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Rainbow Trout (Oncorhynchus mykiss) as a Sensitive Animal Model for Investigating the Effects of the Fusarium Mycotoxin Deoxynivalenol (DON)

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Title: Rainbow Trout (Oncorhynchus mykiss) as a Sensitive Animal Model for Investigating the Effects of the Fusarium Mycotoxin Deoxynivalenol (DON)
Author: Hooft, Jamie
Department: Department of Animal Biosciences
Program: Animal and Poultry Science
Advisor: Bureau, Dominique
Abstract: The Fusarium mycotoxin deoxynivalenol (DON) is a ubiquitous contaminant of cereal grains. Rainbow trout, a carnivorous species, are highly sensitive to diets containing realistic concentrations of DON (< 1 ppm), whereas omnivorous species (e.g. channel catfish) are able to tolerate much higher levels (e.g. up to 10 ppm) of DON without reduced performance. The basis of the sensitivity of rainbow trout to DON and the efficacy of a commercial feed additive (CFA) were investigated in a series of three experimental trials. In the first trial, rainbow trout fed diets containing purified DON (0-2.1 ppm) or DON from naturally contaminated corn (0-5.9 ppm) experienced decreases in growth performance, carcass composition, and nutrient utilization parameters. The adverse effects of the diets on trout appeared to be exclusively associated with DON and not related to the presence of co-occurring mycotoxins in the grain. Histopathological analysis indicated cellular changes consistent with the ability of DON to activate mitogen-activated protein kinases (MAPKs), notably increases in the number of dead cells and decreases in the number of mitotic cells in the pyloric caeca and/or liver with increasing dietary levels of DON. In a second trial, the inclusion of a CFA in diets containing 0.3 to 2.0 ppm DON was not effective in preventing the negative effects of DON on the performance of rainbow trout. Finally, a comparative study revealed that Nile tilapia were unaffected by diets containing up to 1.3 ppm DON which otherwise resulted in decreased performance of trout. The species-specific sensitivity to DON could not be explained by differences in the total hepatic UDP-glucuronosyltransferase (UDPGT) activity nor was the response to DON affected by the digestible starch content of the diet (12 or 24%). This finding was in contrast to the hypothesis that the ability of omnivorous species to more effectively utilize dietary carbohydrates compared to carnivorous species may be related to glucuronidation capacity and consequently, sensitivity to DON. This thesis indicates that DON contamination of fish feeds has the potential to result in deleterious clinical and subclinical effects in some species. Furthermore, rainbow trout may be a valuable model species for future investigation.
Date: 2016
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