Rainbow trout (Oncorhynchus mykiss) is extremely sensitive to the feed-borne Fusarium mycotoxin deoxynivalenol (DON)

Deoxynivalenol (DON), a Fusarium mycotoxin, is a major contaminant of cereal grains worldwide. The effects of feeding six diets containing low, graded levels of DON from two naturally contaminated sources of corn on the performance, health and apparent nutrient digestibility of rainbow trout were investigated. Feeding diets with increasing levels of DON (0.3, 0.8, 1.4, 2.0 and 2.6 ppm) for eight weeks to rainbow trout (initial weight = 24 g/fish) resulted in significant linear or quadratic decreases in feed intake, weight gain, growth rate (expressed as thermal-unit growth coefficient, TGC), feed efficiency (FE, gain:feed), retained nitrogen (RN), recovered energy (RE), energy retention efficiency (ERE), and nitrogen retention efficiency (NRE). Fish pair-fed the control diet (0.3 ppm DON) had significantly higher TGC (P < 0.01), FE (P < 0.0001) and whole body crude protein (CP) concentration (P < 0.01) compared to their counterparts fed the diet containing 2.6 ppm DON. No significant differences (P > 0.05) were observed in the apparent digestibility coefficients (ADC) of CP and gross energy (GE) of fish fed diets containing 0.3 (control) to 2.0 ppm DON. In addition, some morphological changes of the liver were noted in fish fed the diet containing 2.6 ppm DON. These results suggest that, relative to other species, rainbow trout are extremely sensitive to DON from naturally contaminated grains and that the effects of DON on rainbow trout are not simply related to a reduction of feed intake, but rather, are due to metabolic effects. More research is required to identify the specific mechanism(s) of toxicity of DON in rainbow trout.