. Japan . Individual fatty acids were identified by comparing the retention times with
Ž .
commercially available standards Sigma-Aldrich, USA . 2.5. Statistical analysis
Ž Total length, percent survival and deformities log- or arcsine-transformed where
. appropriate , individual fatty acid levels, total n y 3, total n y 6, DHArEPA and total
n y 3rn y 6 ratios between the two treatments were subjected to Student’s t-test Ž
. Ž
. Ž
analysis P s 0.05 using the Statistical Analysis System SAS software program SAS .
Institute, 1988 for PCs.
3. Results
Table 1 presents the fatty acid profile of rotifers cultured in Chlorella sp. and those enriched with DHA-Protein Selco. The individual fatty acids, including the EFAs
Ž .
Ž .
Ž .
Ž .
linoleic acid 18:2 n y 6 , linolenic acid 18:3n y 3 , ARA 20:4 n y 6 , EPA 20:5n y 3 Ž
. and DHA 22:6 n y 3 , as well as the total n y 6 and n y 3 were significantly higher
Ž .
P - 0.05 in the DHA-enriched rotifers compared with the unenriched rotifers. The
Ž .
Fig. 2. Percent survival meanS.E.M. of 25-day-old milkfish fed Chlorella-cultured rotifers and newly Ž
. Ž
hatched Artemia nauplii Trt 1, control
and DHA-enriched rotifers and Artemia metanauplii Trt 2,
. DHA-treated .
Ž .
DHArEPA ratio in DHA-enriched rotifers 1.50 was likewise significantly higher Ž
. Ž
. P - 0.05 than those cultured in Chlorella sp. 0.07 . Total n y 3rn y 6 ratio, how-
ever, was not statistically significant between the control and DHA-enriched rotifers. The fatty acid composition of the newly hatched and DHA-enriched Artemia are
shown in Table 2. EPA was present in low amounts while no DHA was detected in the Ž
newly hatched Artemia nauplii confirming earlier reports Leger et al., 1987; Tuncer .
and Harrell, 1992 . This may perhaps explain why Artemia is an inferior live food for marine fish larvae unless enriched with HUFA-rich marine fish oils. The DHA-enriched
Ž .
Ž .
Artemia contained relatively substantial amounts of DHA 0.61 and EPA 0.48 with a ratio of 1.28 compared with the control. The rest of the EFAs, as well as 16:0,
Ž .
18:4 n y 6 and 22:4 n y 6, were significantly elevated P - 0.05 in the DHA-enriched Artemia compared with the newly hatched Artemia nauplii. In terms of total n y 3rn y 6
Ž .
Ž .
ratio, value for the DHA-enriched Artemia 2.31 was significantly higher P - 0.05 Ž
. than the newly hatched Artemia 1.54 .
The whole-body tissue fatty acid pattern of 25-day old milkfish larvae fed DHA-en- Ž
. riched rotifers and Artemia and fish fed unenriched live food control is presented in
Table 3. Generally, the DHA-treated fish have increased n y 3 and n y 6 PUFA levels Ž
compared with the untreated fish reflecting the fatty acid compositions of their diet see .
Ž .
Ž .
Tables 1 and 2 . As expected, the DHA 0.60 and EPA 0.39 levels in the body Ž
. tissue of the fish fed DHA-enriched live food were significantly higher P - 0.05 than
Ž .
Ž .
Fig. 3. Percent incidence meanS.E.M. of opercular deformity mainly cleft branchiostegal membrane Ž
. among 85-day-old milkfish fed Chlorella-cultured rotifers and newly hatched Artemia nauplii Trt 1, control
Ž .
and DHA-enriched rotifers and Artemia metanauplii Trt 2, DHA-treated .
Ž .
Fig. 4. Mean total length S.E.M. of 85-day-old milkfish fed Chlorella-cultured rotifers and newly hatched Ž
. Ž
. Artemia nauplii Trt 1, control and DHA-enriched rotifers and Artemia metanauplii Trt 2, DHA-treated .
Ž .
Fig. 5. Percent survival meanS.E.M. of 85-day-old milkfish fed Chlorella-cultured rotifers and newly Ž
. Ž
hatched Artemia nauplii Trt 1, control
and DHA-enriched rotifers and Artemia metanauplii Trt 2,
. DHA-treated for trial 2 only.
Ž .
those of the untreated fish 0.16 and 0.30 for DHA and EPA, respectively . ARA seemed to be conserved at certain levels, i.e., 0.13 in the control, 0.16 in the
DHA-treated fish and 0.12 in the wild fry. The DHArEPA ratio was significantly Ž
. Ž
. Ž
. higher
P - 0.05 for the DHA-treated fish 1.54 than the control 0.53 . EPA and DHA levels in the tissue of wild milkfish postlarvae or fry were 0.42 and 0.96,
respectively while newly hatched milkfish eggs had 0.29 EPA, 1.99 DHA and Ž
. 0.36 ARA Table 3 .
Ž .
Growth, in terms of total length, was not significantly different P 0.05 between Ž
. the DHA-treated and the control fish during the 25-day culture period Fig. 1 . Survival
Ž .
of 25-day old milkfish larvae, however, was significantly higher P - 0.05 among the Ž
. fish fed DHA-enriched live food 25.9–31.2 compared with those given unenriched
Ž .
Ž .
diet 19.3–23.7, Fig. 2 in contrast to the previous findings Gapasin et al., 1998 . After 60-day extensive culture in earthen nursery ponds, incidence of deformity was
Ž .
significantly lower P - 0.05
in milkfish fingerlings fed DHA-enriched live food Ž
. Ž
. 6.8–17.8 than those given unenriched diet 19.4–32.4, Fig. 3 . Total length was
Ž .
observed to be significantly better P - 0.05 in 85-day old milkfish juveniles fed
Ž .
DHA-enriched rotifers and Artemia during the hatchery phase compared with the Ž
. control Fig. 4 . Although mean percent survival was slightly higher in the DHA-treated
Ž .
Ž .
fish range: 93.2–100 than the untreated fish range: 87.3–99.4 , values were not Ž
. statistically different Fig. 5 .
4. Discussion
