Aflatoxins from Moldy Corn Cause No Reductions in Channel Catfish Ictalurus punctatus Performance

Abstract

Aflatoxins are a group of mycotoxins produced by the mold organisms Aspergillus flavus and A. parasiticus on feed grains and oil seeds such as corn, peanuts, and cottonseed. Research conducted in aquaria, about 15 yr ago, demonstrated that channel catfish Ictalurus punctatus are very tolerant to dietary aflatoxin B1 (AFB1) from a purified source. To evaluate the effect of feeding diets containing aflatoxin from a natural source, moldy corn (MC) naturally contaminated with a high concentration (550 pg/kg) of total aflatoxins was incorporated into practical diets. The diets were fed to Juvenile catfish in two experiments. Experiment 1 consisted of feeding catfish (mean body weight 7.1 g/fish) four diets containing 20% or 40% of two lots of corn; one with no apparent mold contamination, which was designated as clean corn (CC), or the previously described MC. Each diet was fed twice daily to five 100-L aquaria of 20 fish each for 12 wk. Experiment 2 consisted of three diets containing either 50% CC or MC, or a combination of 25% CC and 25% MC prepared by the cooker-extrusion method. Each diet was fed once daily for 130 d to five replicate 0.04-ha ponds of catfish fingerlings. Results of these experiments indicate that feeding diets containing aflatoxin from moldy corn does not affect channel catfish weight gain, feed consumption, feed efficiency, survival, hematocrit, or hepatosomatic ratio. No liver abnormalities were observed upon gross examination. Levels of aflatoxin were reduced approximately 63% in the diets used in experiment 2 after exposure to the high temperature (ca. 120 C) of the cooker-extrusion process used to manufacture commercial catfish diets.