抄録
The energy budget of Marsupenaeus japonicus postlarvae (PL) fed highly unsaturated fatty acid-enriched (EA) and non-enriched (NEA) Artemia nauplii was determined by equating energy intake (EI) with the summation of energy channeled to feces (F), metabolism (M), excretion (U), growth (G) and exuvia (Ev). Stage PL4 (mean wet weight 1.14±0.31 mg, 14 days post-hatching) of M. japonicus were reared in six 80 L circular tanks, with three replicates, and fed EA and NEA for 21 days. The EI was calculated from the energy content of consumed nauplii, M was calculated from the summation of energy for routine metabolism, active metabolism and heat increment based on oxygen consumption, U was calculated from urinary loss based on ammonia excretion, G was calculated from energy increase based on weight gain, Ev was calculated from energy loss based on molting and F was obtained from the difference between EI and the total of the other variables. The values of EI, M and U were expressed as a function of the wet body weight (W) of PL in a power function: EI, M or U=aWb, where a and b were estimated by least squares regression after a logarithmic transformation of the raw data. After 21 days, the growth rate of PL fed EA was higher than those fed NEA. The daily ingested energy of 5 mg wet wt of M. japonicus PL was partitioned as follows: 13.9% to fecal loss, 50.9% to metabolism, 4.8% to urinary loss, 24.6% to growth and 5.8% to exuvia for the EA group; 40.2% to fecal loss, 28.9% to metabolism, 4.0% to urinary loss, 21.8% to growth and 5.2% to exuvia for NEA group. Assimilation and gross conversion efficiencies were higher, but net conversion efficiency lower, in the EA group compared with the NEA group. The higher essential fatty acid intakes in the EA improved the growth of PL due to better assimilation.
