Response to pulmonary challenge of various feedlot dust associated fungal spores in a caprine model

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Title: Response to pulmonary challenge of various feedlot dust associated fungal spores in a caprine model
Author: Layton, Robert Colby
Abstract: Many genera of fungi are found in the dust of feedlots . Several of these fungi are capable of inducing infections or toxic reactions in animals . Animals raised in feedlots are continually challenged by the dust containing these fungi . The hypothesis of this study was that fungal conidia from various genera differ in their virulence in the lungs of goats following feedlot dust exposure . Nine groups of six goats were used in these experiments , one pen control group that received neither dust nor saline , one tent control group that received dust and saline containing no conidia , and seven groups each challenged transtracheally with dust and spores from one fungus . The seven fungi , Aspergillus fumigatus , Chaetomium globosum , Monotospora lanuginosa , Mucor ramosissimus , Penicillium chrysogenum , Stachybotrys chartarum , and Trichoderma viride , were administered weekly in 30 ml of physiological saline . In order to determine the virulence of the fungi , the body temperatures and white blood cell counts were evaluated throughout the challenges , and measurements of the atelectatic surface area and histopathological examinations were made at necropsy . The fungi were placed into 4 categories of virulence based primarily on the diagnoses , which were then supported by the other parameters . The first category contained the most virulent fungus , M . ramosissimus . Category two contained the second most virulent fungi , S . chartarum and T . viride . The least virulent fungi , C . globosum , P . chrysogenum , and A . fumigatus were placed in the third category . Finally , M . lanuginosa was considered to be avirulent and was placed in the last category , as challenge with this organism resulted in the least observable pathology . Resultant antibody production by these animals was also determined and was correlated with the virulence of various fungi . It was found that antibody production against the fungi was independent of virulence . A tenth group was added and challenged with S . chartarum in order to determine the catabolism and detectability of macrocyclic trichothecene mycotoxins . It was found that these mycotoxins were detectable at a level of 1 .63 ng /ml of serum 6 days after challenge , and in the lymph node at 340 ng /g of tissue after 24 hours .
URI: http : / /hdl .handle .net /2346 /8570
Date: 2007-05

Citation

Layton, Robert Colby Response to pulmonary challenge of various feedlot dust associated fungal spores in a caprine model. Doctoral dissertation, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /8570 .

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