2009 Volume 57 Issue 1 Pages 31-38
A feeding trial was conducted to determine the effect of different particle size of a diet made from Porphyra spheroplasts (PS) for short-neck clam Ruditapes philippinarum. Three experimental micro-particle diets (approximate particle diameter: diet S; 6.8μm, diet M; 14.8μm, diet L; 56.6μm) were formulated and a condensed natural diatom Chaetoceros calcitrans (diet C) was used as a control. Duplicated test clams (mean shell length 33 mm) were fed test diets three times a day at ad libitum for 56 days. Its effects on growth and biochemical compositions of the body were assessed in a flow-through rearing system under the artificial photo condition of 12L: 12D.
After the feeding trial a high survival of 95.0% was observed in all the dietary groups, despite the best growth was obtained in the diet C. Among PS diet groups, there appeared no difference in dietary performance for survival rate, carcass ratio and biochemical compositions of the body. Whilst a higher carcass protein content and fecal C/N ratio was obtained in the diet M among PS groups. From the difference in diet and fecal C/N ratios, the diet M indicated the highest utilization efficiency of dietary protein, followed by the diet S. Also higher level of carcass DHA and notably lower amount of EPA were obtained in PS groups than those in the diet C group.
