Safety of Aquaflor (florfenicol, 50% type A medicated article), administered in feed to channel catfish, Ictalurus punctatus.
Aquaflor, a feed premix containing the broad spectrum antibacterial agent florfenicol (50% w/w), is being developed for use to control enteric septicemia (ESC) in channel catfish Ictalurus punctatus caused by the gram-negative enterobacterium Edwardsiella ictaluri. The recommended dose of Aquaflor to control ESC is 10 mg/kg body weight (BW)/day for 10 days. The study objective was to determine the safety of Aquaflor administered in feed to channel catfish at doses of 0 (control), 10, 30, and 50 mg/kg BW/day for 20 consecutive days. Parameters evaluated included daily mortality, behavioral (appetite, distribution, flight/fright response), and water chemistry observations, initial and terminal weight measurements, and gross and microscopic pathology. Medicated feed consumption was 67-86% of target with group mean doses of 8.5 mg/kg BW/day, 24.6 mg/kg BW/day, and 34.9 mg/kg BW/day. There were no mortalities or clinically observable changes noted at any of the dose levels tested. Aquaflor-related changes were limited to the food consumption and histopathology data. Although Aquaflor-related decreased feed consumption was noted in the 30 and 50 mg/kg BW/day groups, there were no differences in fish growth among the treatment groups. Aquaflor-related histopathology findings were limited to a histomorphologically evident dose-dependent decrease in hematopoietic/lymphopoietic tissue in the anterior kidneys, posterior kidneys, and spleens of channel catfish.
US Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, Wisconsin 54603, USA. mark_gaikowski@usgs.gov
Mark P
MP
Gaikowski
Jeffrey C
JC
Wolf
Richard G
RG
Endris
William H
WH
Gingerich
D000821:Animal Feed; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000633:toxicity*; D001522:Behavior, Animal / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D004032:Diet; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects; D006410:Hematopoiesis / Q000187:drug effects; D007059:Ictaluridae; D007668:Kidney / Q000187:drug effects / Q000473:pathology; D008136:Longevity / Q000187:drug effects; D008221:Lymphoid Tissue / Q000187:drug effects / Q000473:pathology; D013154:Spleen / Q000187:drug effects / Q000473:pathology; D013839:Thiamphenicol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000633:toxicity*; D018675:Toxicity Tests
D000900:Anti-Bacterial Agents; C035534:florfenicol; D013839:Thiamphenicol