Energy budget of the
Japanese flounder Paralichthys olivaceus (Temminck & Schlegel)
larvae fed HUFA-enriched and non-enriched Artemia nauplii
O. Sumule, S. Koshio, S. Teshima, M. Ishikawa-2003
Aquaculture
Research, 34(10):
877
Abstract:
The energy budget of the Japanese flounder Paralichthys
olivaceus (Temminck & Schlegel) larvae fed enriched (EA) and
non-enriched (NEA) Artemia nauplii was determined by equating energy
intake (EI) with the summation of energy channelled to faeces (F),
metabolism (M), excretion (U) and growth (G). Larvae
(21 days post hatching, 2.2 mg mean wet wt) were reared in six 80-L
circular tanks with three replicates of 160 larvae per tank and fed EA and
NEA for 20 days. EI was calculated from the energy content of consumed
nauplii, M from the summation of energy for routine, feeding and
active metabolisms, U from ammonia excretion and G from energy
gained based on weight gain, while F was the difference between EI
and the total of other components. The heat increment of larvae was
calculated from the difference of O2 consumption at post-prandial
and routine conditions. Except for G and F, variables were
correlated to the dry body weight (W) of larvae in a power function: Y=aWb.
Coefficients a and b were estimated by regression after a
logarithmic transformation of the raw data. Overall, growth and survival
rates of the larvae fed EA were higher than those fed NEA. For a larval
flounder growing from 2 to 20 mg wet wt, the ingested energy was
partitioned as follows: 22.8% to faecal loss, 38.3% to metabolism, 1.5% to
urinary loss and 37.4% to growth for the EA group, whereas 35.4% to faecal
loss, 28.4% to metabolism, 1.3% to urinary loss and 34.9% to growth for the
NEA group. Gross conversion and assimilation efficiencies were higher, but
the net conversion efficiency was lower in EA-fed larvae than NEA-fed
larvae. This study suggests that the higher growth and survival rates of the
EA-fed group compared with the NEA-fed group were attributed to their higher
intake of essential fatty acids, higher metabolism and lower energy loss of
faeces.
(Laboratory of Aquatic Animal Nutrition, Faculty of
Fisheries, Kagoshima University, 4-50-20 Shimoarata, Kagoshima 890-0056,
Japan. E-mail of S. Koshio: koshio@fish.kagoshima-u.ac.jp)