Dietary choline requirement of juvenile yellow perch (Perca flavescens)

We conducted an Il-wk feeding trial to determine the dietary choline requir ement of juvenile yellow perch (Perca flavescens) and to investigate whethe r dietary phosphatidylcholine (PC) could meet this requirement. Six dietary treatments contained choline concentrations of <0.11, 0.23, 0.34, 0.75, 1. 22 or 3.37 g/kg diet. Two additional diets contained 31 g of lecithin/kg di et, with or without supplemental choline chloride (4.0 g choline/kg diet). The total sulfur amino acid concentration was maintained at 1.0 g/100 g die t (methionine/cyst(e)ine, 49.51). Diets were fed to satiation twice daily t o triplicate groups of yellow perch initially weighing 16.0 g/fish. Weight gain, feed intake and carcass proximate composition were significantly affe cted by dietary choline. Weight gains and feed intakes increased as dietary choline increased from 0 to 0.75 g/kg. Both values tended to plateau in fi sh fed dietary choline levels above 0.75 g/kg. Broken-line analyses of weig ht gain and feed intake data indicated the dietary choline requirement was 0.598 and 0.634 g/kg diet, respectively. Hepatic lipid concentrations and f eed efficiency values were not significantly different. Whole-body fat conc entrations increased significantly, whereas ash levels decreased significan tly in fish fed increasing levels of dietary choline. Weight gain and feed intake of fish fed diets containing PC were not significantly different fro m fish fed 0.75 g/kg of dietary choline. However, hepatic lipid concentrati ons were significantly higher in fish fed the diet containing PC and no cho line chloride. Thus, yellow perch require a maximum of 0.598-0.634 g of cho line/kg diet for maximum growth and this requirement may potentially be met with 31 g of lecithin/kg diet.