The Influence of Symmetrical Feed:Fast Regimes on Oxytetracycline Uptakeand Otolith Score in Yellow Perch

摘要

Periods of growth from symmetric feed:fast regimes (i.e., days fed followed by the same number of daysfasted) may increase the uptake of oxytetracycline (C22H24N2O9.HCL[OTC]) compounds in fishes; however, little empiricaldata exists. Therefore, we experimentally determined if such feeding regimes influenced the concentration of OTC incorporatedin muscle and skeletal (e.g., otoliths) tissues. Individually-reared female and batch-reared (male and female),age-1 yellow perch Perca flavescens were subjected to one of four experimental feeding regimes: control (i.e., fed daily),D2 (i.e., 2d feed, 2d deprivation), D6, or D12 symmetrical feed:fast regimes. Following several feeding cycles on thesefeeding regimes, fish were submersed in a 600mg/L buffered OTC solution; otoliths and muscle tissue were excised andprocessed to determine OTC uptake via mark quality and concentrations. Ranked otolith scores (mark quality) were significantlylower for the D2 feeding regime than control, D6, and D12 scores for both individual and batch trials suggestingthat frequent food deprivation restricts osteogenesis, while daily or extended feeding periods contribute to osteogenesis. Inbatch-reared fish, total OTC and 4-epioxytetracycline peak concentrations in muscle tissue did not significantly differamong treatments but were significantly greater for smaller individuals within treatments suggesting that the OTC uptakeand elimination response is mechanistically related to higher gill ventilation volume and gastric ingestion rate of smallfish providing increased chemical assimilation and decreased clearing time following OTC immersions. Increased otolithmark quality derived from such feeding protocols may be of particular interest to fisheries managers conducting stockcontribution assessments of yellow perch, but this induction strategy may apply to other species as well as therapies forhatchery stocks.