Now showing items 1-20 of 20

    • Book chapter

      Amino and fatty acid profiles of wild-sourced grouper (Epinephelus coioides) broodstock and larvae 

      VR Alava, FMP Priolo, JD Toledo, JC Rodriguez Jr., GF Quinitio, AC Sa-an, MR de la Peña & RD Caturao - In MA Rimmer, S McBride & KC Williams (Eds.), Advances in grouper aquaculture, 2004 - Australian Centre for International Agricultural Research
      Series: ACIAR Monograph 110
      This study was undertaken to provide information on the levels of amino acids in the muscle, liver and gonad of wild-sourced broodstock and larvae, as well as in neurula eggs and day 35 larvae from a hatchery. The fatty acid composition of grouper broodstock tissues was also determined. Samples were analysed for crude protein, amino acids, total lipids and fatty acid contents. Muscle contained higher levels of crude protein and amino acids than the ovary and liver. At the early maturing stage, the grouper ovarian protein was 73.3% and lipid was 19.3%, indicating the high dietary requirements of these nutrients for ovarian development. The crude protein and amino acid contents in wild-sourced larvae were higher than that in eggs and larvae from the hatchery.
    • Article

      Artificial diets for milkfish, Chanos chanos (Forsskal), fry reared in seawater 

      VR Alava & C Lim - Aquaculture, 1988 - Elsevier
      Milkfish fry obtained from the wild (0.009 g body weight, 10 mm total length) were stocked at 200 individuals in each of 18 fiberglass tanks containing 30 l of filtered aerated seawater. Mean salinity and temperature were 33 ppt and 28.3°C, respectively. The fry were fed with six artificial dry diets containing a mean crude protein of 40.8%. The diets were fed at the rate of 20% of the biomass/day for the first 14 days and 15% of the biomass/day for the last 14 days.

      Results indicated that there were no significant differences among the treatment means (P>0.05). Milkfish fry had mean body weights of 0.173–0.202 g, mean total lengths of 29–31 mm, mean feed efficiency values of 0.94–1.16, and mean survival rates of 92–98%. The remarkably similar response of milkfish fry to the six diets demonstrated that the diets contain the essential nutrients necessary for a fast-growing fish. Soybean meal can replace corn gluten meal and meat and bone meal can substitute shrimp head meal for up to 8% of the crude protein.
    • Conference paper

      Breeding and culture of the polychaete, Marphysa mossambica, as feed for the mud crab 

      VR Alava, JB Biñas & MAE Mandario - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Marine worms (Annelida: Polychaeta) are considered as important food for crustacean broodstock because they contain hormones and correct balance of essential nutrients for reproduction. Marphysa mossambica (Peters, 1854) occurs in muddy coastal areas and is abundant in fish farms where it builds burrows in nutrient-rich sediments. This species encapsulates their eggs and larvae in gelatinous masses (jelly cocoons). It is a multiple spawner, and breeders are repeatedly spawning in tanks. Culture techniques have also been developed and established in tanks. Based on dry weight, cultured M. mossambica contained 62-66% crude protein and 7-12% lipids with levels of highly unsaturated fatty acids (HUFAs) such as arachidonic (20:4n-6), eicosapentaenoic (20:5n-3) and docosahexaenoic acid (22:6n-3) at 0.2-0.5%, 0.2-0.3% and 0.3-0.5%, respectively. Stocks were monitored for the presence of white spot syndrome virus (WSSV) using polymerase chain reaction-based diagnostic methods. The WSSV-free polychaetes mass-produced in tanks were utilized as live food for mud crab S. serrata broodstock. Mud crab broodstock fed natural food (mussel, fish, and squid) with live Marphysa on daily feed rotation produced higher number of crab zoeae, larval survival, total lipids and HUFAs than those fed natural food without live Marphysa. Production of nutrient-rich WSSV-free polychaetes in captivity can play a significant role in supporting crustacean hatcheries that supply seeds to the nursery and grow-out.
    • Article

      Carbohydrate requirements of Penaeus monodon (Fabricius) juveniles 

      VR Alava & FP Pascual - Aquaculture, 1987 - Elsevier
      P. monodon juveniles with an initial mean weight of 0.62 g were fed isonitrogenous (45%) and isolipidic (10%) semi-purified diets containing 10, 20 and 30% trehalose, sucrose and glucose for 56 days. Shrimp fed the diet with 20% trehalose had the highest weight gain. Of the three types of sugar tested, shrimp fed diets containing trehalose and sucrose exhibited better weight gains than those fed glucose diets. A dietary sugar level of 20% resulted in the best weight gain whereas the 30% level gave the lowest weight gain.

      The survival of shrimp was also affected by the type of carbohydrate fed. Trehalose and sucrose diets promoted higher survival rates than glucose diets. The different types and levels of carbohydrates showed combined effects on the dry matter percentages of crude protein and total lipid. Trehalose and sucrose diets generally promoted increased protein deposition. Trehalose at 30% and sucrose at 20% depressed lipid content.
    • Conference paper

      Combinations of dietary fat sources in dry diets for Chanos chanos fingerlings 

      VR Alava - In JL Maclean, LB Dizon & LV Hosillos (Eds.), The First Asian Fisheries Forum. Proceedings of the First Asian Fisheries Forum, 26-31 May 1986, Manila, Philippines, 1986 - Asian Fisheries Society
      A study was conducted to determine the effects of 1:1 ratio of several dietary fat sources added in semipurified diets at 10% level on milkfish fingerlings. Results showed that the cod liver oil + coconut oil diet promoted significantly the highest growth rate. However, beef tallow + coconut oil and pork lard + coconut oil also gave good growth, feed conversion and survival. The hepatosomatic index of milkfish did not differ significantly among treatments. Proximate analysis of whole milkfish body showed that as body fat increased, body protein, ash and moisture levels decreased. Weight gains were positively correlated with body fat. Also, the various groups of fatty acids in diets and in milkfish have positive correlations. Diets containing high levels of saturated fatty acids resulted in low levels of milkfish polyunsaturated fatty acids.
    • Conference paper

      Development of hatchery techniques for the mud crab Scylla serrata (Forskål): Comparison of feeding schemes 

      ET Quinitio, F Parado-Estepa & V Alava - In CP Keenan & A Blackshaw (Eds.), Mud Crab Aquaculture and Biology. Proceedings of an international scientific forum held in Darwin, Australia, 21–24 April 1997, 1999 - Australian Centre for International Agricultural Research
      Scylla serrata larvae were reared in 3 L plastic containers and fed various amounts of artificial diets (AD) with or without natural food (NF: Brachionus rotundiformis and newly-hatched Artemia). The amounts of AD fed alone to zoea in treatments (T) 1 to 4 were as follows: 1) 2.0 mg/L/day + 0.25 mg/L/day increment/substage; 2) 2.0 mg/L/day + 0.5 mg/L/day increment/ substage; 3) 4.0 mg/L/day + 0.5 mg/L/day increment/substage; 4) 4.0 mg/L/day + 1.0 mg/L/day increment/ substage. NF were given in addition to the respective amounts of artificial diet in T5, T6, T7 and T8. T9 served as the control (NF only). Based on three experimental runs, only larvae in T5, T6, and T9 survived until the megalopa stage. Thus, only these three treatments were compared in succeeding experiments using a commercial shrimp diet in 250 L fibreglass tanks. Of the three runs conducted using a commercial diet, two runs showed significant differences (P<0.05) in survival. T5 gave higher survival (3.71% and 1.33%) than T9 (1.84% and 0.45%) and T6 (1.37% and 0.45%). Population development index did not differ among treatments in three runs.
    • Article

      Effect of dietary fatty acids on growth of milkfish Chanos chanos fry in brackish water 

      VR Alava & A Kanazawa - Aquaculture, 1996 - Elsevier
      Five purified microbound diets containing 1% of 18:2n − 6, 18:3n − 3, 20:4n − 6, or n − 3 highly unsaturated fatty acids (HUFA: 60% 20:5n − 3 + 40% 22:6n − 3) in addition to 8% 18:1n − 9, and a control diet containing 9% 18:1n − 9 were fed to milkfish fry or late postlarvae for 30 days (Trial 1) and 35 days (Trial 2). The salinity was 16–17‰ and temperature was 27 ± 1 °C during the culture periods. A completely randomized design with three replicates per treatment per trial was followed. In each trial, 60 fish (5mg, 6mm) were stocked per 301 oval plastic tank and fed the experimental diets at 20% of biomass per day.

      Survival of 100% observed for all groups in both trials demonstrated that the milkfish fry reared in brackish water utilized the test diets. Specific growth rates did not differ significantly among treatments (P 0.05), with values of 9.5–9.9% and 10.0–10.3% in Trials 1 and 2, respectively. Weight, length and feed conversion ratio of milkfish fry fed the various diets also did not differ significantly (P 0.05). Although not significantly differentiated in Trial 1 (P 0.05), incidence of eye abnormality was highest in milkfish fry fed the 18:1n − 9 diet in Trial 2 (P 0.05).
    • Article

      Effect of salinity, dietary lipid source and level on growth of milkfish (Chanos chanos) fry 

      VR Alava - Aquaculture, 1998 - Elsevier
      Six semi-purified microparticulate diets containing coconut oil (CO), cod liver oil (CLO), and their 1:1 combination (CO+CLO) at 9% and 18% levels were fed to milkfish fry or late postlarvae in freshwater (0 ‰), brackishwater (16‰), and seawater (34‰) for 30 days. A three-factor factorial design (3×2×3) with three replicates per treatment was followed. Sixty-five milkfish fry (5 mg, 6 mm) were stocked per 15-l rectangular glass aquarium and fed with the experimental diets at 20% of biomass daily. Water temperature was 28±1°C during the culture period. Survival was not affected by water salinity, and lipid source or level. Among the 18 treatments, freshwater-reared milkfish fry fed with 9% CO+CLO had the highest specific growth rate, but this was not significantly different from those of freshwater-reared fish fed with 9–18% CO and 9% CLO diets or brackishwater-reared fish fed with 9% CO diet (P>0.05). As a main factor, salinity or dietary lipid level, but not lipid source, had significant effects on growth and feed conversion ratio of milkfish fry. Highest growth was observed in fish reared in freshwater and as salinity was increased, growth decreased (P<0.05). Overall, the 9% lipid diets promoted better growth than the 18% lipid diets (P<0.05). Except for the significant interaction between dietary lipid source and level indicating that milkfish fry fed with the 18% CLO was the shortest (P<0.05), no other significant effects of the two- or three-factor interactions were found.
    • Conference paper

      Evaluation of the bioremediation capacity of the polychaete, Marphysa mossambica (Peters, 1854) in pond sediments 

      MAE Mandario, VR Alava & NC Anasco - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Marphysa mossambica is commonly found in brackishwater ponds and is an important natural food for cultured stocks particularly mud crabs. To understand the burrowing activity of polychaete, survival and capacity to bioremediate pond sediments, tank experiments were conducted. In a completely randomized design with three replicates per treatment, small (1-month old, 28 mg) and large (3-month old, 139 mg) hatchery-bred M. mossambica were reared in two sediment types for 30 days without feeding. Aeration was supplied and water change was done every other day. Polychaete-free sediments served as control. Sediments obtained from SEAFDEC/AQD Dumangas Brackishwater Station were sun-dried, ground and passed through 1-mm sieve.

      Initial sediment A had 1.86% organic matter, 1,171 ppm available sulfur (SO42-), 194.23 ppm iron (Fe) and 7.86 pH while initial sediment B contained higher organic matter (4.1%), available sulfur (2,456.67 ppm), similar iron level (199.34 ppm) and was more acidic (4.91 pH). In sediment A, small and large polychaetes did not differ (p>0.05) with the control in reducing organic matter but both significantly reduced (p<0.05) available sulfur (77-73%) and iron (69-71%). However, only the large polychaetes increased the pH (p< 0.05, 2.67%). In sediment B, only the large polychaetes reduced (p<0.05) organic matter (27%) but both small and large polychaetes significantly reduced (p<0.05) available sulfur (64-70%) and iron (70-74%). The pH increase was similar to control (17-24%). Large polychaetes had higher survival (93%, p<0.05) than small polychaetes (60%) in sediment B but not different (p>0.05) in sediment A (97%, 87%). The study demonstrated the bioremediation capacity of M. mossambica particularly in reducing available sulfur and iron in sediments.
    • Conference paper

      Growth, survival, proximate and fatty acid composition of sandworm Perinereis quatrefagesi (Grube, 1878) fed variable feed types 

      JB Biñas, VR Alava & WL Campos - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Sandworm Perinereis quatrefagesi has been used as feed for crustacean broodstock due to its reproductive-enhancing properties particularly protein and highly unsaturated fatty acids (HUFAs). Juvenile sandworms collected along the coast of Guimbal, Iloilo were reared in tanks and fed three nutritionally variable feed types: fish fecal waste, fish meal and rice bran. After 56 days, feeds affected (p<0.05) sandworm growth and crude fat contents but not (p<0.05) survival and crude protein levels. Survival rates were 86~c3 to 89~c5% while crude protein levels were 57.0 ~c 2.5 to 68.0 ~c 5.3 g 100 g-1 dry weight. High crude protein fish meal promoted better (p<0.05) growth (2.2~c0.4% day-1) than fish feces (1.2~c0.3% day-1) and rice bran (1.1~c0.3 % day-1). However, crude fat content of sandworm was higher (p<0.05) in rice bran (18.9~c1.6 g 100 g-1) than in fecal waste (13.6~c2.9 g 100 g-1) and fish meal (10.5~c3.1 g 100 g-1) treatments. Levels of highly unsaturated fatty acids (HUFAs) such as 20:4 n-6, 22:6 n-3 and 20:5 n-3 did not differ significantly (p>0.05) at 0.41~c0.21 to 0.89~c0.51 g 100 g-1, 0.21~c0.24 to 0.43~c0.22 g 100 g-1 and 0.57~c0.46 to 0.88~c0.31 g 100 g-1, respectively.

      The study demonstrated that P. quatrefagesi: (1) can survive well in nutritionally variable feed types although it grows better in high protein diet; (2) crude protein levels were high regardless of feed types; and (3) crude fat content was high in high fat diet but n-3 and n-6 HUFAs were not significantly different regardless of feed types.
    • Book chapter

      Lipid nutrition studies on grouper (Epinephelus coioides) larvae 

      VR Alava, FMP Priolo, JD Toledo, JC Rodriguez Jr., GF Quinitio, AC Sa-an, MR de la Peña & RD Caturao - In MA Rimmer, S McBride & KC Williams (Eds.), Advances in grouper aquaculture, 2004 - Australian Centre for International Agricultural Research
      Series: ACIAR Monograph 110
      The main objectives of this project were to study the lipid chain transfer from the egg stage through hatching and the patterns of lipid conservation or loss during starvation and feeding of larvae in order to elucidate the lipid metabolism of grouper (Phase 1); to determine the fatty acid composition of highly unsaturated fatty acid (HUFA) boosters and enriched live food organisms to enable the possibility of choosing food organisms that provide various dietary levels and ratios of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and arachidonic acid (ARA, Phase 2); and to determine the effect of Brachionus and Artemia, containing different levels and ratios of DHA:EPA:ARA, on the growth and survival of grouper larvae (Phase 3). Total lipids (TL) of samples were extracted and separated into neutral (NL) and polar lipids (PL). The samples collected in Phase 1 were floating neurula eggs, newly hatched (NHL) and unfed 4-day larvae; larvae fed with live food organisms for 25 and 35 days or starved for 3 days; and wild-sourced larvae starved for a week. In Phase 2, the samples collected were phytoplanktons, Brachionus cultured in phytoplankton for 4 days, Diaphanosoma celebensis and Pseudodiaptomus annandalei. In phase 3, larvae were fed Brachionus until day 14 and at day 25 with Artemia. E. coioides eggs contained high DHA, EPA and ARA, demonstrating their importance in larval development. Larvae primarily spent NL as energy, whereas PL was generally conserved. Wild grouper larvae had higher levels of PL than NL, whereas hatchery-sourced eggs and larvae contained higher levels of NL than PL. Based on the lipid content of wild larvae, high phospholipid diets were essential for larvae survival and normal development. A variety of products were effective in enriching the HUFA content (particularly ratios of DHA, EPA and ARA) of live food organisms. HUFA-enriched live food organisms enhanced the growth, survival and pigmentation in grouper larvae.
    • Article

      Lipids and fatty acids in wild and pond-reared mud crab Scylla serrata (Forsskål) during ovarian maturation and spawning 

      VR Alava, ET Quinitio, JB De Pedro, FMP Priolo, ZGA Orozco & M Wille - Aquaculture Research, 2007 - Wiley-Blackwell
      Wild-caught and pond-reared female mud crab Scylla serrata at different stages of ovarian maturation were collected from Samar and Capiz, Philippines. Crabs were categorized into five stages according to the external morphological and microscopic appearance of the most advanced oocytes. The ovaries, hepatopancreas, muscle and newly spawned eggs (NSE) were analysed for lipid class components and fatty acids. Total lipid was higher in pond-reared than in wild-caught crabs but increased with ovarian maturation in both groups. Ovarian lipid peaked at the fully mature stage, coinciding with a decline in hepatopancreatic and muscle lipids. Lipid levels declined significantly in spent females. The tissues contained elevated highly unsaturated fatty acids such as arachidonic (20:4n-6), eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) acids, but at higher levels in late maturing and fully mature ovaries and in NSE. The type of lipid class and fatty acid components in mature ovaries as well as in NSE are generally considered to be indicative of their importance in reproductive physiology and embryonic and larval development.
    • Book chapter

      Management of feeding aquaculture species 

      VR Alava - In OM Millamena, RM Coloso & FP Pascual (Eds.), Nutrition in Tropical Aquaculture: Essentials of fish nutrition, feeds, and feeding of tropical aquatic species, 2002 - Aquaculture Department, Southeast Asian Fisheries Development Center
      This chapter teaches the reader to: differentiate the different feeding strategies in pond culture; learn feeding management methods such as stock sampling and record keeping, calculating daily feed ration, choosing appropriate feed size, and methods of applying feeds; understand the impact of feeding management on water quality and environment and on the cultured animal’s growth, survival, and feed conversion ratio; and describe the different feeding schemes used to culture fishes (milkfish, tilapia, rabbitfish, bighead carp, native catfish, sea bass, orange-spotted grouper, and mangrove red snapper; and crustaceans (tiger shrimp and mud crab). Other species for aquaculture stock enhancement (donkey’s ear abalone, seahorses, window-pane oyster) are also discussed.
    • Article

      Mud crab pen culture: replacement of fish feed requirement and impacts on mangrove community structure. 

      JH Primavera, JB Binas, GPB Samonte-Tan, MJJ Lebata, VR Alava, M Walton & L LeVay - Aquaculture Research, 2010 - Blackwell Publishing
      Brackishwater pond culture has been a major factor in mangrove loss in Southeast Asia, hence, the need to develop environment-friendly technologies such as mud crab Scylla (Portunidae) culture in mangrove pens exists. This study evaluated the effects of mud crab netpen systems in central Philippines on mangrove macroflora, and the replacement of dietary fish with low-cost pellets. Wild or hatchery-sourced Scylla olivacea and Scylla serrata were stocked at 0.5–0.8 m-2 in 167–200 m2 nylon netpens (2.3 cm stretched mesh) in Avicennia-dominated mangrove habitats. The feeding treatments were: (A) Zarraga: (1) no feeding (natural productivity), (2) no feeding for 1 month+supplementary feeding, (3) fish biomass and (4) low-cost pellets, and (B) Batan: (1) fish biomass and (2) pellets+fish biomass. Feeds were given ad libitum twice daily. Growth and survival rates of S. olivacea in Zarraga pens were not significantly different among treatments, although crabs fed fish biomass had the highest survival, body weight and production. Similarly, growth and survival of S. serrata were not significantly different between the Batan treatments. Economic analysis of the latter gave a 38.5% return on investment (ROI) and 2.6 years payback period (PP) for pellets+fish biomass treatment compared with 27.5% ROI and 3.6 years PP for fish alone. Sensitivity analysis showed an improved economic performance of the pellets+fish biomass treatment by increasing the survival rate. Evaluation of mangrove community structure showed that crab culture reduced species diversity, numbers and biomass of seedlings and saplings, but not of mangrove trees. Therefore, mud crab pen culture is recommended for mangrove sites with mature trees, but not seedlings and saplings, and low-cost pellets can reduce dependence on fish biomass.
    • Article

      Nursery culture of grouper (Epinephelus fuscoguttatus Forsskal) and sea bass (Lates calcarifer Bloch) in brackish water ponds: Co-feeding of zooplankton and formulated diets containing L-tryptophan 

      RSJ Gapasin, VR Alava & CL Marte - Journal of Applied Aquaculture, 2012 - Taylor & Francis
      This study compared co-feeding zooplankton (ZP, mixed copepods and mysids) and formulated diets (FD) supplemented with L-tryptophan (TRP) on the survival and growth of grouper and sea bass fry nursed in brackish water ponds. Grouper (84 fry m−3) and sea bass (150 fry m−3) were reared for 30 days and 60 days, respectively, in net cages within two separate 743 m2 nursery ponds. Five treatments (with three replicates each) were compared (P < 0.05): FD-1 = ZP + basal FD (no added TRP, but containing 0.29% endogenous TRP); FD-2 = ZP + (FD 0.58% TRP); FD-3 = ZP + (FD 1.22% TRP); FD-4 = ZP + (FD 2.50% TRP); and FD-5 = minced fish (Sardinella sp.) + basal FD (no additional TRP). TRP supplementation in grouper diets produced no significant affect on growth but increased survival at rates of 0.58% and above. TRP supplementation at 2.5% (FD-4) produced significantly better sea bass growth than other diets but had no affect on survival. Zooplankton improved both survival and growth in both grouper and sea bass juveniles compared to the minced fish diet, and may be a practical and lower cost alternative to indoor nursing.
    • Conference paper

      Nursery culture of mud crab Scylla serrata fed diets supplemented with trytophan at two stocking densities 

      VR Alava, MA Lucero, JD Sumile & FD Parado-Estepa - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Cannibalism has been recognized as one of the major problems in crab culture. The use of dietary tryptophan (TRP) that has been reported to reduce cannibalism in crabs under laboratory conditions was verified in pond nursery culture at two stocking densities. The first phase used hatchery-produced early crab instar. After 3-4 weeks, survivors were sorted and the small size crabs were further reared in the second phase. Crabs were stocked in 12-m2 net cages installed in brackishwater pond and fed three times daily at 0830, 1300 and 1630 h. The feeding scheme used was a combination of mussel meat (M) and formulated diet (FD) at 30:70 ratio. The original FD contained 45% crude protein (used in Experiment 1, 2 and 3) that was lowered to 40% crude protein in the new basal diet used in the succeeding experiment. The two TRP-supplemented diets had 0.5% and 0.7% TRP levels. Results showed that the TRP-supplemented feeds did not give consistent results in terms of growth and feed conversion ratio, indicating that the original basal diet (0.4% TRP and 45% crude protein) or the new basal diet (0.4% TRP and 40% crude protein) were sufficient to be used together with mussel meat as feed for crab juveniles. Higher survival rates were obtained at 50 m-2 (phase 1) and 10 m-2 (phase 2) than at 30 m-2 and 5 m-2 stocking density, respectively. All trial runs produced positive returns on investment.
    • Conference paper

      Nursery culture of mud crab Scylla serrata using different feeding rates 

      VR Alava, JD Sumile & FD Parado-Estepa - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The effect of different feeding rates on the production and profitability of Phases 1 and 2 (3-week each) nursery culture of hatchery-produced crab Scylla serrata was determined. Minced mussel meat and formulated diet (at a ratio of 30:70) were fed to crabs. The crabs were stocked randomly in 12-m2 net cages installed in the nursery earthen pond at stocking densities of 50 m-2 for Phase 1 and 10 m-2 for Phase 2. Crabs were fed three times daily at 0830, 1300 and 1630h h. In Phase 1, feed conversion ratio (FCR) at a feeding rate of 100% of initial crab biomass day-1 for the entire three weeks was the lowest (p<0.05) while survival, body weight (BW), carapace width (CW) and carapace length (CL) were not different (p>0.05) among crabs given different feeding rates. For Phase 2, the feeding rate of 40-30-20% of crab biomass day-1 (week 1-2-3) resulted in lowest (p<0.05) FCR that was not significantly different from FCRs of crabs fed 50-40-30% and 60-50-40% of BW. Crab BW, CW and CL were not different (p>0.05) among feeding rate treatments. Profitability was better when feeding rate used was 100% of initial crab biomass day-1 for the entire Phase 1 or 100-50-40% of crab biomass day-1 (for week 1-2-3). A feeding rate of 50-40-30 % of crab biomass day-1 (week 1-2-3) was more profitable in Phase 2.
    • Conference paper

      Nursery culture of mud crab, Scylla serrata, using different ratios of natural food to formulated feed 

      VR Alava, JD Sumile & FD Parado-Estepa - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The effect of feeding different ratios of natural food to formulated feed on the production and profitability of Phases 1 and 2 of nursery culture (3 weeks per phase) of hatchery-produced crab Scylla serrata was investigated. The feeds consisted of: mussel meat (M) alone, formulated diet (FD) alone, and their combination at M:FD ratios of 5 : 95, 10 : 90, 15 : 85, 20 : 80, 25 : 75 and 30 : 70. The crabs were stocked randomly in 12-m2 net cages installed in the nursery pond at stocking density of 50 m-2 for Phase 1 and 10 m-2 for Phase 2. Crabs were fed three times daily at 0830, 1300 and 1630 h. Results showed that in both phases, the survival rate, body weight, carapace width, and feed conversion ratio of crabs fed M, FD, and combination at different ratios were not significantly different (p>0.05). Profitability was better in 15 M:85 FD or 20 M :80 FD (Phase 1) and 30 M:70 FD ratio (Phase 2). The use of complete formulated diet as feed for crabs reduced the reliance on wet natural food.
    • Article

      The quantitative dietary protein requirements of Penaeus monodon juveniles in a controlled environment 

      VR Alava & C Lim - Aquaculture, 1983 - Elsevier
      Penaeus monodon juveniles (average weight = 1.32 g) were kept in individual 2 l perforated plastic containers, 10 of which were placed in each of the twenty-four 50 l rectangular wooden-glass aquaria supplied with seawater filtered through a sand-gravel filter (32–34 ppt; 26.5–29.0°C; pH, 7.6–8.2) at 0.8–1.01 l/min. Eight diets were prepared containing 25–60% protein and fed at 10% of the body weight/day for the first 2 weeks and 8% for the succeeding 4 weeks.

      Shrimps fed the 40% protein diet produced the best growth, feed conversion ratio (FCR), protein efficiency ratio (PER) and survival rate. However, shrimps fed the 30, 35 and 45% protein diets produced comparable results. The protein content of the shrimps was directly related to the level of protein diet up to 50%; whereas fat content seemed to be inversely related up to 50% protein diet.
    • Article

      Reproductive performance, lipids and fatty acids of mud crab Scylla serrata (Forsskål) fed dietary lipid levels 

      VR Alava, ET Quinitio, JB de Pedro, ZGA Orosco & M Wille - Aquaculture Research, 2007 - Blackwell Publishing
      Natural food (NF, control), artificial diets (AD) containing total lipid levels of 10%, 12% and 14% (AD10, AD12 and AD14) and their combinations (AD10+NF, AD12+NF and AD14+NF) were fed for 112 days to pond-sourced eyestalk-ablated mud crab Scylla serrata (625±6.4 g) in tanks in order to determine their effects on reproduction and lipid profiles in broodstock tissues and zoeae. Crabs fed NF had the highest number of spawning followed by crabs fed AD10+NF and AD14+NF. Higher offspring production (number of zoeae) was obtained from crabs fed NF and AD+NF than from AD. As dietary total lipid levels increased, total lipid of broodstock ovaries, hepatopancreas, muscle and zoeae correspondingly increased in which AD+NF promoted higher levels than AD. Increased dietary total lipid levels enhanced lipid classes such as triacylglycerols and phosphatidyl choline levels in zoeae, all higher in crabs fed AD+NF than in AD. The major fatty acids in zoeae, particularly 16:0, 18:0, 18:1n-9 and 20:4n-6, 20:5n-3 and 22:6n-3, were higher in crabs fed AD+NF than in AD, the contents corresponding to broodstock dietary total lipid levels. A 10% total lipid in AD in combination with NF was sufficient to provide the essential lipids in crabs in the improvement of larval production and quality.