The dietary L-Methionine requirement of the juvenile yellow catfish Pelteobagrus fulvidraco

Abstract

An 8 week feeding trial was conducted to investigate the effects of dietary methionine levels on growth, feed utilization, body composition, and morphometric parameters of juvenile yellow catfish (Pelteobagrus fulvidraco), and to determine their dietary methionine requirement. Six isonitrogenous and isoenergetic diets (405.0 g/kg crude protein and 18.0 kJ/g gross energy) were formulated, and crystalline L-methionine was added to obtain dietary methionine levels of 5.5, 6.7, 7.5, 8.7, 9.5 and 11.3 g/kg dry diet. Fish with an initial weight of 1.4 g were randomly distributed into six groups and fed the respective formulated diets. Increasing amounts of dietary methionine up to 8.7 g/kg dry diet resulted in increased final body weight, rate of weight gain, specific growth rate, feed conversion efficiency and protein efficiency ratio however, a further increase in methionine level resulted in a decrease in these parameters. No significant difference in survival percentages was detected among the dietary treatments. A one-slope quadratic broken-line analysis model, based on specific growth rate and dietary methionine levels, indicated that the dietary L-methionine requirement of juvenile P. fulvidraco is 10.5 g/kg dry diet (accounting for 26.0 g/kg of dietary protein).