Feed intake and tissue distribution of florfenicol in cod (Gadus morhua) administered feed with different fat contents

Summary This study was performed to examine the appetite and the corresponding plasma and tissue distribution of florfenicol when administered to healthy groups of cod using medicated and non-medicated salmonid and marine feeds. Marine feed contains approximately 18% fat whereas salmonid feed contains approx. 30% fat. Two groups of fish were medicated with florfenicol at a dosage of 10 mg kg−1 day−1 for 10 consecutive days when the drug was administered either via marine or salmonid pellets. Two groups of fish also received either non-medicated marine or salmonid pellets. Twenty-four hours after giving the medicated marine feed, 14 out of 20 fish contained detectable concentrations of florfenicol with mean values (n = 14) of 4.67 ± 4.02 μg ml−1 in plasma, 2.29 ± 2.11 μg g−1 in muscle and 0.79 ± 0.69 μg g−1 in the liver. In the fish given medicated salmonid feed, 18 of 20 fish contained detectable concentrations of florfenicol with mean values (n = 18) of 1.77 ± 1.84 μg ml−1 in plasma, 0.75 ± 0.66 μg g−1 in muscle and 0.30 ± 0.25 μg g−1 in the liver. Decreased feed intake of the salmonid feed, both medicated and non-medicated, was noted when compared to medicated and non-medicated marine feed. No difference in feed consumption was registered between medicated and non-medicated marine feed, however a difference was noted between the medicated and non-medicated salmonid feed.