Optimal protein level in a semipurified diet for juvenile greenlip abalone Haliotis laevigata

To optimize dietary protein level in relation to growth, semipurified diets with an essential amino acid profile similar to that of the soft body profile were fed for 59 days to young greenlip abalone, Haliotis laevigata (initial shell length, 15-25 mm). Animals were housed in 10-L acrylic tanks, with flow-through seawater supplied at 1 L min(-1) (20 degreesC, salinity = 36 g L-1). Protein level of feeds ranged from 122 g kg(-1) to 461 g kg(-1) crude protein (CP) on an 'as is' basis. Second-order polynomial regression analysis of specific growth rate indicated that maximal growth occurs at 270 g kg(-1) CP. The protein and energy components of the feed were estimated to have a digestibility of 71.7% and 55.6%, respectively.