Enrichment of live food with essential fatty acids and vitamin C: effects on milkfish (Chanos chanos) larval performance
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The effects of essential fatty acids (EFA) and vitamin C-enriched live food on growth, survival, resistance to salinity stress and incidence of deformity in milkfish larvae reared in tanks were investigated. Larvae were either fed rotifers cultured on Chlorella sp. and newly hatched Artemia nauplii (control), highly unsaturated fatty acid (HUFA)-enriched rotifers and Artemia nauplii or HUFA+vitamin C-enriched rotifers and Artemia nauplii. Milkfish growth in outdoor nursery ponds was also assessed to compare with growth in indoor tanks. Milkfish fed rotifers/Artemia enriched with HUFA (32–48 mg dry weight, DW) or HUFA+vitamin C (33–45 mg DW) exhibited significantly (P<0.05) higher growth than those given unenriched live food (24–27 mg DW) after 40 days of culture. Growth of milkfish in nursery ponds (albeit lower in stocking density) showed similar trends as those reared in tanks. When subjected to salinity stress (Day 25), mortality of the HUFA+vitamin C-treated fish and HUFA-treated fish were significantly lower (P<0.05) than the control fish. Survival of 26-day old milkfish, however, did not differ significantly (P>0.05) among the treatment groups. Forty-day-old milkfish fed HUFA+vitamin C-enriched live food had significantly lower (P<0.05) incidence of opercular deformity (mainly cleft branchiostegal membrane) (8.4–14.7%) compared with those given HUFA-enriched (15.8–23.5%) or unenriched (27.3–33.5%) live food. Results demonstrated the effect of HUFA enrichment in enhancing milkfish larval growth and resistance to salinity stress but not overall survival. Moreover, HUFA and ascorbate supplementation decreased but did not totally eliminate incidence of opercular deformity in milkfish larvae.
CitationGapasin, R. S. J., Bombeo, R., Lavens, P., Sorgeloos, P., & Nelis, H. (1998). Enrichment of live food with essential fatty acids and vitamin C: effects on milkfish (Chanos chanos) larval performance.
This study was financially supported by the Southeast Asian Fisheries Development Center-Aquaculture Department (SEAFDEC/AQD) and the Belgian Administration for Development Cooperation (BADC) under the Laboratory of Aquaculture and Artemia Reference Center, University of Ghent (LAARC/RUG) and SEAFDEC/AQD Collaborative Project. The able help of the Belgian junior expert mission is appreciated with special mention to D. Delbare, T. DeWolfe, B. Vanderberghe, G. Van Stappen, G. Merchie and R. Bijnens. The authors wish to thank G. Van de Wiele and P. Hoste for the fatty acid methyl esters (FAME) and vitamin C analyses, respectively. Thanks are also due to the SEAFDEC’s Centralized Analytical Laboratory (CAL) for the water quality analyses, D. Chavez for the rotifer culture, T. Hautea, Jr. for providing the nursery ponds and V. Balinas for the statistical analysis. The excellent technical assistance of F. Pudadera, Jr. is gratefully acknowledged.
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Lactate dehydrogenase isozyme patterns during the development of milkfish, (Chanos chanos (Forskal)) PD Requintina, LM Engle & LV Benitez -
Kalikasan, The Philippine Journal of Biology, 1981 - University of the Philippines at Los BañosPolyacrylamide disc gel electrophoresis was done to determine the lactate dehydrogenase (LDH) isozyme patterns for fry (5-3 mg), fingerling (6-12 g), pond-size (150-250 g) and adult (6-9 kg) milkfish. The patterns were tissue specific; the different tissues examined, viz., eye, liver, heart, and skeletal muscle had different expressions of LDH isozymes. The resolved patterns appeared to be products of LDH gene loci A, B, and C. Subunits A and B were present in all tissues. A4 and B4 were predominant in skeletal and heart muscle, respectively; the two associated non-randomly in vivo and formed only the heteropolymers A3B and AB3. A liver band, L4, was most conspicuous in the fingerling, pond-size, and adult; it was assumed to be coded by locus C. A negatively charged band, X4, was detected in fully developed ovary and in fry homogenized as whole individuals, but it could not be resolved in tissues of fingerling. Six-mo old stunts and 3-mo old fingerlings had similar LDH patterns for all tissues examined. The patterns for 11-mo old stunts and fingerlings also were similar but the one for the eye of the former was the same pattern resolved for the eye of adults. There was no change in the LDH isozyme patterns of milk fish stunted for 6 mo under different salinity levels (0-5, 15-20, 32-35 ppt).
Conference paperLV Benitez - In RD Fortes, LC Darvin & DL de Guzman (Eds.), Fish and crustacean feeds and nutrition : Proceedings of the seminar-workshop on fish and crustacean feeds and nutrition held on 25-26 February 1985 at UPV, Iloilo City, 1989 - Philippine Council for Aquatic and Marine Research and DevelopmentThis paper reviews recent work on milkfish nutrition. Substantial progress had been made towards understanding the digestive physiology of milkfish. Major enzaymes envolved in the digestions of carbohydrates, protein and lipids had been detected in the pyloric caece, intestines and pancreas of milkfish. The most active carbohydrates were involved in the hydrolysis of α - glocosidic bonds. Intestinal amylase activity consistently reached the peak at about noon when milkfish gut was full. This confirms that milkfish is s daytime feeder. No cellulase activity was detected in any region orf the digertive treat although the fish relies heavily algae and other plant source for food. Trypsin, chymotrypsin and general proteases were also detected in milkfish digestive tract. A powerful milkfish trypsin inhabitor was detected in the filementous algae, Chaetomorpha brachygona which is predominant species in lumot. Lipass in the pancreas and intestines had two pH optima, suggesting a physiologic versatility for lipid digestion in milkfish. There is a limit information on the nutrient requirement of milkfish. Most studies showed that milkfish fry has a dietary requirement of 40% protein, and 7-10 lipid. Studies on the protein-energy requirement of fingerlings suggested that 30-40% protein, 10% fat and 25% carbohydrates are required. Subsequent studies showed an optimum protein energy to total metabolizable energy ratio of 44.4%. Amino acid test diets for milkfish had been formulated to contain white fish meal, gelatin and approprate amino acid mix.
Economic analysis of an integrated milkfish broodstock and hatchery operation as a public enterprise The National Bangus (Milkfish) Breeding Program of the Philippines, which was launched by the Philippine government in 1981, had succeeded in spawning milkfish in captivity and in rearing the eggs to fry that were stockable in ponds. The physical productivity and economic viability of an integrated milkfish broodstock and hatchery as a public enterprise is analyzed, using SEAFDEC research findings as bases for analysis. Discounted cash flow computations show the repayment schedule for investments in structures and equipment, and operations and maintenance expenses for both broodstock and hatchery operations covering a period of 15 years. Revenues came from the sales of fry. The analysis was based on an annual stocking of 100 milkfish (200–250 g/piece) per cage with a diameter of 10 m. Egg production started during the fifth year. Investment in the hatchery facilities started during the fourth year and expansion occurred in the subsequent years to accommodate the eggs produced for rearing to the fry stage. Economic indicators, net present value (NPV) and internal rate of return (IRR), showed negative figures. The trend, however, was upward, starting during the sixth year of operation. Sensitivity analysis was done to determine the effects of changes in operational efficiencies, such as survival rates and stocking densities to the return on investment (ROI) in private hatcheries.