Now showing items 1-3 of 3

    • 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.