Validated assay shows that AQUAFLOR® remains stable in floating or sinking pelleted feed for catfish, salmonids
John Hayes, Schering-Plough Research Institute, USA
Table 1: Production characteristics of five florfenicol-medicated feed batches
(three sinking salmonid feeds and two floating catfish feeds).
26 February 2007
San Antonio, Texas
Key Points
AQUAFLOR® (florfenicol) was tested for stability and consistency after incorporation into pelleted feeds for catfish and salmonids.
A validated assay demonstrated that AQUAFLOR survives the high temperatures used in the pelleting production process and that it is highly stable in both floating and sinking pelleted fish feeds.
Feed medicated with AQUAFLOR also remains stable for at least 4 to 13 weeks, depending on storage conditions.
Studies have demonstrated that AQUAFLOR® (florfenicol) remains stable in both floating and sinking pelleted feed for catfish and freshwater-reared salmonids, providing producers with a reliable method of controlling bacterial disease and preventing devastating losses, said John Hayes, of Schering-Plough Research Institute.
“Medicated feed is usually the most cost-effective method for stemming a bacterial disease outbreak and restoring fish health, but the availability of antimicrobials approved for use in aquaculture is limited and bacterial resistance to some agents has been reported,” he said.
In addition, incorporating antimicrobials into pelleted feed can be difficult because some antibiotic compounds cannot survive the high heat and moist conditions involved in the manufacturing process, Hayes explained.
AQUAFLOR, known in some markets as AQUAFEN®, is a palatable, broad-spectrum in-feed antimicrobial. Formulated for aquaculture use, it is effective against a variety of bacteria affecting fish and has been widely used throughout the world for treating disease in both warmwater and coldwater fish. AQUAFLOR may be added to fish feed before pelleting/extrusion or by top-dress and, depending on the species, is used in both floating and sinking feed. The medication is administered to catfish and salmonids at the rate of 10 mg florfenicol per kg body weight daily for 10 days, he said.
Medicated feed study
To demonstrate the stability and consistency of AQUAFLOR, a study was conducted with five medicated feeds. Three of the feeds were sinking salmonid feeds and two were floating catfish feeds. Some were expanded and some were extruded feeds (Table 1).
A validated assay was used to determine the concentration of florfenicol in the medicated feeds.i The homogeneity of active ingredient in the finished feed was characterized by sampling feed at regular intervals at the bagging point in the feed mill. To see if florfenicol segregated during transportation of the medicated feeds, samples were taken from the top, middle and bottom of bags randomly chosen from each batch before and after the bags were transported 50 miles.
“In contrast to some of the other antimicrobials used in aquaculture, appropriate target drug concentrations of florfenicol were seen across batches and throughout bags after transportation in all the feed formulations tested, regardless of the manufacturing processes used,” Hayes said. “AQUAFLOR-medicated feed remained homogenous, and there was no tendency for segregation in any of the batches tested.”
“These studies show that AQUAFLOR readily survives the pelleting production process and that it’s highly stable in pelleted fish feed,” Hayes said.
Storage, high-temp testing
Feed medicated with AQUAFLOR was shown to remain stable for 3 months under long-term storage conditions of 25º C (77º F) and 60% relative humidity and for 4 weeks under accelerated storage conditions of 40º C (104º F), he added.
Besides stability, AQUAFLOR has some other advantages, Hayes said. It can be used during any stage of production, and because it can be used as a top-dress, any size batch of feed can be produced.
AQUAFLOR’s ability to survive the high production temperatures needed to make pelleted feed helps keep feed production costs in check; in contrast, antibiotics such as oxytetracycline that degrade during the manufacturing process require that extreme overages of the drug be used to produce feed pellets containing adequate amounts of antibiotic, he said.
