Now showing items 18-22 of 22

    • Conference paper

      A preliminary study on the effect of hypoxia on carotenoid metabolism in black tiger shrimp Penaeus monodon Fabricius 

      FI Heralde, M Leaño, A Reyes & R Coloso - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The pigmentation of black tiger shrimp Penaeus monodon is due to astaxanthin, astaxanthin monoester, and astaxanthin diester. These carotenoids are biosynthesized from beta-carotene or zeaxanthin. Biosynthesis is postulated to be mediated by the enzymes C3 and C4 monooxygenase and caroten-4-ol dehydrogenase. Blue-shrimp syndrome, characterized by low total astaxanthin levels in shrimp epidermis, is associated with nutritional deficiency for carotenoids but other factors such as high organic matter, hypoxia, high density, and high pH may also be involved. In this study, the effect of hypoxia on carotenoid metabolism in P. monodon was investigated with respect to retention and transformation of carotenoids and the activity of the enzymes C3 and C4 monooxygenase and caroten-4-ol dehydrogenase.Two tanks were prepared each containing 25 pieces of shrimp fed a control diet (not containing any carotenoid) for two weeks. Shrimps in one tank (Treatment 1) were given beta-carotene supplemented diet (3.8 ppm) in the next two weeks while those in the other (treatment 2) were fed the control diet. Two days after introduction of the test diets, both treatments were subjected to hypoxia challenge (dissolved oxygen, 2.5-2.7 mg/L) and the carotenoid content and profile of feces monitored for succeeding days. Assay of enzyme activity was performed five days after hypoxia challenge. Results showed a ten-fold increase in fecal total carotenoid content of shrimps in treatment 2 (122.2 ppm) compared with that in treatment 1 (12.4 ppm) on hypoxia challenge and restores to basal level (3.9-4.1 ppm) after three days. The carotenoids found in the feces of shrimps in treatment 2 were astaxanthin, astaxanthin monoester, astaxanthin diesters, and an unidentified carotenoid which was also found in the muscle of stressed shrimp. Using beta-carotene as substrate, conversion to astaxanthin was not observed in the hepatopancreas homogenates of shrimps in both treatments. Instead, a slow conversion of astaxanthin to betacarotene (i.e., a reverse reaction) was noted in treatment 2 exhibiting twice the activity in treatment 1. Radiolabelling studies using 14C-labelled astaxanthin as substrate confirmed the existence of this enzyme-mediated reductive pathway from astaxanthin which occurs at a very slow rate. This study demonstrated the carotenoid-depleting effect of hypoxia on shrimp, both through enhanced fecal release and moderately elevated reductive pathway from astaxanthin. This effect suggests a possible mechanism by which blue-shrimp syndrome may develop.
    • Conference paper

      Reproductive performance of captive Penaeus monodon fed various sources of carotenoids 

      ET Quinitio, FD Parado-Estepa, OM Millamena & H Biona - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Three groups of pond-reared Penaeus monodon broodstock were fed formulated diet in combination with carotenoid-containing natural food: mussel + shrimp broodstock pellet (MBP), crab + BP (CBP), and Artemia + BP (ABP). After four months, maturation and spawning rates did not differ significantly among treatments. After eyestalk ablation, MBP-fed shrimps Initially spawned 20 days; 34 days for CBP-fed; 50 days for ABP-fed shrimps. The number of eggs per g body weight of spawner (1616-2359 eggs /g BW) did not differ significantly among all groups. Only nauplii from MBP-fed broodstock reached postlarval stage. Rematuration was observed only in MBP- and CBP fed shrimps. Sperm count was highest in MBP- and lowest in ABP-fed shrimps at the final phase of the test.
    • Conference paper

      Screening of inexpensive and indigeneous ingredients for use in practical feed for juvile sea bass (Lates calcarifer Bloch) 

      RM Coloso, JR Hipolito & D Murillo - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      An eight-week feeding experiment with juvenile sea bass (about 15 g) was conducted in 500-1 fiberglass tanks to screen the most cost-effective practical diet for use in ponds and floating cages. Eleven formulations and one control feed were tested. Protein sources used were locally available ingredients such as fish meal, shrimp head meal, scrap squid meal, cow's blood meal, poultry feather meal, leaf meals, soybean meal, and mung bean meal. The diets contained a combination of animal and vegetable protein sources such that the essential amino acid composition was close to the requirement or tissue levels. Crude protein and fat levels were about 42% and 8.3%, respectively. Fish were fed ad libitum twice a day at 0800 and 1600 h. Best weight gain (189%) and feed conversion ratio (FCR, 1.7) were observed in fish given a combination of fish meal, shrimp head meal, scrap squid meal, soybean bean meal, and kangkong leaf meal as protein sources. This was followed by those given a combination of fish meal, shrimp head meal, scrap squid meal, soybean meal, and ipil-ipil leaf meal (139% weight gain, FCR of 2.2). Worst growth (22%) and FCR were observed in fish given a combination of fish meal, cow's blood meal, scrap squid meal, soybean meal, and mulberry leaf meal. Control fish given a combination of fish meal, shrimp meal, and soybean meal showed weight gain of 195% and FCR of 1.8. Survival was high (83-100%) in all treatments. The two diets which gave the best growth rates, survival, and FCR in the screening phase can be tried in ponds and floating net cages.
    • Conference paper

      Use of the golden apple snail, cassava, and maize as feeds for the tiger shrimp Penaeus monodon in ponds 

      I Bombeo-Tuburan, S Fukumoto & E Rodriguez - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Penaeus monodon stocked in ponds at 8,000/ha were fed four types of farm-made feeds starting on day 16 of a 4-month culture period. The feeds were golden apple snail alone or in combination with cooked cassava or maize, or maize alone. Mixed feeds resulted in significantly higher production and better size-frequency distribution of shrimp. Survival (88-99%) was not significantly different among the treatments. Maize alone and snails alone were inadequate. Presumably, the high amount of carbohydrate in cassava (92%) or maize (87%) provided the needed energy, and the high protein content of golden snail (54%) was available for growth. The fatty acid profile of the golden snail shows that it is a good source of 18:2n-6, 18:3n-3, and 20:5n-3 which are essential fatty acids for P. monodon. Golden snails, with an essential amino acid index (EAAI) of 0.91, are a suitable alternative source of protein for tiger shrimp. Feeding shrimps with golden snails and cassava yielded the highest net income (P 49,332/ha-crop) and return on investment (ROI = 213%) better than feeding with maize alone (net income = P 23,626/ha-crop; ROI = 125%). If shrimp farmers tap golden snails as direct feed or as feed ingredient, the problem of snail infestation in rice fields may be reduced.
    • Conference paper

      Weaning of the Asian catfish, Clarias macrocephalus Gunther, larvae to formulated dry diet 

      AC Fermin & MEC Bolivar - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Two feeding trials lasting 10 days each were conducted to determine the weaning time in the Asian catfish, Clarias macrocephalus, larvae to dry diet feeding. Three-day-old catfish larvae were fed newly-hatched Artemia nauplii for 2,4, and 6 days after which ad libitum feeding with a commercial feed (trial 1) or a formulated diet (trial 2) was started. Fish fed exclusively dry diet (0-day Artemia feeding) or those fed only Artemia for 10 days served as the controls. In trial 1, fish fed Artemia at different durations had significantly higher growth and survival than those reared exclusively on dry diet. In trial 2, percent survival was not significantly different among fish with or without Artemia pre-feeding. However, fish had significantly higher final body weight and SGR when reared initially on Artemia prior to dry diet than those fed exclusively dry diet. Based on the results, catfish larvae can be successfully weaned to dry diet after feeding Artemia for a maximum period of four days (ave. BW=12.25 mg).