), and control non-dry heat dust (n=6). Principals were treated with appropriate dust for one 4 hr treatment in a closed tent. The data from the principal dust group (n=9) and the control non-dust group (n=9) were recorded after one 4 hr dust treatment prior to the start of the present study. The endotoxin (ET) concentrations were determined for autoclaved dust (13.3 g ET/g), dry-heated dust (0.173 g ET/g), and non-treated dust 26.9 g ET/g. The tent aerosolized dust concentrations were: autoclaved dust 0.369 g/m3/min with 4.904 g ETm3/min; dry-heated dust 0.347 g/m3/min with 0.0015 g ET/m3/min; and non-treated dust 0.539 g/m3/min with 4.904 g ET/m3/min. These ET aerosol concentrations caused the autoclave dust goat group and the non-treated dust goat group to significantly increase their rectal temperatures at 4, and 8 hr and total white blood cells (WBC) increased at 12 and 24 hr compared to their respective non-dust control groups. The dry-heat aerosol dust ET concentration in the tent did not induce an increased mean rectal temperature response or an increased mean total WBC count. Of the 3 principal dust products only the non-treated dust contained viable microbes.